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Source Code - Root / forked / sssh / XRegExp.js
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// XRegExp 1.5.0
// (c) 2007-2010 Steven Levithan
// MIT License
// Provides an augmented, extensible, cross-browser implementation of regular expressions,
// including support for additional syntax, flags, and methods
 
var XRegExp;
 
if (XRegExp) {
    // Avoid running twice, since that would break references to native globals
    throw Error("can't load XRegExp twice in the same frame");
}
 
// Run within an anonymous function to protect variables and avoid new globals
(function () {
 
    //---------------------------------
    //  Constructor
    //---------------------------------
 
    // Accepts a pattern and flags; returns a new, extended `RegExp` object. Differs from a native
    // regular expression in that additional syntax and flags are supported and cross-browser
    // syntax inconsistencies are ameliorated
    XRegExp = function (pattern, flags) {
        var output = [],
            currScope = XRegExp.OUTSIDE_CLASS,
            pos = 0,
            context, tokenResult, match, chr, regex;
 
        if (XRegExp.isRegExp(pattern)) {
            if (flags !== undefined)
                throw TypeError("can't supply flags when constructing one RegExp from another");
            return clone(pattern);
        }
        // Tokens become part of the regex construction process, so protect against infinite
        // recursion when an XRegExp is constructed within a token handler or trigger
        if (isInsideConstructor)
            throw Error("can't call the XRegExp constructor within token definition functions");
 
        flags = flags || "";
        context = { // `this` object for custom tokens
            hasNamedCapture: false,
            captureNames: [],
            hasFlag: function (flag) {return flags.indexOf(flag) > -1;},
            setFlag: function (flag) {flags += flag;}
        };
 
        while (pos < pattern.length) {
            // Check for custom tokens at the current position
            tokenResult = runTokens(pattern, pos, currScope, context);
 
            if (tokenResult) {
                output.push(tokenResult.output);
                pos += (tokenResult.match[0].length || 1);
            } else {
                // Check for native multicharacter metasequences (excluding character classes) at
                // the current position
                if (match = real.exec.call(nativeTokens[currScope], pattern.slice(pos))) {
                    output.push(match[0]);
                    pos += match[0].length;
                } else {
                    chr = pattern.charAt(pos);
                    if (chr === "[")
                        currScope = XRegExp.INSIDE_CLASS;
                    else if (chr === "]")
                        currScope = XRegExp.OUTSIDE_CLASS;
                    // Advance position one character
                    output.push(chr);
                    pos++;
                }
            }
        }
 
        regex = RegExp(output.join(""), real.replace.call(flags, flagClip, ""));
        regex._xregexp = {
            source: pattern,
            captureNames: context.hasNamedCapture ? context.captureNames : null
        };
        return regex;
    };
 
 
    //---------------------------------
    //  Public properties
    //---------------------------------
 
    XRegExp.version = "1.5.0";
 
    // Token scope bitflags
    XRegExp.INSIDE_CLASS = 1;
    XRegExp.OUTSIDE_CLASS = 2;
 
 
    //---------------------------------
    //  Private variables
    //---------------------------------
 
    var replacementToken = /\$(?:(\d\d?|[
// XRegExp 1.5.0
// (c) 2007-2010 Steven Levithan
// MIT License
// <http://xregexp.com>
// Provides an augmented, extensible, cross-browser implementation of regular expressions,
// including support for additional syntax, flags, and methods

var XRegExp;

if (XRegExp) {
    // Avoid running twice, since that would break references to native globals
    throw Error("can't load XRegExp twice in the same frame");
}

// Run within an anonymous function to protect variables and avoid new globals
(function () {

    //---------------------------------
    //  Constructor
    //---------------------------------

    // Accepts a pattern and flags; returns a new, extended `RegExp` object. Differs from a native
    // regular expression in that additional syntax and flags are supported and cross-browser
    // syntax inconsistencies are ameliorated
    XRegExp = function (pattern, flags) {
        var output = [],
            currScope = XRegExp.OUTSIDE_CLASS,
            pos = 0,
            context, tokenResult, match, chr, regex;

        if (XRegExp.isRegExp(pattern)) {
            if (flags !== undefined)
                throw TypeError("can't supply flags when constructing one RegExp from another");
            return clone(pattern);
        }
        // Tokens become part of the regex construction process, so protect against infinite
        // recursion when an XRegExp is constructed within a token handler or trigger
        if (isInsideConstructor)
            throw Error("can't call the XRegExp constructor within token definition functions");

        flags = flags || "";
        context = { // `this` object for custom tokens
            hasNamedCapture: false,
            captureNames: [],
            hasFlag: function (flag) {return flags.indexOf(flag) > -1;},
            setFlag: function (flag) {flags += flag;}
        };

        while (pos < pattern.length) {
            // Check for custom tokens at the current position
            tokenResult = runTokens(pattern, pos, currScope, context);

            if (tokenResult) {
                output.push(tokenResult.output);
                pos += (tokenResult.match[0].length || 1);
            } else {
                // Check for native multicharacter metasequences (excluding character classes) at
                // the current position
                if (match = real.exec.call(nativeTokens[currScope], pattern.slice(pos))) {
                    output.push(match[0]);
                    pos += match[0].length;
                } else {
                    chr = pattern.charAt(pos);
                    if (chr === "[")
                        currScope = XRegExp.INSIDE_CLASS;
                    else if (chr === "]")
                        currScope = XRegExp.OUTSIDE_CLASS;
                    // Advance position one character
                    output.push(chr);
                    pos++;
                }
            }
        }

        regex = RegExp(output.join(""), real.replace.call(flags, flagClip, ""));
        regex._xregexp = {
            source: pattern,
            captureNames: context.hasNamedCapture ? context.captureNames : null
        };
        return regex;
    };


    //---------------------------------
    //  Public properties
    //---------------------------------

    XRegExp.version = "1.5.0";

    // Token scope bitflags
    XRegExp.INSIDE_CLASS = 1;
    XRegExp.OUTSIDE_CLASS = 2;


    //---------------------------------
    //  Private variables
    //---------------------------------

    var replacementToken = /\$(?:(\d\d?|[$&`'])|{([$\w]+)})/g,
        flagClip = /[^gimy]+|([\s\S])(?=[\s\S]*\1)/g, // Nonnative and duplicate flags
        quantifier = /^(?:[?*+]|{\d+(?:,\d*)?})\??/,
        isInsideConstructor = false,
        tokens = [],
        // Copy native globals for reference ("native" is an ES3 reserved keyword)
        real = {
            exec: RegExp.prototype.exec,
            test: RegExp.prototype.test,
            match: String.prototype.match,
            replace: String.prototype.replace,
            split: String.prototype.split
        },
        compliantExecNpcg = real.exec.call(/()??/, "")[1] === undefined, // check `exec` handling of nonparticipating capturing groups
        compliantLastIndexIncrement = function () {
            var x = /^/g;
            real.test.call(x, "");
            return !x.lastIndex;
        }(),
        compliantLastIndexReset = function () {
            var x = /x/g;
            real.replace.call("x", x, "");
            return !x.lastIndex;
        }(),
        hasNativeY = RegExp.prototype.sticky !== undefined,
        nativeTokens = {};

    // `nativeTokens` match native multicharacter metasequences only (including deprecated octals,
    // excluding character classes)
    nativeTokens[XRegExp.INSIDE_CLASS] = /^(?:\\(?:[0-3][0-7]{0,2}|[4-7][0-7]?|x[\dA-Fa-f]{2}|u[\dA-Fa-f]{4}|c[A-Za-z]|[\s\S]))/;
    nativeTokens[XRegExp.OUTSIDE_CLASS] = /^(?:\\(?:0(?:[0-3][0-7]{0,2}|[4-7][0-7]?)?|[1-9]\d*|x[\dA-Fa-f]{2}|u[\dA-Fa-f]{4}|c[A-Za-z]|[\s\S])|\(\?[:=!]|[?*+]\?|{\d+(?:,\d*)?}\??)/;


    //---------------------------------
    //  Public methods
    //---------------------------------

    // Lets you extend or change XRegExp syntax and create custom flags. This is used internally by
    // the XRegExp library and can be used to create XRegExp plugins. This function is intended for
    // users with advanced knowledge of JavaScript's regular expression syntax and behavior. It can
    // be disabled by `XRegExp.freezeTokens`
    XRegExp.addToken = function (regex, handler, scope, trigger) {
        tokens.push({
            pattern: clone(regex, "g" + (hasNativeY ? "y" : "")),
            handler: handler,
            scope: scope || XRegExp.OUTSIDE_CLASS,
            trigger: trigger || null
        });
    };

    // Accepts a pattern and flags; returns an extended `RegExp` object. If the pattern and flag
    // combination has previously been cached, the cached copy is returned; otherwise the newly
    // created regex is cached
    XRegExp.cache = function (pattern, flags) {
        var key = pattern + "/" + (flags || "");
        return XRegExp.cache[key] || (XRegExp.cache[key] = XRegExp(pattern, flags));
    };

    // Accepts a `RegExp` instance; returns a copy with the `/g` flag set. The copy has a fresh
    // `lastIndex` (set to zero). If you want to copy a regex without forcing the `global`
    // property, use `XRegExp(regex)`. Do not use `RegExp(regex)` because it will not preserve
    // special properties required for named capture
    XRegExp.copyAsGlobal = function (regex) {
        return clone(regex, "g");
    };

    // Accepts a string; returns the string with regex metacharacters escaped. The returned string
    // can safely be used at any point within a regex to match the provided literal string. Escaped
    // characters are [ ] { } ( ) * + ? - . , \ ^ $ | # and whitespace
    XRegExp.escape = function (str) {
        return str.replace(/[-[\]{}()*+?.,\\^$|#\s]/g, "\\$&");
    };

    // Accepts a string to search, regex to search with, position to start the search within the
    // string (default: 0), and an optional Boolean indicating whether matches must start at-or-
    // after the position or at the specified position only. This function ignores the `lastIndex`
    // property of the provided regex
    XRegExp.execAt = function (str, regex, pos, anchored) {
        regex = clone(regex, "g" + ((anchored && hasNativeY) ? "y" : ""));
        regex.lastIndex = pos = pos || 0;
        var match = regex.exec(str);
        if (anchored)
            return (match && match.index === pos) ? match : null;
        else
            return match;
    };

    // Breaks the unrestorable link to XRegExp's private list of tokens, thereby preventing
    // syntax and flag changes. Should be run after XRegExp and any plugins are loaded
    XRegExp.freezeTokens = function () {
        XRegExp.addToken = function () {
            throw Error("can't run addToken after freezeTokens");
        };
    };

    // Accepts any value; returns a Boolean indicating whether the argument is a `RegExp` object.
    // Note that this is also `true` for regex literals and regexes created by the `XRegExp`
    // constructor. This works correctly for variables created in another frame, when `instanceof`
    // and `constructor` checks would fail to work as intended
    XRegExp.isRegExp = function (o) {
        return Object.prototype.toString.call(o) === "[object RegExp]";
    };

    // Executes `callback` once per match within `str`. Provides a simpler and cleaner way to
    // iterate over regex matches compared to the traditional approaches of subverting
    // `String.prototype.replace` or repeatedly calling `exec` within a `while` loop
    XRegExp.iterate = function (str, origRegex, callback, context) {
        var regex = clone(origRegex, "g"),
            i = -1, match;
        while (match = regex.exec(str)) {
            callback.call(context, match, ++i, str, regex);
            if (regex.lastIndex === match.index)
                regex.lastIndex++;
        }
        if (origRegex.global)
            origRegex.lastIndex = 0;
    };

    // Accepts a string and an array of regexes; returns the result of using each successive regex
    // to search within the matches of the previous regex. The array of regexes can also contain
    // objects with `regex` and `backref` properties, in which case the named or numbered back-
    // references specified are passed forward to the next regex or returned. E.g.:
    // var xregexpImgFileNames = XRegExp.matchChain(html, [
    //     {regex: /<img\b([^>]+)>/i, backref: 1}, // <img> tag attributes
    //     {regex: XRegExp('(?ix) \\s src=" (?<src> [^"]+ )'), backref: "src"}, // src attribute values
    //     {regex: XRegExp("^http://xregexp\\.com(/[^#?]+)", "i"), backref: 1}, // xregexp.com paths
    //     /[^\/]+$/ // filenames (strip directory paths)
    // ]);
    XRegExp.matchChain = function (str, chain) {
        return function recurseChain (values, level) {
            var item = chain[level].regex ? chain[level] : {regex: chain[level]},
                regex = clone(item.regex, "g"),
                matches = [], i;
            for (i = 0; i < values.length; i++) {
                XRegExp.iterate(values[i], regex, function (match) {
                    matches.push(item.backref ? (match[item.backref] || "") : match[0]);
                });
            }
            return ((level === chain.length - 1) || !matches.length) ?
                matches : recurseChain(matches, level + 1);
        }([str], 0);
    };


