behave according to precedence rules from spec

fixed webpack#1792

lib/dependencies/HarmonyExportImportedSpecifierDependency.js

@@ -3,6 +3,7 @@
  Author Tobias Koppers @sokra
 */
 var NullDependency = require("./NullDependency");
+var HarmonyModulesHelpers = require("./HarmonyModulesHelpers");
 
 function HarmonyExportImportedSpecifierDependency(originModule, importDependency, importedVar, id, name, position) {
  NullDependency.call(this);
@@ -21,10 +22,19 @@ HarmonyExportImportedSpecifierDependency.prototype.type = "harmony export import
 
 HarmonyExportImportedSpecifierDependency.prototype.getReference = function() {
  var used = this.originModule.isUsed(this.name);
- if(!this.importDependency.module || !used) return null;
+ var active = HarmonyModulesHelpers.isActive(this.originModule, this);
+ if(!this.importDependency.module || !used || !active) return null;
  return {
  module: this.importDependency.module,
- importedNames: this.id ? [this.id] : true
+ importedNames: this.id ? [this.id] : true,
+ precedence: this.name ? 2 : 3
+ };
+};
+
+HarmonyExportImportedSpecifierDependency.prototype.describeHarmonyExport = function() {
+ return {
+ exportedName: this.name,
+ precedence: this.name ? 2 : 3
  };
 };
 
@@ -33,17 +43,29 @@ HarmonyExportImportedSpecifierDependency.Template = function HarmonyExportImport
 HarmonyExportImportedSpecifierDependency.Template.prototype.apply = function(dep, source, outputOptions, requestShortener) {
  var name = dep.importedVar;
  var used = dep.originModule.isUsed(dep.name);
+ var active = HarmonyModulesHelpers.isActive(dep.originModule, dep);
  var comment = "";
  if(outputOptions.pathinfo) comment = "/*! " + requestShortener.shorten(dep.request) + " */ ";
  var content;
  if(!used) {
  content = "/* unused harmony reexport " + (dep.name || "namespace") + " */;";
+ } else if(!active) {
+ content = "/* inactive harmony reexport " + (dep.name || "namespace") + " */;";
  } else if(dep.name === "default" && !dep.importDependency.module.meta.harmonyModule) {
  content = "/* harmony reexport */ Object.defineProperty(exports, " + JSON.stringify(dep.name) + ", {configurable: false, enumerable: true, get: function() { return " + comment + name + "_default.a; }});";
  } else if(dep.name) {
  content = "/* harmony reexport */ Object.defineProperty(exports, " + JSON.stringify(dep.name) + ", {configurable: false, enumerable: true, get: function() { return " + comment + (name + "[" + JSON.stringify(dep.id) + "]") + "; }});";
  } else {
- content = "/* harmony namespace reexport */ for(var __WEBPACK_IMPORT_KEY__ in " + comment + name + ") (function(key) { Object.defineProperty(exports, key, {configurable: false, enumerable: true, get: function() { return " + name + "[key]; }}) }(__WEBPACK_IMPORT_KEY__));";
+ var activeExports = HarmonyModulesHelpers.getActiveExports(dep.originModule);
+ content = "/* harmony namespace reexport */ for(var __WEBPACK_IMPORT_KEY__ in " + comment + name + ") ";
+
+ // Filter out exports which are defined by other exports
+ // and filter out default export because it cannot be reexported with *
+ if(activeExports.length > 0)
+ content += "if(" + JSON.stringify(activeExports.concat("default")) + ".indexOf(__WEBPACK_IMPORT_KEY__) < 0) ";
+ else
+ content += "if(__WEBPACK_IMPORT_KEY__ !== 'default') ";
+ content += "(function(key) { Object.defineProperty(exports, key, {configurable: false, enumerable: true, get: function() { return " + name + "[key]; }}) }(__WEBPACK_IMPORT_KEY__));";
  }
  source.insert(dep.position, content);
 

lib/dependencies/HarmonyExportSpecifierDependency.js

@@ -3,6 +3,7 @@
  Author Tobias Koppers @sokra
 */
 var NullDependency = require("./NullDependency");
+var HarmonyModulesHelpers = require("./HarmonyModulesHelpers");
 
 function HarmonyExportSpecifierDependency(originModule, id, name, position, immutable) {
  NullDependency.call(this);
@@ -18,13 +19,23 @@ HarmonyExportSpecifierDependency.prototype = Object.create(NullDependency.protot
 HarmonyExportSpecifierDependency.prototype.constructor = HarmonyExportSpecifierDependency;
 HarmonyExportSpecifierDependency.prototype.type = "harmony export specifier";
 
