webpack/lib/DefinePlugin.js

Packs CommonJs/AMD modules for the browser. Allows to split your codebase into multiple bundles, which can be loaded on demand. Support loaders to preprocess files, i.e. json, jade, coffee, css, less, ... and your custom stuff.

/*
	MIT License http://www.opensource.org/licenses/mit-license.php
	Author Tobias Koppers @sokra
*/
var ConstDependency = require("./dependencies/ConstDependency");
var BasicEvaluatedExpression = require("./BasicEvaluatedExpression");

var NullFactory = require("./NullFactory");

function DefinePlugin(definitions) {
	this.definitions = definitions;
}
module.exports = DefinePlugin;
DefinePlugin.prototype.apply = function(compiler) {
	compiler.plugin("compilation", function(compilation, params) {
		compilation.dependencyFactories.set(ConstDependency, new NullFactory());
		compilation.dependencyTemplates.set(ConstDependency, new ConstDependency.Template());
	});
	(function walkDefinitions(definitions, prefix) {
		Object.keys(definitions).forEach(function(key) {
			var code = definitions[key];
			if(code === undefined || code === null) code = code + "";
			else if(typeof code === "object") {
				walkDefinitions(code, key + ".");
				applyObjectDefine(key, code);
				return;
			}
			else code = code.toString();
			applyDefine(prefix + key, code);
		});
	}(this.definitions, ""));
	function applyDefine(key, code) {
		var isTypeof = /^typeof\s+/.test(key);
		if(isTypeof) key = key.replace(/^typeof\s+/, "");
		var recurse = false;
		var recurseTypeof = false;
		if(!isTypeof) {
			compiler.parser.plugin("can-rename " + key, function(expr) {
				return true;
			});
			compiler.parser.plugin("evaluate Identifier " + key, function(expr) {
				if(recurse) return;
				recurse = true;
				var res = compiler.parser.evaluate(code);
				recurse = false;
				res.setRange(expr.range);
				return res;
			});
			compiler.parser.plugin("expression " + key, function(expr) {
				var dep = new ConstDependency("("+code+")", expr.range);
				dep.loc = expr.loc;
				this.state.current.addDependency(dep);
				return true;
			});
		}
		var typeofCode = isTypeof ? code : "typeof (" + code + ")"
		compiler.parser.plugin("evaluate typeof " + key, function(expr) {
			if(recurseTypeof) return;
			recurseTypeof = true;
			var res = compiler.parser.evaluate(typeofCode);
			recurseTypeof = false;
			res.setRange(expr.range);
			return res;
		});
		compiler.parser.plugin("typeof " + key, function(expr) {
			var res = compiler.parser.evaluate(typeofCode);
			if(!res.isString()) return;
			var dep = new ConstDependency(JSON.stringify(res.string), expr.range);
			dep.loc = expr.loc;
			this.state.current.addDependency(dep);
			return true;
		});
	}
	function applyObjectDefine(key, obj) {
		var code = "{" + Object.keys(obj).map(function(key) {
			var code = obj[key];
			if(typeof code !== "string" && code.toString) code = code.toString();
			else if(typeof code !== "string") code = code + "";
			return JSON.stringify(key) + ":" + code;
		}).join(",") + "}";
		compiler.parser.plugin("can-rename " + key, function(expr) {
			return true;
		});
		compiler.parser.plugin("evaluate Identifier " + key, function(expr) {
			return new BasicEvaluatedExpression().setRange(expr.range);
		});
		compiler.parser.plugin("evaluate typeof " + key, function(expr) {
			return new BasicEvaluatedExpression().setString("object").setRange(expr.range);
		});
		compiler.parser.plugin("expression " + key, function(expr) {
			var dep = new ConstDependency("("+code+")", expr.range);
			dep.loc = expr.loc;
			this.state.current.addDependency(dep);
			return true;
		});
		compiler.parser.plugin("typeof " + key, function(expr) {
			var dep = new ConstDependency("\"object\"", expr.range);
			dep.loc = expr.loc;
			this.state.current.addDependency(dep);
			return true;
		});
	}
};