    //---------------------------------
    //  New RegExp prototype methods
    //---------------------------------

    // Accepts a context object and arguments array; returns the result of calling `exec` with the
    // first value in the arguments array. the context is ignored but is accepted for congruity
    // with `Function.prototype.apply`
    RegExp.prototype.apply = function (context, args) {
        return this.exec(args[0]);
    };

    // Accepts a context object and string; returns the result of calling `exec` with the provided
    // string. the context is ignored but is accepted for congruity with `Function.prototype.call`
    RegExp.prototype.call = function (context, str) {
        return this.exec(str);
    };


    //---------------------------------
    //  Overriden native methods
    //---------------------------------

    // Adds named capture support (with backreferences returned as `result.name`), and fixes two
    // cross-browser issues per ES3:
    // - Captured values for nonparticipating capturing groups should be returned as `undefined`,
    //   rather than the empty string.
    // - `lastIndex` should not be incremented after zero-length matches.
    RegExp.prototype.exec = function (str) {
        var match = real.exec.apply(this, arguments),
            name, r2;
        if (match) {
            // Fix browsers whose `exec` methods don't consistently return `undefined` for
            // nonparticipating capturing groups
            if (!compliantExecNpcg && match.length > 1 && indexOf(match, "") > -1) {
                r2 = RegExp(this.source, real.replace.call(getNativeFlags(this), "g", ""));
                // Using `str.slice(match.index)` rather than `match[0]` in case lookahead allowed
                // matching due to characters outside the match
                real.replace.call(str.toString().slice(match.index), r2, function () {
                    for (var i = 1; i < arguments.length - 2; i++) {
                        if (arguments[i] === undefined)
                            match[i] = undefined;
                    }
                });
            }
            // Attach named capture properties
            if (this._xregexp && this._xregexp.captureNames) {
                for (var i = 1; i < match.length; i++) {
                    name = this._xregexp.captureNames[i - 1];
                    if (name)
                       match[name] = match[i];
                }
            }
            // Fix browsers that increment `lastIndex` after zero-length matches
            if (!compliantLastIndexIncrement && this.global && !match[0].length && (this.lastIndex > match.index))
                this.lastIndex--;
        }
        return match;
    };

    // Don't override `test` if it won't change anything
    if (!compliantLastIndexIncrement) {
        // Fix browser bug in native method
        RegExp.prototype.test = function (str) {
            // Use the native `exec` to skip some processing overhead, even though the overriden
            // `exec` would take care of the `lastIndex` fix
            var match = real.exec.call(this, str);
            // Fix browsers that increment `lastIndex` after zero-length matches
            if (match && this.global && !match[0].length && (this.lastIndex > match.index))
                this.lastIndex--;
            return !!match;
        };
    }

    // Adds named capture support and fixes browser bugs in native method
    String.prototype.match = function (regex) {
        if (!XRegExp.isRegExp(regex))
            regex = RegExp(regex); // Native `RegExp`
        if (regex.global) {
            var result = real.match.apply(this, arguments);
            regex.lastIndex = 0; // Fix IE bug
            return result;
        }
        return regex.exec(this); // Run the altered `exec`
    };

    // Adds support for `${n}` tokens for named and numbered backreferences in replacement text,
    // and provides named backreferences to replacement functions as `arguments[0].name`. Also
    // fixes cross-browser differences in replacement text syntax when performing a replacement
    // using a nonregex search value, and the value of replacement regexes' `lastIndex` property
    // during replacement iterations. Note that this doesn't support SpiderMonkey's proprietary
    // third (`flags`) parameter
    String.prototype.replace = function (search, replacement) {
        var isRegex = XRegExp.isRegExp(search),
            captureNames, result, str;

        // There are many combinations of search/replacement types/values and browser bugs that
        // preclude passing to native `replace`, so just keep this check relatively simple
        if (isRegex && typeof replacement.valueOf() === "string" && replacement.indexOf("${") === -1 && compliantLastIndexReset)
            return real.replace.apply(this, arguments);

        if (!isRegex)
            search = search + ""; // Type conversion
        else if (search._xregexp)
            captureNames = search._xregexp.captureNames; // Array or `null`

        if (typeof replacement === "function") {
            result = real.replace.call(this, search, function () {
                if (captureNames) {
                    // Change the `arguments[0]` string primitive to a String object which can store properties
                    arguments[0] = new String(arguments[0]);
                    // Store named backreferences on `arguments[0]`
                    for (var i = 0; i < captureNames.length; i++) {
                        if (captureNames[i])
                            arguments[0][captureNames[i]] = arguments[i + 1];
                    }
                }
                // Update `lastIndex` before calling `replacement`
                if (isRegex && search.global)
                    search.lastIndex = arguments[arguments.length - 2] + arguments[0].length;
                return replacement.apply(null, arguments);
            });
        } else {
            str = this + ""; // Type conversion, so `args[args.length - 1]` will be a string (given nonstring `this`)
            result = real.replace.call(str, search, function () {
                var args = arguments; // Keep this function's `arguments` available through closure
                return real.replace.call(replacement, replacementToken, function ($0, $1, $2) {
                    // Numbered backreference (without delimiters) or special variable
                    if ($1) {
                        switch ($1) {
                            case "$": return "$";
                            case "&": return args[0];
                            case "`": return args[args.length - 1].slice(0, args[args.length - 2]);
                            case "'": return args[args.length - 1].slice(args[args.length - 2] + args[0].length);
                            // Numbered backreference
                            default:
                                // What does "$10" mean?
                                // - Backreference 10, if 10 or more capturing groups exist
                                // - Backreference 1 followed by "0", if 1-9 capturing groups exist
                                // - Otherwise, it's the string "$10"
                                // Also note:
                                // - Backreferences cannot be more than two digits (enforced by `replacementToken`)
                                // - "$01" is equivalent to "$1" if a capturing group exists, otherwise it's the string "$01"
                                // - There is no "$0" token ("$&" is the entire match)
                                var literalNumbers = "";
                                $1 = +$1; // Type conversion; drop leading zero
                                if (!$1) // `$1` was "0" or "00"
                                    return $0;
                                while ($1 > args.length - 3) {
                                    literalNumbers = String.prototype.slice.call($1, -1) + literalNumbers;
                                    $1 = Math.floor($1 / 10); // Drop the last digit
                                }
                                return ($1 ? args[$1] || "" : "$") + literalNumbers;
                        }
                    // Named backreference or delimited numbered backreference
                    } else {
                        // What does "${n}" mean?
                        // - Backreference to numbered capture n. Two differences from "$n":
                        //   - n can be more than two digits
                        //   - Backreference 0 is allowed, and is the entire match
                        // - Backreference to named capture n, if it exists and is not a number overridden by numbered capture
                        // - Otherwise, it's the string "${n}"
                        var n = +$2; // Type conversion; drop leading zeros
                        if (n <= args.length - 3)
                            return args[n];
                        n = captureNames ? indexOf(captureNames, $2) : -1;
                        return n > -1 ? args[n + 1] : $0;
                    }
                });
            });
        }

        if (isRegex && search.global)
            search.lastIndex = 0; // Fix IE bug

        return result;
    };

    // A consistent cross-browser, ES3 compliant `split`
    String.prototype.split = function (s /* separator */, limit) {
        // If separator `s` is not a regex, use the native `split`
        if (!XRegExp.isRegExp(s))
            return real.split.apply(this, arguments);

        var str = this + "", // Type conversion
            output = [],
            lastLastIndex = 0,
            match, lastLength;

        // Behavior for `limit`: if it's...
        // - `undefined`: No limit
        // - `NaN` or zero: Return an empty array
        // - A positive number: Use `Math.floor(limit)`
        // - A negative number: No limit
        // - Other: Type-convert, then use the above rules
        if (limit === undefined || +limit < 0) {
            limit = Infinity;
        } else {
            limit = Math.floor(+limit);
            if (!limit)
                return [];
        }

        // This is required if not `s.global`, and it avoids needing to set `s.lastIndex` to zero
        // and restore it to its original value when we're done using the regex
        s = XRegExp.copyAsGlobal(s);

        while (match = s.exec(str)) { // Run the altered `exec` (required for `lastIndex` fix, etc.)
            if (s.lastIndex > lastLastIndex) {
                output.push(str.slice(lastLastIndex, match.index));

                if (match.length > 1 && match.index < str.length)
                    Array.prototype.push.apply(output, match.slice(1));

                lastLength = match[0].length;
                lastLastIndex = s.lastIndex;

                if (output.length >= limit)
                    break;
            }

            if (s.lastIndex === match.index)
                s.lastIndex++;
        }

        if (lastLastIndex === str.length) {
            if (!real.test.call(s, "") || lastLength)
                output.push("");
        } else {
            output.push(str.slice(lastLastIndex));
        }

        return output.length > limit ? output.slice(0, limit) : output;
    };


    //---------------------------------
    //  Private helper functions
    //---------------------------------

    // Supporting function for `XRegExp`, `XRegExp.copyAsGlobal`, etc. Returns a copy of a `RegExp`
    // instance with a fresh `lastIndex` (set to zero), preserving properties required for named
    // capture. Also allows adding new flags in the process of copying the regex
    function clone (regex, additionalFlags) {
        if (!XRegExp.isRegExp(regex))
            throw TypeError("type RegExp expected");
        var x = regex._xregexp;
        regex = XRegExp(regex.source, getNativeFlags(regex) + (additionalFlags || ""));
        if (x) {
            regex._xregexp = {
                source: x.source,
                captureNames: x.captureNames ? x.captureNames.slice(0) : null
            };
        }
        return regex;
    };

    function getNativeFlags (regex) {
        return (regex.global     ? "g" : "") +
               (regex.ignoreCase ? "i" : "") +
               (regex.multiline  ? "m" : "") +
               (regex.extended   ? "x" : "") + // Proposed for ES4; included in AS3
               (regex.sticky     ? "y" : "");
    };

    function runTokens (pattern, index, scope, context) {
        var i = tokens.length,
            result, match, t;
        // Protect against constructing XRegExps within token handler and trigger functions
        isInsideConstructor = true;
        // Must reset `isInsideConstructor`, even if a `trigger` or `handler` throws
        try {
            while (i--) { // Run in reverse order
                t = tokens[i];
                if ((scope & t.scope) && (!t.trigger || t.trigger.call(context))) {
                    t.pattern.lastIndex = index;
                    match = t.pattern.exec(pattern); // Running the altered `exec` here allows use of named backreferences, etc.
                    if (match && match.index === index) {
                        result = {
                            output: t.handler.call(context, match, scope),
                            match: match
                        };
                        break;
                    }
                }
            }
        } catch (err) {
            throw err;
        } finally {
            isInsideConstructor = false;
        }
        return result;
    };

    function indexOf (array, item, from) {
        if (Array.prototype.indexOf) // Use the native array method if available
            return array.indexOf(item, from);
        for (var i = from || 0; i < array.length; i++) {
            if (array[i] === item)
                return i;
        }
        return -1;
    };


    //---------------------------------
    //  Built-in tokens
    //---------------------------------

    // Augment XRegExp's regular expression syntax and flags. Note that when adding tokens, the
    // third (`scope`) argument defaults to `XRegExp.OUTSIDE_CLASS`

    // Comment pattern: (?# )
    XRegExp.addToken(
        /\(\?#[^)]*\)/,
        function (match) {
            // Keep tokens separated unless the following token is a quantifier
            return real.test.call(quantifier, match.input.slice(match.index + match[0].length)) ? "" : "(?:)";
        }
    );

    // Capturing group (match the opening parenthesis only).
    // Required for support of named capturing groups
    XRegExp.addToken(
        /\((?!\?)/,
        function () {
            this.captureNames.push(null);
            return "(";
        }
    );

