Move constant implementation out of generated

pkg/analyzer/lib/src/dart/constant/value.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.
+
+/**
+ * The implementation of the class [DartObject].
+ */
+library analyzer.src.dart.constant.value;
+
+import 'dart:collection';
+
+import 'package:analyzer/dart/constant/value.dart';
+import 'package:analyzer/dart/element/element.dart';
+import 'package:analyzer/dart/element/type.dart';
+import 'package:analyzer/src/generated/error.dart';
+import 'package:analyzer/src/generated/java_core.dart';
+import 'package:analyzer/src/generated/resolver.dart' show TypeProvider;
+import 'package:analyzer/src/generated/utilities_general.dart';
+
+/**
+ * The state of an object representing a boolean value.
+ */
+class BoolState extends InstanceState {
+  /**
+   * An instance representing the boolean value 'false'.
+   */
+  static BoolState FALSE_STATE = new BoolState(false);
+
+  /**
+   * An instance representing the boolean value 'true'.
+   */
+  static BoolState TRUE_STATE = new BoolState(true);
+
+  /**
+   * A state that can be used to represent a boolean whose value is not known.
+   */
+  static BoolState UNKNOWN_VALUE = new BoolState(null);
+
+  /**
+   * The value of this instance.
+   */
+  final bool value;
+
+  /**
+   * Initialize a newly created state to represent the given [value].
+   */
+  BoolState(this.value);
+
+  @override
+  int get hashCode => value == null ? 0 : (value ? 2 : 3);
+
+  @override
+  bool get isBool => true;
+
+  @override
+  bool get isBoolNumStringOrNull => true;
+
+  @override
+  bool get isUnknown => value == null;
+
+  @override
+  String get typeName => "bool";
+
+  @override
+  bool operator ==(Object object) =>
+      object is BoolState && identical(value, object.value);
+
+  @override
+  BoolState convertToBool() => this;
+
+  @override
+  StringState convertToString() {
+    if (value == null) {
+      return StringState.UNKNOWN_VALUE;
+    }
+    return new StringState(value ? "true" : "false");
+  }
+
+  @override
+  BoolState equalEqual(InstanceState rightOperand) {
+    assertBoolNumStringOrNull(rightOperand);
+    return isIdentical(rightOperand);
+  }
+
+  @override
+  BoolState isIdentical(InstanceState rightOperand) {
+    if (value == null) {
+      return UNKNOWN_VALUE;
+    }
+    if (rightOperand is BoolState) {
+      bool rightValue = rightOperand.value;
+      if (rightValue == null) {
+        return UNKNOWN_VALUE;
+      }
+      return BoolState.from(identical(value, rightValue));
+    } else if (rightOperand is DynamicState) {
+      return UNKNOWN_VALUE;
+    }
+    return FALSE_STATE;
+  }
+
+  @override
+  BoolState logicalAnd(InstanceState rightOperand) {
+    assertBool(rightOperand);
+    if (value == null) {
+      return UNKNOWN_VALUE;
+    }
+    return value ? rightOperand.convertToBool() : FALSE_STATE;
+  }
+
+  @override
+  BoolState logicalNot() {
+    if (value == null) {
+      return UNKNOWN_VALUE;
+    }
+    return value ? FALSE_STATE : TRUE_STATE;
+  }
+
+  @override
+  BoolState logicalOr(InstanceState rightOperand) {
+    assertBool(rightOperand);
+    if (value == null) {
+      return UNKNOWN_VALUE;
+    }
+    return value ? TRUE_STATE : rightOperand.convertToBool();
+  }
+
+  @override
+  String toString() => value == null ? "-unknown-" : (value ? "true" : "false");
+
+  /**
+   * Return the boolean state representing the given boolean [value].
+   */
+  static BoolState from(bool value) =>
+      value ? BoolState.TRUE_STATE : BoolState.FALSE_STATE;
+}
+
+/**
+ * A representation of an instance of a Dart class.
+ */
+class DartObjectImpl implements DartObject {
+  /**
+   * An empty list of objects.
