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Editing: less.js

/**
 * Less - Leaner CSS v4.1.2
 * http://lesscss.org
 * 
 * Copyright (c) 2009-2021, Alexis Sellier <self@cloudhead.net>
 * Licensed under the Apache-2.0 License.
 *
 * @license Apache-2.0
 */

(function (global, factory) {
    typeof exports === 'object' && typeof module !== 'undefined' ? module.exports = factory() :
    typeof define === 'function' && define.amd ? define(factory) :
    (global = typeof globalThis !== 'undefined' ? globalThis : global || self, global.less = factory());
}(this, (function () { 'use strict';

// Export a new default each time
    function defaultOptions () {
        return {
            /* Inline Javascript - @plugin still allowed */
            javascriptEnabled: false,
            /* Outputs a makefile import dependency list to stdout. */
            depends: false,
            /* (DEPRECATED) Compress using less built-in compression.
             * This does an okay job but does not utilise all the tricks of
             * dedicated css compression. */
            compress: false,
            /* Runs the less parser and just reports errors without any output. */
            lint: false,
            /* Sets available include paths.
             * If the file in an @import rule does not exist at that exact location,
             * less will look for it at the location(s) passed to this option.
             * You might use this for instance to specify a path to a library which
             * you want to be referenced simply and relatively in the less files. */
            paths: [],
            /* color output in the terminal */
            color: true,
            /* The strictImports controls whether the compiler will allow an @import inside of either
             * @media blocks or (a later addition) other selector blocks.
             * See: https://github.com/less/less.js/issues/656 */
            strictImports: false,
            /* Allow Imports from Insecure HTTPS Hosts */
            insecure: false,
            /* Allows you to add a path to every generated import and url in your css.
             * This does not affect less import statements that are processed, just ones
             * that are left in the output css. */
            rootpath: '',
            /* By default URLs are kept as-is, so if you import a file in a sub-directory
             * that references an image, exactly the same URL will be output in the css.
             * This option allows you to re-write URL's in imported files so that the
             * URL is always relative to the base imported file */
            rewriteUrls: false,
            /* How to process math
             *   0 always           - eagerly try to solve all operations
             *   1 parens-division  - require parens for division "/"
             *   2 parens | strict  - require parens for all operations
             *   3 strict-legacy    - legacy strict behavior (super-strict)
             */
            math: 1,
            /* Without this option, less attempts to guess at the output unit when it does maths. */
            strictUnits: false,
            /* Effectively the declaration is put at the top of your base Less file,
             * meaning it can be used but it also can be overridden if this variable
             * is defined in the file. */
            globalVars: null,
            /* As opposed to the global variable option, this puts the declaration at the
             * end of your base file, meaning it will override anything defined in your Less file. */
            modifyVars: null,
            /* This option allows you to specify a argument to go on to every URL.  */
            urlArgs: ''
        };
    }

/**
     * @todo Document why this abstraction exists, and the relationship between
     *       environment, file managers, and plugin manager
     */
    var Environment = /** @class */ (function () {
        function Environment(externalEnvironment, fileManagers) {
            this.fileManagers = fileManagers || [];
            externalEnvironment = externalEnvironment || {};
            var optionalFunctions = ['encodeBase64', 'mimeLookup', 'charsetLookup', 'getSourceMapGenerator'];
            var requiredFunctions = [];
            var functions = requiredFunctions.concat(optionalFunctions);
            for (var i = 0; i < functions.length; i++) {
                var propName = functions[i];
                var environmentFunc = externalEnvironment[propName];
                if (environmentFunc) {
                    this[propName] = environmentFunc.bind(externalEnvironment);
                }
                else if (i < requiredFunctions.length) {
                    this.warn("missing required function in environment - " + propName);
                }
            }
        }
        Environment.prototype.getFileManager = function (filename, currentDirectory, options, environment, isSync) {
            if (!filename) {
                logger$1.warn('getFileManager called with no filename.. Please report this issue. continuing.');
            }
            if (currentDirectory == null) {
                logger$1.warn('getFileManager called with null directory.. Please report this issue. continuing.');
            }
            var fileManagers = this.fileManagers;
            if (options.pluginManager) {
                fileManagers = [].concat(fileManagers).concat(options.pluginManager.getFileManagers());
            }
            for (var i = fileManagers.length - 1; i >= 0; i--) {
                var fileManager = fileManagers[i];
                if (fileManager[isSync ? 'supportsSync' : 'supports'](filename, currentDirectory, options, environment)) {
                    return fileManager;
                }
            }
            return null;
        };
        Environment.prototype.addFileManager = function (fileManager) {
            this.fileManagers.push(fileManager);
        };
        Environment.prototype.clearFileManagers = function () {
            this.fileManagers = [];
        };
        return Environment;
    }());

var colors = {
        'aliceblue': '#f0f8ff',
        'antiquewhite': '#faebd7',
        'aqua': '#00ffff',
        'aquamarine': '#7fffd4',
        'azure': '#f0ffff',
        'beige': '#f5f5dc',
        'bisque': '#ffe4c4',
        'black': '#000000',
        'blanchedalmond': '#ffebcd',
        'blue': '#0000ff',
        'blueviolet': '#8a2be2',
        'brown': '#a52a2a',
        'burlywood': '#deb887',
        'cadetblue': '#5f9ea0',
        'chartreuse': '#7fff00',
        'chocolate': '#d2691e',
        'coral': '#ff7f50',
        'cornflowerblue': '#6495ed',
        'cornsilk': '#fff8dc',
        'crimson': '#dc143c',
        'cyan': '#00ffff',
        'darkblue': '#00008b',
        'darkcyan': '#008b8b',
        'darkgoldenrod': '#b8860b',
        'darkgray': '#a9a9a9',
        'darkgrey': '#a9a9a9',
        'darkgreen': '#006400',
        'darkkhaki': '#bdb76b',
        'darkmagenta': '#8b008b',
        'darkolivegreen': '#556b2f',
        'darkorange': '#ff8c00',
        'darkorchid': '#9932cc',
        'darkred': '#8b0000',
        'darksalmon': '#e9967a',
        'darkseagreen': '#8fbc8f',
        'darkslateblue': '#483d8b',
        'darkslategray': '#2f4f4f',
        'darkslategrey': '#2f4f4f',
        'darkturquoise': '#00ced1',
        'darkviolet': '#9400d3',
        'deeppink': '#ff1493',
        'deepskyblue': '#00bfff',
        'dimgray': '#696969',
        'dimgrey': '#696969',
        'dodgerblue': '#1e90ff',
        'firebrick': '#b22222',
        'floralwhite': '#fffaf0',
        'forestgreen': '#228b22',
        'fuchsia': '#ff00ff',
        'gainsboro': '#dcdcdc',
        'ghostwhite': '#f8f8ff',
        'gold': '#ffd700',
        'goldenrod': '#daa520',
        'gray': '#808080',
        'grey': '#808080',
        'green': '#008000',
        'greenyellow': '#adff2f',
        'honeydew': '#f0fff0',
        'hotpink': '#ff69b4',
        'indianred': '#cd5c5c',
        'indigo': '#4b0082',
        'ivory': '#fffff0',
        'khaki': '#f0e68c',
        'lavender': '#e6e6fa',
        'lavenderblush': '#fff0f5',
        'lawngreen': '#7cfc00',
        'lemonchiffon': '#fffacd',
        'lightblue': '#add8e6',
        'lightcoral': '#f08080',
        'lightcyan': '#e0ffff',
        'lightgoldenrodyellow': '#fafad2',
        'lightgray': '#d3d3d3',
        'lightgrey': '#d3d3d3',
        'lightgreen': '#90ee90',
        'lightpink': '#ffb6c1',
        'lightsalmon': '#ffa07a',
        'lightseagreen': '#20b2aa',
        'lightskyblue': '#87cefa',
        'lightslategray': '#778899',
        'lightslategrey': '#778899',
        'lightsteelblue': '#b0c4de',
        'lightyellow': '#ffffe0',
        'lime': '#00ff00',
        'limegreen': '#32cd32',
        'linen': '#faf0e6',
        'magenta': '#ff00ff',
        'maroon': '#800000',
        'mediumaquamarine': '#66cdaa',
        'mediumblue': '#0000cd',
        'mediumorchid': '#ba55d3',
        'mediumpurple': '#9370d8',
        'mediumseagreen': '#3cb371',
        'mediumslateblue': '#7b68ee',
        'mediumspringgreen': '#00fa9a',
        'mediumturquoise': '#48d1cc',
        'mediumvioletred': '#c71585',
        'midnightblue': '#191970',
        'mintcream': '#f5fffa',
        'mistyrose': '#ffe4e1',
        'moccasin': '#ffe4b5',
        'navajowhite': '#ffdead',
        'navy': '#000080',
        'oldlace': '#fdf5e6',
        'olive': '#808000',
        'olivedrab': '#6b8e23',
        'orange': '#ffa500',
        'orangered': '#ff4500',
        'orchid': '#da70d6',
        'palegoldenrod': '#eee8aa',
        'palegreen': '#98fb98',
        'paleturquoise': '#afeeee',
        'palevioletred': '#d87093',
        'papayawhip': '#ffefd5',
        'peachpuff': '#ffdab9',
        'peru': '#cd853f',
        'pink': '#ffc0cb',
        'plum': '#dda0dd',
        'powderblue': '#b0e0e6',
        'purple': '#800080',
        'rebeccapurple': '#663399',
        'red': '#ff0000',
        'rosybrown': '#bc8f8f',
        'royalblue': '#4169e1',
        'saddlebrown': '#8b4513',
        'salmon': '#fa8072',
        'sandybrown': '#f4a460',
        'seagreen': '#2e8b57',
        'seashell': '#fff5ee',
        'sienna': '#a0522d',
        'silver': '#c0c0c0',
        'skyblue': '#87ceeb',
        'slateblue': '#6a5acd',
        'slategray': '#708090',
        'slategrey': '#708090',
        'snow': '#fffafa',
        'springgreen': '#00ff7f',
        'steelblue': '#4682b4',
        'tan': '#d2b48c',
        'teal': '#008080',
        'thistle': '#d8bfd8',
        'tomato': '#ff6347',
        'turquoise': '#40e0d0',
        'violet': '#ee82ee',
        'wheat': '#f5deb3',
        'white': '#ffffff',
        'whitesmoke': '#f5f5f5',
        'yellow': '#ffff00',
        'yellowgreen': '#9acd32'
    };

var unitConversions = {
        length: {
            'm': 1,
            'cm': 0.01,
            'mm': 0.001,
            'in': 0.0254,
            'px': 0.0254 / 96,
            'pt': 0.0254 / 72,
            'pc': 0.0254 / 72 * 12
        },
        duration: {
            's': 1,
            'ms': 0.001
        },
        angle: {
            'rad': 1 / (2 * Math.PI),
            'deg': 1 / 360,
            'grad': 1 / 400,
            'turn': 1
        }
    };

var data = { colors: colors, unitConversions: unitConversions };

/**
     * The reason why Node is a class and other nodes simply do not extend
     * from Node (since we're transpiling) is due to this issue:
     *
     * https://github.com/less/less.js/issues/3434
     */
    var Node = /** @class */ (function () {
        function Node() {
            this.parent = null;
            this.visibilityBlocks = undefined;
            this.nodeVisible = undefined;
            this.rootNode = null;
            this.parsed = null;
        }
        Object.defineProperty(Node.prototype, "currentFileInfo", {
            get: function () {
                return this.fileInfo();
            },
            enumerable: false,
            configurable: true
        });
        Object.defineProperty(Node.prototype, "index", {
            get: function () {
                return this.getIndex();
            },
            enumerable: false,
            configurable: true
        });
        Node.prototype.setParent = function (nodes, parent) {
            function set(node) {
                if (node && node instanceof Node) {
                    node.parent = parent;
                }
            }
            if (Array.isArray(nodes)) {
                nodes.forEach(set);
            }
            else {
                set(nodes);
            }
        };
        Node.prototype.getIndex = function () {
            return this._index || (this.parent && this.parent.getIndex()) || 0;
        };
        Node.prototype.fileInfo = function () {
            return this._fileInfo || (this.parent && this.parent.fileInfo()) || {};
        };
        Node.prototype.isRulesetLike = function () { return false; };
        Node.prototype.toCSS = function (context) {
            var strs = [];
            this.genCSS(context, {
                add: function (chunk, fileInfo, index) {
                    strs.push(chunk);
                },
                isEmpty: function () {
                    return strs.length === 0;
                }
            });
            return strs.join('');
        };
        Node.prototype.genCSS = function (context, output) {
            output.add(this.value);
        };
        Node.prototype.accept = function (visitor) {
            this.value = visitor.visit(this.value);
        };
        Node.prototype.eval = function () { return this; };
        Node.prototype._operate = function (context, op, a, b) {
            switch (op) {
                case '+': return a + b;
                case '-': return a - b;
                case '*': return a * b;
                case '/': return a / b;
            }
        };
        Node.prototype.fround = function (context, value) {
            var precision = context && context.numPrecision;
            // add "epsilon" to ensure numbers like 1.000000005 (represented as 1.000000004999...) are properly rounded:
            return (precision) ? Number((value + 2e-16).toFixed(precision)) : value;
        };
        Node.compare = function (a, b) {
            /* returns:
             -1: a < b
             0: a = b
             1: a > b
             and *any* other value for a != b (e.g. undefined, NaN, -2 etc.) */
            if ((a.compare) &&
                // for "symmetric results" force toCSS-based comparison
                // of Quoted or Anonymous if either value is one of those
                !(b.type === 'Quoted' || b.type === 'Anonymous')) {
                return a.compare(b);
            }
            else if (b.compare) {
                return -b.compare(a);
            }
            else if (a.type !== b.type) {
                return undefined;
            }
            a = a.value;
            b = b.value;
            if (!Array.isArray(a)) {
                return a === b ? 0 : undefined;
            }
            if (a.length !== b.length) {
                return undefined;
            }
            for (var i = 0; i < a.length; i++) {
                if (Node.compare(a[i], b[i]) !== 0) {
                    return undefined;
                }
            }
            return 0;
        };
        Node.numericCompare = function (a, b) {
            return a < b ? -1
                : a === b ? 0
                    : a > b ? 1 : undefined;
        };
        // Returns true if this node represents root of ast imported by reference
        Node.prototype.blocksVisibility = function () {
            if (this.visibilityBlocks == null) {
                this.visibilityBlocks = 0;
            }
            return this.visibilityBlocks !== 0;
        };
        Node.prototype.addVisibilityBlock = function () {
            if (this.visibilityBlocks == null) {
                this.visibilityBlocks = 0;
            }
            this.visibilityBlocks = this.visibilityBlocks + 1;
        };
        Node.prototype.removeVisibilityBlock = function () {
            if (this.visibilityBlocks == null) {
                this.visibilityBlocks = 0;
            }
            this.visibilityBlocks = this.visibilityBlocks - 1;
        };
        // Turns on node visibility - if called node will be shown in output regardless
        // of whether it comes from import by reference or not
        Node.prototype.ensureVisibility = function () {
            this.nodeVisible = true;
        };
        // Turns off node visibility - if called node will NOT be shown in output regardless
        // of whether it comes from import by reference or not
        Node.prototype.ensureInvisibility = function () {
            this.nodeVisible = false;
        };
        // return values:
        // false - the node must not be visible
        // true - the node must be visible
        // undefined or null - the node has the same visibility as its parent
        Node.prototype.isVisible = function () {
            return this.nodeVisible;
        };
        Node.prototype.visibilityInfo = function () {
            return {
                visibilityBlocks: this.visibilityBlocks,
                nodeVisible: this.nodeVisible
            };
        };
        Node.prototype.copyVisibilityInfo = function (info) {
            if (!info) {
                return;
            }
            this.visibilityBlocks = info.visibilityBlocks;
            this.nodeVisible = info.nodeVisible;
        };
        return Node;
    }());

//
    // RGB Colors - #ff0014, #eee
    //
    var Color = function (rgb, a, originalForm) {
        var self = this;
        //
        // The end goal here, is to parse the arguments
        // into an integer triplet, such as `128, 255, 0`
        //
        // This facilitates operations and conversions.
        //
        if (Array.isArray(rgb)) {
            this.rgb = rgb;
        }
        else if (rgb.length >= 6) {
            this.rgb = [];
            rgb.match(/.{2}/g).map(function (c, i) {
                if (i < 3) {
                    self.rgb.push(parseInt(c, 16));
                }
                else {
                    self.alpha = (parseInt(c, 16)) / 255;
                }
            });
        }
        else {
            this.rgb = [];
            rgb.split('').map(function (c, i) {
                if (i < 3) {
                    self.rgb.push(parseInt(c + c, 16));
                }
                else {
                    self.alpha = (parseInt(c + c, 16)) / 255;
                }
            });
        }
        this.alpha = this.alpha || (typeof a === 'number' ? a : 1);
        if (typeof originalForm !== 'undefined') {
            this.value = originalForm;
        }
    };
    Color.prototype = Object.assign(new Node(), {
        type: 'Color',
        luma: function () {
            var r = this.rgb[0] / 255, g = this.rgb[1] / 255, b = this.rgb[2] / 255;
            r = (r <= 0.03928) ? r / 12.92 : Math.pow(((r + 0.055) / 1.055), 2.4);
            g = (g <= 0.03928) ? g / 12.92 : Math.pow(((g + 0.055) / 1.055), 2.4);
            b = (b <= 0.03928) ? b / 12.92 : Math.pow(((b + 0.055) / 1.055), 2.4);
            return 0.2126 * r + 0.7152 * g + 0.0722 * b;
        },
        genCSS: function (context, output) {
            output.add(this.toCSS(context));
        },
        toCSS: function (context, doNotCompress) {
            var compress = context && context.compress && !doNotCompress;
            var color;
            var alpha;
            var colorFunction;
            var args = [];
            // `value` is set if this color was originally
            // converted from a named color string so we need
            // to respect this and try to output named color too.
            alpha = this.fround(context, this.alpha);
            if (this.value) {
                if (this.value.indexOf('rgb') === 0) {
                    if (alpha < 1) {
                        colorFunction = 'rgba';
                    }
                }
                else if (this.value.indexOf('hsl') === 0) {
                    if (alpha < 1) {
                        colorFunction = 'hsla';
                    }
                    else {
                        colorFunction = 'hsl';
                    }
                }
                else {
                    return this.value;
                }
            }
            else {
                if (alpha < 1) {
                    colorFunction = 'rgba';
                }
            }
            switch (colorFunction) {
                case 'rgba':
                    args = this.rgb.map(function (c) {
                        return clamp$1(Math.round(c), 255);
                    }).concat(clamp$1(alpha, 1));
                    break;
                case 'hsla':
                    args.push(clamp$1(alpha, 1));
                case 'hsl':
                    color = this.toHSL();
                    args = [
                        this.fround(context, color.h),
                        this.fround(context, color.s * 100) + "%",
                        this.fround(context, color.l * 100) + "%"
                    ].concat(args);
            }
            if (colorFunction) {
                // Values are capped between `0` and `255`, rounded and zero-padded.
                return colorFunction + "(" + args.join("," + (compress ? '' : ' ')) + ")";
            }
            color = this.toRGB();
            if (compress) {
                var splitcolor = color.split('');
                // Convert color to short format
                if (splitcolor[1] === splitcolor[2] && splitcolor[3] === splitcolor[4] && splitcolor[5] === splitcolor[6]) {
                    color = "#" + splitcolor[1] + splitcolor[3] + splitcolor[5];
                }
            }
            return color;
        },
        //
        // Operations have to be done per-channel, if not,
        // channels will spill onto each other. Once we have
        // our result, in the form of an integer triplet,
        // we create a new Color node to hold the result.
        //
        operate: function (context, op, other) {
            var rgb = new Array(3);
            var alpha = this.alpha * (1 - other.alpha) + other.alpha;
            for (var c = 0; c < 3; c++) {
                rgb[c] = this._operate(context, op, this.rgb[c], other.rgb[c]);
            }
            return new Color(rgb, alpha);
        },
        toRGB: function () {
            return toHex(this.rgb);
        },
        toHSL: function () {
            var r = this.rgb[0] / 255, g = this.rgb[1] / 255, b = this.rgb[2] / 255, a = this.alpha;
            var max = Math.max(r, g, b), min = Math.min(r, g, b);
            var h;
            var s;
            var l = (max + min) / 2;
            var d = max - min;
            if (max === min) {
                h = s = 0;
            }
            else {
                s = l > 0.5 ? d / (2 - max - min) : d / (max + min);
                switch (max) {
                    case r:
                        h = (g - b) / d + (g < b ? 6 : 0);
                        break;
                    case g:
                        h = (b - r) / d + 2;
                        break;
                    case b:
                        h = (r - g) / d + 4;
                        break;
                }
                h /= 6;
            }
            return { h: h * 360, s: s, l: l, a: a };
        },
        // Adapted from http://mjijackson.com/2008/02/rgb-to-hsl-and-rgb-to-hsv-color-model-conversion-algorithms-in-javascript
        toHSV: function () {
            var r = this.rgb[0] / 255, g = this.rgb[1] / 255, b = this.rgb[2] / 255, a = this.alpha;
            var max = Math.max(r, g, b), min = Math.min(r, g, b);
            var h;
            var s;
            var v = max;
            var d = max - min;
            if (max === 0) {
                s = 0;
            }
            else {
                s = d / max;
            }
            if (max === min) {
                h = 0;
            }
            else {
                switch (max) {
                    case r:
                        h = (g - b) / d + (g < b ? 6 : 0);
                        break;
                    case g:
                        h = (b - r) / d + 2;
                        break;
                    case b:
                        h = (r - g) / d + 4;
                        break;
                }
                h /= 6;
            }
            return { h: h * 360, s: s, v: v, a: a };
        },
        toARGB: function () {
            return toHex([this.alpha * 255].concat(this.rgb));
        },
        compare: function (x) {
            return (x.rgb &&
                x.rgb[0] === this.rgb[0] &&
                x.rgb[1] === this.rgb[1] &&
                x.rgb[2] === this.rgb[2] &&
                x.alpha === this.alpha) ? 0 : undefined;
        }
    });
    Color.fromKeyword = function (keyword) {
        var c;
        var key = keyword.toLowerCase();
        if (colors.hasOwnProperty(key)) {
            c = new Color(colors[key].slice(1));
        }
        else if (key === 'transparent') {
            c = new Color([0, 0, 0], 0);
        }
        if (c) {
            c.value = keyword;
            return c;
        }
    };
    function clamp$1(v, max) {
        return Math.min(Math.max(v, 0), max);
    }
    function toHex(v) {
        return "#" + v.map(function (c) {
            c = clamp$1(Math.round(c), 255);
            return (c < 16 ? '0' : '') + c.toString(16);
        }).join('');
    }

var Math$1 = {
        ALWAYS: 0,
        PARENS_DIVISION: 1,
        PARENS: 2
        // removed - STRICT_LEGACY: 3
    };
    var RewriteUrls = {
        OFF: 0,
        LOCAL: 1,
        ALL: 2
    };