+HarmonyExportSpecifierDependency.prototype.describeHarmonyExport = function() {
+ return {
+ exportedName: this.name,
+ precedence: 1
+ };
+};
+
 HarmonyExportSpecifierDependency.Template = function HarmonyExportSpecifierDependencyTemplate() {};
 
 HarmonyExportSpecifierDependency.Template.prototype.apply = function(dep, source) {
  var used = dep.originModule.isUsed(dep.name);
+ var active = HarmonyModulesHelpers.isActive(dep.originModule, dep);
  var content;
  if(!used) {
  content = "/* unused harmony export " + (dep.name || "namespace") + " */;";
+ } else if(!active) {
+ content = "/* inactive harmony export " + (dep.name || "namespace") + " */;";
  } else if(dep.immutable) {
  content = "/* harmony export */ exports[" + JSON.stringify(dep.name) + "] = " + dep.id + ";";
  } else {

lib/dependencies/HarmonyModulesHelpers.js

@@ -24,4 +24,46 @@ HarmonyModulesHelpers.checkModuleVar = function(state, request) {
  if(!state.harmonyModules || state.harmonyModules.indexOf(request) < 0)
  return null;
  return HarmonyModulesHelpers.getModuleVar(state, request);
-}
+};
+
+// checks if an harmory dependency is active in a module according to
+// precedence rules.
+HarmonyModulesHelpers.isActive = function(module, depInQuestion) {
+ var desc = depInQuestion.describeHarmonyExport();
+ if(!desc.exportedName) return true;
+ var before = true;
+ for(var i = 0; i < module.dependencies.length; i++) {
+ var dep = module.dependencies[i];
+ if(dep === depInQuestion) {
+ before = false;
+ continue;
+ }
+ if(!dep.describeHarmonyExport) continue;
+ var d = dep.describeHarmonyExport();
+ if(!d || !d.exportedName) continue;
+ if(d.exportedName === desc.exportedName) {
+ if(d.precedence < desc.precedence) {
+ return false;
+ }
+ if(d.precedence === desc.precedence && !before) {
+ return false;
+ }
+ }
+ }
+ return true;
+};
+
+// get a list of named exports defined in a module
+// doesn't include * reexports.
+HarmonyModulesHelpers.getActiveExports = function(module) {
+ return module.dependencies.reduce(function(arr, dep) {
+ if(!dep.describeHarmonyExport) return arr;
+ var d = dep.describeHarmonyExport();
+ if(!d) return arr;
+ var name = d.exportedName;
+ if(!name || arr.indexOf(name) >= 0) return arr;
+ arr.push(name);
+ return arr;
+ }, [])
+};
+

test/cases/parsing/harmony-export-precedence/a.js

@@ -0,0 +1,5 @@
+export function a() { return "a1"; }
+export { a, b } from "./b";
+export * from "./c";
+export { d, e } from "./b";
+export var e = "e1";

test/cases/parsing/harmony-export-precedence/b.js

@@ -0,0 +1,5 @@
+export var a = "a2";
+export var b = "b2";
+export var c = "c2";
+export var d = "d2";
+export var e = "e2";

test/cases/parsing/harmony-export-precedence/c.js

@@ -0,0 +1,6 @@
+export var a = "a3";
+export var b = "b3";
+export var c = "c3";
+export var e = "e3";
+export var f = "f3";
+export default "default";

test/cases/parsing/harmony-export-precedence/d.js

@@ -0,0 +1 @@
+export default "default";

test/cases/parsing/harmony-export-precedence/index.js

@@ -0,0 +1,21 @@
+import { a, b, c, d, e } from "./a";
+
+import defaultImport from "./a";
+
+it("should prefer local exports", function() {
+ a().should.be.eql("a1");
+ e.should.be.eql("e1");
+});
+
+it("should prefer indirect exports over star exports", function() {
+ b.should.be.eql("b2");
+ d.should.be.eql("d2");
+});
+
+it("should use star exports", function() {
+ c.should.be.eql("c3");
+});
+
+it("should not export default via star export", function() {
+ (typeof defaultImport).should.be.eql("undefined");
+});