Merge kernel closure conversion into the Dart SDK

pkg/kernel/lib/transformations/closure/info.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.transformations.closure.info;
+
+import '../../ast.dart'
+    show
+        Class,
+        Constructor,
+        Field,
+        FunctionDeclaration,
+        FunctionNode,
+        Member,
+        Name,
+        Procedure,
+        ProcedureKind,
+        PropertyGet,
+        ThisExpression,
+        TypeParameter,
+        TypeParameterType,
+        VariableDeclaration,
+        VariableGet,
+        VariableSet;
+
+import '../../visitor.dart' show RecursiveVisitor;
+
+class ClosureInfo extends RecursiveVisitor {
+  FunctionNode currentFunction;
+  final Map<VariableDeclaration, FunctionNode> function =
+      <VariableDeclaration, FunctionNode>{};
+
+  final Set<VariableDeclaration> variables = new Set<VariableDeclaration>();
+
+  final Map<FunctionNode, Set<TypeParameter>> typeVariables =
+      <FunctionNode, Set<TypeParameter>>{};
+
+  /// Map from members to synthetic variables for accessing `this` in a local
+  /// function.
+  final Map<FunctionNode, VariableDeclaration> thisAccess =
+      <FunctionNode, VariableDeclaration>{};
+
+  final Set<String> currentMemberLocalNames = new Set<String>();
+
+  final Map<FunctionNode, String> localNames = <FunctionNode, String>{};
+
+  /// Contains all names used as getter through a [PropertyGet].
+  final Set<Name> invokedGetters = new Set<Name>();
+
+  /// Contains all names of declared regular instance methods (not including
+  /// accessors and operators).
+  final Set<Name> declaredInstanceMethodNames = new Set<Name>();
+
+  Class currentClass;
+
+  Member currentMember;
+
+  FunctionNode currentMemberFunction;
+
+  bool get isOuterMostContext {
+    return currentFunction == null || currentMemberFunction == currentFunction;
+  }
+
+  /// Maps the names of all instance methods that may be torn off (aka
+  /// implicitly closurized) to `${name.name}#get`.
+  Map<Name, Name> get tearOffGetterNames {
+    Map<Name, Name> result = <Name, Name>{};
+    for (Name name in declaredInstanceMethodNames) {
+      if (invokedGetters.contains(name)) {
+        result[name] = new Name("${name.name}#get", name.library);
+      }
+    }
+    return result;
+  }
+
+  void beginMember(Member member, [FunctionNode function]) {
+    currentMemberLocalNames.clear();
+    if (function != null) {
+      localNames[function] = computeUniqueLocalName(member.name.name);
+    }
+    currentMember = member;
+    currentMemberFunction = function;
+  }
+
+  void endMember() {
+    currentMember = null;
+    currentMemberFunction = null;
+  }
+
+  visitClass(Class node) {
+    currentClass = node;
+    super.visitClass(node);
+    currentClass = null;
+  }
+
+  visitConstructor(Constructor node) {
+    beginMember(node, node.function);
+    super.visitConstructor(node);
+    endMember();
+  }
+
+  visitProcedure(Procedure node) {
+    beginMember(node, node.function);
+    if (node.isInstanceMember && node.kind == ProcedureKind.Method) {
+      // Ignore the `length` method of [File] subclasses for now, as they
+      // will force us to rename the `length` getter (kernel issue #43).
+      // TODO(ahe): remove this condition.
+      Class parent = node.parent;
+      if (node.name.name != "length" ||
+          parent.enclosingLibrary.importUri.toString() != "dart:io") {
+        declaredInstanceMethodNames.add(node.name);
+      }
+    }
+    super.visitProcedure(node);
+    endMember();
+  }
+
+  visitField(Field node) {
+    beginMember(node);
+    super.visitField(node);
+    endMember();
+  }
+
+  String computeUniqueLocalName([String name]) {
+    if (name == null || name.isEmpty) {
+      name = "function";
+    }
+    if (currentFunction == null) {
+      if (currentMember != null) {
+        name = "${currentMember.name.name}#$name";
+      }
+      if (currentClass != null) {
+        name = "${currentClass.name}#$name";
+      }
+    } else {
+      name = "${localNames[currentFunction]}#$name";
+    }
+    int count = 1;
+    String candidate = name;
+    while (currentMemberLocalNames.contains(candidate)) {
+      candidate = "$name#${count++}";
+    }
+    currentMemberLocalNames.add(candidate);
+    return candidate;
+  }
+
+  visitFunctionDeclaration(FunctionDeclaration node) {
+    assert(!localNames.containsKey(node));
+    localNames[node.function] = computeUniqueLocalName(node.variable.name);
+    return super.visitFunctionDeclaration(node);
+  }
+
+  visitFunctionNode(FunctionNode node) {
+    localNames.putIfAbsent(node, computeUniqueLocalName);
+    var saved = currentFunction;
+    currentFunction = node;
+    node.visitChildren(this);
+    currentFunction = saved;
+    Set<TypeParameter> capturedTypeVariables = typeVariables[node];
+    if (capturedTypeVariables != null && !isOuterMostContext) {
+      // Propagate captured type variables to enclosing function.
+      typeVariables
+          .putIfAbsent(currentFunction, () => new Set<TypeParameter>())
+          .addAll(capturedTypeVariables);
+    }
+  }
+
+  visitVariableDeclaration(VariableDeclaration node) {
+    function[node] = currentFunction;
+    node.visitChildren(this);
+  }
+
+  visitVariableGet(VariableGet node) {
+    if (function[node.variable] != currentFunction) {
+      variables.add(node.variable);
+    }
+    node.visitChildren(this);
+  }
+
+  visitVariableSet(VariableSet node) {
+    if (function[node.variable] != currentFunction) {
+      variables.add(node.variable);
+    }
+    node.visitChildren(this);
+  }
+
+  visitTypeParameterType(TypeParameterType node) {
+    if (!isOuterMostContext) {
+      typeVariables
+          .putIfAbsent(currentFunction, () => new Set<TypeParameter>())
+          .add(node.parameter);
+    }
+  }
+
+  visitThisExpression(ThisExpression node) {
+    if (!isOuterMostContext) {
+      thisAccess.putIfAbsent(
+          currentMemberFunction, () => new VariableDeclaration("#self"));
+    }
+  }
+
+  visitPropertyGet(PropertyGet node) {
+    invokedGetters.add(node.name);
+    super.visitPropertyGet(node);
+  }
+}