/**
     * Returns the object type of the given payload
     *
     * @param {*} payload
     * @returns {string}
     */
    function getType(payload) {
        return Object.prototype.toString.call(payload).slice(8, -1);
    }
    /**
     * Returns whether the payload is a plain JavaScript object (excluding special classes or objects with other prototypes)
     *
     * @param {*} payload
     * @returns {payload is Record<string, any>}
     */
    function isPlainObject(payload) {
        if (getType(payload) !== 'Object')
            return false;
        return payload.constructor === Object && Object.getPrototypeOf(payload) === Object.prototype;
    }
    /**
     * Returns whether the payload is an array
     *
     * @param {any} payload
     * @returns {payload is any[]}
     */
    function isArray(payload) {
        return getType(payload) === 'Array';
    }

/*! *****************************************************************************
    Copyright (c) Microsoft Corporation. All rights reserved.
    Licensed under the Apache License, Version 2.0 (the "License"); you may not use
    this file except in compliance with the License. You may obtain a copy of the
    License at http://www.apache.org/licenses/LICENSE-2.0

THIS CODE IS PROVIDED ON AN *AS IS* BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
    KIND, EITHER EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION ANY IMPLIED
    WARRANTIES OR CONDITIONS OF TITLE, FITNESS FOR A PARTICULAR PURPOSE,
    MERCHANTABLITY OR NON-INFRINGEMENT.

See the Apache Version 2.0 License for specific language governing permissions
    and limitations under the License.
    ***************************************************************************** */

function __spreadArrays() {
        for (var s = 0, i = 0, il = arguments.length; i < il; i++) s += arguments[i].length;
        for (var r = Array(s), k = 0, i = 0; i < il; i++)
            for (var a = arguments[i], j = 0, jl = a.length; j < jl; j++, k++)
                r[k] = a[j];
        return r;
    }

/* jshint proto: true */
    function getLocation(index, inputStream) {
        var n = index + 1;
        var line = null;
        var column = -1;
        while (--n >= 0 && inputStream.charAt(n) !== '\n') {
            column++;
        }
        if (typeof index === 'number') {
            line = (inputStream.slice(0, index).match(/\n/g) || '').length;
        }
        return {
            line: line,
            column: column
        };
    }
    function copyArray(arr) {
        var i;
        var length = arr.length;
        var copy = new Array(length);
        for (i = 0; i < length; i++) {
            copy[i] = arr[i];
        }
        return copy;
    }
    function clone(obj) {
        var cloned = {};
        for (var prop in obj) {
            if (obj.hasOwnProperty(prop)) {
                cloned[prop] = obj[prop];
            }
        }
        return cloned;
    }
    function defaults(obj1, obj2) {
        var newObj = obj2 || {};
        if (!obj2._defaults) {
            newObj = {};
            var defaults_1 = copy(obj1);
            newObj._defaults = defaults_1;
            var cloned = obj2 ? copy(obj2) : {};
            Object.assign(newObj, defaults_1, cloned);
        }
        return newObj;
    }
    function copyOptions(obj1, obj2) {
        if (obj2 && obj2._defaults) {
            return obj2;
        }
        var opts = defaults(obj1, obj2);
        if (opts.strictMath) {
            opts.math = Math$1.PARENS;
        }
        // Back compat with changed relativeUrls option
        if (opts.relativeUrls) {
            opts.rewriteUrls = RewriteUrls.ALL;
        }
        if (typeof opts.math === 'string') {
            switch (opts.math.toLowerCase()) {
                case 'always':
                    opts.math = Math$1.ALWAYS;
                    break;
                case 'parens-division':
                    opts.math = Math$1.PARENS_DIVISION;
                    break;
                case 'strict':
                case 'parens':
                    opts.math = Math$1.PARENS;
                    break;
                default:
                    opts.math = Math$1.PARENS;
            }
        }
        if (typeof opts.rewriteUrls === 'string') {
            switch (opts.rewriteUrls.toLowerCase()) {
                case 'off':
                    opts.rewriteUrls = RewriteUrls.OFF;
                    break;
                case 'local':
                    opts.rewriteUrls = RewriteUrls.LOCAL;
                    break;
                case 'all':
                    opts.rewriteUrls = RewriteUrls.ALL;
                    break;
            }
        }
        return opts;
    }
    function merge(obj1, obj2) {
        for (var prop in obj2) {
            if (obj2.hasOwnProperty(prop)) {
                obj1[prop] = obj2[prop];
            }
        }
        return obj1;
    }
    function flattenArray(arr, result) {
        if (result === void 0) { result = []; }
        for (var i = 0, length_1 = arr.length; i < length_1; i++) {
            var value = arr[i];
            if (Array.isArray(value)) {
                flattenArray(value, result);
            }
            else {
                if (value !== undefined) {
                    result.push(value);
                }
            }
        }
        return result;
    }

var utils = /*#__PURE__*/Object.freeze({
        __proto__: null,
        getLocation: getLocation,
        copyArray: copyArray,
        clone: clone,
        defaults: defaults,
        copyOptions: copyOptions,
        merge: merge,
        flattenArray: flattenArray
    });

//
    // A number with a unit
    //
    var Dimension = function (value, unit) {
        this.value = parseFloat(value);
        if (isNaN(this.value)) {
            throw new Error('Dimension is not a number.');
        }
        this.unit = (unit && unit instanceof Unit) ? unit :
            new Unit(unit ? [unit] : undefined);
        this.setParent(this.unit, this);
    };
    Dimension.prototype = Object.assign(new Node(), {
        type: 'Dimension',
        accept: function (visitor) {
            this.unit = visitor.visit(this.unit);
        },
        eval: function (context) {
            return this;
        },
        toColor: function () {
            return new Color([this.value, this.value, this.value]);
        },
        genCSS: function (context, output) {
            if ((context && context.strictUnits) && !this.unit.isSingular()) {
                throw new Error("Multiple units in dimension. Correct the units or use the unit function. Bad unit: " + this.unit.toString());
            }
            var value = this.fround(context, this.value);
            var strValue = String(value);
            if (value !== 0 && value < 0.000001 && value > -0.000001) {
                // would be output 1e-6 etc.
                strValue = value.toFixed(20).replace(/0+$/, '');
            }
            if (context && context.compress) {
                // Zero values doesn't need a unit
                if (value === 0 && this.unit.isLength()) {
                    output.add(strValue);
                    return;
                }
                // Float values doesn't need a leading zero
                if (value > 0 && value < 1) {
                    strValue = (strValue).substr(1);
                }
            }
            output.add(strValue);
            this.unit.genCSS(context, output);
        },
        // In an operation between two Dimensions,
        // we default to the first Dimension's unit,
        // so `1px + 2` will yield `3px`.
        operate: function (context, op, other) {
            /* jshint noempty:false */
            var value = this._operate(context, op, this.value, other.value);
            var unit = this.unit.clone();
            if (op === '+' || op === '-') {
                if (unit.numerator.length === 0 && unit.denominator.length === 0) {
                    unit = other.unit.clone();
                    if (this.unit.backupUnit) {
                        unit.backupUnit = this.unit.backupUnit;
                    }
                }
                else if (other.unit.numerator.length === 0 && unit.denominator.length === 0) ;
                else {
                    other = other.convertTo(this.unit.usedUnits());
                    if (context.strictUnits && other.unit.toString() !== unit.toString()) {
                        throw new Error("Incompatible units. Change the units or use the unit function. "
                            + ("Bad units: '" + unit.toString() + "' and '" + other.unit.toString() + "'."));
                    }
                    value = this._operate(context, op, this.value, other.value);
                }
            }
            else if (op === '*') {
                unit.numerator = unit.numerator.concat(other.unit.numerator).sort();
                unit.denominator = unit.denominator.concat(other.unit.denominator).sort();
                unit.cancel();
            }
            else if (op === '/') {
                unit.numerator = unit.numerator.concat(other.unit.denominator).sort();
                unit.denominator = unit.denominator.concat(other.unit.numerator).sort();
                unit.cancel();
            }
            return new Dimension(value, unit);
        },
        compare: function (other) {
            var a, b;
            if (!(other instanceof Dimension)) {
                return undefined;
            }
            if (this.unit.isEmpty() || other.unit.isEmpty()) {
                a = this;
                b = other;
            }
            else {
                a = this.unify();
                b = other.unify();
                if (a.unit.compare(b.unit) !== 0) {
                    return undefined;
                }
            }
            return Node.numericCompare(a.value, b.value);
        },
        unify: function () {
            return this.convertTo({ length: 'px', duration: 's', angle: 'rad' });
        },
        convertTo: function (conversions) {
            var value = this.value;
            var unit = this.unit.clone();
            var i;
            var groupName;
            var group;
            var targetUnit;
            var derivedConversions = {};
            var applyUnit;
            if (typeof conversions === 'string') {
                for (i in unitConversions) {
                    if (unitConversions[i].hasOwnProperty(conversions)) {
                        derivedConversions = {};
                        derivedConversions[i] = conversions;
                    }
                }
                conversions = derivedConversions;
            }
            applyUnit = function (atomicUnit, denominator) {
                /* jshint loopfunc:true */
                if (group.hasOwnProperty(atomicUnit)) {
                    if (denominator) {
                        value = value / (group[atomicUnit] / group[targetUnit]);
                    }
                    else {
                        value = value * (group[atomicUnit] / group[targetUnit]);
                    }
                    return targetUnit;
                }
                return atomicUnit;
            };
            for (groupName in conversions) {
                if (conversions.hasOwnProperty(groupName)) {
                    targetUnit = conversions[groupName];
                    group = unitConversions[groupName];
                    unit.map(applyUnit);
                }
            }
            unit.cancel();
            return new Dimension(value, unit);
        }
    });

/*! *****************************************************************************
    Copyright (c) Microsoft Corporation.

Permission to use, copy, modify, and/or distribute this software for any
    purpose with or without fee is hereby granted.

THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
    REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
    AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
    INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
    LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
    OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
    PERFORMANCE OF THIS SOFTWARE.
    ***************************************************************************** */

//
    // A function call node.
    //
    var Call = function (name, args, index, currentFileInfo) {
        this.name = name;
        this.args = args;
        this.calc = name === 'calc';
        this._index = index;
        this._fileInfo = currentFileInfo;
    };
    Call.prototype = Object.assign(new Node(), {
        type: 'Call',
        accept: function (visitor) {
            if (this.args) {
                this.args = visitor.visitArray(this.args);
            }
        },
        //
        // When evaluating a function call,
        // we either find the function in the functionRegistry,
        // in which case we call it, passing the  evaluated arguments,
        // if this returns null or we cannot find the function, we
        // simply print it out as it appeared originally [2].
        //
        // The reason why we evaluate the arguments, is in the case where
        // we try to pass a variable to a function, like: `saturate(@color)`.
        // The function should receive the value, not the variable.
        //
        eval: function (context) {
            var _this = this;
            /**
             * Turn off math for calc(), and switch back on for evaluating nested functions
             */
            var currentMathContext = context.mathOn;
            context.mathOn = !this.calc;
            if (this.calc || context.inCalc) {
                context.enterCalc();
            }
            var exitCalc = function () {
                if (_this.calc || context.inCalc) {
                    context.exitCalc();
                }
                context.mathOn = currentMathContext;
            };
            var result;
            var funcCaller = new functionCaller(this.name, context, this.getIndex(), this.fileInfo());
            if (funcCaller.isValid()) {
                try {
                    result = funcCaller.call(this.args);
                    exitCalc();
                }
                catch (e) {
                    if (e.hasOwnProperty('line') && e.hasOwnProperty('column')) {
                        throw e;
                    }
                    throw {
                        type: e.type || 'Runtime',
                        message: "Error evaluating function `" + this.name + "`" + (e.message ? ": " + e.message : ''),
                        index: this.getIndex(),
                        filename: this.fileInfo().filename,
                        line: e.lineNumber,
                        column: e.columnNumber
                    };
                }
            }
            if (result !== null && result !== undefined) {
                // Results that that are not nodes are cast as Anonymous nodes
                // Falsy values or booleans are returned as empty nodes
                if (!(result instanceof Node)) {
                    if (!result || result === true) {
                        result = new Anonymous(null);
                    }
                    else {
                        result = new Anonymous(result.toString());
                    }
                }
                result._index = this._index;
                result._fileInfo = this._fileInfo;
                return result;
            }
            var args = this.args.map(function (a) { return a.eval(context); });
            exitCalc();
            return new Call(this.name, args, this.getIndex(), this.fileInfo());
        },
        genCSS: function (context, output) {
            output.add(this.name + "(", this.fileInfo(), this.getIndex());
            for (var i = 0; i < this.args.length; i++) {
                this.args[i].genCSS(context, output);
                if (i + 1 < this.args.length) {
                    output.add(', ');
                }
            }
            output.add(')');
        }
    });

//
    // CSS @import node
    //
    // The general strategy here is that we don't want to wait
    // for the parsing to be completed, before we start importing
    // the file. That's because in the context of a browser,
    // most of the time will be spent waiting for the server to respond.
    //
    // On creation, we push the import path to our import queue, though
    // `import,push`, we also pass it a callback, which it'll call once
    // the file has been fetched, and parsed.
    //
    var Import = function (path, features, options, index, currentFileInfo, visibilityInfo) {
        this.options = options;
        this._index = index;
        this._fileInfo = currentFileInfo;
        this.path = path;
        this.features = features;
        this.allowRoot = true;
        if (this.options.less !== undefined || this.options.inline) {
            this.css = !this.options.less || this.options.inline;
        }
        else {
            var pathValue = this.getPath();
            if (pathValue && /[#\.\&\?]css([\?;].*)?$/.test(pathValue)) {
                this.css = true;
            }
        }
        this.copyVisibilityInfo(visibilityInfo);
        this.setParent(this.features, this);
        this.setParent(this.path, this);
    };
    Import.prototype = Object.assign(new Node(), {
        type: 'Import',
        accept: function (visitor) {
            if (this.features) {
                this.features = visitor.visit(this.features);
            }
            this.path = visitor.visit(this.path);
            if (!this.options.isPlugin && !this.options.inline && this.root) {
                this.root = visitor.visit(this.root);
            }
        },
        genCSS: function (context, output) {
            if (this.css && this.path._fileInfo.reference === undefined) {
                output.add('@import ', this._fileInfo, this._index);
                this.path.genCSS(context, output);
                if (this.features) {
                    output.add(' ');
                    this.features.genCSS(context, output);
                }
                output.add(';');
            }
        },
        getPath: function () {
            return (this.path instanceof URL) ?
                this.path.value.value : this.path.value;
        },
        isVariableImport: function () {
            var path = this.path;
            if (path instanceof URL) {
                path = path.value;
            }
            if (path instanceof Quoted) {
                return path.containsVariables();
            }
            return true;
        },
        evalForImport: function (context) {
            var path = this.path;
            if (path instanceof URL) {
                path = path.value;
            }
            return new Import(path.eval(context), this.features, this.options, this._index, this._fileInfo, this.visibilityInfo());
        },
        evalPath: function (context) {
            var path = this.path.eval(context);
            var fileInfo = this._fileInfo;
            if (!(path instanceof URL)) {
                // Add the rootpath if the URL requires a rewrite
                var pathValue = path.value;
                if (fileInfo &&
                    pathValue &&
                    context.pathRequiresRewrite(pathValue)) {
                    path.value = context.rewritePath(pathValue, fileInfo.rootpath);
                }
                else {
                    path.value = context.normalizePath(path.value);
                }
            }
            return path;
        },
        eval: function (context) {
            var result = this.doEval(context);
            if (this.options.reference || this.blocksVisibility()) {
                if (result.length || result.length === 0) {
                    result.forEach(function (node) {
                        node.addVisibilityBlock();
                    });
                }
                else {
                    result.addVisibilityBlock();
                }
            }
            return result;
        },
        doEval: function (context) {
            var ruleset;
            var registry;
            var features = this.features && this.features.eval(context);
            if (this.options.isPlugin) {
                if (this.root && this.root.eval) {
                    try {
                        this.root.eval(context);
                    }
                    catch (e) {
                        e.message = 'Plugin error during evaluation';
                        throw new LessError(e, this.root.imports, this.root.filename);
                    }
                }
                registry = context.frames[0] && context.frames[0].functionRegistry;
                if (registry && this.root && this.root.functions) {
                    registry.addMultiple(this.root.functions);
                }
                return [];
            }
            if (this.skip) {
                if (typeof this.skip === 'function') {
                    this.skip = this.skip();
                }
                if (this.skip) {
                    return [];
                }
            }
            if (this.options.inline) {
                var contents = new Anonymous(this.root, 0, {
                    filename: this.importedFilename,
                    reference: this.path._fileInfo && this.path._fileInfo.reference
                }, true, true);
                return this.features ? new Media([contents], this.features.value) : [contents];
            }
            else if (this.css) {
                var newImport = new Import(this.evalPath(context), features, this.options, this._index);
                if (!newImport.css && this.error) {
                    throw this.error;
                }
                return newImport;
            }
            else if (this.root) {
                ruleset = new Ruleset(null, copyArray(this.root.rules));
                ruleset.evalImports(context);
                return this.features ? new Media(ruleset.rules, this.features.value) : ruleset.rules;
            }
            else {
                return [];
            }
        }
    });

var UnicodeDescriptor = function (value) {
        this.value = value;
    };
    UnicodeDescriptor.prototype = Object.assign(new Node(), {
        type: 'UnicodeDescriptor'
    });

var tree = {
        Node: Node,
        Color: Color,
        AtRule: AtRule,
        DetachedRuleset: DetachedRuleset,
        Operation: Operation,
        Dimension: Dimension,
        Unit: Unit,
        Keyword: Keyword,
        Variable: Variable,
        Property: Property,
        Ruleset: Ruleset,
        Element: Element,
        Attribute: Attribute,
        Combinator: Combinator,
        Selector: Selector,
        Quoted: Quoted,
        Expression: Expression,
        Declaration: Declaration,
        Call: Call,
        URL: URL,
        Import: Import,
        Comment: Comment,
        Anonymous: Anonymous,
        Value: Value,
        JavaScript: JavaScript,
        Assignment: Assignment,
        Condition: Condition,
        Paren: Paren,
        Media: Media,
        UnicodeDescriptor: UnicodeDescriptor,
        Negative: Negative,
        Extend: Extend,
        VariableCall: VariableCall,
        NamespaceValue: NamespaceValue,
        mixin: {
            Call: MixinCall,
            Definition: Definition
        }
    };

