alloy/Alloy/commands/compile/optimizer.js

Appcelerator Titanium MVC Framework

/**
 * Code in this file will attempt to optimize generated code so it's more compact
 * and executes faster, better, etc.
 */
var uglifyjs = require('uglify-js'),
	path = require('path'),
	fs = require('fs'),
	_ = require('../../lib/alloy/underscore')._;

var JSON_NULL = JSON.parse('null');

function dotCheck(node, name) {
	return node instanceof uglifyjs.AST_Dot && node.property === name;
}

function subCheck(node, name) {
	return node instanceof uglifyjs.AST_Sub && node.property.value === name;
}

function dotSubCheck(node, name) {
	return dotCheck(node, name) || subCheck(node, name);
}

// Optimize Titanium namespaces with static strings where possible
exports.optimize = function(ast, defines, fn) {
	//var platform = {};
	var theKey;
	_.find(defines, function(value, key) {
		var ret = key.indexOf('OS_') === 0 && value;
		if (ret) { theKey = key; }
		return ret;
	});
	if (!theKey) { return ast; }

	// make sure the platform require includes
	var platformString = theKey.substring(3).toLowerCase();
	var platformPath = path.join(__dirname,'..','..','..','platforms',platformString,'index');
	if (!fs.existsSync(platformPath + '.js')) { return ast; }

	// create, transform, and validate the platform object
	var platform = require(platformPath);
	if (!_.isString(platform.name)) { platform.name = undefined; }
	if (!_.isString(platform.osname)) { platform.osname = undefined; }
	if (!platform.osname && !platform.name) { return ast; }

	// Walk tree transformer changing (Ti|Titanium).Platform.(osname|name)
	// into static strings where possible. This will allow the following
	// compression step to reduce the code further.
	var transformer = new uglifyjs.TreeTransformer(function(node, descend){
		var convert = false;
		if (dotSubCheck(node, 'name') || dotSubCheck(node, 'osname')) {
			descend(node, new uglifyjs.TreeTransformer(function(node, descend) {
				if (dotSubCheck(node, 'Platform')) {
					descend(node, new uglifyjs.TreeTransformer(function(node) {
						if (node instanceof uglifyjs.AST_SymbolRef &&
							(node.name === 'Titanium' || node.name === 'Ti')) {
							convert = true;
						}
						return node;
					}));
				}
				return node;
			}));
			if (convert) {
				var value = node instanceof uglifyjs.AST_Dot ? node.property : node.property.value;
				if (platform[value]) {
					return new uglifyjs.AST_String({
						start: node.start,
						end: node.end,
						value: platform[value]
					});
				} else {
					return node;
				}
			}
			return node;
		}
	});
	return ast.transform(transformer);
};

// strips null and undefined values out of Alloy styles
exports.optimizeStyle = function(styleList) {
	for (var style in styleList) {
		for (var key in styleList[style]) {
			var v = styleList[style][key];
			if (v == JSON_NULL || typeof(v) === 'undefined' || typeof(v) === 'null') {
				delete styleList[style][key];
			}
		}
	}
};