Extract NativeClassResolver from NativeResolutionEnqueuer

pkg/compiler/lib/src/native/resolver.dart

Index: pkg/compiler/lib/src/native/resolver.dart
diff --git a/pkg/compiler/lib/src/native/resolver.dart b/pkg/compiler/lib/src/native/resolver.dart
index 557e9698c9920a6297f09a41a6aab771c43e52f6..5d055ccd356883267dd2f0a6a60d668862a1cda7 100644
--- a/pkg/compiler/lib/src/native/resolver.dart
+++ b/pkg/compiler/lib/src/native/resolver.dart
@@ -2,10 +2,13 @@
 // 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:front_end/src/fasta/scanner.dart' show StringToken, Token;
+import 'package:front_end/src/fasta/scanner.dart'
+    show BeginGroupToken, StringToken, Token;
+import 'package:front_end/src/fasta/scanner.dart' as Tokens show EOF_TOKEN;
 
 import '../common.dart';
 import '../common/backend_api.dart';
+import '../common/resolution.dart';
 import '../compiler.dart' show Compiler;
 import '../constants/values.dart';
 import '../elements/elements.dart'
@@ -17,8 +20,10 @@ import '../elements/elements.dart'
         MemberElement,
         MetadataAnnotation,
         MethodElement;
+import '../elements/entities.dart';
 import '../elements/modelx.dart' show FunctionElementX, MetadataAnnotationX;
 import '../elements/resolution_types.dart' show ResolutionDartType;
+import '../js_backend/backend_helpers.dart';
 import '../js_backend/js_backend.dart';
 import '../js_backend/native_data.dart';
 import '../patch_parser.dart';
@@ -378,3 +383,188 @@ class JsInteropAnnotationHandler implements EagerAnnotationHandler<bool> {
 
