regex-split.js

//============================================================================
// Cross-browser RegEx Split
//============================================================================

// This code has been MODIFIED from the code licensed below to not replace the
// default browser split.  The license is reproduced here.

// see http://blog.stevenlevithan.com/archives/cross-browser-split for more info:
/*!
 * Cross-Browser Split 1.1.1
 * Copyright 2007-2012 Steven Levithan <stevenlevithan.com>
 * Available under the MIT License
 * ECMAScript compliant, uniform cross-browser split method
 */

/**
 * Splits a string into an array of strings using a regex or string
 * separator. Matches of the separator are not included in the result array.
 * However, if `separator` is a regex that contains capturing groups,
 * backreferences are spliced into the result each time `separator` is
 * matched. Fixes browser bugs compared to the native
 * `String.prototype.split` and can be used reliably cross-browser.
 * @param {String} str String to split.
 * @param {RegExp} separator Regex to use for separating
 *     the string.
 * @param {Number} [limit] Maximum number of items to include in the result
 *     array.
 * @returns {Array} Array of substrings.
 * @example
 *
 * // Basic use
 * regex_split('a b c d', ' ');
 * // -> ['a', 'b', 'c', 'd']
 *
 * // With limit
 * regex_split('a b c d', ' ', 2);
 * // -> ['a', 'b']
 *
 * // Backreferences in result array
 * regex_split('..word1 word2..', /([a-z]+)(\d+)/i);
 * // -> ['..', 'word', '1', ' ', 'word', '2', '..']
 */
exports.regex_split = function (str, separator, limit) {
    var output = [],
        flags = (separator.ignoreCase ? "i" : "") +
                (separator.multiline  ? "m" : "") +
                (separator.extended   ? "x" : "") + // Proposed for ES6
                (separator.sticky     ? "y" : ""), // Firefox 3+
        lastLastIndex = 0,
        separator2, match, lastIndex, lastLength;
    // Make `global` and avoid `lastIndex` issues by working with a copy
    separator = new RegExp(separator.source, flags + "g");

    var compliantExecNpcg = typeof(/()??/.exec("")[1]) === "undefined";
    if (!compliantExecNpcg) {
        // Doesn't need flags gy, but they don't hurt
        separator2 = new RegExp("^" + separator.source + "$(?!\\s)", flags);
    }
    /* Values for `limit`, per the spec:
     * If undefined: 4294967295 // Math.pow(2, 32) - 1
     * If 0, Infinity, or NaN: 0
     * If positive number: limit = Math.floor(limit); if (limit > 4294967295) limit -= 4294967296;
     * If negative number: 4294967296 - Math.floor(Math.abs(limit))
     * If other: Type-convert, then use the above rules
     */
    limit = typeof(limit) === "undefined" ?
        -1 >>> 0 : // Math.pow(2, 32) - 1
        limit >>> 0; // ToUint32(limit)
    for (match = separator.exec(str); match; match = separator.exec(str)) {
        // `separator.lastIndex` is not reliable cross-browser
        lastIndex = match.index + match[0].length;
        if (lastIndex > lastLastIndex) {
            output.push(str.slice(lastLastIndex, match.index));
            // Fix browsers whose `exec` methods don't consistently return `undefined` for
            // nonparticipating capturing groups
            if (!compliantExecNpcg && match.length > 1) {
                match[0].replace(separator2, function () {
                    for (var i = 1; i < arguments.length - 2; i++) {
                        if (typeof(arguments[i]) === "undefined") {
                            match[i] = undefined;
                        }
                    }
                });
            }
            if (match.length > 1 && match.index < str.length) {
                Array.prototype.push.apply(output, match.slice(1));
            }
            lastLength = match[0].length;
            lastLastIndex = lastIndex;
            if (output.length >= limit) {
                break;
            }
        }
        if (separator.lastIndex === match.index) {
            separator.lastIndex++; // Avoid an infinite loop
        }
    }
    if (lastLastIndex === str.length) {
        if (lastLength || !separator.test("")) {
            output.push("");
        }
    } else {
        output.push(str.slice(lastLastIndex));
    }
    return output.length > limit ? output.slice(0, limit) : output;
};

//============================================================================
// End contributed Cross-browser RegEx Split
//============================================================================