    // Named capturing group (match the opening delimiter only): (?<name>
    XRegExp.addToken(
        /\(\?<([$\w]+)>/,
        function (match) {
            this.captureNames.push(match[1]);
            this.hasNamedCapture = true;
            return "(";
        }
    );

    // Named backreference: \k<name>
    XRegExp.addToken(
        /\\k<([\w$]+)>/,
        function (match) {
            var index = indexOf(this.captureNames, match[1]);
            // Keep backreferences separate from subsequent literal numbers. Preserve back-
            // references to named groups that are undefined at this point as literal strings
            return index > -1 ?
                "\\" + (index + 1) + (isNaN(match.input.charAt(match.index + match[0].length)) ? "" : "(?:)") :
                match[0];
        }
    );

    // Empty character class: [] or [^]
    XRegExp.addToken(
        /\[\^?]/,
        function (match) {
            // For cross-browser compatibility with ES3, convert [] to \b\B and [^] to [\s\S].
            // (?!) should work like \b\B, but is unreliable in Firefox
            return match[0] === "[]" ? "\\b\\B" : "[\\s\\S]";
        }
    );

    // Mode modifier at the start of the pattern only, with any combination of flags imsx: (?imsx)
    // Does not support x(?i), (?-i), (?i-m), (?i: ), (?i)(?m), etc.
    XRegExp.addToken(
        /^\(\?([imsx]+)\)/,
        function (match) {
            this.setFlag(match[1]);
            return "";
        }
    );

    // Whitespace and comments, in free-spacing (aka extended) mode only
    XRegExp.addToken(
        /(?:\s+|#.*)+/,
        function (match) {
            // Keep tokens separated unless the following token is a quantifier
            return real.test.call(quantifier, match.input.slice(match.index + match[0].length)) ? "" : "(?:)";
        },
        XRegExp.OUTSIDE_CLASS,
        function () {return this.hasFlag("x");}
    );

    // Dot, in dotall (aka singleline) mode only
    XRegExp.addToken(
        /\./,
        function () {return "[\\s\\S]";},
        XRegExp.OUTSIDE_CLASS,
        function () {return this.hasFlag("s");}
    );


    //---------------------------------
    //  Backward compatibility
    //---------------------------------

    // Uncomment the following block for compatibility with XRegExp 1.0-1.2:
    /*
    XRegExp.matchWithinChain = XRegExp.matchChain;
    RegExp.prototype.addFlags = function (s) {return clone(this, s);};
    RegExp.prototype.execAll = function (s) {var r = []; XRegExp.iterate(s, this, function (m) {r.push(m);}); return r;};
    RegExp.prototype.forEachExec = function (s, f, c) {return XRegExp.iterate(s, this, f, c);};
    RegExp.prototype.validate = function (s) {var r = RegExp("^(?:" + this.source + ")$(?!\\s)", getNativeFlags(this)); if (this.global) this.lastIndex = 0; return s.search(r) === 0;};
    */

})();

// CommonJS
typeof(exports) != 'undefined' ? exports.XRegExp = XRegExp : null;

`'])|{([$\w]+)})/g,
        flagClip = /[^gimy]+|([\s\S])(?=[\s\S]*\1)/g, // Nonnative and duplicate flags
        quantifier = /^(?:[?*+]|{\d+(?:,\d*)?})\??/,
        isInsideConstructor = false,
        tokens = [],
        // Copy native globals for reference ("native" is an ES3 reserved keyword)
        real = {
            exec: RegExp.prototype.exec,
            test: RegExp.prototype.test,
            match: String.prototype.match,
            replace: String.prototype.replace,
            split: String.prototype.split
        },
        compliantExecNpcg = real.exec.call(/()??/, "")[1] === undefined, // check `exec` handling of nonparticipating capturing groups
        compliantLastIndexIncrement = function () {
            var x = /^/g;
            real.test.call(x, "");
            return !x.lastIndex;
        }(),
        compliantLastIndexReset = function () {
            var x = /x/g;
            real.replace.call("x", x, "");
            return !x.lastIndex;
        }(),
        hasNativeY = RegExp.prototype.sticky !== undefined,
        nativeTokens = {};
 
    // `nativeTokens` match native multicharacter metasequences only (including deprecated octals,
    // excluding character classes)
    nativeTokens[XRegExp.INSIDE_CLASS] = /^(?:\\(?:[0-3][0-7]{0,2}|[4-7][0-7]?|x[\dA-Fa-f]{2}|u[\dA-Fa-f]{4}|c[A-Za-z]|[\s\S]))/;
    nativeTokens[XRegExp.OUTSIDE_CLASS] = /^(?:\\(?:0(?:[0-3][0-7]{0,2}|[4-7][0-7]?)?|[1-9]\d*|x[\dA-Fa-f]{2}|u[\dA-Fa-f]{4}|c[A-Za-z]|[\s\S])|\(\?[:=!]|[?*+]\?|{\d+(?:,\d*)?}\??)/;
 
 
    //---------------------------------
    //  Public methods
    //---------------------------------
 
    // Lets you extend or change XRegExp syntax and create custom flags. This is used internally by
    // the XRegExp library and can be used to create XRegExp plugins. This function is intended for
    // users with advanced knowledge of JavaScript's regular expression syntax and behavior. It can
    // be disabled by `XRegExp.freezeTokens`
    XRegExp.addToken = function (regex, handler, scope, trigger) {
        tokens.push({
            pattern: clone(regex, "g" + (hasNativeY ? "y" : "")),
            handler: handler,
            scope: scope || XRegExp.OUTSIDE_CLASS,
            trigger: trigger || null
        });
    };
 
    // Accepts a pattern and flags; returns an extended `RegExp` object. If the pattern and flag
    // combination has previously been cached, the cached copy is returned; otherwise the newly
    // created regex is cached
    XRegExp.cache = function (pattern, flags) {
        var key = pattern + "/" + (flags || "");
        return XRegExp.cache[key] || (XRegExp.cache[key] = XRegExp(pattern, flags));
    };
 
    // Accepts a `RegExp` instance; returns a copy with the `/g` flag set. The copy has a fresh
    // `lastIndex` (set to zero). If you want to copy a regex without forcing the `global`
    // property, use `XRegExp(regex)`. Do not use `RegExp(regex)` because it will not preserve
    // special properties required for named capture
    XRegExp.copyAsGlobal = function (regex) {
        return clone(regex, "g");
    };
 
    // Accepts a string; returns the string with regex metacharacters escaped. The returned string
    // can safely be used at any point within a regex to match the provided literal string. Escaped
    // characters are [ ] { } ( ) * + ? - . , \ ^ $ | # and whitespace
    XRegExp.escape = function (str) {
        return str.replace(/[-[\]{}()*+?.,\\^$|#\s]/g, "\\
// XRegExp 1.5.0
// (c) 2007-2010 Steven Levithan
// MIT License
// <http://xregexp.com>
// Provides an augmented, extensible, cross-browser implementation of regular expressions,
// including support for additional syntax, flags, and methods

var XRegExp;

if (XRegExp) {
    // Avoid running twice, since that would break references to native globals
    throw Error("can't load XRegExp twice in the same frame");
}

// Run within an anonymous function to protect variables and avoid new globals
(function () {

    //---------------------------------
    //  Constructor
    //---------------------------------

    // Accepts a pattern and flags; returns a new, extended `RegExp` object. Differs from a native
    // regular expression in that additional syntax and flags are supported and cross-browser
    // syntax inconsistencies are ameliorated
    XRegExp = function (pattern, flags) {
        var output = [],
            currScope = XRegExp.OUTSIDE_CLASS,
            pos = 0,
            context, tokenResult, match, chr, regex;

        if (XRegExp.isRegExp(pattern)) {
            if (flags !== undefined)
                throw TypeError("can't supply flags when constructing one RegExp from another");
            return clone(pattern);
        }
        // Tokens become part of the regex construction process, so protect against infinite
        // recursion when an XRegExp is constructed within a token handler or trigger
        if (isInsideConstructor)
            throw Error("can't call the XRegExp constructor within token definition functions");

        flags = flags || "";
        context = { // `this` object for custom tokens
            hasNamedCapture: false,
            captureNames: [],
            hasFlag: function (flag) {return flags.indexOf(flag) > -1;},
            setFlag: function (flag) {flags += flag;}
        };

        while (pos < pattern.length) {
            // Check for custom tokens at the current position
            tokenResult = runTokens(pattern, pos, currScope, context);

            if (tokenResult) {
                output.push(tokenResult.output);
                pos += (tokenResult.match[0].length || 1);
            } else {
                // Check for native multicharacter metasequences (excluding character classes) at
                // the current position
                if (match = real.exec.call(nativeTokens[currScope], pattern.slice(pos))) {
                    output.push(match[0]);
                    pos += match[0].length;
                } else {
                    chr = pattern.charAt(pos);
                    if (chr === "[")
                        currScope = XRegExp.INSIDE_CLASS;
                    else if (chr === "]")
                        currScope = XRegExp.OUTSIDE_CLASS;
                    // Advance position one character
                    output.push(chr);
                    pos++;
                }
            }
        }

        regex = RegExp(output.join(""), real.replace.call(flags, flagClip, ""));
        regex._xregexp = {
            source: pattern,
            captureNames: context.hasNamedCapture ? context.captureNames : null
        };
        return regex;
    };


    //---------------------------------
    //  Public properties
    //---------------------------------

    XRegExp.version = "1.5.0";

    // Token scope bitflags
    XRegExp.INSIDE_CLASS = 1;
    XRegExp.OUTSIDE_CLASS = 2;


    //---------------------------------
    //  Private variables
    //---------------------------------

    var replacementToken = /\$(?:(\d\d?|[$&`'])|{([$\w]+)})/g,
        flagClip = /[^gimy]+|([\s\S])(?=[\s\S]*\1)/g, // Nonnative and duplicate flags
        quantifier = /^(?:[?*+]|{\d+(?:,\d*)?})\??/,
        isInsideConstructor = false,
        tokens = [],
        // Copy native globals for reference ("native" is an ES3 reserved keyword)
        real = {
            exec: RegExp.prototype.exec,
            test: RegExp.prototype.test,
            match: String.prototype.match,
            replace: String.prototype.replace,
            split: String.prototype.split
        },
        compliantExecNpcg = real.exec.call(/()??/, "")[1] === undefined, // check `exec` handling of nonparticipating capturing groups
        compliantLastIndexIncrement = function () {
            var x = /^/g;
            real.test.call(x, "");
            return !x.lastIndex;
        }(),
        compliantLastIndexReset = function () {
            var x = /x/g;
            real.replace.call("x", x, "");
            return !x.lastIndex;
        }(),
        hasNativeY = RegExp.prototype.sticky !== undefined,
        nativeTokens = {};

    // `nativeTokens` match native multicharacter metasequences only (including deprecated octals,
    // excluding character classes)
    nativeTokens[XRegExp.INSIDE_CLASS] = /^(?:\\(?:[0-3][0-7]{0,2}|[4-7][0-7]?|x[\dA-Fa-f]{2}|u[\dA-Fa-f]{4}|c[A-Za-z]|[\s\S]))/;
    nativeTokens[XRegExp.OUTSIDE_CLASS] = /^(?:\\(?:0(?:[0-3][0-7]{0,2}|[4-7][0-7]?)?|[1-9]\d*|x[\dA-Fa-f]{2}|u[\dA-Fa-f]{4}|c[A-Za-z]|[\s\S])|\(\?[:=!]|[?*+]\?|{\d+(?:,\d*)?}\??)/;


    //---------------------------------
    //  Public methods
    //---------------------------------

    // Lets you extend or change XRegExp syntax and create custom flags. This is used internally by
    // the XRegExp library and can be used to create XRegExp plugins. This function is intended for
    // users with advanced knowledge of JavaScript's regular expression syntax and behavior. It can
    // be disabled by `XRegExp.freezeTokens`
    XRegExp.addToken = function (regex, handler, scope, trigger) {
        tokens.push({
            pattern: clone(regex, "g" + (hasNativeY ? "y" : "")),
            handler: handler,
            scope: scope || XRegExp.OUTSIDE_CLASS,
            trigger: trigger || null
        });
    };

