Determine used exports for CJS modules

Based on the entire graph, not just the subset of the graph that has
already loaded.

lib/graph/each_dependants.js

@@ -0,0 +1,34 @@
+var isString = require("lodash/isString");
+
+/**
+ * @method graph.eachDependants
+ */
+module.exports = function(graph, names, callback){
+	var deps = {};
+	var nodeNames = isString(names) ? [names] : names;
+
+	function visit(name, node) {
+		if(!deps[name]) {
+			deps[name] = true;
+
+			if(node && node.dependencies.length) {
+				if(includes(node.dependencies, nodeNames)) {
+					callback(name, node);
+				}
+			}
+		}
+	}
+
+	for(var name in graph) {
+		visit(name, graph[name]);
+	}
+};
+
+function includes(arr1, arr2) {
+	for(var i = 0; i < arr2.length; i++) {
+		if(arr1.indexOf(arr2[i]) !== -1) {
+			return true;
+		}
+	}
+	return false;
+}

lib/graph/get_dependants.js

@@ -0,0 +1,9 @@
+var eachDependants = require("./each_dependants");
+
+module.exports = function(graph, name) {
+	var deps = [];
+	eachDependants(graph, name, function(depName) {
+		deps.push(depName);
+	});
+	return deps;
+};

lib/graph/treeshake.js

@@ -4,6 +4,7 @@ var os = require("os");
 var babel = require("babel-standalone");
 var entries = require("object.entries");
 var dependencyResolver = require("../node/dependency_resolver");
+var getDependants = require("./get_dependants");
 var processBabelPlugins = require("../process_babel_plugins");
 var processBabelPresets = require("../process_babel_presets");
 var rollup = require("steal-rollup");
@@ -31,7 +32,7 @@ function treeshake(data) {
 		experimentalPreserveModules: true,
 		experimentalCodeSplitting: true,
 		plugins: [
-			loadFromGraph(getNode),
+			loadFromGraph(getNode, data),
 			transpile(getNode, data)
 		],
 		onwarn: function(){}
@@ -75,7 +76,7 @@ function treeshake(data) {
 	});
 }
 
-function loadFromGraph(getNode) {
+function loadFromGraph(getNode, data) {
 	return {
 		resolveId: function(id, importer) {
 			if(importer) {
@@ -90,25 +91,23 @@ function loadFromGraph(getNode) {
 
 			if(notESModule(node)) {
 				let needToExport = new Set();
-				let dependants = (node && node.load.metadata.dependants) || [];
+				let dependants = (node && getDependants(data.graph, node.load.name)) || [];
 
 				// Determine what to export by looking at dependants imports
 				for(let depName of dependants) {
 					let localNode = getNode(depName);
-					let subgraph = localNode.load.metadata.subgraph;
-					if(!subgraph) {
-						continue;
-					}
+					let specifiers = localNode.load.metadata.importSpecifiers || {};
 
-					for(let imp of subgraph.imports) {
-						let depName = moduleNameFromSpecifier(localNode, imp.source);
+					for(let [impSource,] of entries(specifiers)) {
+						let depName = moduleNameFromSpecifier(localNode, impSource);
 						if(depName !== id) {
 							continue;
 						}
 
-						for(let spec of imp.specifiers) {
-							needToExport.add(spec.imported);
-						}
+						let imported = localNode.load.metadata.importNames[impSource] || [];
+						imported.forEach(imported => {
+							needToExport.add(imported);
+						});
 					}
 				}
 
@@ -214,20 +213,6 @@ function transpile(getNode, data) {
 
 			let result = babel.transform(code, opts);
 
-			for(let depName of node.load.metadata.dependencies) {
-				let localNode = getNode(depName);
-				if(!localNode) {
-					continue;
-				}
-				if(!localNode.load.metadata.dependants) {
-					localNode.load.metadata.dependants = [];
-				}
-				localNode.load.metadata.dependants.push(id);
-			}
-
-			// Update metadata with specifiers
-			node.load.metadata.subgraph = result.metadata.modules;
-
 			return {
 				code: result.code,
 				map: result.map

test/tree_shaking_test.js

@@ -271,5 +271,41 @@ describe("Tree-shaking", function(){
 			assert.equal(app.a, "a", "main bundle loaded");
 			assert.equal(app.b, "b", "this bundle loaded");
 		});
-	})
+	});
+
+	describe("import { dep } from 'cjs'", function() {
+		before(function(done){
+			this.timeout(20000);
+			var base = path.join(__dirname, "treeshake", "cjs");
+			var config = { config: path.join(base, "package.json!npm") };
+			var page = `prod.html`;
+
+			rmdir(path.join(base, "dist"))
+				.then(function() {
+					return build(config, {
+						quiet: true,
+						minify: false
+					});
+				})
+				.then(function() {
+					var close;
+					return open(path.join("test", "treeshake", "cjs", page))
+						.then(function(args) {
+							close = args.close;
+							browser = args.browser;
+							return find(browser, "APP");
+						})
+						.then(function(mod) {
+							app = mod;
+							close();
+							done();
+						});
+				})
+				.catch(done);
+		});
+
+		it("Used imports are available", function() {
+			assert.equal(typeof app.assign, "function", "got the exported value");
+		});
+	});
 });

test/treeshake/cjs/dep.js

@@ -0,0 +1,6 @@
+
+exports.pick = function(){};
+
+exports.assign = function(){};
+
+exports.isUndefined = function(){};

test/treeshake/cjs/index.js

@@ -0,0 +1,4 @@
+import { assign } from './dep';
+import './other';
+
+window.APP = { assign };

test/treeshake/cjs/other.js

@@ -0,0 +1,4 @@
+import { pick } from './dep';
+
+window.APP = window.APP || {};
+window.APP.pick = pick;

test/treeshake/cjs/package.json

@@ -0,0 +1,8 @@
+{
+  "name": "app",
+  "main": "index.js",
+  "version": "1.0.0",
+  "steal": {
+    "bundle": ["~/page"]
+  }
+}

test/treeshake/cjs/page.js

@@ -0,0 +1,4 @@
+import { isUndefined } from './dep';
+
+window.APP = window.APP || {};
+window.APP.isUndefined = isUndefined;

test/treeshake/cjs/prod.html

@@ -0,0 +1 @@
+<script src="./dist/steal.production.js"></script>