Merge the work on Generic Types Reification from 'dart-lang/reify' repo

pkg/kernel/lib/transformations/reify/analysis/program_analysis.dart

+// Copyright (c) 2016, 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 kernel.transformation.reify.analysis.program_analysis;
+
+import '../asts.dart';
+import 'package:kernel/ast.dart';
+
+// TODO(karlklose): keep all predicates and derived information here and move
+// the actual data to a builder class.
+class ProgramKnowledge {
+  Map<Member, Set<TypeParameter>> _usedTypeVariables =
+      <Member, Set<TypeParameter>>{};
+
+  Map<Member, Set<DartType>> isTests = <Member, Set<DartType>>{};
+
+  Set<Class> _classTests;
+
+  /// Contains all classes that are used as the declaration of a type expression
+  /// in a type test.
+  Set<Class> get classTests {
+    if (_classTests == null) {
+      _classTests = isTests.values
+          .expand((set) => set)
+          .where((DartType type) => type is InterfaceType)
+          .map((DartType type) => (type as InterfaceType).classNode)
+          .toSet();
+    }
+    return _classTests;
+  }
+
+  recordTypeVariableUse(Expression expression, TypeParameter parameter) {
+    // TODO(karlklose): also record expression.
+    add(_usedTypeVariables, getEnclosingMember(expression), parameter);
+  }
+
+  Set<TypeParameter> usedParameters(Member member) {
+    return _usedTypeVariables[member] ?? new Set<TypeParameter>();
+  }
+
+  void recordIsTest(IsExpression node, DartType type) {
+    add(isTests, getEnclosingMember(node), type);
+  }
+
+  add(Map<dynamic, Set> map, key, value) {
+    map.putIfAbsent(key, () => new Set()).add(value);
+  }
+}
+
+typedef bool LibraryFilter(Library library);
+
+class ProgramAnalysis extends Visitor {
+  final ProgramKnowledge knowledge;
+  final LibraryFilter analyzeLibrary;
+
+  ProgramAnalysis(this.knowledge, this.analyzeLibrary);
+
+  defaultTreeNode(TreeNode node) => node.visitChildren(this);
+
+  visitLibrary(Library library) {
+    if (!analyzeLibrary(library)) {
+      return;
+    }
+    super.visitLibrary(library);
+  }
+
+  handleTypeReference(TreeNode node, DartType type) {
+    typeVariables(type).forEach((TypeParameter parameter) {
+      knowledge.recordTypeVariableUse(node, parameter);
+    });
+  }
+
+  handleInstantiation(InvocationExpression node) {
+    node.arguments.types.forEach((DartType type) {
+      handleTypeReference(node, type);
+    });
+  }
+
+  visitIsExpression(IsExpression node) {
+    knowledge.recordIsTest(node, node.type);
+    handleTypeReference(node, node.type);
+    node.visitChildren(this);
+  }
+
+  visitConstructorInvocation(ConstructorInvocation node) {
+    handleInstantiation(node);
+    node.visitChildren(this);
+  }
+
+  visitStaticInvocation(StaticInvocation node) {
+    if (node.target.kind == ProcedureKind.Factory) {
+      handleInstantiation(node);
+    }
+    node.visitChildren(this);
+  }
+}
+
+bool _analyzeAll(Library library) => true;
+
+ProgramKnowledge analyze(Program program,
+    {LibraryFilter analyzeLibrary: _analyzeAll}) {
+  ProgramKnowledge knowledge = new ProgramKnowledge();
+  program.accept(new ProgramAnalysis(knowledge, analyzeLibrary));
+  return knowledge;
+}