pkg/compiler/lib/src/inferrer/map_tracer.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 compiler.src.inferrer.map_tracer;

import '../elements/entities.dart';
import '../js_backend/backend.dart' show JavaScriptBackend;
import '../universe/selector.dart' show Selector;
import 'node_tracer.dart';
import 'type_graph_nodes.dart';

Set<String> okMapSelectorsSet = new Set.from(const <String>[
  // From Object.
  "==",
  "hashCode",
  "toString",
  "noSuchMethod",
  "runtimeType",
  // From Map
  "[]",
  "isEmpty",
  "isNotEmpty",
  "keys",
  "length",
  "values",
  "clear",
  "containsKey",
  "containsValue",
  "forEach",
  "remove"
]);

class MapTracerVisitor extends TracerVisitor {
  // These lists are used to keep track of newly discovered assignments to
  // the map. Note that elements at corresponding indices are expected to
  // belong to the same assignment operation.
  List<TypeInformation> keyAssignments = <TypeInformation>[];
  List<TypeInformation> valueAssignments = <TypeInformation>[];
  // This list is used to keep track of assignments of entire maps to
  // this map.
  List<MapTypeInformation> mapAssignments = <MapTypeInformation>[];

  MapTracerVisitor(tracedType, inferrer) : super(tracedType, inferrer);

  /// Returns [true] if the analysis completed successfully, [false]
  /// if it bailed out. In the former case, [keyAssignments] and
  /// [valueAssignments] hold a list of [TypeInformation] nodes that
  /// flow into the key and value types of this map.
  bool run() {
    analyze();
    MapTypeInformation map = tracedType;
    if (continueAnalyzing) {
      map.addFlowsIntoTargets(flowsInto);
      return true;
    }
    keyAssignments = valueAssignments = mapAssignments = null;
    return false;
  }

  @override
  visitClosureCallSiteTypeInformation(ClosureCallSiteTypeInformation info) {
    bailout('Passed to a closure');
  }

  @override
  visitStaticCallSiteTypeInformation(StaticCallSiteTypeInformation info) {
    super.visitStaticCallSiteTypeInformation(info);
    MemberEntity called = info.calledElement;
    if (inferrer.closedWorld.commonElements.isForeign(called) &&
        called.name == JavaScriptBackend.JS) {
      bailout('Used in JS ${info.debugName}');
    }
  }

  @override
  visitDynamicCallSiteTypeInformation(DynamicCallSiteTypeInformation info) {
    super.visitDynamicCallSiteTypeInformation(info);
    Selector selector = info.selector;
    String selectorName = selector.name;
    if (currentUser == info.receiver) {
      if (!okMapSelectorsSet.contains(selectorName)) {
        if (selector.isCall) {
          if (selectorName == 'addAll') {
            // All keys and values from the argument flow into
            // the map.
            TypeInformation map = info.arguments.positional[0];
            if (map is MapTypeInformation) {
              inferrer.analyzeMapAndEnqueue(map);
              mapAssignments.add(map);
            } else {
              // If we could select a component from a [TypeInformation],
              // like the keytype or valuetype in this case, we could
              // propagate more here.
              // TODO(herhut): implement selection on [TypeInformation].
              bailout('Adding map with unknown typeinfo to current map');
            }
          } else if (selectorName == 'putIfAbsent') {
            // The first argument is a new key, the result type of
            // the second argument becomes a new value.
            // Unfortunately, the type information does not
            // explicitly track the return type, yet, so we have
            // to go to dynamic.
            // TODO(herhut,16507): Use return type of closure in
            // Map.putIfAbsent.
            keyAssignments.add(info.arguments.positional[0]);
            valueAssignments.add(inferrer.types.dynamicType);
          } else {
            // It would be nice to handle [Map.keys] and [Map.values], too.
            // However, currently those calls do not trigger the creation
            // of a [ListTypeInformation], so I have nowhere to propagate
            // that information.
            // TODO(herhut): add support for Map.keys and Map.values.
            bailout('Map used in a not-ok selector [$selectorName]');
            return;
          }
        } else if (selector.isIndexSet) {
          keyAssignments.add(info.arguments.positional[0]);
          valueAssignments.add(info.arguments.positional[1]);
        } else if (!selector.isIndex) {
          bailout('Map used in a not-ok selector [$selectorName]');
          return;
        }
      }
    } else if (selector.isCall &&
        (info.hasClosureCallTargets ||
            info.concreteTargets.any((element) => !element.isFunction))) {
      bailout('Passed to a closure');
      return;
    }
  }
}