sh.Brushes.Cpp = function() {}
 
sh.Brushes.Cpp.aliases = 'cpp';
 
sh.Brushes.Cpp.regexList = [
    {regex: new RegExp('//.*$', 'gm'), css: 'comment'},    // one line comments
    {regex: new RegExp('/\\*[\\s\\S]*?\\*/', 'g'), css: 'comment'},    // multi line comments
    {regex: new RegExp("\'(?:[^\\\\']|\\\\.)*\'|" +
                       "\"(?:[^\\\\\"]|\\\\.)*\"", 'g'), css: 'string'},    // string literals
    {regex: new RegExp('^\\s*#.*', 'gm'), css: 'preprocessor'},    // preprocessor directives
    {regex: new RegExp('\\b(?:auto|break|case|char|const|continue|default|do' +
                       'double|else|enum|extern|float|for|goto|if|int|long|register' +
                       'return|short|signed|sizeof|static|struct|switch|typedef|union' +
                       'unsigned|void|volatile|while)\\b', 'gm'), css: 'keyword'}    // keyword
];

.cpp .comment { color: gray; }
.cpp .string { color: red; }
.cpp .preprocessor { color: green; }
.cpp .keyword { color: blue; }

// create namespaces
var sh = {
    Brushes : {}
}
 
// Match object
sh.Match = function(regex, css)
{
    this.regex = regex;    // regeax to match
    this.css = css;    // color the matches
    this.match = null;    // match result, return of re.exec(str)
    this.index = 0;
}
 
sh.Parser = function(lang)
{
    this.minIndex = -1;
    this.matches = new Array();
    this.style = null;
    this.InitMatches(lang);
}
 
// Init match regex list
sh.Parser.prototype.InitMatches = function(lang)
{
    var brush;
    for(brush in sh.Brushes)
        if(sh.Brushes[brush].aliases == lang)
            break;
 
    // If lang can be found, set matches and style
    if(sh.Brushes[brush].aliases == lang)
    {
        this.matches = sh.Brushes[brush].regexList;
        this.style = sh.Brushes[brush].aliases;
    }
}
 
// Compare this.matches[i].match.index and store min i into this.minIndex, skip null
sh.Parser.prototype.RefreshMin = function()
{
    var i;
    // get the first not null in this.matchers[i].match
    for(i=0; i<this.matches.length; i++)
    {
        if(this.matches[i].match != null)
        {
            this.minIndex = i;
            break;
        }
    }
    // get min and store into this.minIndex
    for(; i<this.matches.length; i++)
    {
        if(this.matches[i].match != null &&
            this.matches[i].match.index < this.matches[this.minIndex].match.index)
        {
            this.minIndex = i;
        }
    }
}
 
// Do first match, refresh this.minIndex
sh.Parser.prototype.PrepareMatch = function(str)
{
    var i;
 
    for(i=0; i<this.matches.length; i++)
        this.matches[i].match = this.matches[i].regex.exec(str);
 
    this.RefreshMin();
}
 
// Find a match, begins at the last matched index, and refresh this.minIndex
// returns found or not(true/false)
sh.Parser.prototype.MatchOnce = function(str)
{
    var index = this.matches[this.minIndex].regex.lastIndex;
 
    var i;
    for(i=0; i<this.matches.length; i++)
    {
        if(this.matches[i].match && this.matches[i].match.index < index)
        {
            if(this.matches[i].regex.lastIndex < index)
            {
                this.matches[i].regex.lastIndex = index;
            }
            this.matches[i].match = this.matches[i].regex.exec(str);
        }
    }
 
    this.RefreshMin();
 
    return (this.matches[this.minIndex].match != null);
}
 
// Main parser
sh.Parser.prototype.HighLight = function(str)
{
    // If no lang matched, return str
    if(this.style == null)
    {
        str  = str.replace(/&/g, '&amp;');    // Replace & whith &amp;
        str  = str.replace(/</g, '&lt;');    // Replace < whith &lt;
        return "<pre>" + str + "< /pre>";
    }
 
    var gIndex = 0;
    var buf = new Array();
 
    this.PrepareMatch(str);
 
    buf.push("<pre class=\"" + this.style + "\">")
 
    if(this.minIndex == -1)
        buf.push(str);
 
    do
    {
        var i = this.minIndex;
        // push not matched
        buf.push(str.substring(gIndex, this.matches[i].match.index));
        // push matched in color
        var matched = "" + this.matches[i].match;
        matched  = matched.replace(/&/g, '&amp;');    // Replace & whith &amp;
        matched  = matched.replace(/</g, '&lt;');    // Replace < whith &lt;
        buf.push("<span class=\"" + this.matches[i].css + "\">" + matched + "</span>");
        gIndex = this.matches[i].regex.lastIndex;
    }
    while(this.MatchOnce(str))
 
    buf.push(str.substr(gIndex));
    buf.push("< /pre>")
 
    return buf.join("");
}

<script class="javascript" src="test.js"></script>
<script class="javascript" src="brushCpp.js"></script>
<link type="text/css" rel="stylesheet" href="brushColor.css"></link>
<script class="javascript">
var input_code = "/* int x = 5; // test */";
var parser = new sh.Parser('cpp');
var highlighted_code = parser.HighLight(input_code);
</script>