/* Unobtrustive Code Highlighter By Dan Webb 11/2005
   Version: 0.4
  
  Usage:
    Add a script tag for this script and any stylesets you need to use
    to the page in question, add correct class names to CODE elements, 
    define CSS styles for elements. That's it! 
  
  Known to work on:
    IE 5.5+ PC
    Firefox/Mozilla PC/Mac
    Opera 7.23 + PC
    Safari 2
    
  Known to degrade gracefully on:
    IE5.0 PC
  
  Note: IE5.0 fails due to the use of lookahead in some stylesets.  To avoid script errors
  in older browsers use expressions that use lookahead in string format when defining stylesets.
  
  This script is inspired by star-light by entirely cunning Dean Edwards
  http://dean.edwards.name/star-light/.  
*/

// replace callback support for safari.
if ("a".replace(/a/, function() {return "b"}) != "b") (function(){
  var default_replace = String.prototype.replace;
  String.prototype.replace = function(search,replace){
  // replace is not function
  if(typeof replace != "function"){
    return default_replace.apply(this,arguments)
  }
  var str = "" + this;
  var callback = replace;
  // search string is not RegExp
  if(!(search instanceof RegExp)){
    var idx = str.indexOf(search);
    return (
      idx == -1 ? str :
      default_replace.apply(str,[search,callback(search, idx, str)])
    )
  }
  var reg = search;
  var result = [];
  var lastidx = reg.lastIndex;
  var re;
  while((re = reg.exec(str)) != null){
    var idx  = re.index;
    var args = re.concat(idx, str);
    result.push(
      str.slice(lastidx,idx),
      callback.apply(null,args).toString()
    );
    if(!reg.global){
      lastidx += RegExp.lastMatch.length;
      break
    }else{
      lastidx = reg.lastIndex;
    }
  }
  result.push(str.slice(lastidx));
  return result.join("")
  }
})();

var CodeHighlighter = { styleSets : new Array };

CodeHighlighter.addStyle = function(name, rules) {
  // using push test to disallow older browsers from adding styleSets
  if ([].push) this.styleSets.push({
    name : name, 
    rules : rules,
    ignoreCase : arguments[2] || false
  })
  
  function setEvent() {
    // set highlighter to run on load (use LowPro if present)
    if (typeof Event != 'undefined' && typeof Event.onReady == 'function') 
      return Event.onReady(CodeHighlighter.init.bind(CodeHighlighter));
    
    var old = window.onload;
    
    if (typeof window.onload != 'function') {
      window.onload = function() { CodeHighlighter.init() };
    } else {
      window.onload = function() {
        old();
        CodeHighlighter.init();
      }
    }
  }
  
  // only set the event when the first style is added
  if (this.styleSets.length==1) setEvent();
}

CodeHighlighter.init = function() {
    if (!document.getElementsByTagName) return;
    if ("a".replace(/a/, function() { return "b" }) != "b") return; // throw out Safari versions that don't support replace function
    // throw out older browsers

    var codeEls = document.getElementsByTagName("CODE");
    // collect array of all pre elements
    codeEls.filter = function(f) {
        var a = new Array;
        for (var i = 0; i < this.length; i++) if (f(this[i])) a[a.length] = this[i];
        return a;
    }

    var rules = new Array;
    rules.toString = function() {
        // joins regexes into one big parallel regex
        var exps = new Array;
        for (var i = 0; i < this.length; i++) exps.push(this[i].exp);
        return exps.join("|");
    }

    function addRule(className, rule) {
        // add a replace rule
        var exp = (typeof rule.exp != "string") ? String(rule.exp).substr(1, String(rule.exp).length - 2) : rule.exp;
        // converts regex rules to strings and chops of the slashes
        rules.push({
            className: className,
            exp: "(" + exp + ")",
            length: (exp.match(/(^|[^\\])\([^?]/g) || "").length + 1, // number of subexps in rule
            replacement: rule.replacement || null
        });
    }

    function parse(text, ignoreCase) {
        // main text parsing and replacement
        return text.replace(new RegExp(rules, (ignoreCase) ? "gi" : "g"), function() {
            var i = 0, j = 1, rule;
            while (rule = rules[i++]) {
                if (arguments[j]) {
                    // if no custom replacement defined do the simple replacement
                    if (!rule.replacement) return "<span class=\"" + rule.className + "\">" + arguments[0] + "</span>";
                    else {
                        // replace $0 with the className then do normal replaces
                        var str = rule.replacement.replace("$0", rule.className);
                        for (var k = 1; k <= rule.length - 1; k++) str = str.replace("$" + k, arguments[j + k]);
                        return str;
                    }
                } else j += rule.length;
            }
        });
    }

    function highlightCode(styleSet) {
        // clear rules array
        var parsed, clsRx = new RegExp("(\\s|^)" + styleSet.name + "(\\s|$)");
        rules.length = 0;

        // get stylable elements by filtering out all code elements without the correct className 
        var stylableEls = codeEls.filter(function(item) { return clsRx.test(item.className) });

        // add style rules to parser
        for (var className in styleSet.rules) addRule(className, styleSet.rules[className]);


        // replace for all elements
        for (var i = 0; i < stylableEls.length; i++) {
            // EVIL hack to fix IE whitespace badness if it's inside a <pre>
            if (/MSIE/.test(navigator.appVersion) && stylableEls[i].parentNode.nodeName == 'PRE') {
                stylableEls[i] = stylableEls[i].parentNode;

                parsed = stylableEls[i].innerHTML.replace(/(<code[^>]*>)([^<]*)<\/code>/i, function() {
                    return arguments[1] + parse(arguments[2], styleSet.ignoreCase) + "</code>"
                });
                parsed = parsed.replace(/\n( *)/g, function() {
                    var spaces = "";
                    for (var i = 0; i < arguments[1].length; i++) spaces += "&nbsp;";
                    return "\n" + spaces;
                });
                parsed = parsed.replace(/\t/g, "&nbsp;&nbsp;&nbsp;&nbsp;");
                parsed = parsed.replace(/\n(<\/\w+>)?/g, "<br />$1").replace(/<br \/>[\n\r\s]*<br \/>/g, "<p><br></p>");

            } else parsed = parse(stylableEls[i].innerHTML, styleSet.ignoreCase);

            stylableEls[i].innerHTML = parsed;
        }
    }

    // run highlighter on all stylesets
    for (var i = 0; i < this.styleSets.length; i++) {
        highlightCode(this.styleSets[i]);
    }
}