XRegExp = function()

in ext/syntaxhighlighter/scripts/XRegExp.js [25:81]
46 lines of code
12 McCabe index (conditional complexity)

    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;
    };