Small and fast template engine

gistfile1.js

(function(namespace) {
	function template(template) {
		var index = 0, depth = 0, source = "var o = '', e = encode;", matches, token, value, tokenRe = /{(\/)?(if|each|\$+|%+)\s*(?:([^}]+)|)?\}/g;

		template = template.replace(/'/g, "\\'");

		while (matches = tokenRe.exec(template)) {
			if (index < matches.index) {
				source += "o += '" + template.substr(index, matches.index - index) + "';";
			}

			index = matches.index + matches[0].length;
			token = matches[2];
			value = matches[3];

			if (token === '$') {
				source += "o += e(d." + value + ");";
			} else if (token === '$$') {
				source += "o += d." + value + ";";
			} else if (matches[1]) {
				source += '} ';

				if (token === 'each') {
					depth--;
				}
			} else if (token === 'each') {
				value = value.replace(/\$/g, 'd.').replace(/%/g, '');

				source += (
					'for (var index% = 0, length% = ' + value + '.length, value%; index% < length%; index%++) {' +
					'value% = ' + value + '[index%];'
				).replace(/%/g, depth ? depth : '');

				depth++;
			} else if (token === 'if') {
				source += 'if (' + value.replace(/\$/g, 'd.') + ') {';
			} else if (token === '%') {
				source += "o += e(" + value + ");";
			} else if (token === '%%') {
				source += "o += " + value + ";";
			}
		}

		if (index < template.length) {
			source += "o += '" + template.substr(index) + "';";
		}

		source += "return o;";

		return new Function("d", "encode", source);
	};

	namespace.template = function(tpl) {
		var rawCharsRegExp = /[<>&\"\']/g, baseEntities = {
			'\"' : '&quot;', // Needs to be escaped since the YUI compressor would otherwise break the code
			"'" : '&#39;',
			'<' : '&lt;',
			'>' : '&gt;',
			'&' : '&amp;'
		};

		function encode(text) {
			return ('' + text).replace(rawCharsRegExp, function(chr) {
				return baseEntities[chr] || chr;
			});
		};

		tpl = template(tpl);

		return function(data) {
			return tpl(data, encode);
		};
	};
})(window);