    // Accepts a pattern and flags; returns an extended `RegExp` object. If the pattern and flag
    // combination has previously been cached, the cached copy is returned; otherwise the newly
    // created regex is cached
    XRegExp.cache = function (pattern, flags) {
        var key = pattern + "/" + (flags || "");
        return XRegExp.cache[key] || (XRegExp.cache[key] = XRegExp(pattern, flags));
    };

    // Accepts a `RegExp` instance; returns a copy with the `/g` flag set. The copy has a fresh
    // `lastIndex` (set to zero). If you want to copy a regex without forcing the `global`
    // property, use `XRegExp(regex)`. Do not use `RegExp(regex)` because it will not preserve
    // special properties required for named capture
    XRegExp.copyAsGlobal = function (regex) {
        return clone(regex, "g");
    };

    // Accepts a string; returns the string with regex metacharacters escaped. The returned string
    // can safely be used at any point within a regex to match the provided literal string. Escaped
    // characters are [ ] { } ( ) * + ? - . , \ ^ $ | # and whitespace
    XRegExp.escape = function (str) {
        return str.replace(/[-[\]{}()*+?.,\\^$|#\s]/g, "\\$&");
    };

    // Accepts a string to search, regex to search with, position to start the search within the
    // string (default: 0), and an optional Boolean indicating whether matches must start at-or-
    // after the position or at the specified position only. This function ignores the `lastIndex`
    // property of the provided regex
    XRegExp.execAt = function (str, regex, pos, anchored) {
        regex = clone(regex, "g" + ((anchored && hasNativeY) ? "y" : ""));
        regex.lastIndex = pos = pos || 0;
        var match = regex.exec(str);
        if (anchored)
            return (match && match.index === pos) ? match : null;
        else
            return match;
    };

    // Breaks the unrestorable link to XRegExp's private list of tokens, thereby preventing
    // syntax and flag changes. Should be run after XRegExp and any plugins are loaded
    XRegExp.freezeTokens = function () {
        XRegExp.addToken = function () {
            throw Error("can't run addToken after freezeTokens");
        };
    };

    // Accepts any value; returns a Boolean indicating whether the argument is a `RegExp` object.
    // Note that this is also `true` for regex literals and regexes created by the `XRegExp`
    // constructor. This works correctly for variables created in another frame, when `instanceof`
    // and `constructor` checks would fail to work as intended
    XRegExp.isRegExp = function (o) {
        return Object.prototype.toString.call(o) === "[object RegExp]";
    };

    // Executes `callback` once per match within `str`. Provides a simpler and cleaner way to
    // iterate over regex matches compared to the traditional approaches of subverting
    // `String.prototype.replace` or repeatedly calling `exec` within a `while` loop
    XRegExp.iterate = function (str, origRegex, callback, context) {
        var regex = clone(origRegex, "g"),
            i = -1, match;
        while (match = regex.exec(str)) {
            callback.call(context, match, ++i, str, regex);
            if (regex.lastIndex === match.index)
                regex.lastIndex++;
        }
        if (origRegex.global)
            origRegex.lastIndex = 0;
    };

    // Accepts a string and an array of regexes; returns the result of using each successive regex
    // to search within the matches of the previous regex. The array of regexes can also contain
    // objects with `regex` and `backref` properties, in which case the named or numbered back-
    // references specified are passed forward to the next regex or returned. E.g.:
    // var xregexpImgFileNames = XRegExp.matchChain(html, [
    //     {regex: /<img\b([^>]+)>/i, backref: 1}, // <img> tag attributes
    //     {regex: XRegExp('(?ix) \\s src=" (?<src> [^"]+ )'), backref: "src"}, // src attribute values
    //     {regex: XRegExp("^http://xregexp\\.com(/[^#?]+)", "i"), backref: 1}, // xregexp.com paths
    //     /[^\/]+$/ // filenames (strip directory paths)
    // ]);
    XRegExp.matchChain = function (str, chain) {
        return function recurseChain (values, level) {
            var item = chain[level].regex ? chain[level] : {regex: chain[level]},
                regex = clone(item.regex, "g"),
                matches = [], i;
            for (i = 0; i < values.length; i++) {
                XRegExp.iterate(values[i], regex, function (match) {
                    matches.push(item.backref ? (match[item.backref] || "") : match[0]);
                });
            }
            return ((level === chain.length - 1) || !matches.length) ?
                matches : recurseChain(matches, level + 1);
        }([str], 0);
    };


    //---------------------------------
    //  New RegExp prototype methods
    //---------------------------------

    // Accepts a context object and arguments array; returns the result of calling `exec` with the
    // first value in the arguments array. the context is ignored but is accepted for congruity
    // with `Function.prototype.apply`
    RegExp.prototype.apply = function (context, args) {
        return this.exec(args[0]);
    };

    // Accepts a context object and string; returns the result of calling `exec` with the provided
    // string. the context is ignored but is accepted for congruity with `Function.prototype.call`
    RegExp.prototype.call = function (context, str) {
        return this.exec(str);
    };


    //---------------------------------
    //  Overriden native methods
    //---------------------------------

    // Adds named capture support (with backreferences returned as `result.name`), and fixes two
    // cross-browser issues per ES3:
    // - Captured values for nonparticipating capturing groups should be returned as `undefined`,
    //   rather than the empty string.
    // - `lastIndex` should not be incremented after zero-length matches.
    RegExp.prototype.exec = function (str) {
        var match = real.exec.apply(this, arguments),
            name, r2;
        if (match) {
            // Fix browsers whose `exec` methods don't consistently return `undefined` for
            // nonparticipating capturing groups
            if (!compliantExecNpcg && match.length > 1 && indexOf(match, "") > -1) {
                r2 = RegExp(this.source, real.replace.call(getNativeFlags(this), "g", ""));
                // Using `str.slice(match.index)` rather than `match[0]` in case lookahead allowed
                // matching due to characters outside the match
                real.replace.call(str.toString().slice(match.index), r2, function () {
                    for (var i = 1; i < arguments.length - 2; i++) {
                        if (arguments[i] === undefined)
                            match[i] = undefined;
                    }
                });
            }
            // Attach named capture properties
            if (this._xregexp && this._xregexp.captureNames) {
                for (var i = 1; i < match.length; i++) {
                    name = this._xregexp.captureNames[i - 1];
                    if (name)
                       match[name] = match[i];
                }
            }
            // Fix browsers that increment `lastIndex` after zero-length matches
            if (!compliantLastIndexIncrement && this.global && !match[0].length && (this.lastIndex > match.index))
                this.lastIndex--;
        }
        return match;
    };

    // Don't override `test` if it won't change anything
    if (!compliantLastIndexIncrement) {
        // Fix browser bug in native method
        RegExp.prototype.test = function (str) {
            // Use the native `exec` to skip some processing overhead, even though the overriden
            // `exec` would take care of the `lastIndex` fix
            var match = real.exec.call(this, str);
            // Fix browsers that increment `lastIndex` after zero-length matches
            if (match && this.global && !match[0].length && (this.lastIndex > match.index))
                this.lastIndex--;
            return !!match;
        };
    }

    // Adds named capture support and fixes browser bugs in native method
    String.prototype.match = function (regex) {
        if (!XRegExp.isRegExp(regex))
            regex = RegExp(regex); // Native `RegExp`
        if (regex.global) {
            var result = real.match.apply(this, arguments);
            regex.lastIndex = 0; // Fix IE bug
            return result;
        }
        return regex.exec(this); // Run the altered `exec`
    };

    // Adds support for `${n}` tokens for named and numbered backreferences in replacement text,
    // and provides named backreferences to replacement functions as `arguments[0].name`. Also
    // fixes cross-browser differences in replacement text syntax when performing a replacement
    // using a nonregex search value, and the value of replacement regexes' `lastIndex` property
    // during replacement iterations. Note that this doesn't support SpiderMonkey's proprietary
    // third (`flags`) parameter
    String.prototype.replace = function (search, replacement) {
        var isRegex = XRegExp.isRegExp(search),
            captureNames, result, str;

        // There are many combinations of search/replacement types/values and browser bugs that
        // preclude passing to native `replace`, so just keep this check relatively simple
        if (isRegex && typeof replacement.valueOf() === "string" && replacement.indexOf("${") === -1 && compliantLastIndexReset)
            return real.replace.apply(this, arguments);

        if (!isRegex)
            search = search + ""; // Type conversion
        else if (search._xregexp)
            captureNames = search._xregexp.captureNames; // Array or `null`

        if (typeof replacement === "function") {
            result = real.replace.call(this, search, function () {
                if (captureNames) {
                    // Change the `arguments[0]` string primitive to a String object which can store properties
                    arguments[0] = new String(arguments[0]);
                    // Store named backreferences on `arguments[0]`
                    for (var i = 0; i < captureNames.length; i++) {
                        if (captureNames[i])
                            arguments[0][captureNames[i]] = arguments[i + 1];
                    }
                }
                // Update `lastIndex` before calling `replacement`
                if (isRegex && search.global)
                    search.lastIndex = arguments[arguments.length - 2] + arguments[0].length;
                return replacement.apply(null, arguments);
            });
        } else {
            str = this + ""; // Type conversion, so `args[args.length - 1]` will be a string (given nonstring `this`)
            result = real.replace.call(str, search, function () {
                var args = arguments; // Keep this function's `arguments` available through closure
                return real.replace.call(replacement, replacementToken, function ($0, $1, $2) {
                    // Numbered backreference (without delimiters) or special variable
                    if ($1) {
                        switch ($1) {
                            case "$": return "$";
                            case "&": return args[0];
                            case "`": return args[args.length - 1].slice(0, args[args.length - 2]);
                            case "'": return args[args.length - 1].slice(args[args.length - 2] + args[0].length);
                            // Numbered backreference
                            default:
                                // What does "$10" mean?
                                // - Backreference 10, if 10 or more capturing groups exist
                                // - Backreference 1 followed by "0", if 1-9 capturing groups exist
                                // - Otherwise, it's the string "$10"
                                // Also note:
                                // - Backreferences cannot be more than two digits (enforced by `replacementToken`)
                                // - "$01" is equivalent to "$1" if a capturing group exists, otherwise it's the string "$01"
                                // - There is no "$0" token ("$&" is the entire match)
                                var literalNumbers = "";
                                $1 = +$1; // Type conversion; drop leading zero
                                if (!$1) // `$1` was "0" or "00"
                                    return $0;
                                while ($1 > args.length - 3) {
                                    literalNumbers = String.prototype.slice.call($1, -1) + literalNumbers;
                                    $1 = Math.floor($1 / 10); // Drop the last digit
                                }
                                return ($1 ? args[$1] || "" : "$") + literalNumbers;
                        }
                    // Named backreference or delimited numbered backreference
                    } else {
                        // What does "${n}" mean?
                        // - Backreference to numbered capture n. Two differences from "$n":
                        //   - n can be more than two digits
                        //   - Backreference 0 is allowed, and is the entire match
                        // - Backreference to named capture n, if it exists and is not a number overridden by numbered capture
                        // - Otherwise, it's the string "${n}"
                        var n = +$2; // Type conversion; drop leading zeros
                        if (n <= args.length - 3)
                            return args[n];
                        n = captureNames ? indexOf(captureNames, $2) : -1;
                        return n > -1 ? args[n + 1] : $0;
                    }
                });
            });
        }

        if (isRegex && search.global)
            search.lastIndex = 0; // Fix IE bug

        return result;
    };

    // A consistent cross-browser, ES3 compliant `split`
    String.prototype.split = function (s /* separator */, limit) {
        // If separator `s` is not a regex, use the native `split`
        if (!XRegExp.isRegExp(s))
            return real.split.apply(this, arguments);

        var str = this + "", // Type conversion
            output = [],
            lastLastIndex = 0,
            match, lastLength;

        // Behavior for `limit`: if it's...
        // - `undefined`: No limit
        // - `NaN` or zero: Return an empty array
        // - A positive number: Use `Math.floor(limit)`
        // - A negative number: No limit
        // - Other: Type-convert, then use the above rules
        if (limit === undefined || +limit < 0) {
            limit = Infinity;
        } else {
            limit = Math.floor(+limit);
            if (!limit)
                return [];
        }

