Add Scope and LibraryElement.scope to API.

Change-Id: I5cfda9ed6c52fde38252d82ee1bc9c9152b906f0
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/154141
Commit-Queue: Konstantin Shcheglov <[email protected]>
Reviewed-by: Brian Wilkerson <[email protected]>

Author: scheglov

pkg/analyzer/CHANGELOG.md

@@ -6,6 +6,7 @@
 * Added `InterfaceType.allSupertypes`.
 * Added `InterfaceType.asInstanceOf(ClassElement)`.
 * Removed deprecated internal `bogus-disabled` and `bogus-enabled`.
+* Added `Scope` and `LibraryElement.scope`.
 
 ## 0.39.12
 * Deprecated `canUseSummaries` in `DartSdkManager` constructor.

pkg/analyzer/lib/dart/element/element.dart

@@ -37,6 +37,7 @@
 import 'package:analyzer/dart/analysis/session.dart';
 import 'package:analyzer/dart/constant/value.dart';
 import 'package:analyzer/dart/element/nullability_suffix.dart';
+import 'package:analyzer/dart/element/scope.dart';
 import 'package:analyzer/dart/element/type.dart';
 import 'package:analyzer/dart/element/type_provider.dart';
 import 'package:analyzer/dart/element/type_system.dart';
@@ -1375,6 +1376,10 @@ abstract class LibraryElement implements Element {
   /// computed yet.
   Namespace get publicNamespace;
 
+  /// Return the name lookup scope for this library. It consists of elements
+  /// that are either declared in the library, or imported into it.
+  Scope get scope;
+
   /// Return the top-level elements defined in each of the compilation units
   /// that are included in this library. This includes both public and private
   /// elements, but does not include imports, exports, or synthetic elements.

pkg/analyzer/lib/dart/element/scope.dart

@@ -0,0 +1,13 @@
+// Copyright (c) 2020, 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.
+
+import 'package:analyzer/dart/element/element.dart';
+import 'package:meta/meta.dart';
+
+/// Scopes are used to resolve names to elements.
+abstract class Scope {
+  /// Return the element with the name `id` or `id=` (if [setter] is `true`),
+  /// `null` if the name is not defined within this scope.
+  Element lookup({@required String id, @required bool setter});
+}

pkg/analyzer/lib/src/dart/element/element.dart

@@ -10,6 +10,7 @@ import 'package:analyzer/dart/ast/token.dart';
 import 'package:analyzer/dart/constant/value.dart';
 import 'package:analyzer/dart/element/element.dart';
 import 'package:analyzer/dart/element/nullability_suffix.dart';
+import 'package:analyzer/dart/element/scope.dart';
 import 'package:analyzer/dart/element/type.dart';
 import 'package:analyzer/error/error.dart';
 import 'package:analyzer/src/dart/analysis/experiments.dart';
@@ -20,11 +21,13 @@ import 'package:analyzer/src/dart/constant/value.dart';
 import 'package:analyzer/src/dart/element/display_string_builder.dart';
 import 'package:analyzer/src/dart/element/member.dart';
 import 'package:analyzer/src/dart/element/nullability_eliminator.dart';
+import 'package:analyzer/src/dart/element/scope.dart';
 import 'package:analyzer/src/dart/element/type.dart';
 import 'package:analyzer/src/dart/element/type_algebra.dart';
 import 'package:analyzer/src/dart/element/type_provider.dart';
 import 'package:analyzer/src/dart/element/type_system.dart';
-import 'package:analyzer/src/dart/resolver/scope.dart';
+import 'package:analyzer/src/dart/resolver/scope.dart'
+    show Namespace, NamespaceBuilder;
 import 'package:analyzer/src/dart/resolver/variance.dart';
 import 'package:analyzer/src/generated/constant.dart' show EvaluationResultImpl;
 import 'package:analyzer/src/generated/element_type_provider.dart';
@@ -5208,6 +5211,9 @@ class LibraryElementImpl extends ElementImpl implements LibraryElement {
   /// The cached list of prefixes.
   List<PrefixElement> _prefixes;
 
+  /// The scope of this library, `null` if it has not been created yet.
+  LibraryScope _scope;
+
   /// Initialize a newly created library element in the given [context] to have
   /// the given [name] and [offset].
   LibraryElementImpl(this.context, this.session, String name, int offset,
@@ -5581,6 +5587,11 @@ class LibraryElementImpl extends ElementImpl implements LibraryElement {
     _publicNamespace = publicNamespace;
   }
 