/* jshint loopfunc:true */
    var ExtendFinderVisitor = /** @class */ (function () {
        function ExtendFinderVisitor() {
            this._visitor = new Visitor(this);
            this.contexts = [];
            this.allExtendsStack = [[]];
        }
        ExtendFinderVisitor.prototype.run = function (root) {
            root = this._visitor.visit(root);
            root.allExtends = this.allExtendsStack[0];
            return root;
        };
        ExtendFinderVisitor.prototype.visitDeclaration = function (declNode, visitArgs) {
            visitArgs.visitDeeper = false;
        };
        ExtendFinderVisitor.prototype.visitMixinDefinition = function (mixinDefinitionNode, visitArgs) {
            visitArgs.visitDeeper = false;
        };
        ExtendFinderVisitor.prototype.visitRuleset = function (rulesetNode, visitArgs) {
            if (rulesetNode.root) {
                return;
            }
            var i;
            var j;
            var extend;
            var allSelectorsExtendList = [];
            var extendList;
            // get &:extend(.a); rules which apply to all selectors in this ruleset
            var rules = rulesetNode.rules, ruleCnt = rules ? rules.length : 0;
            for (i = 0; i < ruleCnt; i++) {
                if (rulesetNode.rules[i] instanceof tree.Extend) {
                    allSelectorsExtendList.push(rules[i]);
                    rulesetNode.extendOnEveryPath = true;
                }
            }
            // now find every selector and apply the extends that apply to all extends
            // and the ones which apply to an individual extend
            var paths = rulesetNode.paths;
            for (i = 0; i < paths.length; i++) {
                var selectorPath = paths[i], selector = selectorPath[selectorPath.length - 1], selExtendList = selector.extendList;
                extendList = selExtendList ? copyArray(selExtendList).concat(allSelectorsExtendList)
                    : allSelectorsExtendList;
                if (extendList) {
                    extendList = extendList.map(function (allSelectorsExtend) {
                        return allSelectorsExtend.clone();
                    });
                }
                for (j = 0; j < extendList.length; j++) {
                    this.foundExtends = true;
                    extend = extendList[j];
                    extend.findSelfSelectors(selectorPath);
                    extend.ruleset = rulesetNode;
                    if (j === 0) {
                        extend.firstExtendOnThisSelectorPath = true;
                    }
                    this.allExtendsStack[this.allExtendsStack.length - 1].push(extend);
                }
            }
            this.contexts.push(rulesetNode.selectors);
        };
        ExtendFinderVisitor.prototype.visitRulesetOut = function (rulesetNode) {
            if (!rulesetNode.root) {
                this.contexts.length = this.contexts.length - 1;
            }
        };
        ExtendFinderVisitor.prototype.visitMedia = function (mediaNode, visitArgs) {
            mediaNode.allExtends = [];
            this.allExtendsStack.push(mediaNode.allExtends);
        };
        ExtendFinderVisitor.prototype.visitMediaOut = function (mediaNode) {
            this.allExtendsStack.length = this.allExtendsStack.length - 1;
        };
        ExtendFinderVisitor.prototype.visitAtRule = function (atRuleNode, visitArgs) {
            atRuleNode.allExtends = [];
            this.allExtendsStack.push(atRuleNode.allExtends);
        };
        ExtendFinderVisitor.prototype.visitAtRuleOut = function (atRuleNode) {
            this.allExtendsStack.length = this.allExtendsStack.length - 1;
        };
        return ExtendFinderVisitor;
    }());
    var ProcessExtendsVisitor = /** @class */ (function () {
        function ProcessExtendsVisitor() {
            this._visitor = new Visitor(this);
        }
        ProcessExtendsVisitor.prototype.run = function (root) {
            var extendFinder = new ExtendFinderVisitor();
            this.extendIndices = {};
            extendFinder.run(root);
            if (!extendFinder.foundExtends) {
                return root;
            }
            root.allExtends = root.allExtends.concat(this.doExtendChaining(root.allExtends, root.allExtends));
            this.allExtendsStack = [root.allExtends];
            var newRoot = this._visitor.visit(root);
            this.checkExtendsForNonMatched(root.allExtends);
            return newRoot;
        };
        ProcessExtendsVisitor.prototype.checkExtendsForNonMatched = function (extendList) {
            var indices = this.extendIndices;
            extendList.filter(function (extend) {
                return !extend.hasFoundMatches && extend.parent_ids.length == 1;
            }).forEach(function (extend) {
                var selector = '_unknown_';
                try {
                    selector = extend.selector.toCSS({});
                }
                catch (_) { }
                if (!indices[extend.index + " " + selector]) {
                    indices[extend.index + " " + selector] = true;
                    logger$1.warn("extend '" + selector + "' has no matches");
                }
            });
        };
        ProcessExtendsVisitor.prototype.doExtendChaining = function (extendsList, extendsListTarget, iterationCount) {
            //
            // chaining is different from normal extension.. if we extend an extend then we are not just copying, altering
            // and pasting the selector we would do normally, but we are also adding an extend with the same target selector
            // this means this new extend can then go and alter other extends
            //
            // this method deals with all the chaining work - without it, extend is flat and doesn't work on other extend selectors
            // this is also the most expensive.. and a match on one selector can cause an extension of a selector we had already
            // processed if we look at each selector at a time, as is done in visitRuleset
            var extendIndex;
            var targetExtendIndex;
            var matches;
            var extendsToAdd = [];
            var newSelector;
            var extendVisitor = this;
            var selectorPath;
            var extend;
            var targetExtend;
            var newExtend;
            iterationCount = iterationCount || 0;
            // loop through comparing every extend with every target extend.
            // a target extend is the one on the ruleset we are looking at copy/edit/pasting in place
            // e.g.  .a:extend(.b) {}  and .b:extend(.c) {} then the first extend extends the second one
            // and the second is the target.
            // the separation into two lists allows us to process a subset of chains with a bigger set, as is the
            // case when processing media queries
            for (extendIndex = 0; extendIndex < extendsList.length; extendIndex++) {
                for (targetExtendIndex = 0; targetExtendIndex < extendsListTarget.length; targetExtendIndex++) {
                    extend = extendsList[extendIndex];
                    targetExtend = extendsListTarget[targetExtendIndex];
                    // look for circular references
                    if (extend.parent_ids.indexOf(targetExtend.object_id) >= 0) {
                        continue;
                    }
                    // find a match in the target extends self selector (the bit before :extend)
                    selectorPath = [targetExtend.selfSelectors[0]];
                    matches = extendVisitor.findMatch(extend, selectorPath);
                    if (matches.length) {
                        extend.hasFoundMatches = true;
                        // we found a match, so for each self selector..
                        extend.selfSelectors.forEach(function (selfSelector) {
                            var info = targetExtend.visibilityInfo();
                            // process the extend as usual
                            newSelector = extendVisitor.extendSelector(matches, selectorPath, selfSelector, extend.isVisible());
                            // but now we create a new extend from it
                            newExtend = new (tree.Extend)(targetExtend.selector, targetExtend.option, 0, targetExtend.fileInfo(), info);
                            newExtend.selfSelectors = newSelector;
                            // add the extend onto the list of extends for that selector
                            newSelector[newSelector.length - 1].extendList = [newExtend];
                            // record that we need to add it.
                            extendsToAdd.push(newExtend);
                            newExtend.ruleset = targetExtend.ruleset;
                            // remember its parents for circular references
                            newExtend.parent_ids = newExtend.parent_ids.concat(targetExtend.parent_ids, extend.parent_ids);
                            // only process the selector once.. if we have :extend(.a,.b) then multiple
                            // extends will look at the same selector path, so when extending
                            // we know that any others will be duplicates in terms of what is added to the css
                            if (targetExtend.firstExtendOnThisSelectorPath) {
                                newExtend.firstExtendOnThisSelectorPath = true;
                                targetExtend.ruleset.paths.push(newSelector);
                            }
                        });
                    }
                }
            }
            if (extendsToAdd.length) {
                // try to detect circular references to stop a stack overflow.
                // may no longer be needed.
                this.extendChainCount++;
                if (iterationCount > 100) {
                    var selectorOne = '{unable to calculate}';
                    var selectorTwo = '{unable to calculate}';
                    try {
                        selectorOne = extendsToAdd[0].selfSelectors[0].toCSS();
                        selectorTwo = extendsToAdd[0].selector.toCSS();
                    }
                    catch (e) { }
                    throw { message: "extend circular reference detected. One of the circular extends is currently:" + selectorOne + ":extend(" + selectorTwo + ")" };
                }
                // now process the new extends on the existing rules so that we can handle a extending b extending c extending
                // d extending e...
                return extendsToAdd.concat(extendVisitor.doExtendChaining(extendsToAdd, extendsListTarget, iterationCount + 1));
            }
            else {
                return extendsToAdd;
            }
        };
        ProcessExtendsVisitor.prototype.visitDeclaration = function (ruleNode, visitArgs) {
            visitArgs.visitDeeper = false;
        };
        ProcessExtendsVisitor.prototype.visitMixinDefinition = function (mixinDefinitionNode, visitArgs) {
            visitArgs.visitDeeper = false;
        };
        ProcessExtendsVisitor.prototype.visitSelector = function (selectorNode, visitArgs) {
            visitArgs.visitDeeper = false;
        };
        ProcessExtendsVisitor.prototype.visitRuleset = function (rulesetNode, visitArgs) {
            if (rulesetNode.root) {
                return;
            }
            var matches;
            var pathIndex;
            var extendIndex;
            var allExtends = this.allExtendsStack[this.allExtendsStack.length - 1];
            var selectorsToAdd = [];
            var extendVisitor = this;
            var selectorPath;
            // look at each selector path in the ruleset, find any extend matches and then copy, find and replace
            for (extendIndex = 0; extendIndex < allExtends.length; extendIndex++) {
                for (pathIndex = 0; pathIndex < rulesetNode.paths.length; pathIndex++) {
                    selectorPath = rulesetNode.paths[pathIndex];
                    // extending extends happens initially, before the main pass
                    if (rulesetNode.extendOnEveryPath) {
                        continue;
                    }
                    var extendList = selectorPath[selectorPath.length - 1].extendList;
                    if (extendList && extendList.length) {
                        continue;
                    }
                    matches = this.findMatch(allExtends[extendIndex], selectorPath);
                    if (matches.length) {
                        allExtends[extendIndex].hasFoundMatches = true;
                        allExtends[extendIndex].selfSelectors.forEach(function (selfSelector) {
                            var extendedSelectors;
                            extendedSelectors = extendVisitor.extendSelector(matches, selectorPath, selfSelector, allExtends[extendIndex].isVisible());
                            selectorsToAdd.push(extendedSelectors);
                        });
                    }
                }
            }
            rulesetNode.paths = rulesetNode.paths.concat(selectorsToAdd);
        };
        ProcessExtendsVisitor.prototype.findMatch = function (extend, haystackSelectorPath) {
            //
            // look through the haystack selector path to try and find the needle - extend.selector
            // returns an array of selector matches that can then be replaced
            //
            var haystackSelectorIndex;
            var hackstackSelector;
            var hackstackElementIndex;
            var haystackElement;
            var targetCombinator;
            var i;
            var extendVisitor = this;
            var needleElements = extend.selector.elements;
            var potentialMatches = [];
            var potentialMatch;
            var matches = [];
            // loop through the haystack elements
            for (haystackSelectorIndex = 0; haystackSelectorIndex < haystackSelectorPath.length; haystackSelectorIndex++) {
                hackstackSelector = haystackSelectorPath[haystackSelectorIndex];
                for (hackstackElementIndex = 0; hackstackElementIndex < hackstackSelector.elements.length; hackstackElementIndex++) {
                    haystackElement = hackstackSelector.elements[hackstackElementIndex];
                    // if we allow elements before our match we can add a potential match every time. otherwise only at the first element.
                    if (extend.allowBefore || (haystackSelectorIndex === 0 && hackstackElementIndex === 0)) {
                        potentialMatches.push({ pathIndex: haystackSelectorIndex, index: hackstackElementIndex, matched: 0,
                            initialCombinator: haystackElement.combinator });
                    }
                    for (i = 0; i < potentialMatches.length; i++) {
                        potentialMatch = potentialMatches[i];
                        // selectors add " " onto the first element. When we use & it joins the selectors together, but if we don't
                        // then each selector in haystackSelectorPath has a space before it added in the toCSS phase. so we need to
                        // work out what the resulting combinator will be
                        targetCombinator = haystackElement.combinator.value;
                        if (targetCombinator === '' && hackstackElementIndex === 0) {
                            targetCombinator = ' ';
                        }
                        // if we don't match, null our match to indicate failure
                        if (!extendVisitor.isElementValuesEqual(needleElements[potentialMatch.matched].value, haystackElement.value) ||
                            (potentialMatch.matched > 0 && needleElements[potentialMatch.matched].combinator.value !== targetCombinator)) {
                            potentialMatch = null;
                        }
                        else {
                            potentialMatch.matched++;
                        }
                        // if we are still valid and have finished, test whether we have elements after and whether these are allowed
                        if (potentialMatch) {
                            potentialMatch.finished = potentialMatch.matched === needleElements.length;
                            if (potentialMatch.finished &&
                                (!extend.allowAfter &&
                                    (hackstackElementIndex + 1 < hackstackSelector.elements.length || haystackSelectorIndex + 1 < haystackSelectorPath.length))) {
                                potentialMatch = null;
                            }
                        }
                        // if null we remove, if not, we are still valid, so either push as a valid match or continue
                        if (potentialMatch) {
                            if (potentialMatch.finished) {
                                potentialMatch.length = needleElements.length;
                                potentialMatch.endPathIndex = haystackSelectorIndex;
                                potentialMatch.endPathElementIndex = hackstackElementIndex + 1; // index after end of match
                                potentialMatches.length = 0; // we don't allow matches to overlap, so start matching again
                                matches.push(potentialMatch);
                            }
                        }
                        else {
                            potentialMatches.splice(i, 1);
                            i--;
                        }
                    }
                }
            }
            return matches;
        };
        ProcessExtendsVisitor.prototype.isElementValuesEqual = function (elementValue1, elementValue2) {
            if (typeof elementValue1 === 'string' || typeof elementValue2 === 'string') {
                return elementValue1 === elementValue2;
            }
            if (elementValue1 instanceof tree.Attribute) {
                if (elementValue1.op !== elementValue2.op || elementValue1.key !== elementValue2.key) {
                    return false;
                }
                if (!elementValue1.value || !elementValue2.value) {
                    if (elementValue1.value || elementValue2.value) {
                        return false;
                    }
                    return true;
                }
                elementValue1 = elementValue1.value.value || elementValue1.value;
                elementValue2 = elementValue2.value.value || elementValue2.value;
                return elementValue1 === elementValue2;
            }
            elementValue1 = elementValue1.value;
            elementValue2 = elementValue2.value;
            if (elementValue1 instanceof tree.Selector) {
                if (!(elementValue2 instanceof tree.Selector) || elementValue1.elements.length !== elementValue2.elements.length) {
                    return false;
                }
                for (var i = 0; i < elementValue1.elements.length; i++) {
                    if (elementValue1.elements[i].combinator.value !== elementValue2.elements[i].combinator.value) {
                        if (i !== 0 || (elementValue1.elements[i].combinator.value || ' ') !== (elementValue2.elements[i].combinator.value || ' ')) {
                            return false;
                        }
                    }
                    if (!this.isElementValuesEqual(elementValue1.elements[i].value, elementValue2.elements[i].value)) {
                        return false;
                    }
                }
                return true;
            }
            return false;
        };
        ProcessExtendsVisitor.prototype.extendSelector = function (matches, selectorPath, replacementSelector, isVisible) {
            // for a set of matches, replace each match with the replacement selector
            var currentSelectorPathIndex = 0, currentSelectorPathElementIndex = 0, path = [], matchIndex, selector, firstElement, match, newElements;
            for (matchIndex = 0; matchIndex < matches.length; matchIndex++) {
                match = matches[matchIndex];
                selector = selectorPath[match.pathIndex];
                firstElement = new tree.Element(match.initialCombinator, replacementSelector.elements[0].value, replacementSelector.elements[0].isVariable, replacementSelector.elements[0].getIndex(), replacementSelector.elements[0].fileInfo());
                if (match.pathIndex > currentSelectorPathIndex && currentSelectorPathElementIndex > 0) {
                    path[path.length - 1].elements = path[path.length - 1]
                        .elements.concat(selectorPath[currentSelectorPathIndex].elements.slice(currentSelectorPathElementIndex));
                    currentSelectorPathElementIndex = 0;
                    currentSelectorPathIndex++;
                }
                newElements = selector.elements
                    .slice(currentSelectorPathElementIndex, match.index)
                    .concat([firstElement])
                    .concat(replacementSelector.elements.slice(1));
                if (currentSelectorPathIndex === match.pathIndex && matchIndex > 0) {
                    path[path.length - 1].elements =
                        path[path.length - 1].elements.concat(newElements);
                }
                else {
                    path = path.concat(selectorPath.slice(currentSelectorPathIndex, match.pathIndex));
                    path.push(new tree.Selector(newElements));
                }
                currentSelectorPathIndex = match.endPathIndex;
                currentSelectorPathElementIndex = match.endPathElementIndex;
                if (currentSelectorPathElementIndex >= selectorPath[currentSelectorPathIndex].elements.length) {
                    currentSelectorPathElementIndex = 0;
                    currentSelectorPathIndex++;
                }
            }
            if (currentSelectorPathIndex < selectorPath.length && currentSelectorPathElementIndex > 0) {
                path[path.length - 1].elements = path[path.length - 1]
                    .elements.concat(selectorPath[currentSelectorPathIndex].elements.slice(currentSelectorPathElementIndex));
                currentSelectorPathIndex++;
            }
            path = path.concat(selectorPath.slice(currentSelectorPathIndex, selectorPath.length));
            path = path.map(function (currentValue) {
                // we can re-use elements here, because the visibility property matters only for selectors
                var derived = currentValue.createDerived(currentValue.elements);
                if (isVisible) {
                    derived.ensureVisibility();
                }
                else {
                    derived.ensureInvisibility();
                }
                return derived;
            });
            return path;
        };
        ProcessExtendsVisitor.prototype.visitMedia = function (mediaNode, visitArgs) {
            var newAllExtends = mediaNode.allExtends.concat(this.allExtendsStack[this.allExtendsStack.length - 1]);
            newAllExtends = newAllExtends.concat(this.doExtendChaining(newAllExtends, mediaNode.allExtends));
            this.allExtendsStack.push(newAllExtends);
        };
        ProcessExtendsVisitor.prototype.visitMediaOut = function (mediaNode) {
            var lastIndex = this.allExtendsStack.length - 1;
            this.allExtendsStack.length = lastIndex;
        };
        ProcessExtendsVisitor.prototype.visitAtRule = function (atRuleNode, visitArgs) {
            var newAllExtends = atRuleNode.allExtends.concat(this.allExtendsStack[this.allExtendsStack.length - 1]);
            newAllExtends = newAllExtends.concat(this.doExtendChaining(newAllExtends, atRuleNode.allExtends));
            this.allExtendsStack.push(newAllExtends);
        };
        ProcessExtendsVisitor.prototype.visitAtRuleOut = function (atRuleNode) {
            var lastIndex = this.allExtendsStack.length - 1;
            this.allExtendsStack.length = lastIndex;
        };
        return ProcessExtendsVisitor;
    }());

var visitors = {
        Visitor: Visitor,
        ImportVisitor: ImportVisitor,
        MarkVisibleSelectorsVisitor: SetTreeVisibilityVisitor,
        ExtendVisitor: ProcessExtendsVisitor,
        JoinSelectorVisitor: JoinSelectorVisitor,
        ToCSSVisitor: ToCSSVisitor
    };