        // This is required if not `s.global`, and it avoids needing to set `s.lastIndex` to zero
        // and restore it to its original value when we're done using the regex
        s = XRegExp.copyAsGlobal(s);

        while (match = s.exec(str)) { // Run the altered `exec` (required for `lastIndex` fix, etc.)
            if (s.lastIndex > lastLastIndex) {
                output.push(str.slice(lastLastIndex, match.index));

                if (match.length > 1 && match.index < str.length)
                    Array.prototype.push.apply(output, match.slice(1));

                lastLength = match[0].length;
                lastLastIndex = s.lastIndex;

                if (output.length >= limit)
                    break;
            }

            if (s.lastIndex === match.index)
                s.lastIndex++;
        }

        if (lastLastIndex === str.length) {
            if (!real.test.call(s, "") || lastLength)
                output.push("");
        } else {
            output.push(str.slice(lastLastIndex));
        }

        return output.length > limit ? output.slice(0, limit) : output;
    };


    //---------------------------------
    //  Private helper functions
    //---------------------------------

    // Supporting function for `XRegExp`, `XRegExp.copyAsGlobal`, etc. Returns a copy of a `RegExp`
    // instance with a fresh `lastIndex` (set to zero), preserving properties required for named
    // capture. Also allows adding new flags in the process of copying the regex
    function clone (regex, additionalFlags) {
        if (!XRegExp.isRegExp(regex))
            throw TypeError("type RegExp expected");
        var x = regex._xregexp;
        regex = XRegExp(regex.source, getNativeFlags(regex) + (additionalFlags || ""));
        if (x) {
            regex._xregexp = {
                source: x.source,
                captureNames: x.captureNames ? x.captureNames.slice(0) : null
            };
        }
        return regex;
    };

    function getNativeFlags (regex) {
        return (regex.global     ? "g" : "") +
               (regex.ignoreCase ? "i" : "") +
               (regex.multiline  ? "m" : "") +
               (regex.extended   ? "x" : "") + // Proposed for ES4; included in AS3
               (regex.sticky     ? "y" : "");
    };

    function runTokens (pattern, index, scope, context) {
        var i = tokens.length,
            result, match, t;
        // Protect against constructing XRegExps within token handler and trigger functions
        isInsideConstructor = true;
        // Must reset `isInsideConstructor`, even if a `trigger` or `handler` throws
        try {
            while (i--) { // Run in reverse order
                t = tokens[i];
                if ((scope & t.scope) && (!t.trigger || t.trigger.call(context))) {
                    t.pattern.lastIndex = index;
                    match = t.pattern.exec(pattern); // Running the altered `exec` here allows use of named backreferences, etc.
                    if (match && match.index === index) {
                        result = {
                            output: t.handler.call(context, match, scope),
                            match: match
                        };
                        break;
                    }
                }
            }
        } catch (err) {
            throw err;
        } finally {
            isInsideConstructor = false;
        }
        return result;
    };

    function indexOf (array, item, from) {
        if (Array.prototype.indexOf) // Use the native array method if available
            return array.indexOf(item, from);
        for (var i = from || 0; i < array.length; i++) {
            if (array[i] === item)
                return i;
        }
        return -1;
    };


    //---------------------------------
    //  Built-in tokens
    //---------------------------------

    // Augment XRegExp's regular expression syntax and flags. Note that when adding tokens, the
    // third (`scope`) argument defaults to `XRegExp.OUTSIDE_CLASS`

    // Comment pattern: (?# )
    XRegExp.addToken(
        /\(\?#[^)]*\)/,
        function (match) {
            // Keep tokens separated unless the following token is a quantifier
            return real.test.call(quantifier, match.input.slice(match.index + match[0].length)) ? "" : "(?:)";
        }
    );

    // Capturing group (match the opening parenthesis only).
    // Required for support of named capturing groups
    XRegExp.addToken(
        /\((?!\?)/,
        function () {
            this.captureNames.push(null);
            return "(";
        }
    );

    // Named capturing group (match the opening delimiter only): (?<name>
    XRegExp.addToken(
        /\(\?<([$\w]+)>/,
        function (match) {
            this.captureNames.push(match[1]);
            this.hasNamedCapture = true;
            return "(";
        }
    );

    // Named backreference: \k<name>
    XRegExp.addToken(
        /\\k<([\w$]+)>/,
        function (match) {
            var index = indexOf(this.captureNames, match[1]);
            // Keep backreferences separate from subsequent literal numbers. Preserve back-
            // references to named groups that are undefined at this point as literal strings
            return index > -1 ?
                "\\" + (index + 1) + (isNaN(match.input.charAt(match.index + match[0].length)) ? "" : "(?:)") :
                match[0];
        }
    );

    // Empty character class: [] or [^]
    XRegExp.addToken(
        /\[\^?]/,
        function (match) {
            // For cross-browser compatibility with ES3, convert [] to \b\B and [^] to [\s\S].
            // (?!) should work like \b\B, but is unreliable in Firefox
            return match[0] === "[]" ? "\\b\\B" : "[\\s\\S]";
        }
    );

    // Mode modifier at the start of the pattern only, with any combination of flags imsx: (?imsx)
    // Does not support x(?i), (?-i), (?i-m), (?i: ), (?i)(?m), etc.
    XRegExp.addToken(
        /^\(\?([imsx]+)\)/,
        function (match) {
            this.setFlag(match[1]);
            return "";
        }
    );

    // Whitespace and comments, in free-spacing (aka extended) mode only
    XRegExp.addToken(
        /(?:\s+|#.*)+/,
        function (match) {
            // Keep tokens separated unless the following token is a quantifier
            return real.test.call(quantifier, match.input.slice(match.index + match[0].length)) ? "" : "(?:)";
        },
        XRegExp.OUTSIDE_CLASS,
        function () {return this.hasFlag("x");}
    );

    // Dot, in dotall (aka singleline) mode only
    XRegExp.addToken(
        /\./,
        function () {return "[\\s\\S]";},
        XRegExp.OUTSIDE_CLASS,
        function () {return this.hasFlag("s");}
    );


    //---------------------------------
    //  Backward compatibility
    //---------------------------------

    // Uncomment the following block for compatibility with XRegExp 1.0-1.2:
    /*
    XRegExp.matchWithinChain = XRegExp.matchChain;
    RegExp.prototype.addFlags = function (s) {return clone(this, s);};
    RegExp.prototype.execAll = function (s) {var r = []; XRegExp.iterate(s, this, function (m) {r.push(m);}); return r;};
    RegExp.prototype.forEachExec = function (s, f, c) {return XRegExp.iterate(s, this, f, c);};
    RegExp.prototype.validate = function (s) {var r = RegExp("^(?:" + this.source + ")$(?!\\s)", getNativeFlags(this)); if (this.global) this.lastIndex = 0; return s.search(r) === 0;};
    */

})();

// CommonJS
typeof(exports) != 'undefined' ? exports.XRegExp = XRegExp : null;

");
    };
 
    // Accepts a string to search, regex to search with, position to start the search within the
    // string (default: 0), and an optional Boolean indicating whether matches must start at-or-
    // after the position or at the specified position only. This function ignores the `lastIndex`
    // property of the provided regex
    XRegExp.execAt = function (str, regex, pos, anchored) {
        regex = clone(regex, "g" + ((anchored && hasNativeY) ? "y" : ""));
        regex.lastIndex = pos = pos || 0;
        var match = regex.exec(str);
        if (anchored)
            return (match && match.index === pos) ? match : null;
        else
            return match;
    };
 
    // Breaks the unrestorable link to XRegExp's private list of tokens, thereby preventing
    // syntax and flag changes. Should be run after XRegExp and any plugins are loaded
    XRegExp.freezeTokens = function () {
        XRegExp.addToken = function () {
            throw Error("can't run addToken after freezeTokens");
        };
    };
 
    // Accepts any value; returns a Boolean indicating whether the argument is a `RegExp` object.
    // Note that this is also `true` for regex literals and regexes created by the `XRegExp`
    // constructor. This works correctly for variables created in another frame, when `instanceof`
    // and `constructor` checks would fail to work as intended
    XRegExp.isRegExp = function (o) {
        return Object.prototype.toString.call(o) === "[object RegExp]";
    };
 
    // Executes `callback` once per match within `str`. Provides a simpler and cleaner way to
    // iterate over regex matches compared to the traditional approaches of subverting
    // `String.prototype.replace` or repeatedly calling `exec` within a `while` loop
    XRegExp.iterate = function (str, origRegex, callback, context) {
        var regex = clone(origRegex, "g"),
            i = -1, match;
        while (match = regex.exec(str)) {
            callback.call(context, match, ++i, str, regex);
            if (regex.lastIndex === match.index)
                regex.lastIndex++;
        }
        if (origRegex.global)
            origRegex.lastIndex = 0;
    };
 
    // Accepts a string and an array of regexes; returns the result of using each successive regex
    // to search within the matches of the previous regex. The array of regexes can also contain
    // objects with `regex` and `backref` properties, in which case the named or numbered back-
    // references specified are passed forward to the next regex or returned. E.g.:
    // var xregexpImgFileNames = XRegExp.matchChain(html, [
    //     {regex: /<img\b([^>]+)>/i, backref: 1}, // <img> tag attributes
    //     {regex: XRegExp('(?ix) \\s src=" (?<src> [^"]+ )'), backref: "src"}, // src attribute values
    //     {regex: XRegExp("^http://xregexp\\.com(/[^#?]+)", "i"), backref: 1}, // xregexp.com paths
    //     /[^\/]+$/ // filenames (strip directory paths)
    // ]);
    XRegExp.matchChain = function (str, chain) {
        return function recurseChain (values, level) {
            var item = chain[level].regex ? chain[level] : {regex: chain[level]},
                regex = clone(item.regex, "g"),
                matches = [], i;
            for (i = 0; i < values.length; i++) {
                XRegExp.iterate(values[i], regex, function (match) {
                    matches.push(item.backref ? (match[item.backref] || "") : match[0]);
                });
            }
            return ((level === chain.length - 1) || !matches.length) ?
                matches : recurseChain(matches, level + 1);
        }([str], 0);
    };
 
 
    //---------------------------------
    //  New RegExp prototype methods
    //---------------------------------
 
    // Accepts a context object and arguments array; returns the result of calling `exec` with the
    // first value in the arguments array. the context is ignored but is accepted for congruity
    // with `Function.prototype.apply`
    RegExp.prototype.apply = function (context, args) {
        return this.exec(args[0]);
    };
 
    // Accepts a context object and string; returns the result of calling `exec` with the provided
    // string. the context is ignored but is accepted for congruity with `Function.prototype.call`
    RegExp.prototype.call = function (context, str) {
        return this.exec(str);
    };
 
 
    //---------------------------------
    //  Overriden native methods
    //---------------------------------
 
    // Adds named capture support (with backreferences returned as `result.name`), and fixes two
    // cross-browser issues per ES3:
    // - Captured values for nonparticipating capturing groups should be returned as `undefined`,
    //   rather than the empty string.
    // - `lastIndex` should not be incremented after zero-length matches.
    RegExp.prototype.exec = function (str) {
        var match = real.exec.apply(this, arguments),
            name, r2;
        if (match) {
            // Fix browsers whose `exec` methods don't consistently return `undefined` for
            // nonparticipating capturing groups
            if (!compliantExecNpcg && match.length > 1 && indexOf(match, "") > -1) {
                r2 = RegExp(this.source, real.replace.call(getNativeFlags(this), "g", ""));
                // Using `str.slice(match.index)` rather than `match[0]` in case lookahead allowed
                // matching due to characters outside the match
                real.replace.call(str.toString().slice(match.index), r2, function () {
                    for (var i = 1; i < arguments.length - 2; i++) {
                        if (arguments[i] === undefined)
                            match[i] = undefined;
                    }
                });
            }
            // Attach named capture properties
            if (this._xregexp && this._xregexp.captureNames) {
                for (var i = 1; i < match.length; i++) {
                    name = this._xregexp.captureNames[i - 1];
                    if (name)
                       match[name] = match[i];
                }
            }
            // Fix browsers that increment `lastIndex` after zero-length matches
            if (!compliantLastIndexIncrement && this.global && !match[0].length && (this.lastIndex > match.index))
                this.lastIndex--;
        }
        return match;
    };
 
    // Don't override `test` if it won't change anything
    if (!compliantLastIndexIncrement) {
        // Fix browser bug in native method
        RegExp.prototype.test = function (str) {
            // Use the native `exec` to skip some processing overhead, even though the overriden
            // `exec` would take care of the `lastIndex` fix
            var match = real.exec.call(this, str);
            // Fix browsers that increment `lastIndex` after zero-length matches
            if (match && this.global && !match[0].length && (this.lastIndex > match.index))
                this.lastIndex--;
            return !!match;
        };
    }
 