   bool get defaultResult => false;
 }
+
+/// Interface for computing all native classes in a set of libraries.
+abstract class NativeClassResolver {
+  Iterable<ClassEntity> computeNativeClasses(Iterable<LibraryEntity> libraries);
+}
+
+class NativeClassResolverImpl implements NativeClassResolver {
+  final DiagnosticReporter _reporter;
+  final Resolution _resolution;
+  final BackendHelpers _helpers;
+  final NativeBasicData _nativeBasicData;
+
+  Map<String, ClassElement> _tagOwner = new Map<String, ClassElement>();
+
+  NativeClassResolverImpl(
+      this._resolution, this._reporter, this._helpers, this._nativeBasicData);
+
+  Iterable<ClassElement> computeNativeClasses(
+      Iterable<LibraryElement> libraries) {
+    Set<ClassElement> nativeClasses = new Set<ClassElement>();
+    libraries.forEach((l) => _processNativeClassesInLibrary(l, nativeClasses));
+    if (_helpers.isolateHelperLibrary != null) {
+      _processNativeClassesInLibrary(
+          _helpers.isolateHelperLibrary, nativeClasses);
+    }
+    _processSubclassesOfNativeClasses(libraries, nativeClasses);
+    return nativeClasses;
+  }
+
+  void _processNativeClassesInLibrary(
+      LibraryElement library, Set<ClassElement> nativeClasses) {
+    // Use implementation to ensure the inclusion of injected members.
+    library.implementation.forEachLocalMember((Element element) {
+      if (element.isClass) {
+        ClassElement cls = element;
+        if (_nativeBasicData.isNativeClass(cls)) {
+          _processNativeClass(element, nativeClasses);
+        }
+      }
+    });
+  }
+
+  void _processNativeClass(
+      ClassElement classElement, Set<ClassElement> nativeClasses) {
+    nativeClasses.add(classElement);
+    // Resolve class to ensure the class has valid inheritance info.
+    classElement.ensureResolved(_resolution);
+    // Js Interop interfaces do not have tags.
+    if (_nativeBasicData.isJsInteropClass(classElement)) return;
+    // Since we map from dispatch tags to classes, a dispatch tag must be used
+    // on only one native class.
+    for (String tag in _nativeBasicData.getNativeTagsOfClass(classElement)) {
+      ClassElement owner = _tagOwner[tag];
+      if (owner != null) {
+        if (owner != classElement) {
+          _reporter.internalError(
+              classElement, "Tag '$tag' already in use by '${owner.name}'");
+        }
+      } else {
+        _tagOwner[tag] = classElement;
+      }
+    }
+  }
+
+  void _processSubclassesOfNativeClasses(
+      Iterable<LibraryElement> libraries, Set<ClassElement> nativeClasses) {
+    Set<ClassElement> nativeClassesAndSubclasses = new Set<ClassElement>();
+    // Collect potential subclasses, e.g.
+    //
+    //     class B extends foo.A {}
+    //
+    // String "A" has a potential subclass B.
+
+    var potentialExtends = new Map<String, Set<ClassElement>>();
+
+    libraries.forEach((library) {
+      library.implementation.forEachLocalMember((element) {
+        if (element.isClass) {
+          String extendsName = _findExtendsNameOfClass(element);
+          if (extendsName != null) {
+            Set<ClassElement> potentialSubclasses = potentialExtends
+                .putIfAbsent(extendsName, () => new Set<ClassElement>());
+            potentialSubclasses.add(element);
+          }
+        }
+      });
+    });
+
+    // Resolve all the native classes and any classes that might extend them in
+    // [potentialExtends], and then check that the properly resolved class is in
+    // fact a subclass of a native class.
+
+    ClassElement nativeSuperclassOf(ClassElement classElement) {
+      if (_nativeBasicData.isNativeClass(classElement)) return classElement;
+      if (classElement.superclass == null) return null;
+      return nativeSuperclassOf(classElement.superclass);
+    }
+
+    void walkPotentialSubclasses(ClassElement element) {
+      if (nativeClassesAndSubclasses.contains(element)) return;
+      element.ensureResolved(_resolution);
+      ClassElement nativeSuperclass = nativeSuperclassOf(element);
+      if (nativeSuperclass != null) {
+        nativeClassesAndSubclasses.add(element);
+        Set<ClassElement> potentialSubclasses = potentialExtends[element.name];
+        if (potentialSubclasses != null) {
+          potentialSubclasses.forEach(walkPotentialSubclasses);
+        }
+      }
+    }
+
+    nativeClasses.forEach(walkPotentialSubclasses);
+    nativeClasses.addAll(nativeClassesAndSubclasses);
+  }
+
+  /**
+   * Returns the source string of the class named in the extends clause, or
+   * `null` if there is no extends clause.
+   */
+  String _findExtendsNameOfClass(ClassElement classElement) {
+    if (classElement.isResolved) {
+      ClassElement superClass = classElement.superclass;
+      while (superClass != null) {
+        if (!superClass.isUnnamedMixinApplication) {
+          return superClass.name;
+        }
+        superClass = superClass.superclass;
+      }
+      return null;
+    }
+
+    //  "class B extends A ... {}"  --> "A"
+    //  "class B extends foo.A ... {}"  --> "A"
+    //  "class B<T> extends foo.A<T,T> with M1, M2 ... {}"  --> "A"
+
+    // We want to avoid calling classElement.parseNode on every class.  Doing so
+    // will slightly increase parse time and size and cause compiler errors and
+    // warnings to me emitted in more unused code.
+
+    // An alternative to this code is to extend the API of ClassElement to
+    // expose the name of the extended element.
+
+    // Pattern match the above cases in the token stream.
+    //  [abstract] class X extends [id.]* id
+
+    Token skipTypeParameters(Token token) {
+      BeginGroupToken beginGroupToken = token;
+      Token endToken = beginGroupToken.endGroup;
+      return endToken.next;
+      //for (;;) {
+      //  token = token.next;
+      //  if (token.stringValue == '>') return token.next;
+      //  if (token.stringValue == '<') return skipTypeParameters(token);
+      //}
+    }
+
+    String scanForExtendsName(Token token) {
+      if (token.stringValue == 'abstract') token = token.next;
+      if (token.stringValue != 'class') return null;
+      token = token.next;
+      if (!token.isIdentifier()) return null;
+      token = token.next;
+      //  class F<X extends B<X>> extends ...
+      if (token.stringValue == '<') {
+        token = skipTypeParameters(token);
+      }
+      if (token.stringValue != 'extends') return null;
+      token = token.next;
+      Token id = token;
+      while (token.kind != Tokens.EOF_TOKEN) {
+        token = token.next;
+        if (token.stringValue != '.') break;
+        token = token.next;
+        if (!token.isIdentifier()) return null;
+        id = token;
+      }
+      // Should be at '{', 'with', 'implements', '<' or 'native'.
+      return id.lexeme;
+    }
+
+    return _reporter.withCurrentElement(classElement, () {
+      return scanForExtendsName(classElement.position);
+    });
+  }
+}