// Split the input into chunks.
    function chunker (input, fail) {
        var len = input.length;
        var level = 0;
        var parenLevel = 0;
        var lastOpening;
        var lastOpeningParen;
        var lastMultiComment;
        var lastMultiCommentEndBrace;
        var chunks = [];
        var emitFrom = 0;
        var chunkerCurrentIndex;
        var currentChunkStartIndex;
        var cc;
        var cc2;
        var matched;
        function emitChunk(force) {
            var len = chunkerCurrentIndex - emitFrom;
            if (((len < 512) && !force) || !len) {
                return;
            }
            chunks.push(input.slice(emitFrom, chunkerCurrentIndex + 1));
            emitFrom = chunkerCurrentIndex + 1;
        }
        for (chunkerCurrentIndex = 0; chunkerCurrentIndex < len; chunkerCurrentIndex++) {
            cc = input.charCodeAt(chunkerCurrentIndex);
            if (((cc >= 97) && (cc <= 122)) || (cc < 34)) {
                // a-z or whitespace
                continue;
            }
            switch (cc) {
                case 40: // (
                    parenLevel++;
                    lastOpeningParen = chunkerCurrentIndex;
                    continue;
                case 41: // )
                    if (--parenLevel < 0) {
                        return fail('missing opening `(`', chunkerCurrentIndex);
                    }
                    continue;
                case 59: // ;
                    if (!parenLevel) {
                        emitChunk();
                    }
                    continue;
                case 123: // {
                    level++;
                    lastOpening = chunkerCurrentIndex;
                    continue;
                case 125: // }
                    if (--level < 0) {
                        return fail('missing opening `{`', chunkerCurrentIndex);
                    }
                    if (!level && !parenLevel) {
                        emitChunk();
                    }
                    continue;
                case 92: // \
                    if (chunkerCurrentIndex < len - 1) {
                        chunkerCurrentIndex++;
                        continue;
                    }
                    return fail('unescaped `\\`', chunkerCurrentIndex);
                case 34:
                case 39:
                case 96: // ", ' and `
                    matched = 0;
                    currentChunkStartIndex = chunkerCurrentIndex;
                    for (chunkerCurrentIndex = chunkerCurrentIndex + 1; chunkerCurrentIndex < len; chunkerCurrentIndex++) {
                        cc2 = input.charCodeAt(chunkerCurrentIndex);
                        if (cc2 > 96) {
                            continue;
                        }
                        if (cc2 == cc) {
                            matched = 1;
                            break;
                        }
                        if (cc2 == 92) { // \
                            if (chunkerCurrentIndex == len - 1) {
                                return fail('unescaped `\\`', chunkerCurrentIndex);
                            }
                            chunkerCurrentIndex++;
                        }
                    }
                    if (matched) {
                        continue;
                    }
                    return fail("unmatched `" + String.fromCharCode(cc) + "`", currentChunkStartIndex);
                case 47: // /, check for comment
                    if (parenLevel || (chunkerCurrentIndex == len - 1)) {
                        continue;
                    }
                    cc2 = input.charCodeAt(chunkerCurrentIndex + 1);
                    if (cc2 == 47) {
                        // //, find lnfeed
                        for (chunkerCurrentIndex = chunkerCurrentIndex + 2; chunkerCurrentIndex < len; chunkerCurrentIndex++) {
                            cc2 = input.charCodeAt(chunkerCurrentIndex);
                            if ((cc2 <= 13) && ((cc2 == 10) || (cc2 == 13))) {
                                break;
                            }
                        }
                    }
                    else if (cc2 == 42) {
                        // /*, find */
                        lastMultiComment = currentChunkStartIndex = chunkerCurrentIndex;
                        for (chunkerCurrentIndex = chunkerCurrentIndex + 2; chunkerCurrentIndex < len - 1; chunkerCurrentIndex++) {
                            cc2 = input.charCodeAt(chunkerCurrentIndex);
                            if (cc2 == 125) {
                                lastMultiCommentEndBrace = chunkerCurrentIndex;
                            }
                            if (cc2 != 42) {
                                continue;
                            }
                            if (input.charCodeAt(chunkerCurrentIndex + 1) == 47) {
                                break;
                            }
                        }
                        if (chunkerCurrentIndex == len - 1) {
                            return fail('missing closing `*/`', currentChunkStartIndex);
                        }
                        chunkerCurrentIndex++;
                    }
                    continue;
                case 42: // *, check for unmatched */
                    if ((chunkerCurrentIndex < len - 1) && (input.charCodeAt(chunkerCurrentIndex + 1) == 47)) {
                        return fail('unmatched `/*`', chunkerCurrentIndex);
                    }
                    continue;
            }
        }
        if (level !== 0) {
            if ((lastMultiComment > lastOpening) && (lastMultiCommentEndBrace > lastMultiComment)) {
                return fail('missing closing `}` or `*/`', lastOpening);
            }
            else {
                return fail('missing closing `}`', lastOpening);
            }
        }
        else if (parenLevel !== 0) {
            return fail('missing closing `)`', lastOpeningParen);
        }
        emitChunk(true);
        return chunks;
    }