    // Adds named capture support and fixes browser bugs in native method
    String.prototype.match = function (regex) {
        if (!XRegExp.isRegExp(regex))
            regex = RegExp(regex); // Native `RegExp`
        if (regex.global) {
            var result = real.match.apply(this, arguments);
            regex.lastIndex = 0; // Fix IE bug
            return result;
        }
        return regex.exec(this); // Run the altered `exec`
    };
 
    // Adds support for `${n}` tokens for named and numbered backreferences in replacement text,
    // and provides named backreferences to replacement functions as `arguments[0].name`. Also
    // fixes cross-browser differences in replacement text syntax when performing a replacement
    // using a nonregex search value, and the value of replacement regexes' `lastIndex` property
    // during replacement iterations. Note that this doesn't support SpiderMonkey's proprietary
    // third (`flags`) parameter
    String.prototype.replace = function (search, replacement) {
        var isRegex = XRegExp.isRegExp(search),
            captureNames, result, str;
 
        // There are many combinations of search/replacement types/values and browser bugs that
        // preclude passing to native `replace`, so just keep this check relatively simple
        if (isRegex && typeof replacement.valueOf() === "string" && replacement.indexOf("${") === -1 && compliantLastIndexReset)
            return real.replace.apply(this, arguments);
 
        if (!isRegex)
            search = search + ""; // Type conversion
        else if (search._xregexp)
            captureNames = search._xregexp.captureNames; // Array or `null`
 
        if (typeof replacement === "function") {
            result = real.replace.call(this, search, function () {
                if (captureNames) {
                    // Change the `arguments[0]` string primitive to a String object which can store properties
                    arguments[0] = new String(arguments[0]);
                    // Store named backreferences on `arguments[0]`
                    for (var i = 0; i < captureNames.length; i++) {
                        if (captureNames[i])
                            arguments[0][captureNames[i]] = arguments[i + 1];
                    }
                }
                // Update `lastIndex` before calling `replacement`
                if (isRegex && search.global)
                    search.lastIndex = arguments[arguments.length - 2] + arguments[0].length;
                return replacement.apply(null, arguments);
            });
        } else {
            str = this + ""; // Type conversion, so `args[args.length - 1]` will be a string (given nonstring `this`)
            result = real.replace.call(str, search, function () {
                var args = arguments; // Keep this function's `arguments` available through closure
                return real.replace.call(replacement, replacementToken, function ($0, $1, $2) {
                    // Numbered backreference (without delimiters) or special variable
                    if ($1) {
                        switch ($1) {
                            case "$": return "$";
                            case "&": return args[0];
                            case "`": return args[args.length - 1].slice(0, args[args.length - 2]);
                            case "'": return args[args.length - 1].slice(args[args.length - 2] + args[0].length);
                            // Numbered backreference
                            default:
                                // What does "$10" mean?
                                // - Backreference 10, if 10 or more capturing groups exist
                                // - Backreference 1 followed by "0", if 1-9 capturing groups exist
                                // - Otherwise, it's the string "$10"
                                // Also note:
                                // - Backreferences cannot be more than two digits (enforced by `replacementToken`)
                                // - "$1" is equivalent to "$1" if a capturing group exists, otherwise it's the string "$1"
                                // - There is no "$0" token ("
// XRegExp 1.5.0
// (c) 2007-2010 Steven Levithan
// MIT License
// <http://xregexp.com>
// Provides an augmented, extensible, cross-browser implementation of regular expressions,
// including support for additional syntax, flags, and methods

var XRegExp;

if (XRegExp) {
    // Avoid running twice, since that would break references to native globals
    throw Error("can't load XRegExp twice in the same frame");
}

// Run within an anonymous function to protect variables and avoid new globals
(function () {

    //---------------------------------
    //  Constructor
    //---------------------------------

    // Accepts a pattern and flags; returns a new, extended `RegExp` object. Differs from a native
    // regular expression in that additional syntax and flags are supported and cross-browser
    // syntax inconsistencies are ameliorated
    XRegExp = function (pattern, flags) {
        var output = [],
            currScope = XRegExp.OUTSIDE_CLASS,
            pos = 0,
            context, tokenResult, match, chr, regex;

        if (XRegExp.isRegExp(pattern)) {
            if (flags !== undefined)
                throw TypeError("can't supply flags when constructing one RegExp from another");
            return clone(pattern);
        }
        // Tokens become part of the regex construction process, so protect against infinite
        // recursion when an XRegExp is constructed within a token handler or trigger
        if (isInsideConstructor)
            throw Error("can't call the XRegExp constructor within token definition functions");

        flags = flags || "";
        context = { // `this` object for custom tokens
            hasNamedCapture: false,
            captureNames: [],
            hasFlag: function (flag) {return flags.indexOf(flag) > -1;},
            setFlag: function (flag) {flags += flag;}
        };

        while (pos < pattern.length) {
            // Check for custom tokens at the current position
            tokenResult = runTokens(pattern, pos, currScope, context);

            if (tokenResult) {
                output.push(tokenResult.output);
                pos += (tokenResult.match[0].length || 1);
            } else {
                // Check for native multicharacter metasequences (excluding character classes) at
                // the current position
                if (match = real.exec.call(nativeTokens[currScope], pattern.slice(pos))) {
                    output.push(match[0]);
                    pos += match[0].length;
                } else {
                    chr = pattern.charAt(pos);
                    if (chr === "[")
                        currScope = XRegExp.INSIDE_CLASS;
                    else if (chr === "]")
                        currScope = XRegExp.OUTSIDE_CLASS;
                    // Advance position one character
                    output.push(chr);
                    pos++;
                }
            }
        }

        regex = RegExp(output.join(""), real.replace.call(flags, flagClip, ""));
        regex._xregexp = {
            source: pattern,
            captureNames: context.hasNamedCapture ? context.captureNames : null
        };
        return regex;
    };


    //---------------------------------
    //  Public properties
    //---------------------------------

    XRegExp.version = "1.5.0";

    // Token scope bitflags
    XRegExp.INSIDE_CLASS = 1;
    XRegExp.OUTSIDE_CLASS = 2;


    //---------------------------------
    //  Private variables
    //---------------------------------

    var replacementToken = /\$(?:(\d\d?|[$&`'])|{([$\w]+)})/g,
        flagClip = /[^gimy]+|([\s\S])(?=[\s\S]*\1)/g, // Nonnative and duplicate flags
        quantifier = /^(?:[?*+]|{\d+(?:,\d*)?})\??/,
        isInsideConstructor = false,
        tokens = [],
        // Copy native globals for reference ("native" is an ES3 reserved keyword)
        real = {
            exec: RegExp.prototype.exec,
            test: RegExp.prototype.test,
            match: String.prototype.match,
            replace: String.prototype.replace,
            split: String.prototype.split
        },
        compliantExecNpcg = real.exec.call(/()??/, "")[1] === undefined, // check `exec` handling of nonparticipating capturing groups
        compliantLastIndexIncrement = function () {
            var x = /^/g;
            real.test.call(x, "");
            return !x.lastIndex;
        }(),
        compliantLastIndexReset = function () {
            var x = /x/g;
            real.replace.call("x", x, "");
            return !x.lastIndex;
        }(),
        hasNativeY = RegExp.prototype.sticky !== undefined,
        nativeTokens = {};

    // `nativeTokens` match native multicharacter metasequences only (including deprecated octals,
    // excluding character classes)
    nativeTokens[XRegExp.INSIDE_CLASS] = /^(?:\\(?:[0-3][0-7]{0,2}|[4-7][0-7]?|x[\dA-Fa-f]{2}|u[\dA-Fa-f]{4}|c[A-Za-z]|[\s\S]))/;
    nativeTokens[XRegExp.OUTSIDE_CLASS] = /^(?:\\(?:0(?:[0-3][0-7]{0,2}|[4-7][0-7]?)?|[1-9]\d*|x[\dA-Fa-f]{2}|u[\dA-Fa-f]{4}|c[A-Za-z]|[\s\S])|\(\?[:=!]|[?*+]\?|{\d+(?:,\d*)?}\??)/;


    //---------------------------------
    //  Public methods
    //---------------------------------

    // Lets you extend or change XRegExp syntax and create custom flags. This is used internally by
    // the XRegExp library and can be used to create XRegExp plugins. This function is intended for
    // users with advanced knowledge of JavaScript's regular expression syntax and behavior. It can
    // be disabled by `XRegExp.freezeTokens`
    XRegExp.addToken = function (regex, handler, scope, trigger) {
        tokens.push({
            pattern: clone(regex, "g" + (hasNativeY ? "y" : "")),
            handler: handler,
            scope: scope || XRegExp.OUTSIDE_CLASS,
            trigger: trigger || null
        });
    };

    // Accepts a pattern and flags; returns an extended `RegExp` object. If the pattern and flag
    // combination has previously been cached, the cached copy is returned; otherwise the newly
    // created regex is cached
    XRegExp.cache = function (pattern, flags) {
        var key = pattern + "/" + (flags || "");
        return XRegExp.cache[key] || (XRegExp.cache[key] = XRegExp(pattern, flags));
    };

    // Accepts a `RegExp` instance; returns a copy with the `/g` flag set. The copy has a fresh
    // `lastIndex` (set to zero). If you want to copy a regex without forcing the `global`
    // property, use `XRegExp(regex)`. Do not use `RegExp(regex)` because it will not preserve
    // special properties required for named capture
    XRegExp.copyAsGlobal = function (regex) {
        return clone(regex, "g");
    };

    // Accepts a string; returns the string with regex metacharacters escaped. The returned string
    // can safely be used at any point within a regex to match the provided literal string. Escaped
    // characters are [ ] { } ( ) * + ? - . , \ ^ $ | # and whitespace
    XRegExp.escape = function (str) {
        return str.replace(/[-[\]{}()*+?.,\\^$|#\s]/g, "\\$&");
    };

    // Accepts a string to search, regex to search with, position to start the search within the
    // string (default: 0), and an optional Boolean indicating whether matches must start at-or-
    // after the position or at the specified position only. This function ignores the `lastIndex`
    // property of the provided regex
    XRegExp.execAt = function (str, regex, pos, anchored) {
        regex = clone(regex, "g" + ((anchored && hasNativeY) ? "y" : ""));
        regex.lastIndex = pos = pos || 0;
        var match = regex.exec(str);
        if (anchored)
            return (match && match.index === pos) ? match : null;
        else
            return match;
    };

    // Breaks the unrestorable link to XRegExp's private list of tokens, thereby preventing
    // syntax and flag changes. Should be run after XRegExp and any plugins are loaded
    XRegExp.freezeTokens = function () {
        XRegExp.addToken = function () {
            throw Error("can't run addToken after freezeTokens");
        };
    };

    // Accepts any value; returns a Boolean indicating whether the argument is a `RegExp` object.
    // Note that this is also `true` for regex literals and regexes created by the `XRegExp`
    // constructor. This works correctly for variables created in another frame, when `instanceof`
    // and `constructor` checks would fail to work as intended
    XRegExp.isRegExp = function (o) {
        return Object.prototype.toString.call(o) === "[object RegExp]";
    };

    // Executes `callback` once per match within `str`. Provides a simpler and cleaner way to
    // iterate over regex matches compared to the traditional approaches of subverting
    // `String.prototype.replace` or repeatedly calling `exec` within a `while` loop
    XRegExp.iterate = function (str, origRegex, callback, context) {
        var regex = clone(origRegex, "g"),
            i = -1, match;
        while (match = regex.exec(str)) {
            callback.call(context, match, ++i, str, regex);
            if (regex.lastIndex === match.index)
                regex.lastIndex++;
        }
        if (origRegex.global)
            origRegex.lastIndex = 0;
    };