+   */
+  static const List<DartObjectImpl> EMPTY_LIST = const <DartObjectImpl>[];
+
+  /**
+   * The run-time type of this object.
+   */
+  @override
+  final ParameterizedType type;
+
+  /**
+   * The state of the object.
+   */
+  final InstanceState _state;
+
+  /**
+   * Initialize a newly created object to have the given [type] and [_state].
+   */
+  DartObjectImpl(this.type, this._state);
+
+  /**
+   * Create an object to represent an unknown value.
+   */
+  factory DartObjectImpl.validWithUnknownValue(InterfaceType type) {
+    if (type.element.library.isDartCore) {
+      String typeName = type.name;
+      if (typeName == "bool") {
+        return new DartObjectImpl(type, BoolState.UNKNOWN_VALUE);
+      } else if (typeName == "double") {
+        return new DartObjectImpl(type, DoubleState.UNKNOWN_VALUE);
+      } else if (typeName == "int") {
+        return new DartObjectImpl(type, IntState.UNKNOWN_VALUE);
+      } else if (typeName == "String") {
+        return new DartObjectImpl(type, StringState.UNKNOWN_VALUE);
+      }
+    }
+    return new DartObjectImpl(type, GenericState.UNKNOWN_VALUE);
+  }
+
+  HashMap<String, DartObjectImpl> get fields => _state.fields;
+
+  @override
+  int get hashCode => JenkinsSmiHash.hash2(type.hashCode, _state.hashCode);
+
+  @override
+  bool get hasKnownValue => !_state.isUnknown;
+
+  /**
+   * Return `true` if this object represents an object whose type is 'bool'.
+   */
+  bool get isBool => _state.isBool;
+
+  /**
+   * Return `true` if this object represents an object whose type is either
+   * 'bool', 'num', 'String', or 'Null'.
+   */
+  bool get isBoolNumStringOrNull => _state.isBoolNumStringOrNull;
+
+  @override
+  bool get isNull => _state is NullState;
+
+  /**
+   * Return `true` if this object represents an unknown value.
+   */
+  bool get isUnknown => _state.isUnknown;
+
+  /**
+   * Return `true` if this object represents an instance of a user-defined
+   * class.
+   */
+  bool get isUserDefinedObject => _state is GenericState;
+
+  @override
+  bool operator ==(Object object) {
+    if (object is! DartObjectImpl) {
+      return false;
+    }
+    DartObjectImpl dartObject = object as DartObjectImpl;
+    return type == dartObject.type && _state == dartObject._state;
+  }
+
+  /**
+   * Return the result of invoking the '+' operator on this object with the
+   * given [rightOperand]. The [typeProvider] is the type provider used to find
+   * known types.
+   *
+   * Throws an [EvaluationException] if the operator is not appropriate for an
+   * object of this kind.
+   */
+  DartObjectImpl add(TypeProvider typeProvider, DartObjectImpl rightOperand) {
+    InstanceState result = _state.add(rightOperand._state);
+    if (result is IntState) {
+      return new DartObjectImpl(typeProvider.intType, result);
+    } else if (result is DoubleState) {
+      return new DartObjectImpl(typeProvider.doubleType, result);
+    } else if (result is NumState) {
+      return new DartObjectImpl(typeProvider.numType, result);
+    } else if (result is StringState) {
+      return new DartObjectImpl(typeProvider.stringType, result);
+    }
+    // We should never get here.
+    throw new IllegalStateException("add returned a ${result.runtimeType}");
+  }
+
+  /**
+   * Return the result of invoking the '&' operator on this object with the
+   * [rightOperand]. The [typeProvider] is the type provider used to find known
+   * types.
+   *
+   * Throws an [EvaluationException] if the operator is not appropriate for an
+   * object of this kind.
+   */
+  DartObjectImpl bitAnd(
+          TypeProvider typeProvider, DartObjectImpl rightOperand) =>
+      new DartObjectImpl(
+          typeProvider.intType, _state.bitAnd(rightOperand._state));
+
+  /**
+   * Return the result of invoking the '~' operator on this object. The
+   * [typeProvider] is the type provider used to find known types.