//
    // less.js - parser
    //
    //    A relatively straight-forward predictive parser.
    //    There is no tokenization/lexing stage, the input is parsed
    //    in one sweep.
    //
    //    To make the parser fast enough to run in the browser, several
    //    optimization had to be made:
    //
    //    - Matching and slicing on a huge input is often cause of slowdowns.
    //      The solution is to chunkify the input into smaller strings.
    //      The chunks are stored in the `chunks` var,
    //      `j` holds the current chunk index, and `currentPos` holds
    //      the index of the current chunk in relation to `input`.
    //      This gives us an almost 4x speed-up.
    //
    //    - In many cases, we don't need to match individual tokens;
    //      for example, if a value doesn't hold any variables, operations
    //      or dynamic references, the parser can effectively 'skip' it,
    //      treating it as a literal.
    //      An example would be '1px solid #000' - which evaluates to itself,
    //      we don't need to know what the individual components are.
    //      The drawback, of course is that you don't get the benefits of
    //      syntax-checking on the CSS. This gives us a 50% speed-up in the parser,
    //      and a smaller speed-up in the code-gen.
    //
    //
    //    Token matching is done with the `$` function, which either takes
    //    a terminal string or regexp, or a non-terminal function to call.
    //    It also takes care of moving all the indices forwards.
    //
    var Parser = function Parser(context, imports, fileInfo) {
        var parsers;
        var parserInput = getParserInput();
        function error(msg, type) {
            throw new LessError({
                index: parserInput.i,
                filename: fileInfo.filename,
                type: type || 'Syntax',
                message: msg
            }, imports);
        }
        function expect(arg, msg) {
            // some older browsers return typeof 'function' for RegExp
            var result = (arg instanceof Function) ? arg.call(parsers) : parserInput.$re(arg);
            if (result) {
                return result;
            }
            error(msg || (typeof arg === 'string'
                ? "expected '" + arg + "' got '" + parserInput.currentChar() + "'"
                : 'unexpected token'));
        }
        // Specialization of expect()
        function expectChar(arg, msg) {
            if (parserInput.$char(arg)) {
                return arg;
            }
            error(msg || "expected '" + arg + "' got '" + parserInput.currentChar() + "'");
        }
        function getDebugInfo(index) {
            var filename = fileInfo.filename;
            return {
                lineNumber: getLocation(index, parserInput.getInput()).line + 1,
                fileName: filename
            };
        }
        /**
         *  Used after initial parsing to create nodes on the fly
         *
         *  @param {String} str          - string to parse
         *  @param {Array}  parseList    - array of parsers to run input through e.g. ["value", "important"]
         *  @param {Number} currentIndex - start number to begin indexing
         *  @param {Object} fileInfo     - fileInfo to attach to created nodes
         */
        function parseNode(str, parseList, currentIndex, fileInfo, callback) {
            var result;
            var returnNodes = [];
            var parser = parserInput;
            try {
                parser.start(str, false, function fail(msg, index) {
                    callback({
                        message: msg,
                        index: index + currentIndex
                    });
                });
                for (var x = 0, p = void 0, i = void 0; (p = parseList[x]); x++) {
                    i = parser.i;
                    result = parsers[p]();
                    if (result) {
                        try {
                            result._index = i + currentIndex;
                            result._fileInfo = fileInfo;
                        }
                        catch (e) { }
                        returnNodes.push(result);
                    }
                    else {
                        returnNodes.push(null);
                    }
                }
                var endInfo = parser.end();
                if (endInfo.isFinished) {
                    callback(null, returnNodes);
                }
                else {
                    callback(true, null);
                }
            }
            catch (e) {
                throw new LessError({
                    index: e.index + currentIndex,
                    message: e.message
                }, imports, fileInfo.filename);
            }
        }
        //
        // The Parser
        //
        return {
            parserInput: parserInput,
            imports: imports,
            fileInfo: fileInfo,
            parseNode: parseNode,
            //
            // Parse an input string into an abstract syntax tree,
            // @param str A string containing 'less' markup
            // @param callback call `callback` when done.
            // @param [additionalData] An optional map which can contains vars - a map (key, value) of variables to apply
            //
            parse: function (str, callback, additionalData) {
                var root;
                var error = null;
                var globalVars;
                var modifyVars;
                var ignored;
                var preText = '';
                globalVars = (additionalData && additionalData.globalVars) ? Parser.serializeVars(additionalData.globalVars) + "\n" : '';
                modifyVars = (additionalData && additionalData.modifyVars) ? "\n" + Parser.serializeVars(additionalData.modifyVars) : '';
                if (context.pluginManager) {
                    var preProcessors = context.pluginManager.getPreProcessors();
                    for (var i = 0; i < preProcessors.length; i++) {
                        str = preProcessors[i].process(str, { context: context, imports: imports, fileInfo: fileInfo });
                    }
                }
                if (globalVars || (additionalData && additionalData.banner)) {
                    preText = ((additionalData && additionalData.banner) ? additionalData.banner : '') + globalVars;
                    ignored = imports.contentsIgnoredChars;
                    ignored[fileInfo.filename] = ignored[fileInfo.filename] || 0;
                    ignored[fileInfo.filename] += preText.length;
                }
                str = str.replace(/\r\n?/g, '\n');
                // Remove potential UTF Byte Order Mark
                str = preText + str.replace(/^\uFEFF/, '') + modifyVars;
                imports.contents[fileInfo.filename] = str;
                // Start with the primary rule.
                // The whole syntax tree is held under a Ruleset node,
                // with the `root` property set to true, so no `{}` are
                // output. The callback is called when the input is parsed.
                try {
                    parserInput.start(str, context.chunkInput, function fail(msg, index) {
                        throw new LessError({
                            index: index,
                            type: 'Parse',
                            message: msg,
                            filename: fileInfo.filename
                        }, imports);
                    });
                    tree.Node.prototype.parse = this;
                    root = new tree.Ruleset(null, this.parsers.primary());
                    tree.Node.prototype.rootNode = root;
                    root.root = true;
                    root.firstRoot = true;
                    root.functionRegistry = functionRegistry.inherit();
                }
                catch (e) {
                    return callback(new LessError(e, imports, fileInfo.filename));
                }
                // If `i` is smaller than the `input.length - 1`,
                // it means the parser wasn't able to parse the whole
                // string, so we've got a parsing error.
                //
                // We try to extract a \n delimited string,
                // showing the line where the parse error occurred.
                // We split it up into two parts (the part which parsed,
                // and the part which didn't), so we can color them differently.
                var endInfo = parserInput.end();
                if (!endInfo.isFinished) {
                    var message = endInfo.furthestPossibleErrorMessage;
                    if (!message) {
                        message = 'Unrecognised input';
                        if (endInfo.furthestChar === '}') {
                            message += '. Possibly missing opening \'{\'';
                        }
                        else if (endInfo.furthestChar === ')') {
                            message += '. Possibly missing opening \'(\'';
                        }
                        else if (endInfo.furthestReachedEnd) {
                            message += '. Possibly missing something';
                        }
                    }
                    error = new LessError({
                        type: 'Parse',
                        message: message,
                        index: endInfo.furthest,
                        filename: fileInfo.filename
                    }, imports);
                }
                var finish = function (e) {
                    e = error || e || imports.error;
                    if (e) {
                        if (!(e instanceof LessError)) {
                            e = new LessError(e, imports, fileInfo.filename);
                        }
                        return callback(e);
                    }
                    else {
                        return callback(null, root);
                    }
                };
                if (context.processImports !== false) {
                    new visitors.ImportVisitor(imports, finish)
                        .run(root);
                }
                else {
                    return finish();
                }
            },
            //
            // Here in, the parsing rules/functions
            //
            // The basic structure of the syntax tree generated is as follows:
            //
            //   Ruleset ->  Declaration -> Value -> Expression -> Entity
            //
            // Here's some Less code:
            //
            //    .class {
            //      color: #fff;
            //      border: 1px solid #000;
            //      width: @w + 4px;
            //      > .child {...}
            //    }
            //
            // And here's what the parse tree might look like:
            //
            //     Ruleset (Selector '.class', [
            //         Declaration ("color",  Value ([Expression [Color #fff]]))
            //         Declaration ("border", Value ([Expression [Dimension 1px][Keyword "solid"][Color #000]]))
            //         Declaration ("width",  Value ([Expression [Operation " + " [Variable "@w"][Dimension 4px]]]))
            //         Ruleset (Selector [Element '>', '.child'], [...])
            //     ])
            //
            //  In general, most rules will try to parse a token with the `$re()` function, and if the return
            //  value is truly, will return a new node, of the relevant type. Sometimes, we need to check
            //  first, before parsing, that's when we use `peek()`.
            //
            parsers: parsers = {
                //
                // The `primary` rule is the *entry* and *exit* point of the parser.
                // The rules here can appear at any level of the parse tree.
                //
                // The recursive nature of the grammar is an interplay between the `block`
                // rule, which represents `{ ... }`, the `ruleset` rule, and this `primary` rule,
                // as represented by this simplified grammar:
                //
                //     primary  →  (ruleset | declaration)+
                //     ruleset  →  selector+ block
                //     block    →  '{' primary '}'
                //
                // Only at one point is the primary rule not called from the
                // block rule: at the root level.
                //
                primary: function () {
                    var mixin = this.mixin;
                    var root = [];
                    var node;
                    while (true) {
                        while (true) {
                            node = this.comment();
                            if (!node) {
                                break;
                            }
                            root.push(node);
                        }
                        // always process comments before deciding if finished
                        if (parserInput.finished) {
                            break;
                        }
                        if (parserInput.peek('}')) {
                            break;
                        }
                        node = this.extendRule();
                        if (node) {
                            root = root.concat(node);
                            continue;
                        }
                        node = mixin.definition() || this.declaration() || mixin.call(false, false) ||
                            this.ruleset() || this.variableCall() || this.entities.call() || this.atrule();
                        if (node) {
                            root.push(node);
                        }
                        else {
                            var foundSemiColon = false;
                            while (parserInput.$char(';')) {
                                foundSemiColon = true;
                            }
                            if (!foundSemiColon) {
                                break;
                            }
                        }
                    }
                    return root;
                },
                // comments are collected by the main parsing mechanism and then assigned to nodes
                // where the current structure allows it
                comment: function () {
                    if (parserInput.commentStore.length) {
                        var comment = parserInput.commentStore.shift();
                        return new (tree.Comment)(comment.text, comment.isLineComment, comment.index, fileInfo);
                    }
                },
                //
                // Entities are tokens which can be found inside an Expression
                //
                entities: {
                    mixinLookup: function () {
                        return parsers.mixin.call(true, true);
                    },
                    //
                    // A string, which supports escaping " and '
                    //
                    //     "milky way" 'he\'s the one!'
                    //
                    quoted: function (forceEscaped) {
                        var str;
                        var index = parserInput.i;
                        var isEscaped = false;
                        parserInput.save();
                        if (parserInput.$char('~')) {
                            isEscaped = true;
                        }
                        else if (forceEscaped) {
                            parserInput.restore();
                            return;
                        }
                        str = parserInput.$quoted();
                        if (!str) {
                            parserInput.restore();
                            return;
                        }
                        parserInput.forget();
                        return new (tree.Quoted)(str.charAt(0), str.substr(1, str.length - 2), isEscaped, index, fileInfo);
                    },
                    //
                    // A catch-all word, such as:
                    //
                    //     black border-collapse
                    //
                    keyword: function () {
                        var k = parserInput.$char('%') || parserInput.$re(/^\[?(?:[\w-]|\\(?:[A-Fa-f0-9]{1,6} ?|[^A-Fa-f0-9]))+\]?/);
                        if (k) {
                            return tree.Color.fromKeyword(k) || new (tree.Keyword)(k);
                        }
                    },
                    //
                    // A function call
                    //
                    //     rgb(255, 0, 255)
                    //
                    // The arguments are parsed with the `entities.arguments` parser.
                    //
                    call: function () {
                        var name;
                        var args;
                        var func;
                        var index = parserInput.i;
                        // http://jsperf.com/case-insensitive-regex-vs-strtolower-then-regex/18
                        if (parserInput.peek(/^url\(/i)) {
                            return;
                        }
                        parserInput.save();
                        name = parserInput.$re(/^([\w-]+|%|~|progid:[\w\.]+)\(/);
                        if (!name) {
                            parserInput.forget();
                            return;
                        }
                        name = name[1];
                        func = this.customFuncCall(name);
                        if (func) {
                            args = func.parse();
                            if (args && func.stop) {
                                parserInput.forget();
                                return args;
                            }
                        }
                        args = this.arguments(args);
                        if (!parserInput.$char(')')) {
                            parserInput.restore('Could not parse call arguments or missing \')\'');
                            return;
                        }
                        parserInput.forget();
                        return new (tree.Call)(name, args, index, fileInfo);
                    },
                    //
                    // Parsing rules for functions with non-standard args, e.g.:
                    //
                    //     boolean(not(2 > 1))
                    //
                    //     This is a quick prototype, to be modified/improved when
                    //     more custom-parsed funcs come (e.g. `selector(...)`)
                    //
                    customFuncCall: function (name) {
                        /* Ideally the table is to be moved out of here for faster perf.,
                           but it's quite tricky since it relies on all these `parsers`
                           and `expect` available only here */
                        return {
                            alpha: f(parsers.ieAlpha, true),
                            boolean: f(condition),
                            'if': f(condition)
                        }[name.toLowerCase()];
                        function f(parse, stop) {
                            return {
                                parse: parse,
                                stop: stop // when true - stop after parse() and return its result, 
                                // otherwise continue for plain args
                            };
                        }
                        function condition() {
                            return [expect(parsers.condition, 'expected condition')];
                        }
                    },
                    arguments: function (prevArgs) {
                        var argsComma = prevArgs || [];
                        var argsSemiColon = [];
                        var isSemiColonSeparated;
                        var value;
                        parserInput.save();
                        while (true) {
                            if (prevArgs) {
                                prevArgs = false;
                            }
                            else {
                                value = parsers.detachedRuleset() || this.assignment() || parsers.expression();
                                if (!value) {
                                    break;
                                }
                                if (value.value && value.value.length == 1) {
                                    value = value.value[0];
                                }
                                argsComma.push(value);
                            }
                            if (parserInput.$char(',')) {
                                continue;
                            }
                            if (parserInput.$char(';') || isSemiColonSeparated) {
                                isSemiColonSeparated = true;
                                value = (argsComma.length < 1) ? argsComma[0]
                                    : new tree.Value(argsComma);
                                argsSemiColon.push(value);
                                argsComma = [];
                            }
                        }
                        parserInput.forget();
                        return isSemiColonSeparated ? argsSemiColon : argsComma;
                    },
                    literal: function () {
                        return this.dimension() ||
                            this.color() ||
                            this.quoted() ||
                            this.unicodeDescriptor();
                    },
                    // Assignments are argument entities for calls.
                    // They are present in ie filter properties as shown below.
                    //
                    //     filter: progid:DXImageTransform.Microsoft.Alpha( *opacity=50* )
                    //
                    assignment: function () {
                        var key;
                        var value;
                        parserInput.save();
                        key = parserInput.$re(/^\w+(?=\s?=)/i);
                        if (!key) {
                            parserInput.restore();
                            return;
                        }
                        if (!parserInput.$char('=')) {
                            parserInput.restore();
                            return;
                        }
                        value = parsers.entity();
                        if (value) {
                            parserInput.forget();
                            return new (tree.Assignment)(key, value);
                        }
                        else {
                            parserInput.restore();
                        }
                    },
                    //
                    // Parse url() tokens
                    //
                    // We use a specific rule for urls, because they don't really behave like
                    // standard function calls. The difference is that the argument doesn't have
                    // to be enclosed within a string, so it can't be parsed as an Expression.
                    //
                    url: function () {
                        var value;
                        var index = parserInput.i;
                        parserInput.autoCommentAbsorb = false;
                        if (!parserInput.$str('url(')) {
                            parserInput.autoCommentAbsorb = true;
                            return;
                        }
                        value = this.quoted() || this.variable() || this.property() ||
                            parserInput.$re(/^(?:(?:\\['"])|[^'"])+/) || '';
                        parserInput.autoCommentAbsorb = true;
                        expectChar(')');
                        return new (tree.URL)((value.value != null ||
                            value instanceof tree.Variable ||
                            value instanceof tree.Property) ?
                            value : new (tree.Anonymous)(value, index), index, fileInfo);
                    },
                    //
                    // A Variable entity, such as `@fink`, in
                    //
                    //     width: @fink + 2px
                    //
                    // We use a different parser for variable definitions,
                    // see `parsers.variable`.
                    //
                    variable: function () {
                        var ch;
                        var name;
                        var index = parserInput.i;
                        parserInput.save();
                        if (parserInput.currentChar() === '@' && (name = parserInput.$re(/^@@?[\w-]+/))) {
                            ch = parserInput.currentChar();
                            if (ch === '(' || ch === '[' && !parserInput.prevChar().match(/^\s/)) {
                                // this may be a VariableCall lookup
                                var result = parsers.variableCall(name);
                                if (result) {
                                    parserInput.forget();
                                    return result;
                                }
                            }
                            parserInput.forget();
                            return new (tree.Variable)(name, index, fileInfo);
                        }
                        parserInput.restore();
                    },
                    // A variable entity using the protective {} e.g. @{var}
                    variableCurly: function () {
                        var curly;
                        var index = parserInput.i;
                        if (parserInput.currentChar() === '@' && (curly = parserInput.$re(/^@\{([\w-]+)\}/))) {
                            return new (tree.Variable)("@" + curly[1], index, fileInfo);
                        }
                    },
                    //
                    // A Property accessor, such as `$color`, in
                    //
                    //     background-color: $color
                    //
                    property: function () {
                        var name;
                        var index = parserInput.i;
                        if (parserInput.currentChar() === '$' && (name = parserInput.$re(/^\$[\w-]+/))) {
                            return new (tree.Property)(name, index, fileInfo);
                        }
                    },
                    // A property entity useing the protective {} e.g. ${prop}
                    propertyCurly: function () {
                        var curly;
                        var index = parserInput.i;
                        if (parserInput.currentChar() === '$' && (curly = parserInput.$re(/^\$\{([\w-]+)\}/))) {
                            return new (tree.Property)("$" + curly[1], index, fileInfo);
                        }
                    },
                    //
                    // A Hexadecimal color
                    //
                    //     #4F3C2F
                    //
                    // `rgb` and `hsl` colors are parsed through the `entities.call` parser.
                    //
                    color: function () {
                        var rgb;
                        parserInput.save();
                        if (parserInput.currentChar() === '#' && (rgb = parserInput.$re(/^#([A-Fa-f0-9]{8}|[A-Fa-f0-9]{6}|[A-Fa-f0-9]{3,4})([\w.#\[])?/))) {
                            if (!rgb[2]) {
                                parserInput.forget();
                                return new (tree.Color)(rgb[1], undefined, rgb[0]);
                            }
                        }
                        parserInput.restore();
                    },
                    colorKeyword: function () {
                        parserInput.save();
                        var autoCommentAbsorb = parserInput.autoCommentAbsorb;
                        parserInput.autoCommentAbsorb = false;
                        var k = parserInput.$re(/^[_A-Za-z-][_A-Za-z0-9-]+/);
                        parserInput.autoCommentAbsorb = autoCommentAbsorb;
                        if (!k) {
                            parserInput.forget();
                            return;
                        }
                        parserInput.restore();
                        var color = tree.Color.fromKeyword(k);
                        if (color) {
                            parserInput.$str(k);
                            return color;
                        }
                    },
                    //
                    // A Dimension, that is, a number and a unit
                    //
                    //     0.5em 95%
                    //
                    dimension: function () {
                        if (parserInput.peekNotNumeric()) {
                            return;
                        }
                        var value = parserInput.$re(/^([+-]?\d*\.?\d+)(%|[a-z_]+)?/i);
                        if (value) {
                            return new (tree.Dimension)(value[1], value[2]);
                        }
                    },
                    //
                    // A unicode descriptor, as is used in unicode-range
                    //
                    // U+0??  or U+00A1-00A9
                    //
                    unicodeDescriptor: function () {
                        var ud;
                        ud = parserInput.$re(/^U\+[0-9a-fA-F?]+(\-[0-9a-fA-F?]+)?/);
                        if (ud) {
                            return new (tree.UnicodeDescriptor)(ud[0]);
                        }
                    },
                    //
                    // JavaScript code to be evaluated
                    //
                    //     `window.location.href`
                    //
                    javascript: function () {
                        var js;
                        var index = parserInput.i;
                        parserInput.save();
                        var escape = parserInput.$char('~');
                        var jsQuote = parserInput.$char('`');
                        if (!jsQuote) {
                            parserInput.restore();
                            return;
                        }
                        js = parserInput.$re(/^[^`]*`/);
                        if (js) {
                            parserInput.forget();
                            return new (tree.JavaScript)(js.substr(0, js.length - 1), Boolean(escape), index, fileInfo);
                        }
                        parserInput.restore('invalid javascript definition');
                    }
                },
                //
                // The variable part of a variable definition. Used in the `rule` parser
                //
                //     @fink:
                //
                variable: function () {
                    var name;
                    if (parserInput.currentChar() === '@' && (name = parserInput.$re(/^(@[\w-]+)\s*:/))) {
                        return name[1];
                    }
                },
                //
                // Call a variable value to retrieve a detached ruleset
                // or a value from a detached ruleset's rules.
                //
                //     @fink();
                //     @fink;
                //     color: @fink[@color];
                //
                variableCall: function (parsedName) {
                    var lookups;
                    var i = parserInput.i;
                    var inValue = !!parsedName;
                    var name = parsedName;
                    parserInput.save();
                    if (name || (parserInput.currentChar() === '@'
                        && (name = parserInput.$re(/^(@[\w-]+)($\s*$)?/)))) {
                        lookups = this.mixin.ruleLookups();
                        if (!lookups && ((inValue && parserInput.$str('()') !== '()') || (name[2] !== '()'))) {
                            parserInput.restore('Missing \'[...]\' lookup in variable call');
                            return;
                        }
                        if (!inValue) {
                            name = name[1];
                        }
                        var call = new tree.VariableCall(name, i, fileInfo);
                        if (!inValue && parsers.end()) {
                            parserInput.forget();
                            return call;
                        }
                        else {
                            parserInput.forget();
                            return new tree.NamespaceValue(call, lookups, i, fileInfo);
                        }
                    }
                    parserInput.restore();
                },
                //
                // extend syntax - used to extend selectors
                //
                extend: function (isRule) {
                    var elements;
                    var e;
                    var index = parserInput.i;
                    var option;
                    var extendList;
                    var extend;
                    if (!parserInput.$str(isRule ? '&:extend(' : ':extend(')) {
                        return;
                    }
                    do {
                        option = null;
                        elements = null;
                        while (!(option = parserInput.$re(/^(all)(?=\s*(\)|,))/))) {
                            e = this.element();
                            if (!e) {
                                break;
                            }
                            if (elements) {
                                elements.push(e);
                            }
                            else {
                                elements = [e];
                            }
                        }
                        option = option && option[1];
                        if (!elements) {
                            error('Missing target selector for :extend().');
                        }
                        extend = new (tree.Extend)(new (tree.Selector)(elements), option, index, fileInfo);
                        if (extendList) {
                            extendList.push(extend);
                        }
                        else {
                            extendList = [extend];
                        }
                    } while (parserInput.$char(','));
                    expect(/^\)/);
                    if (isRule) {
                        expect(/^;/);
                    }
                    return extendList;
                },
                //
                // extendRule - used in a rule to extend all the parent selectors
                //
                extendRule: function () {
                    return this.extend(true);
                },
                //
                // Mixins
                //
                mixin: {
                    //
                    // A Mixin call, with an optional argument list
                    //
                    //     #mixins > .square(#fff);
                    //     #mixins.square(#fff);
                    //     .rounded(4px, black);
                    //     .button;
                    //
                    // We can lookup / return a value using the lookup syntax:
                    //
                    //     color: #mixin.square(#fff)[@color];
                    //
                    // The `while` loop is there because mixins can be
                    // namespaced, but we only support the child and descendant
                    // selector for now.
                    //
                    call: function (inValue, getLookup) {
                        var s = parserInput.currentChar();
                        var important = false;
                        var lookups;
                        var index = parserInput.i;
                        var elements;
                        var args;
                        var hasParens;
                        if (s !== '.' && s !== '#') {
                            return;
                        }
                        parserInput.save(); // stop us absorbing part of an invalid selector
                        elements = this.elements();
                        if (elements) {
                            if (parserInput.$char('(')) {
                                args = this.args(true).args;
                                expectChar(')');
                                hasParens = true;
                            }
                            if (getLookup !== false) {
                                lookups = this.ruleLookups();
                            }
                            if (getLookup === true && !lookups) {
                                parserInput.restore();
                                return;
                            }
                            if (inValue && !lookups && !hasParens) {
                                // This isn't a valid in-value mixin call
                                parserInput.restore();
                                return;
                            }
                            if (!inValue && parsers.important()) {
                                important = true;
                            }
                            if (inValue || parsers.end()) {
                                parserInput.forget();
                                var mixin = new (tree.mixin.Call)(elements, args, index, fileInfo, !lookups && important);
                                if (lookups) {
                                    return new tree.NamespaceValue(mixin, lookups);
                                }
                                else {
                                    return mixin;
                                }
                            }
                        }
                        parserInput.restore();
                    },
                    /**
                     * Matching elements for mixins
                     * (Start with . or # and can have > )
                     */
                    elements: function () {
                        var elements;
                        var e;
                        var c;
                        var elem;
                        var elemIndex;
                        var re = /^[#.](?:[\w-]|\\(?:[A-Fa-f0-9]{1,6} ?|[^A-Fa-f0-9]))+/;
                        while (true) {
                            elemIndex = parserInput.i;
                            e = parserInput.$re(re);
                            if (!e) {
                                break;
                            }
                            elem = new (tree.Element)(c, e, false, elemIndex, fileInfo);
                            if (elements) {
                                elements.push(elem);
                            }
                            else {
                                elements = [elem];
                            }
                            c = parserInput.$char('>');
                        }
                        return elements;
                    },
                    args: function (isCall) {
                        var entities = parsers.entities;
                        var returner = { args: null, variadic: false };
                        var expressions = [];
                        var argsSemiColon = [];
                        var argsComma = [];
                        var isSemiColonSeparated;
                        var expressionContainsNamed;
                        var name;
                        var nameLoop;
                        var value;
                        var arg;
                        var expand;
                        var hasSep = true;
                        parserInput.save();
                        while (true) {
                            if (isCall) {
                                arg = parsers.detachedRuleset() || parsers.expression();
                            }
                            else {
                                parserInput.commentStore.length = 0;
                                if (parserInput.$str('...')) {
                                    returner.variadic = true;
                                    if (parserInput.$char(';') && !isSemiColonSeparated) {
                                        isSemiColonSeparated = true;
                                    }
                                    (isSemiColonSeparated ? argsSemiColon : argsComma)
                                        .push({ variadic: true });
                                    break;
                                }
                                arg = entities.variable() || entities.property() || entities.literal() || entities.keyword() || this.call(true);
                            }
                            if (!arg || !hasSep) {
                                break;
                            }
                            nameLoop = null;
                            if (arg.throwAwayComments) {
                                arg.throwAwayComments();
                            }
                            value = arg;
                            var val = null;
                            if (isCall) {
                                // Variable
                                if (arg.value && arg.value.length == 1) {
                                    val = arg.value[0];
                                }
                            }
                            else {
                                val = arg;
                            }
                            if (val && (val instanceof tree.Variable || val instanceof tree.Property)) {
                                if (parserInput.$char(':')) {
                                    if (expressions.length > 0) {
                                        if (isSemiColonSeparated) {
                                            error('Cannot mix ; and , as delimiter types');
                                        }
                                        expressionContainsNamed = true;
                                    }
                                    value = parsers.detachedRuleset() || parsers.expression();
                                    if (!value) {
                                        if (isCall) {
                                            error('could not understand value for named argument');
                                        }
                                        else {
                                            parserInput.restore();
                                            returner.args = [];
                                            return returner;
                                        }
                                    }
                                    nameLoop = (name = val.name);
                                }
                                else if (parserInput.$str('...')) {
                                    if (!isCall) {
                                        returner.variadic = true;
                                        if (parserInput.$char(';') && !isSemiColonSeparated) {
                                            isSemiColonSeparated = true;
                                        }
                                        (isSemiColonSeparated ? argsSemiColon : argsComma)
                                            .push({ name: arg.name, variadic: true });
                                        break;
                                    }
                                    else {
                                        expand = true;
                                    }
                                }
                                else if (!isCall) {
                                    name = nameLoop = val.name;
                                    value = null;
                                }
                            }
                            if (value) {
                                expressions.push(value);
                            }
                            argsComma.push({ name: nameLoop, value: value, expand: expand });
                            if (parserInput.$char(',')) {
                                hasSep = true;
                                continue;
                            }
                            hasSep = parserInput.$char(';') === ';';
                            if (hasSep || isSemiColonSeparated) {
                                if (expressionContainsNamed) {
                                    error('Cannot mix ; and , as delimiter types');
                                }
                                isSemiColonSeparated = true;
                                if (expressions.length > 1) {
                                    value = new (tree.Value)(expressions);
                                }
                                argsSemiColon.push({ name: name, value: value, expand: expand });
                                name = null;
                                expressions = [];
                                expressionContainsNamed = false;
                            }
                        }
                        parserInput.forget();
                        returner.args = isSemiColonSeparated ? argsSemiColon : argsComma;
                        return returner;
                    },
                    //
                    // A Mixin definition, with a list of parameters
                    //
                    //     .rounded (@radius: 2px, @color) {
                    //        ...
                    //     }
                    //
                    // Until we have a finer grained state-machine, we have to
                    // do a look-ahead, to make sure we don't have a mixin call.
                    // See the `rule` function for more information.
                    //
                    // We start by matching `.rounded (`, and then proceed on to
                    // the argument list, which has optional default values.
                    // We store the parameters in `params`, with a `value` key,
                    // if there is a value, such as in the case of `@radius`.
                    //
                    // Once we've got our params list, and a closing `)`, we parse
                    // the `{...}` block.
                    //
                    definition: function () {
                        var name;
                        var params = [];
                        var match;
                        var ruleset;
                        var cond;
                        var variadic = false;
                        if ((parserInput.currentChar() !== '.' && parserInput.currentChar() !== '#') ||
                            parserInput.peek(/^[^{]*\}/)) {
                            return;
                        }
                        parserInput.save();
                        match = parserInput.$re(/^([#.](?:[\w-]|\\(?:[A-Fa-f0-9]{1,6} ?|[^A-Fa-f0-9]))+)\s*\(/);
                        if (match) {
                            name = match[1];
                            var argInfo = this.args(false);
                            params = argInfo.args;
                            variadic = argInfo.variadic;
                            // .mixincall("@{a}");
                            // looks a bit like a mixin definition..
                            // also
                            // .mixincall(@a: {rule: set;});
                            // so we have to be nice and restore
                            if (!parserInput.$char(')')) {
                                parserInput.restore('Missing closing \')\'');
                                return;
                            }
                            parserInput.commentStore.length = 0;
                            if (parserInput.$str('when')) { // Guard
                                cond = expect(parsers.conditions, 'expected condition');
                            }
                            ruleset = parsers.block();
                            if (ruleset) {
                                parserInput.forget();
                                return new (tree.mixin.Definition)(name, params, ruleset, cond, variadic);
                            }
                            else {
                                parserInput.restore();
                            }
                        }
                        else {
                            parserInput.restore();
                        }
                    },
                    ruleLookups: function () {
                        var rule;
                        var lookups = [];
                        if (parserInput.currentChar() !== '[') {
                            return;
                        }
                        while (true) {
                            parserInput.save();
                            rule = this.lookupValue();
                            if (!rule && rule !== '') {
                                parserInput.restore();
                                break;
                            }
                            lookups.push(rule);
                            parserInput.forget();
                        }
                        if (lookups.length > 0) {
                            return lookups;
                        }
                    },
                    lookupValue: function () {
                        parserInput.save();
                        if (!parserInput.$char('[')) {
                            parserInput.restore();
                            return;
                        }
                        var name = parserInput.$re(/^(?:[@$]{0,2})[_a-zA-Z0-9-]*/);
                        if (!parserInput.$char(']')) {
                            parserInput.restore();
                            return;
                        }
                        if (name || name === '') {
                            parserInput.forget();
                            return name;
                        }
                        parserInput.restore();
                    }
                },
                //
                // Entities are the smallest recognized token,
                // and can be found inside a rule's value.
                //
                entity: function () {
                    var entities = this.entities;
                    return this.comment() || entities.literal() || entities.variable() || entities.url() ||
                        entities.property() || entities.call() || entities.keyword() || this.mixin.call(true) ||
                        entities.javascript();
                },
                //
                // A Declaration terminator. Note that we use `peek()` to check for '}',
                // because the `block` rule will be expecting it, but we still need to make sure
                // it's there, if ';' was omitted.
                //
                end: function () {
                    return parserInput.$char(';') || parserInput.peek('}');
                },
                //
                // IE's alpha function
                //
                //     alpha(opacity=88)
                //
                ieAlpha: function () {
                    var value;
                    // http://jsperf.com/case-insensitive-regex-vs-strtolower-then-regex/18
                    if (!parserInput.$re(/^opacity=/i)) {
                        return;
                    }
                    value = parserInput.$re(/^\d+/);
                    if (!value) {
                        value = expect(parsers.entities.variable, 'Could not parse alpha');
                        value = "@{" + value.name.slice(1) + "}";
                    }
                    expectChar(')');
                    return new tree.Quoted('', "alpha(opacity=" + value + ")");
                },
                //
                // A Selector Element
                //
                //     div
                //     + h1
                //     #socks
                //     input[type="text"]
                //
                // Elements are the building blocks for Selectors,
                // they are made out of a `Combinator` (see combinator rule),
                // and an element name, such as a tag a class, or `*`.
                //
                element: function () {
                    var e;
                    var c;
                    var v;
                    var index = parserInput.i;
                    c = this.combinator();
                    e = parserInput.$re(/^(?:\d+\.\d+|\d+)%/) ||
                        parserInput.$re(/^(?:[.#]?|:*)(?:[\w-]|[^\x00-\x9f]|\$?:[A-Fa-f0-9]{1,6} ?|[^A-Fa-f0-9]))+/) ||
                        parserInput.$char('*') || parserInput.$char('&') || this.attribute() ||
                        parserInput.$re(/^\([^&()@]+$/) || parserInput.$re(/^[\.#:](?=@)/) ||
                        this.entities.variableCurly();
                    if (!e) {
                        parserInput.save();
                        if (parserInput.$char('(')) {
                            if ((v = this.selector(false)) && parserInput.$char(')')) {
                                e = new (tree.Paren)(v);
                                parserInput.forget();
                            }
                            else {
                                parserInput.restore('Missing closing \')\'');
                            }
                        }
                        else {
                            parserInput.forget();
                        }
                    }
                    if (e) {
                        return new (tree.Element)(c, e, e instanceof tree.Variable, index, fileInfo);
                    }
                },
                //
                // Combinators combine elements together, in a Selector.
                //
                // Because our parser isn't white-space sensitive, special care
                // has to be taken, when parsing the descendant combinator, ` `,
                // as it's an empty space. We have to check the previous character
                // in the input, to see if it's a ` ` character. More info on how
                // we deal with this in *combinator.js*.
                //
                combinator: function () {
                    var c = parserInput.currentChar();
                    if (c === '/') {
                        parserInput.save();
                        var slashedCombinator = parserInput.$re(/^\/[a-z]+\//i);
                        if (slashedCombinator) {
                            parserInput.forget();
                            return new (tree.Combinator)(slashedCombinator);
                        }
                        parserInput.restore();
                    }
                    if (c === '>' || c === '+' || c === '~' || c === '|' || c === '^') {
                        parserInput.i++;
                        if (c === '^' && parserInput.currentChar() === '^') {
                            c = '^^';
                            parserInput.i++;
                        }
                        while (parserInput.isWhitespace()) {
                            parserInput.i++;
                        }
                        return new (tree.Combinator)(c);
                    }
                    else if (parserInput.isWhitespace(-1)) {
                        return new (tree.Combinator)(' ');
                    }
                    else {
                        return new (tree.Combinator)(null);
                    }
                },
                //
                // A CSS Selector
                // with less extensions e.g. the ability to extend and guard
                //
                //     .class > div + h1
                //     li a:hover
                //
                // Selectors are made out of one or more Elements, see above.
                //
                selector: function (isLess) {
                    var index = parserInput.i;
                    var elements;
                    var extendList;
                    var c;
                    var e;
                    var allExtends;
                    var when;
                    var condition;
                    isLess = isLess !== false;
                    while ((isLess && (extendList = this.extend())) || (isLess && (when = parserInput.$str('when'))) || (e = this.element())) {
                        if (when) {
                            condition = expect(this.conditions, 'expected condition');
                        }
                        else if (condition) {
                            error('CSS guard can only be used at the end of selector');
                        }
                        else if (extendList) {
                            if (allExtends) {
                                allExtends = allExtends.concat(extendList);
                            }
                            else {
                                allExtends = extendList;
                            }
                        }
                        else {
                            if (allExtends) {
                                error('Extend can only be used at the end of selector');
                            }
                            c = parserInput.currentChar();
                            if (elements) {
                                elements.push(e);
                            }
                            else {
                                elements = [e];
                            }
                            e = null;
                        }
                        if (c === '{' || c === '}' || c === ';' || c === ',' || c === ')') {
                            break;
                        }
                    }
                    if (elements) {
                        return new (tree.Selector)(elements, allExtends, condition, index, fileInfo);
                    }
                    if (allExtends) {
                        error('Extend must be used to extend a selector, it cannot be used on its own');
                    }
                },
                selectors: function () {
                    var s;
                    var selectors;
                    while (true) {
                        s = this.selector();
                        if (!s) {
                            break;
                        }
                        if (selectors) {
                            selectors.push(s);
                        }
                        else {
                            selectors = [s];
                        }
                        parserInput.commentStore.length = 0;
                        if (s.condition && selectors.length > 1) {
                            error("Guards are only currently allowed on a single selector.");
                        }
                        if (!parserInput.$char(',')) {
                            break;
                        }
                        if (s.condition) {
                            error("Guards are only currently allowed on a single selector.");
                        }
                        parserInput.commentStore.length = 0;
                    }
                    return selectors;
                },
                attribute: function () {
                    if (!parserInput.$char('[')) {
                        return;
                    }
                    var entities = this.entities;
                    var key;
                    var val;
                    var op;
                    if (!(key = entities.variableCurly())) {
                        key = expect(/^(?:[_A-Za-z0-9-\*]*\|)?(?:[_A-Za-z0-9-]|\\.)+/);
                    }
                    op = parserInput.$re(/^[|~*$^]?=/);
                    if (op) {
                        val = entities.quoted() || parserInput.$re(/^[0-9]+%/) || parserInput.$re(/^[\w-]+/) || entities.variableCurly();
                    }
                    expectChar(']');
                    return new (tree.Attribute)(key, op, val);
                },
                //
                // The `block` rule is used by `ruleset` and `mixin.definition`.
                // It's a wrapper around the `primary` rule, with added `{}`.
                //
                block: function () {
                    var content;
                    if (parserInput.$char('{') && (content = this.primary()) && parserInput.$char('}')) {
                        return content;
                    }
                },
                blockRuleset: function () {
                    var block = this.block();
                    if (block) {
                        block = new tree.Ruleset(null, block);
                    }
                    return block;
                },
                detachedRuleset: function () {
                    var argInfo;
                    var params;
                    var variadic;
                    parserInput.save();
                    if (parserInput.$re(/^[.#]\(/)) {
                        /**
                         * DR args currently only implemented for each() function, and not
                         * yet settable as `@dr: #(@arg) {}`
                         * This should be done when DRs are merged with mixins.
                         * See: https://github.com/less/less-meta/issues/16
                         */
                        argInfo = this.mixin.args(false);
                        params = argInfo.args;
                        variadic = argInfo.variadic;
                        if (!parserInput.$char(')')) {
                            parserInput.restore();
                            return;
                        }
                    }
                    var blockRuleset = this.blockRuleset();
                    if (blockRuleset) {
                        parserInput.forget();
                        if (params) {
                            return new tree.mixin.Definition(null, params, blockRuleset, null, variadic);
                        }
                        return new tree.DetachedRuleset(blockRuleset);
                    }
                    parserInput.restore();
                },
                //
                // div, .class, body > p {...}
                //
                ruleset: function () {
                    var selectors;
                    var rules;
                    var debugInfo;
                    parserInput.save();
                    if (context.dumpLineNumbers) {
                        debugInfo = getDebugInfo(parserInput.i);
                    }
                    selectors = this.selectors();
                    if (selectors && (rules = this.block())) {
                        parserInput.forget();
                        var ruleset = new (tree.Ruleset)(selectors, rules, context.strictImports);
                        if (context.dumpLineNumbers) {
                            ruleset.debugInfo = debugInfo;
                        }
                        return ruleset;
                    }
                    else {
                        parserInput.restore();
                    }
                },
                declaration: function () {
                    var name;
                    var value;
                    var index = parserInput.i;
                    var hasDR;
                    var c = parserInput.currentChar();
                    var important;
                    var merge;
                    var isVariable;
                    if (c === '.' || c === '#' || c === '&' || c === ':') {
                        return;
                    }
                    parserInput.save();
                    name = this.variable() || this.ruleProperty();
                    if (name) {
                        isVariable = typeof name === 'string';
                        if (isVariable) {
                            value = this.detachedRuleset();
                            if (value) {
                                hasDR = true;
                            }
                        }
                        parserInput.commentStore.length = 0;
                        if (!value) {
                            // a name returned by this.ruleProperty() is always an array of the form:
                            // [string-1, ..., string-n, ""] or [string-1, ..., string-n, "+"]
                            // where each item is a tree.Keyword or tree.Variable
                            merge = !isVariable && name.length > 1 && name.pop().value;
                            // Custom property values get permissive parsing
                            if (name[0].value && name[0].value.slice(0, 2) === '--') {
                                value = this.permissiveValue();
                            }
                            // Try to store values as anonymous
                            // If we need the value later we'll re-parse it in ruleset.parseValue
                            else {
                                value = this.anonymousValue();
                            }
                            if (value) {
                                parserInput.forget();
                                // anonymous values absorb the end ';' which is required for them to work
                                return new (tree.Declaration)(name, value, false, merge, index, fileInfo);
                            }
                            if (!value) {
                                value = this.value();
                            }
                            if (value) {
                                important = this.important();
                            }
                            else if (isVariable) {
                                // As a last resort, try permissiveValue
                                value = this.permissiveValue();
                            }
                        }
                        if (value && (this.end() || hasDR)) {
                            parserInput.forget();
                            return new (tree.Declaration)(name, value, important, merge, index, fileInfo);
                        }
                        else {
                            parserInput.restore();
                        }
                    }
                    else {
                        parserInput.restore();
                    }
                },
                anonymousValue: function () {
                    var index = parserInput.i;
                    var match = parserInput.$re(/^([^.#@\$+\/'"*`(;{}-]*);/);
                    if (match) {
                        return new (tree.Anonymous)(match[1], index);
                    }
                },
                /**
                 * Used for custom properties, at-rules, and variables (as fallback)
                 * Parses almost anything inside of {} [] () "" blocks
                 * until it reaches outer-most tokens.
                 *
                 * First, it will try to parse comments and entities to reach
                 * the end. This is mostly like the Expression parser except no
                 * math is allowed.
                 */
                permissiveValue: function (untilTokens) {
                    var i;
                    var e;
                    var done;
                    var value;
                    var tok = untilTokens || ';';
                    var index = parserInput.i;
                    var result = [];
                    function testCurrentChar() {
                        var char = parserInput.currentChar();
                        if (typeof tok === 'string') {
                            return char === tok;
                        }
                        else {
                            return tok.test(char);
                        }
                    }
                    if (testCurrentChar()) {
                        return;
                    }
                    value = [];
                    do {
                        e = this.comment();
                        if (e) {
                            value.push(e);
                            continue;
                        }
                        e = this.entity();
                        if (e) {
                            value.push(e);
                        }
                    } while (e);
                    done = testCurrentChar();
                    if (value.length > 0) {
                        value = new (tree.Expression)(value);
                        if (done) {
                            return value;
                        }
                        else {
                            result.push(value);
                        }
                        // Preserve space before $parseUntil as it will not
                        if (parserInput.prevChar() === ' ') {
                            result.push(new tree.Anonymous(' ', index));
                        }
                    }
                    parserInput.save();
                    value = parserInput.$parseUntil(tok);
                    if (value) {
                        if (typeof value === 'string') {
                            error("Expected '" + value + "'", 'Parse');
                        }
                        if (value.length === 1 && value[0] === ' ') {
                            parserInput.forget();
                            return new tree.Anonymous('', index);
                        }
                        var item = void 0;
                        for (i = 0; i < value.length; i++) {
                            item = value[i];
                            if (Array.isArray(item)) {
                                // Treat actual quotes as normal quoted values
                                result.push(new tree.Quoted(item[0], item[1], true, index, fileInfo));
                            }
                            else {
                                if (i === value.length - 1) {
                                    item = item.trim();
                                }
                                // Treat like quoted values, but replace vars like unquoted expressions
                                var quote = new tree.Quoted('\'', item, true, index, fileInfo);
                                quote.variableRegex = /@([\w-]+)/g;
                                quote.propRegex = /\$([\w-]+)/g;
                                result.push(quote);
                            }
                        }
                        parserInput.forget();
                        return new tree.Expression(result, true);
                    }
                    parserInput.restore();
                },
                //
                // An @import atrule
                //
                //     @import "lib";
                //
                // Depending on our environment, importing is done differently:
                // In the browser, it's an XHR request, in Node, it would be a
                // file-system operation. The function used for importing is
                // stored in `import`, which we pass to the Import constructor.
                //
                'import': function () {
                    var path;
                    var features;
                    var index = parserInput.i;
                    var dir = parserInput.$re(/^@import?\s+/);
                    if (dir) {
                        var options = (dir ? this.importOptions() : null) || {};
                        if ((path = this.entities.quoted() || this.entities.url())) {
                            features = this.mediaFeatures();
                            if (!parserInput.$char(';')) {
                                parserInput.i = index;
                                error('missing semi-colon or unrecognised media features on import');
                            }
                            features = features && new (tree.Value)(features);
                            return new (tree.Import)(path, features, options, index, fileInfo);
                        }
                        else {
                            parserInput.i = index;
                            error('malformed import statement');
                        }
                    }
                },
                importOptions: function () {
                    var o;
                    var options = {};
                    var optionName;
                    var value;
                    // list of options, surrounded by parens
                    if (!parserInput.$char('(')) {
                        return null;
                    }
                    do {
                        o = this.importOption();
                        if (o) {
                            optionName = o;
                            value = true;
                            switch (optionName) {
                                case 'css':
                                    optionName = 'less';
                                    value = false;
                                    break;
                                case 'once':
                                    optionName = 'multiple';
                                    value = false;
                                    break;
                            }
                            options[optionName] = value;
                            if (!parserInput.$char(',')) {
                                break;
                            }
                        }
                    } while (o);
                    expectChar(')');
                    return options;
                },
                importOption: function () {
                    var opt = parserInput.$re(/^(less|css|multiple|once|inline|reference|optional)/);
                    if (opt) {
                        return opt[1];
                    }
                },
                mediaFeature: function () {
                    var entities = this.entities;
                    var nodes = [];
                    var e;
                    var p;
                    parserInput.save();
                    do {
                        e = entities.keyword() || entities.variable() || entities.mixinLookup();
                        if (e) {
                            nodes.push(e);
                        }
                        else if (parserInput.$char('(')) {
                            p = this.property();
                            e = this.value();
                            if (parserInput.$char(')')) {
                                if (p && e) {
                                    nodes.push(new (tree.Paren)(new (tree.Declaration)(p, e, null, null, parserInput.i, fileInfo, true)));
                                }
                                else if (e) {
                                    nodes.push(new (tree.Paren)(e));
                                }
                                else {
                                    error('badly formed media feature definition');
                                }
                            }
                            else {
                                error('Missing closing \')\'', 'Parse');
                            }
                        }
                    } while (e);
                    parserInput.forget();
                    if (nodes.length > 0) {
                        return new (tree.Expression)(nodes);
                    }
                },
                mediaFeatures: function () {
                    var entities = this.entities;
                    var features = [];
                    var e;
                    do {
                        e = this.mediaFeature();
                        if (e) {
                            features.push(e);
                            if (!parserInput.$char(',')) {
                                break;
                            }
                        }
                        else {
                            e = entities.variable() || entities.mixinLookup();
                            if (e) {
                                features.push(e);
                                if (!parserInput.$char(',')) {
                                    break;
                                }
                            }
                        }
                    } while (e);
                    return features.length > 0 ? features : null;
                },
                media: function () {
                    var features;
                    var rules;
                    var media;
                    var debugInfo;
                    var index = parserInput.i;
                    if (context.dumpLineNumbers) {
                        debugInfo = getDebugInfo(index);
                    }
                    parserInput.save();
                    if (parserInput.$str('@media')) {
                        features = this.mediaFeatures();
                        rules = this.block();
                        if (!rules) {
                            error('media definitions require block statements after any features');
                        }
                        parserInput.forget();
                        media = new (tree.Media)(rules, features, index, fileInfo);
                        if (context.dumpLineNumbers) {
                            media.debugInfo = debugInfo;
                        }
                        return media;
                    }
                    parserInput.restore();
                },
                //
                // A @plugin directive, used to import plugins dynamically.
                //
                //     @plugin (args) "lib";
                //
                plugin: function () {
                    var path;
                    var args;
                    var options;
                    var index = parserInput.i;
                    var dir = parserInput.$re(/^@plugin?\s+/);
                    if (dir) {
                        args = this.pluginArgs();
                        if (args) {
                            options = {
                                pluginArgs: args,
                                isPlugin: true
                            };
                        }
                        else {
                            options = { isPlugin: true };
                        }
                        if ((path = this.entities.quoted() || this.entities.url())) {
                            if (!parserInput.$char(';')) {
                                parserInput.i = index;
                                error('missing semi-colon on @plugin');
                            }
                            return new (tree.Import)(path, null, options, index, fileInfo);
                        }
                        else {
                            parserInput.i = index;
                            error('malformed @plugin statement');
                        }
                    }
                },
                pluginArgs: function () {
                    // list of options, surrounded by parens
                    parserInput.save();
                    if (!parserInput.$char('(')) {
                        parserInput.restore();
                        return null;
                    }
                    var args = parserInput.$re(/^\s*([^\);]+)\)\s*/);
                    if (args[1]) {
                        parserInput.forget();
                        return args[1].trim();
                    }
                    else {
                        parserInput.restore();
                        return null;
                    }
                },
                //
                // A CSS AtRule
                //
                //     @charset "utf-8";
                //
                atrule: function () {
                    var index = parserInput.i;
                    var name;
                    var value;
                    var rules;
                    var nonVendorSpecificName;
                    var hasIdentifier;
                    var hasExpression;
                    var hasUnknown;
                    var hasBlock = true;
                    var isRooted = true;
                    if (parserInput.currentChar() !== '@') {
                        return;
                    }
                    value = this['import']() || this.plugin() || this.media();
                    if (value) {
                        return value;
                    }
                    parserInput.save();
                    name = parserInput.$re(/^@[a-z-]+/);
                    if (!name) {
                        return;
                    }
                    nonVendorSpecificName = name;
                    if (name.charAt(1) == '-' && name.indexOf('-', 2) > 0) {
                        nonVendorSpecificName = "@" + name.slice(name.indexOf('-', 2) + 1);
                    }
                    switch (nonVendorSpecificName) {
                        case '@charset':
                            hasIdentifier = true;
                            hasBlock = false;
                            break;
                        case '@namespace':
                            hasExpression = true;
                            hasBlock = false;
                            break;
                        case '@keyframes':
                        case '@counter-style':
                            hasIdentifier = true;
                            break;
                        case '@document':
                        case '@supports':
                            hasUnknown = true;
                            isRooted = false;
                            break;
                        default:
                            hasUnknown = true;
                            break;
                    }
                    parserInput.commentStore.length = 0;
                    if (hasIdentifier) {
                        value = this.entity();
                        if (!value) {
                            error("expected " + name + " identifier");
                        }
                    }
                    else if (hasExpression) {
                        value = this.expression();
                        if (!value) {
                            error("expected " + name + " expression");
                        }
                    }
                    else if (hasUnknown) {
                        value = this.permissiveValue(/^[{;]/);
                        hasBlock = (parserInput.currentChar() === '{');
                        if (!value) {
                            if (!hasBlock && parserInput.currentChar() !== ';') {
                                error(name + " rule is missing block or ending semi-colon");
                            }
                        }
                        else if (!value.value) {
                            value = null;
                        }
                    }
                    if (hasBlock) {
                        rules = this.blockRuleset();
                    }
                    if (rules || (!hasBlock && value && parserInput.$char(';'))) {
                        parserInput.forget();
                        return new (tree.AtRule)(name, value, rules, index, fileInfo, context.dumpLineNumbers ? getDebugInfo(index) : null, isRooted);
                    }
                    parserInput.restore('at-rule options not recognised');
                },
                //
                // A Value is a comma-delimited list of Expressions
                //
                //     font-family: Baskerville, Georgia, serif;
                //
                // In a Rule, a Value represents everything after the `:`,
                // and before the `;`.
                //
                value: function () {
                    var e;
                    var expressions = [];
                    var index = parserInput.i;
                    do {
                        e = this.expression();
                        if (e) {
                            expressions.push(e);
                            if (!parserInput.$char(',')) {
                                break;
                            }
                        }
                    } while (e);
                    if (expressions.length > 0) {
                        return new (tree.Value)(expressions, index);
                    }
                },
                important: function () {
                    if (parserInput.currentChar() === '!') {
                        return parserInput.$re(/^! *important/);
                    }
                },
                sub: function () {
                    var a;
                    var e;
                    parserInput.save();
                    if (parserInput.$char('(')) {
                        a = this.addition();
                        if (a && parserInput.$char(')')) {
                            parserInput.forget();
                            e = new (tree.Expression)([a]);
                            e.parens = true;
                            return e;
                        }
                        parserInput.restore('Expected \')\'');
                        return;
                    }
                    parserInput.restore();
                },
                multiplication: function () {
                    var m;
                    var a;
                    var op;
                    var operation;
                    var isSpaced;
                    m = this.operand();
                    if (m) {
                        isSpaced = parserInput.isWhitespace(-1);
                        while (true) {
                            if (parserInput.peek(/^\/[*\/]/)) {
                                break;
                            }
                            parserInput.save();
                            op = parserInput.$char('/') || parserInput.$char('*') || parserInput.$str('./');
                            if (!op) {
                                parserInput.forget();
                                break;
                            }
                            a = this.operand();
                            if (!a) {
                                parserInput.restore();
                                break;
                            }
                            parserInput.forget();
                            m.parensInOp = true;
                            a.parensInOp = true;
                            operation = new (tree.Operation)(op, [operation || m, a], isSpaced);
                            isSpaced = parserInput.isWhitespace(-1);
                        }
                        return operation || m;
                    }
                },
                addition: function () {
                    var m;
                    var a;
                    var op;
                    var operation;
                    var isSpaced;
                    m = this.multiplication();
                    if (m) {
                        isSpaced = parserInput.isWhitespace(-1);
                        while (true) {
                            op = parserInput.$re(/^[-+]\s+/) || (!isSpaced && (parserInput.$char('+') || parserInput.$char('-')));
                            if (!op) {
                                break;
                            }
                            a = this.multiplication();
                            if (!a) {
                                break;
                            }
                            m.parensInOp = true;
                            a.parensInOp = true;
                            operation = new (tree.Operation)(op, [operation || m, a], isSpaced);
                            isSpaced = parserInput.isWhitespace(-1);
                        }
                        return operation || m;
                    }
                },
                conditions: function () {
                    var a;
                    var b;
                    var index = parserInput.i;
                    var condition;
                    a = this.condition(true);
                    if (a) {
                        while (true) {
                            if (!parserInput.peek(/^,\s*(not\s*)?\(/) || !parserInput.$char(',')) {
                                break;
                            }
                            b = this.condition(true);
                            if (!b) {
                                break;
                            }
                            condition = new (tree.Condition)('or', condition || a, b, index);
                        }
                        return condition || a;
                    }
                },
                condition: function (needsParens) {
                    var result;
                    var logical;
                    var next;
                    function or() {
                        return parserInput.$str('or');
                    }
                    result = this.conditionAnd(needsParens);
                    if (!result) {
                        return;
                    }
                    logical = or();
                    if (logical) {
                        next = this.condition(needsParens);
                        if (next) {
                            result = new (tree.Condition)(logical, result, next);
                        }
                        else {
                            return;
                        }
                    }
                    return result;
                },
                conditionAnd: function (needsParens) {
                    var result;
                    var logical;
                    var next;
                    var self = this;
                    function insideCondition() {
                        var cond = self.negatedCondition(needsParens) || self.parenthesisCondition(needsParens);
                        if (!cond && !needsParens) {
                            return self.atomicCondition(needsParens);
                        }
                        return cond;
                    }
                    function and() {
                        return parserInput.$str('and');
                    }
                    result = insideCondition();
                    if (!result) {
                        return;
                    }
                    logical = and();
                    if (logical) {
                        next = this.conditionAnd(needsParens);
                        if (next) {
                            result = new (tree.Condition)(logical, result, next);
                        }
                        else {
                            return;
                        }
                    }
                    return result;
                },
                negatedCondition: function (needsParens) {
                    if (parserInput.$str('not')) {
                        var result = this.parenthesisCondition(needsParens);
                        if (result) {
                            result.negate = !result.negate;
                        }
                        return result;
                    }
                },
                parenthesisCondition: function (needsParens) {
                    function tryConditionFollowedByParenthesis(me) {
                        var body;
                        parserInput.save();
                        body = me.condition(needsParens);
                        if (!body) {
                            parserInput.restore();
                            return;
                        }
                        if (!parserInput.$char(')')) {
                            parserInput.restore();
                            return;
                        }
                        parserInput.forget();
                        return body;
                    }
                    var body;
                    parserInput.save();
                    if (!parserInput.$str('(')) {
                        parserInput.restore();
                        return;
                    }
                    body = tryConditionFollowedByParenthesis(this);
                    if (body) {
                        parserInput.forget();
                        return body;
                    }
                    body = this.atomicCondition(needsParens);
                    if (!body) {
                        parserInput.restore();
                        return;
                    }
                    if (!parserInput.$char(')')) {
                        parserInput.restore("expected ')' got '" + parserInput.currentChar() + "'");
                        return;
                    }
                    parserInput.forget();
                    return body;
                },
                atomicCondition: function (needsParens) {
                    var entities = this.entities;
                    var index = parserInput.i;
                    var a;
                    var b;
                    var c;
                    var op;
                    function cond() {
                        return this.addition() || entities.keyword() || entities.quoted() || entities.mixinLookup();
                    }
                    cond = cond.bind(this);
                    a = cond();
                    if (a) {
                        if (parserInput.$char('>')) {
                            if (parserInput.$char('=')) {
                                op = '>=';
                            }
                            else {
                                op = '>';
                            }
                        }
                        else if (parserInput.$char('<')) {
                            if (parserInput.$char('=')) {
                                op = '<=';
                            }
                            else {
                                op = '<';
                            }
                        }
                        else if (parserInput.$char('=')) {
                            if (parserInput.$char('>')) {
                                op = '=>';
                            }
                            else if (parserInput.$char('<')) {
                                op = '=<';
                            }
                            else {
                                op = '=';
                            }
                        }
                        if (op) {
                            b = cond();
                            if (b) {
                                c = new (tree.Condition)(op, a, b, index, false);
                            }
                            else {
                                error('expected expression');
                            }
                        }
                        else {
                            c = new (tree.Condition)('=', a, new (tree.Keyword)('true'), index, false);
                        }
                        return c;
                    }
                },
                //
                // An operand is anything that can be part of an operation,
                // such as a Color, or a Variable
                //
                operand: function () {
                    var entities = this.entities;
                    var negate;
                    if (parserInput.peek(/^-[@\$\(]/)) {
                        negate = parserInput.$char('-');
                    }
                    var o = this.sub() || entities.dimension() ||
                        entities.color() || entities.variable() ||
                        entities.property() || entities.call() ||
                        entities.quoted(true) || entities.colorKeyword() ||
                        entities.mixinLookup();
                    if (negate) {
                        o.parensInOp = true;
                        o = new (tree.Negative)(o);
                    }
                    return o;
                },
                //
                // Expressions either represent mathematical operations,
                // or white-space delimited Entities.
                //
                //     1px solid black
                //     @var * 2
                //
                expression: function () {
                    var entities = [];
                    var e;
                    var delim;
                    var index = parserInput.i;
                    do {
                        e = this.comment();
                        if (e) {
                            entities.push(e);
                            continue;
                        }
                        e = this.addition() || this.entity();
                        if (e instanceof tree.Comment) {
                            e = null;
                        }
                        if (e) {
                            entities.push(e);
                            // operations do not allow keyword "/" dimension (e.g. small/20px) so we support that here
                            if (!parserInput.peek(/^\/[\/*]/)) {
                                delim = parserInput.$char('/');
                                if (delim) {
                                    entities.push(new (tree.Anonymous)(delim, index));
                                }
                            }
                        }
                    } while (e);
                    if (entities.length > 0) {
                        return new (tree.Expression)(entities);
                    }
                },
                property: function () {
                    var name = parserInput.$re(/^(\*?-?[_a-zA-Z0-9-]+)\s*:/);
                    if (name) {
                        return name[1];
                    }
                },
                ruleProperty: function () {
                    var name = [];
                    var index = [];
                    var s;
                    var k;
                    parserInput.save();
                    var simpleProperty = parserInput.$re(/^([_a-zA-Z0-9-]+)\s*:/);
                    if (simpleProperty) {
                        name = [new (tree.Keyword)(simpleProperty[1])];
                        parserInput.forget();
                        return name;
                    }
                    function match(re) {
                        var i = parserInput.i;
                        var chunk = parserInput.$re(re);
                        if (chunk) {
                            index.push(i);
                            return name.push(chunk[1]);
                        }
                    }
                    match(/^(\*?)/);
                    while (true) {
                        if (!match(/^((?:[\w-]+)|(?:[@\$]\{[\w-]+\}))/)) {
                            break;
                        }
                    }
                    if ((name.length > 1) && match(/^((?:\+_|\+)?)\s*:/)) {
                        parserInput.forget();
                        // at last, we have the complete match now. move forward,
                        // convert name particles to tree objects and return:
                        if (name[0] === '') {
                            name.shift();
                            index.shift();
                        }
                        for (k = 0; k < name.length; k++) {
                            s = name[k];
                            name[k] = (s.charAt(0) !== '@' && s.charAt(0) !== '$') ?
                                new (tree.Keyword)(s) :
                                (s.charAt(0) === '@' ?
                                    new (tree.Variable)("@" + s.slice(2, -1), index[k], fileInfo) :
                                    new (tree.Property)("$" + s.slice(2, -1), index[k], fileInfo));
                        }
                        return name;
                    }
                    parserInput.restore();
                }
            }
        };
    };
    Parser.serializeVars = function (vars) {
        var s = '';
        for (var name_1 in vars) {
            if (Object.hasOwnProperty.call(vars, name_1)) {
                var value = vars[name_1];
                s += ((name_1[0] === '@') ? '' : '@') + name_1 + ": " + value + ((String(value).slice(-1) === ';') ? '' : ';');
            }
        }
        return s;
    };