+  @override
+  Scope get scope {
+    return _scope ??= LibraryScope(this);
+  }
+
   @override
   Source get source {
     if (_definingCompilationUnit == null) {

pkg/analyzer/lib/src/dart/element/scope.dart

@@ -0,0 +1,28 @@
+// Copyright (c) 2020, 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.
+
+import 'package:analyzer/dart/ast/standard_ast_factory.dart';
+import 'package:analyzer/dart/ast/token.dart';
+import 'package:analyzer/dart/element/element.dart';
+import 'package:analyzer/dart/element/scope.dart';
+import 'package:analyzer/src/dart/ast/token.dart';
+import 'package:analyzer/src/dart/resolver/scope.dart' as impl;
+import 'package:meta/meta.dart';
+
+class LibraryScope implements Scope {
+  final LibraryElement _libraryElement;
+  final impl.LibraryScope _implScope;
+
+  LibraryScope(LibraryElement libraryElement)
+      : _libraryElement = libraryElement,
+        _implScope = impl.LibraryScope(libraryElement);
+
+  @override
+  Element lookup({@required String id, @required bool setter}) {
+    var name = setter ? '$id=' : id;
+    var token = SyntheticStringToken(TokenType.IDENTIFIER, name, 0);
+    var identifier = astFactory.simpleIdentifier(token);
+    return _implScope.lookup(identifier, _libraryElement);
+  }
+}

pkg/analyzer/test/src/dart/resolution/library_element_test.dart

@@ -123,6 +123,124 @@ class A {}
     await _assertLanguageVersionCurrent('package:aaa/c.dart');
   }
 
+  test_scope() async {
+    await assertNoErrorsInCode(r'''
+int foo;
+''');
+
+    var scope = result.libraryElement.scope;
+
+    assertElement(
+      scope.lookup(id: 'foo', setter: false),
+      findElement.topGet('foo'),
+    );
+    assertElement(
+      scope.lookup(id: 'foo', setter: true),
+      findElement.topSet('foo'),
+    );
+  }
+
+  test_scope_implicitCoreImport() async {
+    await assertNoErrorsInCode('');
+
+    var scope = result.libraryElement.scope;
+
+    assertElement(
+      scope.lookup(id: 'int', setter: false),
+      intElement,
+    );
+  }
+
+  test_scope_notFound() async {
+    await assertNoErrorsInCode('');
+
+    var scope = result.libraryElement.scope;
+
+    assertElementNull(
+      scope.lookup(id: 'noSuchGetter', setter: false),
+    );
+
+    assertElementNull(
+      scope.lookup(id: 'noSuchSetter', setter: true),
+    );
+  }
+
+  test_scope_prefersLocal() async {
+    await assertNoErrorsInCode(r'''
+// ignore:unused_import
+import 'dart:math';
+
+int sin() => 3;
+''');
+
+    var scope = result.libraryElement.scope;
+
+    assertElement(
+      scope.lookup(id: 'sin', setter: false),
+      findElement.topFunction('sin'),
+    );
+
+    assertElement(
+      scope.lookup(id: 'cos', setter: false),
+      findElement.importFind('dart:math').topFunction('cos'),
+    );
+  }
+
+  test_scope_prefix() async {
+    await assertNoErrorsInCode(r'''
+// ignore:unused_import
+import 'dart:math' as math;
+''');
+
+    var scope = result.libraryElement.scope;
+
+    assertElement(
+      scope.lookup(id: 'math', setter: false),
+      findElement.prefix('math'),
+    );
+  }
+
+  test_scope_respectsCombinator_hide() async {
+    await assertNoErrorsInCode(r'''
+// ignore:unused_import
+import 'dart:math' hide sin;
+''');
+
+    var scope = result.libraryElement.scope;
+
+    assertElementNull(
+      scope.lookup(id: 'sin', setter: false),
+    );
+
+    var mathFind = findElement.importFind('dart:math');
+    assertElement(
+      scope.lookup(id: 'cos', setter: false),
+      mathFind.topFunction('cos'),
+    );
+    assertElement(
+      scope.lookup(id: 'tan', setter: false),
+      mathFind.topFunction('tan'),
+    );
+  }
+
+  test_scope_respectsCombinator_show() async {
+    await assertNoErrorsInCode(r'''
+// ignore:unused_import
+import 'dart:math' show sin;
+''');
+
+    var scope = result.libraryElement.scope;
+
+    assertElement(
+      scope.lookup(id: 'sin', setter: false),
+      findElement.importFind('dart:math').topFunction('sin'),
+    );
+
+    assertElementNull(
+      scope.lookup(id: 'cos', setter: false),
+    );
+  }
+
   Future<void> _assertLanguageVersion({
     @required String uriStr,
     @required Version package,

pkg/analyzer/test/src/dart/resolution/resolution.dart

@@ -206,9 +206,15 @@ mixin ResolutionTest implements ResourceProviderMixin {
     }
   }
 
-  void assertElementNull(Expression node) {
-    Element actual = getNodeElement(node);
-    expect(actual, isNull);
+  void assertElementNull(Object nodeOrElement) {
+    Element element;
+    if (nodeOrElement is AstNode) {
+      element = getNodeElement(nodeOrElement);
+    } else {
+      element = nodeOrElement as Element;
+    }
+
+    expect(element, isNull);
   }
 
   void assertElementString(Element element, String expected) {