    // Accepts a string and an array of regexes; returns the result of using each successive regex
    // to search within the matches of the previous regex. The array of regexes can also contain
    // objects with `regex` and `backref` properties, in which case the named or numbered back-
    // references specified are passed forward to the next regex or returned. E.g.:
    // var xregexpImgFileNames = XRegExp.matchChain(html, [
    //     {regex: /<img\b([^>]+)>/i, backref: 1}, // <img> tag attributes
    //     {regex: XRegExp('(?ix) \\s src=" (?<src> [^"]+ )'), backref: "src"}, // src attribute values
    //     {regex: XRegExp("^http://xregexp\\.com(/[^#?]+)", "i"), backref: 1}, // xregexp.com paths
    //     /[^\/]+$/ // filenames (strip directory paths)
    // ]);
    XRegExp.matchChain = function (str, chain) {
        return function recurseChain (values, level) {
            var item = chain[level].regex ? chain[level] : {regex: chain[level]},
                regex = clone(item.regex, "g"),
                matches = [], i;
            for (i = 0; i < values.length; i++) {
                XRegExp.iterate(values[i], regex, function (match) {
                    matches.push(item.backref ? (match[item.backref] || "") : match[0]);
                });
            }
            return ((level === chain.length - 1) || !matches.length) ?
                matches : recurseChain(matches, level + 1);
        }([str], 0);
    };


    //---------------------------------
    //  New RegExp prototype methods
    //---------------------------------

    // Accepts a context object and arguments array; returns the result of calling `exec` with the
    // first value in the arguments array. the context is ignored but is accepted for congruity
    // with `Function.prototype.apply`
    RegExp.prototype.apply = function (context, args) {
        return this.exec(args[0]);
    };

    // Accepts a context object and string; returns the result of calling `exec` with the provided
    // string. the context is ignored but is accepted for congruity with `Function.prototype.call`
    RegExp.prototype.call = function (context, str) {
        return this.exec(str);
    };


    //---------------------------------
    //  Overriden native methods
    //---------------------------------

    // Adds named capture support (with backreferences returned as `result.name`), and fixes two
    // cross-browser issues per ES3:
    // - Captured values for nonparticipating capturing groups should be returned as `undefined`,
    //   rather than the empty string.
    // - `lastIndex` should not be incremented after zero-length matches.
    RegExp.prototype.exec = function (str) {
        var match = real.exec.apply(this, arguments),
            name, r2;
        if (match) {
            // Fix browsers whose `exec` methods don't consistently return `undefined` for
            // nonparticipating capturing groups
            if (!compliantExecNpcg && match.length > 1 && indexOf(match, "") > -1) {
                r2 = RegExp(this.source, real.replace.call(getNativeFlags(this), "g", ""));
                // Using `str.slice(match.index)` rather than `match[0]` in case lookahead allowed
                // matching due to characters outside the match
                real.replace.call(str.toString().slice(match.index), r2, function () {
                    for (var i = 1; i < arguments.length - 2; i++) {
                        if (arguments[i] === undefined)
                            match[i] = undefined;
                    }
                });
            }
            // Attach named capture properties
            if (this._xregexp && this._xregexp.captureNames) {
                for (var i = 1; i < match.length; i++) {
                    name = this._xregexp.captureNames[i - 1];
                    if (name)
                       match[name] = match[i];
                }
            }
            // Fix browsers that increment `lastIndex` after zero-length matches
            if (!compliantLastIndexIncrement && this.global && !match[0].length && (this.lastIndex > match.index))
                this.lastIndex--;
        }
        return match;
    };

    // Don't override `test` if it won't change anything
    if (!compliantLastIndexIncrement) {
        // Fix browser bug in native method
        RegExp.prototype.test = function (str) {
            // Use the native `exec` to skip some processing overhead, even though the overriden
            // `exec` would take care of the `lastIndex` fix
            var match = real.exec.call(this, str);
            // Fix browsers that increment `lastIndex` after zero-length matches
            if (match && this.global && !match[0].length && (this.lastIndex > match.index))
                this.lastIndex--;
            return !!match;
        };
    }

    // Adds named capture support and fixes browser bugs in native method
    String.prototype.match = function (regex) {
        if (!XRegExp.isRegExp(regex))
            regex = RegExp(regex); // Native `RegExp`
        if (regex.global) {
            var result = real.match.apply(this, arguments);
            regex.lastIndex = 0; // Fix IE bug
            return result;
        }
        return regex.exec(this); // Run the altered `exec`
    };

    // Adds support for `${n}` tokens for named and numbered backreferences in replacement text,
    // and provides named backreferences to replacement functions as `arguments[0].name`. Also
    // fixes cross-browser differences in replacement text syntax when performing a replacement
    // using a nonregex search value, and the value of replacement regexes' `lastIndex` property
    // during replacement iterations. Note that this doesn't support SpiderMonkey's proprietary
    // third (`flags`) parameter
    String.prototype.replace = function (search, replacement) {
        var isRegex = XRegExp.isRegExp(search),
            captureNames, result, str;

        // There are many combinations of search/replacement types/values and browser bugs that
        // preclude passing to native `replace`, so just keep this check relatively simple
        if (isRegex && typeof replacement.valueOf() === "string" && replacement.indexOf("${") === -1 && compliantLastIndexReset)
            return real.replace.apply(this, arguments);

        if (!isRegex)
            search = search + ""; // Type conversion
        else if (search._xregexp)
            captureNames = search._xregexp.captureNames; // Array or `null`

        if (typeof replacement === "function") {
            result = real.replace.call(this, search, function () {
                if (captureNames) {
                    // Change the `arguments[0]` string primitive to a String object which can store properties
                    arguments[0] = new String(arguments[0]);
                    // Store named backreferences on `arguments[0]`
                    for (var i = 0; i < captureNames.length; i++) {
                        if (captureNames[i])
                            arguments[0][captureNames[i]] = arguments[i + 1];
                    }
                }
                // Update `lastIndex` before calling `replacement`
                if (isRegex && search.global)
                    search.lastIndex = arguments[arguments.length - 2] + arguments[0].length;
                return replacement.apply(null, arguments);
            });
        } else {
            str = this + ""; // Type conversion, so `args[args.length - 1]` will be a string (given nonstring `this`)
            result = real.replace.call(str, search, function () {
                var args = arguments; // Keep this function's `arguments` available through closure
                return real.replace.call(replacement, replacementToken, function ($0, $1, $2) {
                    // Numbered backreference (without delimiters) or special variable
                    if ($1) {
                        switch ($1) {
                            case "$": return "$";
                            case "&": return args[0];
                            case "`": return args[args.length - 1].slice(0, args[args.length - 2]);
                            case "'": return args[args.length - 1].slice(args[args.length - 2] + args[0].length);
                            // Numbered backreference
                            default:
                                // What does "$10" mean?
                                // - Backreference 10, if 10 or more capturing groups exist
                                // - Backreference 1 followed by "0", if 1-9 capturing groups exist
                                // - Otherwise, it's the string "$10"
                                // Also note:
                                // - Backreferences cannot be more than two digits (enforced by `replacementToken`)
                                // - "$01" is equivalent to "$1" if a capturing group exists, otherwise it's the string "$01"
                                // - There is no "$0" token ("$&" is the entire match)
                                var literalNumbers = "";
                                $1 = +$1; // Type conversion; drop leading zero
                                if (!$1) // `$1` was "0" or "00"
                                    return $0;
                                while ($1 > args.length - 3) {
                                    literalNumbers = String.prototype.slice.call($1, -1) + literalNumbers;
                                    $1 = Math.floor($1 / 10); // Drop the last digit
                                }
                                return ($1 ? args[$1] || "" : "$") + literalNumbers;
                        }
                    // Named backreference or delimited numbered backreference
                    } else {
                        // What does "${n}" mean?
                        // - Backreference to numbered capture n. Two differences from "$n":
                        //   - n can be more than two digits
                        //   - Backreference 0 is allowed, and is the entire match
                        // - Backreference to named capture n, if it exists and is not a number overridden by numbered capture
                        // - Otherwise, it's the string "${n}"
                        var n = +$2; // Type conversion; drop leading zeros
                        if (n <= args.length - 3)
                            return args[n];
                        n = captureNames ? indexOf(captureNames, $2) : -1;
                        return n > -1 ? args[n + 1] : $0;
                    }
                });
            });
        }

        if (isRegex && search.global)
            search.lastIndex = 0; // Fix IE bug

        return result;
    };

    // A consistent cross-browser, ES3 compliant `split`
    String.prototype.split = function (s /* separator */, limit) {
        // If separator `s` is not a regex, use the native `split`
        if (!XRegExp.isRegExp(s))
            return real.split.apply(this, arguments);

        var str = this + "", // Type conversion
            output = [],
            lastLastIndex = 0,
            match, lastLength;

        // Behavior for `limit`: if it's...
        // - `undefined`: No limit
        // - `NaN` or zero: Return an empty array
        // - A positive number: Use `Math.floor(limit)`
        // - A negative number: No limit
        // - Other: Type-convert, then use the above rules
        if (limit === undefined || +limit < 0) {
            limit = Infinity;
        } else {
            limit = Math.floor(+limit);
            if (!limit)
                return [];
        }

        // This is required if not `s.global`, and it avoids needing to set `s.lastIndex` to zero
        // and restore it to its original value when we're done using the regex
        s = XRegExp.copyAsGlobal(s);

        while (match = s.exec(str)) { // Run the altered `exec` (required for `lastIndex` fix, etc.)
            if (s.lastIndex > lastLastIndex) {
                output.push(str.slice(lastLastIndex, match.index));

                if (match.length > 1 && match.index < str.length)
                    Array.prototype.push.apply(output, match.slice(1));

                lastLength = match[0].length;
                lastLastIndex = s.lastIndex;

                if (output.length >= limit)
                    break;
            }

            if (s.lastIndex === match.index)
                s.lastIndex++;
        }

        if (lastLastIndex === str.length) {
            if (!real.test.call(s, "") || lastLength)
                output.push("");
        } else {
            output.push(str.slice(lastLastIndex));
        }

        return output.length > limit ? output.slice(0, limit) : output;
    };


    //---------------------------------
    //  Private helper functions
    //---------------------------------

    // Supporting function for `XRegExp`, `XRegExp.copyAsGlobal`, etc. Returns a copy of a `RegExp`
    // instance with a fresh `lastIndex` (set to zero), preserving properties required for named
    // capture. Also allows adding new flags in the process of copying the regex
    function clone (regex, additionalFlags) {
        if (!XRegExp.isRegExp(regex))
            throw TypeError("type RegExp expected");
        var x = regex._xregexp;
        regex = XRegExp(regex.source, getNativeFlags(regex) + (additionalFlags || ""));
        if (x) {
            regex._xregexp = {
                source: x.source,
                captureNames: x.captureNames ? x.captureNames.slice(0) : null
            };
        }
        return regex;
    };

    function getNativeFlags (regex) {
        return (regex.global     ? "g" : "") +
               (regex.ignoreCase ? "i" : "") +
               (regex.multiline  ? "m" : "") +
               (regex.extended   ? "x" : "") + // Proposed for ES4; included in AS3
               (regex.sticky     ? "y" : "");
    };

    function runTokens (pattern, index, scope, context) {
        var i = tokens.length,
            result, match, t;
        // Protect against constructing XRegExps within token handler and trigger functions
        isInsideConstructor = true;
        // Must reset `isInsideConstructor`, even if a `trigger` or `handler` throws
        try {
            while (i--) { // Run in reverse order
                t = tokens[i];
                if ((scope & t.scope) && (!t.trigger || t.trigger.call(context))) {
                    t.pattern.lastIndex = index;
                    match = t.pattern.exec(pattern); // Running the altered `exec` here allows use of named backreferences, etc.
                    if (match && match.index === index) {
                        result = {
                            output: t.handler.call(context, match, scope),
                            match: match
                        };
                        break;
                    }
                }
            }
        } catch (err) {
            throw err;
        } finally {
            isInsideConstructor = false;
        }
        return result;
    };

    function indexOf (array, item, from) {
        if (Array.prototype.indexOf) // Use the native array method if available
            return array.indexOf(item, from);
        for (var i = from || 0; i < array.length; i++) {
            if (array[i] === item)
                return i;
        }
        return -1;
    };


    //---------------------------------
    //  Built-in tokens
    //---------------------------------

    // Augment XRegExp's regular expression syntax and flags. Note that when adding tokens, the
    // third (`scope`) argument defaults to `XRegExp.OUTSIDE_CLASS`

    // Comment pattern: (?# )
    XRegExp.addToken(
        /\(\?#[^)]*\)/,
        function (match) {
            // Keep tokens separated unless the following token is a quantifier
            return real.test.call(quantifier, match.input.slice(match.index + match[0].length)) ? "" : "(?:)";
        }
    );