var colorFunctions;
    function clamp(val) {
        return Math.min(1, Math.max(0, val));
    }
    function hsla(origColor, hsl) {
        var color = colorFunctions.hsla(hsl.h, hsl.s, hsl.l, hsl.a);
        if (color) {
            if (origColor.value &&
                /^(rgb|hsl)/.test(origColor.value)) {
                color.value = origColor.value;
            }
            else {
                color.value = 'rgb';
            }
            return color;
        }
    }
    function toHSL(color) {
        if (color.toHSL) {
            return color.toHSL();
        }
        else {
            throw new Error('Argument cannot be evaluated to a color');
        }
    }
    function toHSV(color) {
        if (color.toHSV) {
            return color.toHSV();
        }
        else {
            throw new Error('Argument cannot be evaluated to a color');
        }
    }
    function number$1(n) {
        if (n instanceof Dimension) {
            return parseFloat(n.unit.is('%') ? n.value / 100 : n.value);
        }
        else if (typeof n === 'number') {
            return n;
        }
        else {
            throw {
                type: 'Argument',
                message: 'color functions take numbers as parameters'
            };
        }
    }
    function scaled(n, size) {
        if (n instanceof Dimension && n.unit.is('%')) {
            return parseFloat(n.value * size / 100);
        }
        else {
            return number$1(n);
        }
    }
    colorFunctions = {
        rgb: function (r, g, b) {
            var a = 1;
            /**
             * Comma-less syntax
             *   e.g. rgb(0 128 255 / 50%)
             */
            if (r instanceof Expression) {
                var val = r.value;
                r = val[0];
                g = val[1];
                b = val[2];
                /**
                 * @todo - should this be normalized in
                 *   function caller? Or parsed differently?
                 */
                if (b instanceof Operation) {
                    var op = b;
                    b = op.operands[0];
                    a = op.operands[1];
                }
            }
            var color = colorFunctions.rgba(r, g, b, a);
            if (color) {
                color.value = 'rgb';
                return color;
            }
        },
        rgba: function (r, g, b, a) {
            try {
                if (r instanceof Color) {
                    if (g) {
                        a = number$1(g);
                    }
                    else {
                        a = r.alpha;
                    }
                    return new Color(r.rgb, a, 'rgba');
                }
                var rgb = [r, g, b].map(function (c) { return scaled(c, 255); });
                a = number$1(a);
                return new Color(rgb, a, 'rgba');
            }
            catch (e) { }
        },
        hsl: function (h, s, l) {
            var a = 1;
            if (h instanceof Expression) {
                var val = h.value;
                h = val[0];
                s = val[1];
                l = val[2];
                if (l instanceof Operation) {
                    var op = l;
                    l = op.operands[0];
                    a = op.operands[1];
                }
            }
            var color = colorFunctions.hsla(h, s, l, a);
            if (color) {
                color.value = 'hsl';
                return color;
            }
        },
        hsla: function (h, s, l, a) {
            try {
                if (h instanceof Color) {
                    if (s) {
                        a = number$1(s);
                    }
                    else {
                        a = h.alpha;
                    }
                    return new Color(h.rgb, a, 'hsla');
                }
                var m1_1;
                var m2_1;
                function hue(h) {
                    h = h < 0 ? h + 1 : (h > 1 ? h - 1 : h);
                    if (h * 6 < 1) {
                        return m1_1 + (m2_1 - m1_1) * h * 6;
                    }
                    else if (h * 2 < 1) {
                        return m2_1;
                    }
                    else if (h * 3 < 2) {
                        return m1_1 + (m2_1 - m1_1) * (2 / 3 - h) * 6;
                    }
                    else {
                        return m1_1;
                    }
                }
                h = (number$1(h) % 360) / 360;
                s = clamp(number$1(s));
                l = clamp(number$1(l));
                a = clamp(number$1(a));
                m2_1 = l <= 0.5 ? l * (s + 1) : l + s - l * s;
                m1_1 = l * 2 - m2_1;
                var rgb = [
                    hue(h + 1 / 3) * 255,
                    hue(h) * 255,
                    hue(h - 1 / 3) * 255
                ];
                a = number$1(a);
                return new Color(rgb, a, 'hsla');
            }
            catch (e) { }
        },
        hsv: function (h, s, v) {
            return colorFunctions.hsva(h, s, v, 1.0);
        },
        hsva: function (h, s, v, a) {
            h = ((number$1(h) % 360) / 360) * 360;
            s = number$1(s);
            v = number$1(v);
            a = number$1(a);
            var i;
            var f;
            i = Math.floor((h / 60) % 6);
            f = (h / 60) - i;
            var vs = [v,
                v * (1 - s),
                v * (1 - f * s),
                v * (1 - (1 - f) * s)];
            var perm = [[0, 3, 1],
                [2, 0, 1],
                [1, 0, 3],
                [1, 2, 0],
                [3, 1, 0],
                [0, 1, 2]];
            return colorFunctions.rgba(vs[perm[i][0]] * 255, vs[perm[i][1]] * 255, vs[perm[i][2]] * 255, a);
        },
        hue: function (color) {
            return new Dimension(toHSL(color).h);
        },
        saturation: function (color) {
            return new Dimension(toHSL(color).s * 100, '%');
        },
        lightness: function (color) {
            return new Dimension(toHSL(color).l * 100, '%');
        },
        hsvhue: function (color) {
            return new Dimension(toHSV(color).h);
        },
        hsvsaturation: function (color) {
            return new Dimension(toHSV(color).s * 100, '%');
        },
        hsvvalue: function (color) {
            return new Dimension(toHSV(color).v * 100, '%');
        },
        red: function (color) {
            return new Dimension(color.rgb[0]);
        },
        green: function (color) {
            return new Dimension(color.rgb[1]);
        },
        blue: function (color) {
            return new Dimension(color.rgb[2]);
        },
        alpha: function (color) {
            return new Dimension(toHSL(color).a);
        },
        luma: function (color) {
            return new Dimension(color.luma() * color.alpha * 100, '%');
        },
        luminance: function (color) {
            var luminance = (0.2126 * color.rgb[0] / 255) +
                (0.7152 * color.rgb[1] / 255) +
                (0.0722 * color.rgb[2] / 255);
            return new Dimension(luminance * color.alpha * 100, '%');
        },
        saturate: function (color, amount, method) {
            // filter: saturate(3.2);
            // should be kept as is, so check for color
            if (!color.rgb) {
                return null;
            }
            var hsl = toHSL(color);
            if (typeof method !== 'undefined' && method.value === 'relative') {
                hsl.s += hsl.s * amount.value / 100;
            }
            else {
                hsl.s += amount.value / 100;
            }
            hsl.s = clamp(hsl.s);
            return hsla(color, hsl);
        },
        desaturate: function (color, amount, method) {
            var hsl = toHSL(color);
            if (typeof method !== 'undefined' && method.value === 'relative') {
                hsl.s -= hsl.s * amount.value / 100;
            }
            else {
                hsl.s -= amount.value / 100;
            }
            hsl.s = clamp(hsl.s);
            return hsla(color, hsl);
        },
        lighten: function (color, amount, method) {
            var hsl = toHSL(color);
            if (typeof method !== 'undefined' && method.value === 'relative') {
                hsl.l += hsl.l * amount.value / 100;
            }
            else {
                hsl.l += amount.value / 100;
            }
            hsl.l = clamp(hsl.l);
            return hsla(color, hsl);
        },
        darken: function (color, amount, method) {
            var hsl = toHSL(color);
            if (typeof method !== 'undefined' && method.value === 'relative') {
                hsl.l -= hsl.l * amount.value / 100;
            }
            else {
                hsl.l -= amount.value / 100;
            }
            hsl.l = clamp(hsl.l);
            return hsla(color, hsl);
        },
        fadein: function (color, amount, method) {
            var hsl = toHSL(color);
            if (typeof method !== 'undefined' && method.value === 'relative') {
                hsl.a += hsl.a * amount.value / 100;
            }
            else {
                hsl.a += amount.value / 100;
            }
            hsl.a = clamp(hsl.a);
            return hsla(color, hsl);
        },
        fadeout: function (color, amount, method) {
            var hsl = toHSL(color);
            if (typeof method !== 'undefined' && method.value === 'relative') {
                hsl.a -= hsl.a * amount.value / 100;
            }
            else {
                hsl.a -= amount.value / 100;
            }
            hsl.a = clamp(hsl.a);
            return hsla(color, hsl);
        },
        fade: function (color, amount) {
            var hsl = toHSL(color);
            hsl.a = amount.value / 100;
            hsl.a = clamp(hsl.a);
            return hsla(color, hsl);
        },
        spin: function (color, amount) {
            var hsl = toHSL(color);
            var hue = (hsl.h + amount.value) % 360;
            hsl.h = hue < 0 ? 360 + hue : hue;
            return hsla(color, hsl);
        },
        //
        // Copyright (c) 2006-2009 Hampton Catlin, Natalie Weizenbaum, and Chris Eppstein
        // http://sass-lang.com
        //
        mix: function (color1, color2, weight) {
            if (!weight) {
                weight = new Dimension(50);
            }
            var p = weight.value / 100.0;
            var w = p * 2 - 1;
            var a = toHSL(color1).a - toHSL(color2).a;
            var w1 = (((w * a == -1) ? w : (w + a) / (1 + w * a)) + 1) / 2.0;
            var w2 = 1 - w1;
            var rgb = [color1.rgb[0] * w1 + color2.rgb[0] * w2,
                color1.rgb[1] * w1 + color2.rgb[1] * w2,
                color1.rgb[2] * w1 + color2.rgb[2] * w2];
            var alpha = color1.alpha * p + color2.alpha * (1 - p);
            return new Color(rgb, alpha);
        },
        greyscale: function (color) {
            return colorFunctions.desaturate(color, new Dimension(100));
        },
        contrast: function (color, dark, light, threshold) {
            // filter: contrast(3.2);
            // should be kept as is, so check for color
            if (!color.rgb) {
                return null;
            }
            if (typeof light === 'undefined') {
                light = colorFunctions.rgba(255, 255, 255, 1.0);
            }
            if (typeof dark === 'undefined') {
                dark = colorFunctions.rgba(0, 0, 0, 1.0);
            }
            // Figure out which is actually light and dark:
            if (dark.luma() > light.luma()) {
                var t = light;
                light = dark;
                dark = t;
            }
            if (typeof threshold === 'undefined') {
                threshold = 0.43;
            }
            else {
                threshold = number$1(threshold);
            }
            if (color.luma() < threshold) {
                return light;
            }
            else {
                return dark;
            }
        },
        // Changes made in 2.7.0 - Reverted in 3.0.0
        // contrast: function (color, color1, color2, threshold) {
        //     // Return which of `color1` and `color2` has the greatest contrast with `color`
        //     // according to the standard WCAG contrast ratio calculation.
        //     // http://www.w3.org/TR/WCAG20/#contrast-ratiodef
        //     // The threshold param is no longer used, in line with SASS.
        //     // filter: contrast(3.2);
        //     // should be kept as is, so check for color
        //     if (!color.rgb) {
        //         return null;
        //     }
        //     if (typeof color1 === 'undefined') {
        //         color1 = colorFunctions.rgba(0, 0, 0, 1.0);
        //     }
        //     if (typeof color2 === 'undefined') {
        //         color2 = colorFunctions.rgba(255, 255, 255, 1.0);
        //     }
        //     var contrast1, contrast2;
        //     var luma = color.luma();
        //     var luma1 = color1.luma();
        //     var luma2 = color2.luma();
        //     // Calculate contrast ratios for each color
        //     if (luma > luma1) {
        //         contrast1 = (luma + 0.05) / (luma1 + 0.05);
        //     } else {
        //         contrast1 = (luma1 + 0.05) / (luma + 0.05);
        //     }
        //     if (luma > luma2) {
        //         contrast2 = (luma + 0.05) / (luma2 + 0.05);
        //     } else {
        //         contrast2 = (luma2 + 0.05) / (luma + 0.05);
        //     }
        //     if (contrast1 > contrast2) {
        //         return color1;
        //     } else {
        //         return color2;
        //     }
        // },
        argb: function (color) {
            return new Anonymous(color.toARGB());
        },
        color: function (c) {
            if ((c instanceof Quoted) &&
                (/^#([A-Fa-f0-9]{8}|[A-Fa-f0-9]{6}|[A-Fa-f0-9]{3,4})$/i.test(c.value))) {
                var val = c.value.slice(1);
                return new Color(val, undefined, "#" + val);
            }
            if ((c instanceof Color) || (c = Color.fromKeyword(c.value))) {
                c.value = undefined;
                return c;
            }
            throw {
                type: 'Argument',
                message: 'argument must be a color keyword or 3|4|6|8 digit hex e.g. #FFF'
            };
        },
        tint: function (color, amount) {
            return colorFunctions.mix(colorFunctions.rgb(255, 255, 255), color, amount);
        },
        shade: function (color, amount) {
            return colorFunctions.mix(colorFunctions.rgb(0, 0, 0), color, amount);
        }
    };
    var color = colorFunctions;

