Uglify files and inline keys in gettext calls

uglify-gettext.js

var UglifyJS = require("uglify-js");
var fs = require('fs');

var defineName = 'define',
	getTextModule = 'shared/gettext',
	currentGetTextName,
	stringDefinitions,
	placeholders,
	stringKeys,
	moduleName;

function getStringNode(node) {
	if (node instanceof UglifyJS.AST_String) {
		return node;
	}
	var value = node.name && stringDefinitions[node.name];
	if (value) {
		return value;
	}
	console.error(JSON.stringify(node, null, 2));
	throw new Error("Unknown string type");
}

function resetState() {
	moduleName = currentGetTextName = null;
	stringDefinitions = {};
	placeholders = [];
	stringKeys = [];
}

function getPlaceholderString(node) {
	var placeholder = new UglifyJS.AST_String({ value: 'KEY PLACEHOLDER' });
	placeholders.push(placeholder);
	stringKeys.push({ node: node, module: moduleName });
	return placeholder;
}

function before(node, descend) {

	if (node instanceof UglifyJS.AST_Call &&
			node.expression.name == defineName && 
			node.args.length >= 2) {

		var defineStarted = false,
			previousModuleName = moduleName,
			localModuleName,
			previousGetTextName = currentGetTextName,
			dependencies,
			names;


		if (node.args.length >= 3 &&
				node.args[0] instanceof UglifyJS.AST_String && 
				node.args[1] instanceof UglifyJS.AST_Array && 
				node.args[2] instanceof UglifyJS.AST_Function) {

			localModuleName = node.args[0].value;
			dependencies = node.args[1].elements;
			names = node.args[2].argnames;

		} else if (node.args[0] instanceof UglifyJS.AST_Array && 
				node.args[1] instanceof UglifyJS.AST_Function) {

			dependencies = node.args[0].elements;
			names = node.args[1].argnames;
		}

		if (dependencies && names) {
			for (var i = 0; i < dependencies.length; i++) {
				if (dependencies[i] instanceof UglifyJS.AST_String && 
					dependencies[i].value.toLowerCase() == getTextModule &&
					names.length > i) {

					currentGetTextName = names[i].name;
					defineStarted = true;
					break;
				}
			}
		}

		if (defineStarted) {
			if (localModuleName) {
				moduleName = localModuleName;
			}

			descend(node, this);
			currentGetTextName = previousGetTextName;
			if (localModuleName) {
				moduleName = previousModuleName;
			}
			return node;
		}
	}
	else if (node instanceof UglifyJS.AST_VarDef && 
			node.value && 
			node.value instanceof UglifyJS.AST_String) {

		// TODO support shadowing
		stringDefinitions[node.name.name] = node.value;

		descend(node, this);
		return node;
	}
}

function after(node) {
	if (node instanceof UglifyJS.AST_Call && 
		node.args.length > 0 && 
		node.expression.name && 
		node.expression.name == currentGetTextName) {

		var stringNode = getStringNode(node.args[0]),
			placeholder = getPlaceholderString(stringNode);

		node.args.unshift(placeholder);
		return node;
	}
}

var getTextWalker = new UglifyJS.TreeTransformer(before, after);

function processFileSync(file, keyCreator, astPrintOptions) {
	resetState();
	var code = fs.readFileSync(file);
	var ast = UglifyJS.parse(String(code), { filename: file, toplevel: null });

	ast = ast.transform(getTextWalker);

	var keys = keyCreator(file, stringKeys);
	placeholders.forEach(function(placeholder, ix) {
		placeholder.value = keys[ix];
	});

	// compressor needs figure_out_scope too
	ast.figure_out_scope();
	var compressor = UglifyJS.Compressor({ pure_getters: true })
	ast = ast.transform(compressor);

	// need to figure out scope again so mangler works optimally
	ast.figure_out_scope();
	ast.compute_char_frequency();
	ast.mangle_names();

	return ast.print_to_string(astPrintOptions || {});
}

var argv,
	exampleKeyCreator;

// process files specified on command line if run directly
if (require.main === module) {

	argv = process.argv.slice(2);

	exampleKeyCreator = function(filename, nodes) {
		return nodes.map(function(node) {
			return 'success - ' + (node.module || filename) + ' - ' + node.node.value;
		});
	}

	if (argv.length == 0) {
		argv = ['something.js'];
	}

	argv.forEach(function(file) {
		console.log('// ' + file);
		console.log(processFileSync(file, exampleKeyCreator, { beautify: true }));
	});
}

module.exports.processFileSync = processFileSync;