    // Capturing group (match the opening parenthesis only).
    // Required for support of named capturing groups
    XRegExp.addToken(
        /\((?!\?)/,
        function () {
            this.captureNames.push(null);
            return "(";
        }
    );

    // Named capturing group (match the opening delimiter only): (?<name>
    XRegExp.addToken(
        /\(\?<([$\w]+)>/,
        function (match) {
            this.captureNames.push(match[1]);
            this.hasNamedCapture = true;
            return "(";
        }
    );

    // Named backreference: \k<name>
    XRegExp.addToken(
        /\\k<([\w$]+)>/,
        function (match) {
            var index = indexOf(this.captureNames, match[1]);
            // Keep backreferences separate from subsequent literal numbers. Preserve back-
            // references to named groups that are undefined at this point as literal strings
            return index > -1 ?
                "\\" + (index + 1) + (isNaN(match.input.charAt(match.index + match[0].length)) ? "" : "(?:)") :
                match[0];
        }
    );

    // Empty character class: [] or [^]
    XRegExp.addToken(
        /\[\^?]/,
        function (match) {
            // For cross-browser compatibility with ES3, convert [] to \b\B and [^] to [\s\S].
            // (?!) should work like \b\B, but is unreliable in Firefox
            return match[0] === "[]" ? "\\b\\B" : "[\\s\\S]";
        }
    );

    // Mode modifier at the start of the pattern only, with any combination of flags imsx: (?imsx)
    // Does not support x(?i), (?-i), (?i-m), (?i: ), (?i)(?m), etc.
    XRegExp.addToken(
        /^\(\?([imsx]+)\)/,
        function (match) {
            this.setFlag(match[1]);
            return "";
        }
    );

    // Whitespace and comments, in free-spacing (aka extended) mode only
    XRegExp.addToken(
        /(?:\s+|#.*)+/,
        function (match) {
            // Keep tokens separated unless the following token is a quantifier
            return real.test.call(quantifier, match.input.slice(match.index + match[0].length)) ? "" : "(?:)";
        },
        XRegExp.OUTSIDE_CLASS,
        function () {return this.hasFlag("x");}
    );

    // Dot, in dotall (aka singleline) mode only
    XRegExp.addToken(
        /\./,
        function () {return "[\\s\\S]";},
        XRegExp.OUTSIDE_CLASS,
        function () {return this.hasFlag("s");}
    );


    //---------------------------------
    //  Backward compatibility
    //---------------------------------

    // Uncomment the following block for compatibility with XRegExp 1.0-1.2:
    /*
    XRegExp.matchWithinChain = XRegExp.matchChain;
    RegExp.prototype.addFlags = function (s) {return clone(this, s);};
    RegExp.prototype.execAll = function (s) {var r = []; XRegExp.iterate(s, this, function (m) {r.push(m);}); return r;};
    RegExp.prototype.forEachExec = function (s, f, c) {return XRegExp.iterate(s, this, f, c);};
    RegExp.prototype.validate = function (s) {var r = RegExp("^(?:" + this.source + ")$(?!\\s)", getNativeFlags(this)); if (this.global) this.lastIndex = 0; return s.search(r) === 0;};
    */

})();

// CommonJS
typeof(exports) != 'undefined' ? exports.XRegExp = XRegExp : null;

" is the entire match)
                                var literalNumbers = "";
                                $1 = +$1; // Type conversion; drop leading zero
                                if (!$1) // `$1` was "0" or "00"
                                    return $0;
                                while ($1 > args.length - 3) {
                                    literalNumbers = String.prototype.slice.call($1, -1) + literalNumbers;
                                    $1 = Math.floor($1 / 10); // Drop the last digit
                                }
                                return ($1 ? args[$1] || "" : "$") + literalNumbers;
                        }
                    // Named backreference or delimited numbered backreference
                    } else {
                        // What does "${n}" mean?
                        // - Backreference to numbered capture n. Two differences from "$n":
                        //   - n can be more than two digits
                        //   - Backreference 0 is allowed, and is the entire match
                        // - Backreference to named capture n, if it exists and is not a number overridden by numbered capture
                        // - Otherwise, it's the string "${n}"
                        var n = +$2; // Type conversion; drop leading zeros
                        if (n <= args.length - 3)
                            return args[n];
                        n = captureNames ? indexOf(captureNames, $2) : -1;
                        return n > -1 ? args[n + 1] : $0;
                    }
                });
            });
        }
 
        if (isRegex && search.global)
            search.lastIndex = 0; // Fix IE bug
 
        return result;
    };
 
    // A consistent cross-browser, ES3 compliant `split`
    String.prototype.split = function (s /* separator */, limit) {
        // If separator `s` is not a regex, use the native `split`
        if (!XRegExp.isRegExp(s))
            return real.split.apply(this, arguments);
 
        var str = this + "", // Type conversion
            output = [],
            lastLastIndex = 0,
            match, lastLength;
 
        // Behavior for `limit`: if it's...
        // - `undefined`: No limit
        // - `NaN` or zero: Return an empty array
        // - A positive number: Use `Math.floor(limit)`
        // - A negative number: No limit
        // - Other: Type-convert, then use the above rules
        if (limit === undefined || +limit < 0) {
            limit = Infinity;
        } else {
            limit = Math.floor(+limit);
            if (!limit)
                return [];
        }
 
        // This is required if not `s.global`, and it avoids needing to set `s.lastIndex` to zero
        // and restore it to its original value when we're done using the regex
        s = XRegExp.copyAsGlobal(s);
 
        while (match = s.exec(str)) { // Run the altered `exec` (required for `lastIndex` fix, etc.)
            if (s.lastIndex > lastLastIndex) {
                output.push(str.slice(lastLastIndex, match.index));
 
                if (match.length > 1 && match.index < str.length)
                    Array.prototype.push.apply(output, match.slice(1));
 
                lastLength = match[0].length;
                lastLastIndex = s.lastIndex;
 
                if (output.length >= limit)
                    break;
            }
 
            if (s.lastIndex === match.index)
                s.lastIndex++;
        }
 
        if (lastLastIndex === str.length) {
            if (!real.test.call(s, "") || lastLength)
                output.push("");
        } else {
            output.push(str.slice(lastLastIndex));
        }
 
        return output.length > limit ? output.slice(0, limit) : output;
    };
 
 
    //---------------------------------
    //  Private helper functions
    //---------------------------------
 
    // Supporting function for `XRegExp`, `XRegExp.copyAsGlobal`, etc. Returns a copy of a `RegExp`
    // instance with a fresh `lastIndex` (set to zero), preserving properties required for named
    // capture. Also allows adding new flags in the process of copying the regex
    function clone (regex, additionalFlags) {
        if (!XRegExp.isRegExp(regex))
            throw TypeError("type RegExp expected");
        var x = regex._xregexp;
        regex = XRegExp(regex.source, getNativeFlags(regex) + (additionalFlags || ""));
        if (x) {
            regex._xregexp = {
                source: x.source,
                captureNames: x.captureNames ? x.captureNames.slice(0) : null
            };
        }
        return regex;
    };
 
    function getNativeFlags (regex) {
        return (regex.global     ? "g" : "") +
               (regex.ignoreCase ? "i" : "") +
               (regex.multiline  ? "m" : "") +
               (regex.extended   ? "x" : "") + // Proposed for ES4; included in AS3
               (regex.sticky     ? "y" : "");
    };
 
    function runTokens (pattern, index, scope, context) {
        var i = tokens.length,
            result, match, t;
        // Protect against constructing XRegExps within token handler and trigger functions
        isInsideConstructor = true;
        // Must reset `isInsideConstructor`, even if a `trigger` or `handler` throws
        try {
            while (i--) { // Run in reverse order
                t = tokens[i];
                if ((scope & t.scope) && (!t.trigger || t.trigger.call(context))) {
                    t.pattern.lastIndex = index;
                    match = t.pattern.exec(pattern); // Running the altered `exec` here allows use of named backreferences, etc.
                    if (match && match.index === index) {
                        result = {
                            output: t.handler.call(context, match, scope),
                            match: match
                        };
                        break;
                    }
                }
            }
        } catch (err) {
            throw err;
        } finally {
            isInsideConstructor = false;
        }
        return result;
    };
 
    function indexOf (array, item, from) {
        if (Array.prototype.indexOf) // Use the native array method if available
            return array.indexOf(item, from);
        for (var i = from || 0; i < array.length; i++) {
            if (array[i] === item)
                return i;
        }
        return -1;
    };
 
 
    //---------------------------------
    //  Built-in tokens
    //---------------------------------
 
    // Augment XRegExp's regular expression syntax and flags. Note that when adding tokens, the
    // third (`scope`) argument defaults to `XRegExp.OUTSIDE_CLASS`
 
    // Comment pattern: (?# )
    XRegExp.addToken(
        /\(\?#[^)]*\)/,
        function (match) {
            // Keep tokens separated unless the following token is a quantifier
            return real.test.call(quantifier, match.input.slice(match.index + match[0].length)) ? "" : "(?:)";
        }
    );
 
    // Capturing group (match the opening parenthesis only).
    // Required for support of named capturing groups
    XRegExp.addToken(
        /\((?!\?)/,
        function () {
            this.captureNames.push(null);
            return "(";
        }
    );
 
    // Named capturing group (match the opening delimiter only): (?<name>
    XRegExp.addToken(
        /\(\?<([$\w]+)>/,
        function (match) {
            this.captureNames.push(match[1]);
            this.hasNamedCapture = true;
            return "(";
        }
    );
 
    // Named backreference: \k<name>
    XRegExp.addToken(
        /\\k<([\w$]+)>/,
        function (match) {
            var index = indexOf(this.captureNames, match[1]);
            // Keep backreferences separate from subsequent literal numbers. Preserve back-
            // references to named groups that are undefined at this point as literal strings
            return index > -1 ?
                "\\" + (index + 1) + (isNaN(match.input.charAt(match.index + match[0].length)) ? "" : "(?:)") :
                match[0];
        }
    );
 
    // Empty character class: [] or [^]
    XRegExp.addToken(
        /\[\^?]/,
        function (match) {
            // For cross-browser compatibility with ES3, convert [] to \b\B and [^] to [\s\S].
            // (?!) should work like \b\B, but is unreliable in Firefox
            return match[0] === "[]" ? "\\b\\B" : "[\\s\\S]";
        }
    );
 
    // Mode modifier at the start of the pattern only, with any combination of flags imsx: (?imsx)
    // Does not support x(?i), (?-i), (?i-m), (?i: ), (?i)(?m), etc.
    XRegExp.addToken(
        /^\(\?([imsx]+)\)/,
        function (match) {
            this.setFlag(match[1]);
            return "";
        }
    );
 
    // Whitespace and comments, in free-spacing (aka extended) mode only
    XRegExp.addToken(
        /(?:\s+|#.*)+/,
        function (match) {
            // Keep tokens separated unless the following token is a quantifier
            return real.test.call(quantifier, match.input.slice(match.index + match[0].length)) ? "" : "(?:)";
        },
        XRegExp.OUTSIDE_CLASS,
        function () {return this.hasFlag("x");}
    );
 
    // Dot, in dotall (aka singleline) mode only
    XRegExp.addToken(
        /\./,
        function () {return "[\\s\\S]";},
        XRegExp.OUTSIDE_CLASS,
        function () {return this.hasFlag("s");}
    );
 
 
    //---------------------------------
    //  Backward compatibility
    //---------------------------------
 
    // Uncomment the following block for compatibility with XRegExp 1.0-1.2:
    /*
    XRegExp.matchWithinChain = XRegExp.matchChain;
    RegExp.prototype.addFlags = function (s) {return clone(this, s);};
    RegExp.prototype.execAll = function (s) {var r = []; XRegExp.iterate(s, this, function (m) {r.push(m);}); return r;};
    RegExp.prototype.forEachExec = function (s, f, c) {return XRegExp.iterate(s, this, f, c);};
    RegExp.prototype.validate = function (s) {var r = RegExp("^(?:" + this.source + ")$(?!\\s)", getNativeFlags(this)); if (this.global) this.lastIndex = 0; return s.search(r) === 0;};
    */
 
})();
 
// CommonJS
typeof(exports) != 'undefined' ? exports.XRegExp = XRegExp : null;