shadow.js

/**
 * @license MIT http://troopjs.mit-license.org/
 */
define([ "text" ], function (text) {
	"use strict";

	/**
	 * RequireJS shadow plugin
	 * @class requirejs.shadow
	 * @static
	 * @alias plugin.requirejs
	 */

	//TODO Add usage docs

	var UNDEFINED;
	var EXPORTS = "exports";
	var EXTENSION = ".js";
	var PATTERN = /(.+?)#(.+)$/;
	var RE_EMPTY = /^empty:/;
	var REQUIRE_VERSION = require.version;
	var buildMap = {};

	function amdify (scriptText, hashVal) {
		var pattern = /([^=&]+)=([^&]+)/g;
		var m;
		var deps = [];
		var args = [];

		while (hashVal && (m = pattern.exec(hashVal))) {
			if (m[1] === EXPORTS) {
				scriptText += ";\nreturn " + m[2] + ";\n";
			}
			else {
				deps.push("'" + m[2] + "'");
				args.push(m[1]);
			}
		}

		return "define([" + deps.join(", ") + "], function (" + args.join(", ") + ") {\n"
			+ scriptText
			+ "});";
	}

	function cmpVersion(a, b) {
		var result;
		var len;
		var i;

		a = a.split(".");
		b = b.split(".");
		len = Math.min(a.length, b.length);

		for (i = 0; i < len; i++) {
			result = parseInt(a[i], null) - parseInt(b[i], null);
			if (result !== 0) {
				return result;
			}
		}
		return a.length - b.length;
	}

	return {
		load : function (name, req, onLoad, config) {
			var m;
			var hashVal;
			var content;
			var url;
			var realName = name;

			// The name is like 'jquery.form#$=jquery&exports=$',
			// So, if macthed, m[1] is 'jquery.form', m[2] is '$=jquery&exports=$'
			if ((m = PATTERN.exec(name))) {
				realName = m[1];
				hashVal = m[2];
			}
			url = req.toUrl(realName + EXTENSION);

			// For Optimization. The url is "empty:" if excluded.
			if (RE_EMPTY.test(url)) {
				onLoad(UNDEFINED);
			}
			else {
				text.get(url, function(data) {
					content = amdify(data, hashVal);
					if (config.isBuild) {
						buildMap[name] = content;
					}

					onLoad.fromText(name, content);
					// On requirejs version below '2.1.0', 
					// need to manually require the module after the call to onLoad.fromText()
					if (cmpVersion(REQUIRE_VERSION, "2.1.0") < 0) {
						req([ name ], onLoad);
					}	
				});
			}
		},

		write : function (pluginName, moduleName, write) { 
			var content;

			if (moduleName in buildMap) {
				content = buildMap[moduleName];
				content = content.replace(/define\(/, function (match) {
					return match + '"' + [pluginName, moduleName].join('!') + '",';
				});
				write(content);
			}
		}
	};
});