// Color Blending
    // ref: http://www.w3.org/TR/compositing-1
    function colorBlend(mode, color1, color2) {
        var ab = color1.alpha; // result
        var // backdrop
        cb;
        var as = color2.alpha;
        var // source
        cs;
        var ar;
        var cr;
        var r = [];
        ar = as + ab * (1 - as);
        for (var i = 0; i < 3; i++) {
            cb = color1.rgb[i] / 255;
            cs = color2.rgb[i] / 255;
            cr = mode(cb, cs);
            if (ar) {
                cr = (as * cs + ab * (cb -
                    as * (cb + cs - cr))) / ar;
            }
            r[i] = cr * 255;
        }
        return new Color(r, ar);
    }
    var colorBlendModeFunctions = {
        multiply: function (cb, cs) {
            return cb * cs;
        },
        screen: function (cb, cs) {
            return cb + cs - cb * cs;
        },
        overlay: function (cb, cs) {
            cb *= 2;
            return (cb <= 1) ?
                colorBlendModeFunctions.multiply(cb, cs) :
                colorBlendModeFunctions.screen(cb - 1, cs);
        },
        softlight: function (cb, cs) {
            var d = 1;
            var e = cb;
            if (cs > 0.5) {
                e = 1;
                d = (cb > 0.25) ? Math.sqrt(cb)
                    : ((16 * cb - 12) * cb + 4) * cb;
            }
            return cb - (1 - 2 * cs) * e * (d - cb);
        },
        hardlight: function (cb, cs) {
            return colorBlendModeFunctions.overlay(cs, cb);
        },
        difference: function (cb, cs) {
            return Math.abs(cb - cs);
        },
        exclusion: function (cb, cs) {
            return cb + cs - 2 * cb * cs;
        },
        // non-w3c functions:
        average: function (cb, cs) {
            return (cb + cs) / 2;
        },
        negation: function (cb, cs) {
            return 1 - Math.abs(cb + cs - 1);
        }
    };
    for (var f$1 in colorBlendModeFunctions) {
        if (colorBlendModeFunctions.hasOwnProperty(f$1)) {
            colorBlend[f$1] = colorBlend.bind(null, colorBlendModeFunctions[f$1]);
        }
    }

var functions = (function (environment) {
        var functions = { functionRegistry: functionRegistry, functionCaller: functionCaller };
        // register functions
        functionRegistry.addMultiple(boolean$1);
        functionRegistry.add('default', defaultFunc.eval.bind(defaultFunc));
        functionRegistry.addMultiple(color);
        functionRegistry.addMultiple(colorBlend);
        functionRegistry.addMultiple(dataUri(environment));
        functionRegistry.addMultiple(list);
        functionRegistry.addMultiple(mathFunctions);
        functionRegistry.addMultiple(number);
        functionRegistry.addMultiple(string);
        functionRegistry.addMultiple(svg());
        functionRegistry.addMultiple(types);
        return functions;
    });

