Issue 26044. Cache and use LibraryElementImpl.exportNamespace.

pkg/analyzer/lib/src/generated/resolver.dart

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library analyzer.src.generated.resolver;
 
 import 'dart:collection';
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/ast/token.dart';
@@ skipping 6591 matching lines @@
    */
   Namespace createExportNamespaceForDirective(ExportElement element) {
     LibraryElement exportedLibrary = element.exportedLibrary;
     if (exportedLibrary == null) {
       //
       // The exported library will be null if the URI does not reference a valid
       // library.
       //
       return Namespace.EMPTY;
     }
-    HashMap<String, Element> definedNames =
-        _createExportMapping(exportedLibrary, new HashSet<LibraryElement>());
-    definedNames = _applyCombinators(definedNames, element.combinators);
-    return new Namespace(definedNames);
+    HashMap<String, Element> exportedNames = _getExportMapping(exportedLibrary);
+    exportedNames = _applyCombinators(exportedNames, element.combinators);
+    return new Namespace(exportedNames);
   }
 
   /**
    * Create a namespace representing the export namespace of the given library.
    *
    * @param library the library whose export namespace is to be created
    * @return the export namespace that was created
    */
-  Namespace createExportNamespaceForLibrary(LibraryElement library) =>
-      new Namespace(
-          _createExportMapping(library, new HashSet<LibraryElement>()));
+  Namespace createExportNamespaceForLibrary(LibraryElement library) {
+    HashMap<String, Element> exportedNames = _getExportMapping(library);
+    return new Namespace(exportedNames);
+  }
 
   /**
    * Create a namespace representing the import namespace of the given library.
    *
    * @param library the library whose import namespace is to be created
    * @return the import namespace that was created
    */
   Namespace createImportNamespaceForDirective(ImportElement element) {
     LibraryElement importedLibrary = element.importedLibrary;
     if (importedLibrary == null) {
       //
       // The imported library will be null if the URI does not reference a valid
       // library.
       //
       return Namespace.EMPTY;
     }
-    HashMap<String, Element> definedNames =
-        _createExportMapping(importedLibrary, new HashSet<LibraryElement>());
-    definedNames = _applyCombinators(definedNames, element.combinators);
-    definedNames = _applyPrefix(definedNames, element.prefix);
-    return new Namespace(definedNames);
+    HashMap<String, Element> exportedNames = _getExportMapping(importedLibrary);
+    exportedNames = _applyCombinators(exportedNames, element.combinators);
+    exportedNames = _applyPrefix(exportedNames, element.prefix);
+    return new Namespace(exportedNames);
   }
 
   /**
    * Create a namespace representing the public namespace of the given library.
    *
    * @param library the library whose public namespace is to be created
    * @return the public namespace that was created
    */
   Namespace createPublicNamespaceForLibrary(LibraryElement library) {
     HashMap<String, Element> definedNames = new HashMap<String, Element>();
@@ skipping 94 matching lines @@
       HashMap<String, Element> newNames = new HashMap<String, Element>();
       definedNames.forEach((String name, Element element) {
         newNames["$prefix.$name"] = element;
       });
       return newNames;
     } else {
       return definedNames;
     }
   }
 
+  HashMap<String, Element> _getExportMapping(LibraryElement library) {
+    if (library is LibraryElementImpl) {
+      if (library.exportNamespace != null) {
+        return library.exportNamespace.definedNames;
+      } else {
+        HashMap<String, Element> exportMapping =
+            _computeExportMapping(library, new HashSet<LibraryElement>());
+        library.exportNamespace = new Namespace(exportMapping);

[Brian Wilkerson, 2016/03/20 21:26:29]

Shouldn't we just return 'exportMapping' at this point? It looks like not doing
so will cause us to re-compute the mapping.

[scheglov, 2016/03/20 22:16:47]

Fixed.
Thanks!

+      }
+    }
+    return _computeExportMapping(library, new HashSet<LibraryElement>());
+  }
+
   /**
    * Create a mapping table representing the export namespace of the given library.
    *
    * @param library the library whose public namespace is to be created
    * @param visitedElements a set of libraries that do not need to be visited when processing the
    *          export directives of the given library because all of the names defined by them will
    *          be added by another library
    * @return the mapping table that was created
    */
-  HashMap<String, Element> _createExportMapping(
+  HashMap<String, Element> _computeExportMapping(
       LibraryElement library, HashSet<LibraryElement> visitedElements) {
     visitedElements.add(library);
     try {
       HashMap<String, Element> definedNames = new HashMap<String, Element>();
       for (ExportElement element in library.exports) {
         LibraryElement exportedLibrary = element.exportedLibrary;
         if (exportedLibrary != null &&
             !visitedElements.contains(exportedLibrary)) {
           //
           // The exported library will be null if the URI does not reference a
           // valid library.
           //
           HashMap<String, Element> exportedNames =
-              _createExportMapping(exportedLibrary, visitedElements);
+              _computeExportMapping(exportedLibrary, visitedElements);
           exportedNames = _applyCombinators(exportedNames, element.combinators);
           definedNames.addAll(exportedNames);
         }
       }
       _addAllFromNamespace(
           definedNames,
           (library.context as InternalAnalysisContext)
               .getPublicNamespace(library));
       return definedNames;
     } finally {
@@ skipping 6164 matching lines @@
     nonFields.add(node);
     return null;
   }
 
   @override
   Object visitNode(AstNode node) => node.accept(TypeResolverVisitor_this);
 
   @override
   Object visitWithClause(WithClause node) => null;
 }