/**
     * Plugin Manager
     */
    var PluginManager = /** @class */ (function () {
        function PluginManager(less) {
            this.less = less;
            this.visitors = [];
            this.preProcessors = [];
            this.postProcessors = [];
            this.installedPlugins = [];
            this.fileManagers = [];
            this.iterator = -1;
            this.pluginCache = {};
            this.Loader = new less.PluginLoader(less);
        }
        /**
         * Adds all the plugins in the array
         * @param {Array} plugins
         */
        PluginManager.prototype.addPlugins = function (plugins) {
            if (plugins) {
                for (var i = 0; i < plugins.length; i++) {
                    this.addPlugin(plugins[i]);
                }
            }
        };
        /**
         *
         * @param plugin
         * @param {String} filename
         */
        PluginManager.prototype.addPlugin = function (plugin, filename, functionRegistry) {
            this.installedPlugins.push(plugin);
            if (filename) {
                this.pluginCache[filename] = plugin;
            }
            if (plugin.install) {
                plugin.install(this.less, this, functionRegistry || this.less.functions.functionRegistry);
            }
        };
        /**
         *
         * @param filename
         */
        PluginManager.prototype.get = function (filename) {
            return this.pluginCache[filename];
        };
        /**
         * Adds a visitor. The visitor object has options on itself to determine
         * when it should run.
         * @param visitor
         */
        PluginManager.prototype.addVisitor = function (visitor) {
            this.visitors.push(visitor);
        };
        /**
         * Adds a pre processor object
         * @param {object} preProcessor
         * @param {number} priority - guidelines 1 = before import, 1000 = import, 2000 = after import
         */
        PluginManager.prototype.addPreProcessor = function (preProcessor, priority) {
            var indexToInsertAt;
            for (indexToInsertAt = 0; indexToInsertAt < this.preProcessors.length; indexToInsertAt++) {
                if (this.preProcessors[indexToInsertAt].priority >= priority) {
                    break;
                }
            }
            this.preProcessors.splice(indexToInsertAt, 0, { preProcessor: preProcessor, priority: priority });
        };
        /**
         * Adds a post processor object
         * @param {object} postProcessor
         * @param {number} priority - guidelines 1 = before compression, 1000 = compression, 2000 = after compression
         */
        PluginManager.prototype.addPostProcessor = function (postProcessor, priority) {
            var indexToInsertAt;
            for (indexToInsertAt = 0; indexToInsertAt < this.postProcessors.length; indexToInsertAt++) {
                if (this.postProcessors[indexToInsertAt].priority >= priority) {
                    break;
                }
            }
            this.postProcessors.splice(indexToInsertAt, 0, { postProcessor: postProcessor, priority: priority });
        };
        /**
         *
         * @param manager
         */
        PluginManager.prototype.addFileManager = function (manager) {
            this.fileManagers.push(manager);
        };
        /**
         *
         * @returns {Array}
         * @private
         */
        PluginManager.prototype.getPreProcessors = function () {
            var preProcessors = [];
            for (var i = 0; i < this.preProcessors.length; i++) {
                preProcessors.push(this.preProcessors[i].preProcessor);
            }
            return preProcessors;
        };
        /**
         *
         * @returns {Array}
         * @private
         */
        PluginManager.prototype.getPostProcessors = function () {
            var postProcessors = [];
            for (var i = 0; i < this.postProcessors.length; i++) {
                postProcessors.push(this.postProcessors[i].postProcessor);
            }
            return postProcessors;
        };
        /**
         *
         * @returns {Array}
         * @private
         */
        PluginManager.prototype.getVisitors = function () {
            return this.visitors;
        };
        PluginManager.prototype.visitor = function () {
            var self = this;
            return {
                first: function () {
                    self.iterator = -1;
                    return self.visitors[self.iterator];
                },
                get: function () {
                    self.iterator += 1;
                    return self.visitors[self.iterator];
                }
            };
        };
        /**
         *
         * @returns {Array}
         * @private
         */
        PluginManager.prototype.getFileManagers = function () {
            return this.fileManagers;
        };
        return PluginManager;
    }());
    var pm;
    var PluginManagerFactory = function (less, newFactory) {
        if (newFactory || !pm) {
            pm = new PluginManager(less);
        }
        return pm;
    };

var version = "4.1.2";

function parseNodeVersion(version) {
      var match = version.match(/^v(\d{1,2})\.(\d{1,2})\.(\d{1,2})(?:-([0-9A-Za-z-.]+))?(?:\+([0-9A-Za-z-.]+))?$/); // eslint-disable-line max-len
      if (!match) {
        throw new Error('Unable to parse: ' + version);
      }

var res = {
        major: parseInt(match[1], 10),
        minor: parseInt(match[2], 10),
        patch: parseInt(match[3], 10),
        pre: match[4] || '',
        build: match[5] || '',
      };

return res;
    }

var parseNodeVersion_1 = parseNodeVersion;

/* global window, XMLHttpRequest */
    var options$1;
    var logger;
    var fileCache = {};
    // TODOS - move log somewhere. pathDiff and doing something similar in node. use pathDiff in the other browser file for the initial load
    var FileManager = function () { };
    FileManager.prototype = Object.assign(new AbstractFileManager(), {
        alwaysMakePathsAbsolute: function () {
            return true;
        },
        join: function (basePath, laterPath) {
            if (!basePath) {
                return laterPath;
            }
            return this.extractUrlParts(laterPath, basePath).path;
        },
        doXHR: function (url, type, callback, errback) {
            var xhr = new XMLHttpRequest();
            var async = options$1.isFileProtocol ? options$1.fileAsync : true;
            if (typeof xhr.overrideMimeType === 'function') {
                xhr.overrideMimeType('text/css');
            }
            logger.debug("XHR: Getting '" + url + "'");
            xhr.open('GET', url, async);
            xhr.setRequestHeader('Accept', type || 'text/x-less, text/css; q=0.9, */*; q=0.5');
            xhr.send(null);
            function handleResponse(xhr, callback, errback) {
                if (xhr.status >= 200 && xhr.status < 300) {
                    callback(xhr.responseText, xhr.getResponseHeader('Last-Modified'));
                }
                else if (typeof errback === 'function') {
                    errback(xhr.status, url);
                }
            }
            if (options$1.isFileProtocol && !options$1.fileAsync) {
                if (xhr.status === 0 || (xhr.status >= 200 && xhr.status < 300)) {
                    callback(xhr.responseText);
                }
                else {
                    errback(xhr.status, url);
                }
            }
            else if (async) {
                xhr.onreadystatechange = function () {
                    if (xhr.readyState == 4) {
                        handleResponse(xhr, callback, errback);
                    }
                };
            }
            else {
                handleResponse(xhr, callback, errback);
            }
        },
        supports: function () {
            return true;
        },
        clearFileCache: function () {
            fileCache = {};
        },
        loadFile: function (filename, currentDirectory, options, environment) {
            // TODO: Add prefix support like less-node?
            // What about multiple paths?
            if (currentDirectory && !this.isPathAbsolute(filename)) {
                filename = currentDirectory + filename;
            }
            filename = options.ext ? this.tryAppendExtension(filename, options.ext) : filename;
            options = options || {};
            // sheet may be set to the stylesheet for the initial load or a collection of properties including
            // some context variables for imports
            var hrefParts = this.extractUrlParts(filename, window.location.href);
            var href = hrefParts.url;
            var self = this;
            return new Promise(function (resolve, reject) {
                if (options.useFileCache && fileCache[href]) {
                    try {
                        var lessText = fileCache[href];
                        return resolve({ contents: lessText, filename: href, webInfo: { lastModified: new Date() } });
                    }
                    catch (e) {
                        return reject({ filename: href, message: "Error loading file " + href + " error was " + e.message });
                    }
                }
                self.doXHR(href, options.mime, function doXHRCallback(data, lastModified) {
                    // per file cache
                    fileCache[href] = data;
                    // Use remote copy (re-parse)
                    resolve({ contents: data, filename: href, webInfo: { lastModified: lastModified } });
                }, function doXHRError(status, url) {
                    reject({ type: 'File', message: "'" + url + "' wasn't found (" + status + ")", href: href });
                });
            });
        }
    });
    var FM = (function (opts, log) {
        options$1 = opts;
        logger = log;
        return FileManager;
    });

// TODO: Add tests for browser @plugin
    /**
     * Browser Plugin Loader
     */
    var PluginLoader = function (less) {
        this.less = less;
        // Should we shim this.require for browser? Probably not?
    };
    PluginLoader.prototype = Object.assign(new AbstractPluginLoader(), {
        loadPlugin: function (filename, basePath, context, environment, fileManager) {
            return new Promise(function (fulfill, reject) {
                fileManager.loadFile(filename, basePath, context, environment)
                    .then(fulfill).catch(reject);
            });
        }
    });

// Cache system is a bit outdated and could do with work
    var Cache = (function (window, options, logger) {
        var cache = null;
        if (options.env !== 'development') {
            try {
                cache = (typeof window.localStorage === 'undefined') ? null : window.localStorage;
            }
            catch (_) { }
        }
        return {
            setCSS: function (path, lastModified, modifyVars, styles) {
                if (cache) {
                    logger.info("saving " + path + " to cache.");
                    try {
                        cache.setItem(path, styles);
                        cache.setItem(path + ":timestamp", lastModified);
                        if (modifyVars) {
                            cache.setItem(path + ":vars", JSON.stringify(modifyVars));
                        }
                    }
                    catch (e) {
                        // TODO - could do with adding more robust error handling
                        logger.error("failed to save \"" + path + "\" to local storage for caching.");
                    }
                }
            },
            getCSS: function (path, webInfo, modifyVars) {
                var css = cache && cache.getItem(path);
                var timestamp = cache && cache.getItem(path + ":timestamp");
                var vars = cache && cache.getItem(path + ":vars");
                modifyVars = modifyVars || {};
                vars = vars || "{}"; // if not set, treat as the JSON representation of an empty object
                if (timestamp && webInfo.lastModified &&
                    (new Date(webInfo.lastModified).valueOf() ===
                        new Date(timestamp).valueOf()) &&
                    JSON.stringify(modifyVars) === vars) {
                    // Use local copy
                    return css;
                }
            }
        };
    });

//
    var root = (function (window, options) {
        var document = window.document;
        var less = lessRoot();
        less.options = options;
        var environment = less.environment;
        var FileManager = FM(options, less.logger);
        var fileManager = new FileManager();
        environment.addFileManager(fileManager);
        less.FileManager = FileManager;
        less.PluginLoader = PluginLoader;
        LogListener(less, options);
        var errors = ErrorReporting(window, less, options);
        var cache = less.cache = options.cache || Cache(window, options, less.logger);
        ImageSize(less.environment);
        // Setup user functions - Deprecate?
        if (options.functions) {
            less.functions.functionRegistry.addMultiple(options.functions);
        }
        var typePattern = /^text\/(x-)?less$/;
        function clone(obj) {
            var cloned = {};
            for (var prop in obj) {
                if (obj.hasOwnProperty(prop)) {
                    cloned[prop] = obj[prop];
                }
            }
            return cloned;
        }
        // only really needed for phantom
        function bind(func, thisArg) {
            var curryArgs = Array.prototype.slice.call(arguments, 2);
            return function () {
                var args = curryArgs.concat(Array.prototype.slice.call(arguments, 0));
                return func.apply(thisArg, args);
            };
        }
        function loadStyles(modifyVars) {
            var styles = document.getElementsByTagName('style');
            var style;
            for (var i = 0; i < styles.length; i++) {
                style = styles[i];
                if (style.type.match(typePattern)) {
                    var instanceOptions = clone(options);
                    instanceOptions.modifyVars = modifyVars;
                    var lessText = style.innerHTML || '';
                    instanceOptions.filename = document.location.href.replace(/#.*$/, '');
                    /* jshint loopfunc:true */
                    // use closure to store current style
                    less.render(lessText, instanceOptions, bind(function (style, e, result) {
                        if (e) {
                            errors.add(e, 'inline');
                        }
                        else {
                            style.type = 'text/css';
                            if (style.styleSheet) {
                                style.styleSheet.cssText = result.css;
                            }
                            else {
                                style.innerHTML = result.css;
                            }
                        }
                    }, null, style));
                }
            }
        }
        function loadStyleSheet(sheet, callback, reload, remaining, modifyVars) {
            var instanceOptions = clone(options);
            addDataAttr(instanceOptions, sheet);
            instanceOptions.mime = sheet.type;
            if (modifyVars) {
                instanceOptions.modifyVars = modifyVars;
            }
            function loadInitialFileCallback(loadedFile) {
                var data = loadedFile.contents;
                var path = loadedFile.filename;
                var webInfo = loadedFile.webInfo;
                var newFileInfo = {
                    currentDirectory: fileManager.getPath(path),
                    filename: path,
                    rootFilename: path,
                    rewriteUrls: instanceOptions.rewriteUrls
                };
                newFileInfo.entryPath = newFileInfo.currentDirectory;
                newFileInfo.rootpath = instanceOptions.rootpath || newFileInfo.currentDirectory;
                if (webInfo) {
                    webInfo.remaining = remaining;
                    var css = cache.getCSS(path, webInfo, instanceOptions.modifyVars);
                    if (!reload && css) {
                        webInfo.local = true;
                        callback(null, css, data, sheet, webInfo, path);
                        return;
                    }
                }
                // TODO add tests around how this behaves when reloading
                errors.remove(path);
                instanceOptions.rootFileInfo = newFileInfo;
                less.render(data, instanceOptions, function (e, result) {
                    if (e) {
                        e.href = path;
                        callback(e);
                    }
                    else {
                        cache.setCSS(sheet.href, webInfo.lastModified, instanceOptions.modifyVars, result.css);
                        callback(null, result.css, data, sheet, webInfo, path);
                    }
                });
            }
            fileManager.loadFile(sheet.href, null, instanceOptions, environment)
                .then(function (loadedFile) {
                loadInitialFileCallback(loadedFile);
            }).catch(function (err) {
                console.log(err);
                callback(err);
            });
        }
        function loadStyleSheets(callback, reload, modifyVars) {
            for (var i = 0; i < less.sheets.length; i++) {
                loadStyleSheet(less.sheets[i], callback, reload, less.sheets.length - (i + 1), modifyVars);
            }
        }
        function initRunningMode() {
            if (less.env === 'development') {
                less.watchTimer = setInterval(function () {
                    if (less.watchMode) {
                        fileManager.clearFileCache();
                        loadStyleSheets(function (e, css, _, sheet, webInfo) {
                            if (e) {
                                errors.add(e, e.href || sheet.href);
                            }
                            else if (css) {
                                browser.createCSS(window.document, css, sheet);
                            }
                        });
                    }
                }, options.poll);
            }
        }
        //
        // Watch mode
        //
        less.watch = function () {
            if (!less.watchMode) {
                less.env = 'development';
                initRunningMode();
            }
            this.watchMode = true;
            return true;
        };
        less.unwatch = function () { clearInterval(less.watchTimer); this.watchMode = false; return false; };
        //
        // Synchronously get all <link> tags with the 'rel' attribute set to
        // "stylesheet/less".
        //
        less.registerStylesheetsImmediately = function () {
            var links = document.getElementsByTagName('link');
            less.sheets = [];
            for (var i = 0; i < links.length; i++) {
                if (links[i].rel === 'stylesheet/less' || (links[i].rel.match(/stylesheet/) &&
                    (links[i].type.match(typePattern)))) {
                    less.sheets.push(links[i]);
                }
            }
        };
        //
        // Asynchronously get all <link> tags with the 'rel' attribute set to
        // "stylesheet/less", returning a Promise.
        //
        less.registerStylesheets = function () { return new Promise(function (resolve, reject) {
            less.registerStylesheetsImmediately();
            resolve();
        }); };
        //
        // With this function, it's possible to alter variables and re-render
        // CSS without reloading less-files
        //
        less.modifyVars = function (record) { return less.refresh(true, record, false); };
        less.refresh = function (reload, modifyVars, clearFileCache) {
            if ((reload || clearFileCache) && clearFileCache !== false) {
                fileManager.clearFileCache();
            }
            return new Promise(function (resolve, reject) {
                var startTime;
                var endTime;
                var totalMilliseconds;
                var remainingSheets;
                startTime = endTime = new Date();
                // Set counter for remaining unprocessed sheets
                remainingSheets = less.sheets.length;
                if (remainingSheets === 0) {
                    endTime = new Date();
                    totalMilliseconds = endTime - startTime;
                    less.logger.info('Less has finished and no sheets were loaded.');
                    resolve({
                        startTime: startTime,
                        endTime: endTime,
                        totalMilliseconds: totalMilliseconds,
                        sheets: less.sheets.length
                    });
                }
                else {
                    // Relies on less.sheets array, callback seems to be guaranteed to be called for every element of the array
                    loadStyleSheets(function (e, css, _, sheet, webInfo) {
                        if (e) {
                            errors.add(e, e.href || sheet.href);
                            reject(e);
                            return;
                        }
                        if (webInfo.local) {
                            less.logger.info("Loading " + sheet.href + " from cache.");
                        }
                        else {
                            less.logger.info("Rendered " + sheet.href + " successfully.");
                        }
                        browser.createCSS(window.document, css, sheet);
                        less.logger.info("CSS for " + sheet.href + " generated in " + (new Date() - endTime) + "ms");
                        // Count completed sheet
                        remainingSheets--;
                        // Check if the last remaining sheet was processed and then call the promise
                        if (remainingSheets === 0) {
                            totalMilliseconds = new Date() - startTime;
                            less.logger.info("Less has finished. CSS generated in " + totalMilliseconds + "ms");
                            resolve({
                                startTime: startTime,
                                endTime: endTime,
                                totalMilliseconds: totalMilliseconds,
                                sheets: less.sheets.length
                            });
                        }
                        endTime = new Date();
                    }, reload, modifyVars);
                }
                loadStyles(modifyVars);
            });
        };
        less.refreshStyles = loadStyles;
        return less;
    });

/**
     * Kicks off less and compiles any stylesheets
     * used in the browser distributed version of less
     * to kick-start less using the browser api
     */
    var options = defaultOptions();
    if (window.less) {
        for (var key in window.less) {
            if (window.less.hasOwnProperty(key)) {
                options[key] = window.less[key];
            }
        }
    }
    addDefaultOptions(window, options);
    options.plugins = options.plugins || [];
    if (window.LESS_PLUGINS) {
        options.plugins = options.plugins.concat(window.LESS_PLUGINS);
    }
    var less = root(window, options);
    window.less = less;
    var css;
    var head;
    var style;
    // Always restore page visibility
    function resolveOrReject(data) {
        if (data.filename) {
            console.warn(data);
        }
        if (!options.async) {
            head.removeChild(style);
        }
    }
    if (options.onReady) {
        if (/!watch/.test(window.location.hash)) {
            less.watch();
        }
        // Simulate synchronous stylesheet loading by hiding page rendering
        if (!options.async) {
            css = 'body { display: none !important }';
            head = document.head || document.getElementsByTagName('head')[0];
            style = document.createElement('style');
            style.type = 'text/css';
            if (style.styleSheet) {
                style.styleSheet.cssText = css;
            }
            else {
                style.appendChild(document.createTextNode(css));
            }
            head.appendChild(style);
        }
        less.registerStylesheetsImmediately();
        less.pageLoadFinished = less.refresh(less.env === 'development').then(resolveOrReject, resolveOrReject);
    }

return less;

})));

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