+   *
+   * Throws an [EvaluationException] if the operator is not appropriate for an
+   * object of this kind.
+   */
+  DartObjectImpl bitNot(TypeProvider typeProvider) =>
+      new DartObjectImpl(typeProvider.intType, _state.bitNot());
+
+  /**
+   * Return the result of invoking the '|' operator on this object with the
+   * [rightOperand]. The [typeProvider] is the type provider used to find known
+   * types.
+   *
+   * Throws an [EvaluationException] if the operator is not appropriate for an
+   * object of this kind.
+   */
+  DartObjectImpl bitOr(
+          TypeProvider typeProvider, DartObjectImpl rightOperand) =>
+      new DartObjectImpl(
+          typeProvider.intType, _state.bitOr(rightOperand._state));
+
+  /**
+   * Return the result of invoking the '^' operator on this object with the
+   * [rightOperand]. The [typeProvider] is the type provider used to find known
+   * types.
+   *
+   * Throws an [EvaluationException] if the operator is not appropriate for an
+   * object of this kind.
+   */
+  DartObjectImpl bitXor(
+          TypeProvider typeProvider, DartObjectImpl rightOperand) =>
+      new DartObjectImpl(
+          typeProvider.intType, _state.bitXor(rightOperand._state));
+
+  /**
+   * Return the result of invoking the ' ' operator on this object with the
+   * [rightOperand]. The [typeProvider] is the type provider used to find known
+   * types.
+   *
+   * Throws an [EvaluationException] if the operator is not appropriate for an
+   * object of this kind.
+   */
+  DartObjectImpl concatenate(
+          TypeProvider typeProvider, DartObjectImpl rightOperand) =>
+      new DartObjectImpl(
+          typeProvider.stringType, _state.concatenate(rightOperand._state));
+
+  /**
+   * Return the result of applying boolean conversion to this object. The
+   * [typeProvider] is the type provider used to find known types.
+   *
+   * Throws an [EvaluationException] if the operator is not appropriate for an
+   * object of this kind.
+   */
+  DartObjectImpl convertToBool(TypeProvider typeProvider) {
+    InterfaceType boolType = typeProvider.boolType;
+    if (identical(type, boolType)) {
+      return this;
+    }
+    return new DartObjectImpl(boolType, _state.convertToBool());
+  }
+
+  /**
+   * Return the result of invoking the '/' operator on this object with the
+   * [rightOperand]. The [typeProvider] is the type provider used to find known
+   * types.
+   *
+   * Throws an [EvaluationException] if the operator is not appropriate for
+   * an object of this kind.
+   */
+  DartObjectImpl divide(
+      TypeProvider typeProvider, DartObjectImpl rightOperand) {
+    InstanceState result = _state.divide(rightOperand._state);
+    if (result is IntState) {
+      return new DartObjectImpl(typeProvider.intType, result);
+    } else if (result is DoubleState) {
+      return new DartObjectImpl(typeProvider.doubleType, result);
+    } else if (result is NumState) {
+      return new DartObjectImpl(typeProvider.numType, result);
+    }
+    // We should never get here.
+    throw new IllegalStateException("divide returned a ${result.runtimeType}");
+  }
+
+  /**
+   * Return the result of invoking the '==' operator on this object with the
+   * [rightOperand]. The [typeProvider] is the type provider used to find known
+   * types.
+   *
+   * Throws an [EvaluationException] if the operator is not appropriate for an
+   * object of this kind.
+   */
+  DartObjectImpl equalEqual(
+      TypeProvider typeProvider, DartObjectImpl rightOperand) {
+    if (type != rightOperand.type) {
+      String typeName = type.name;
+      if (!(typeName == "bool" ||
+          typeName == "double" ||
+          typeName == "int" ||
+          typeName == "num" ||
+          typeName == "String" ||
+          typeName == "Null" ||
+          type.isDynamic)) {
+        throw new EvaluationException(
+            CompileTimeErrorCode.CONST_EVAL_TYPE_BOOL_NUM_STRING);
+      }
+    }
+    return new DartObjectImpl(
+        typeProvider.boolType, _state.equalEqual(rightOperand._state));
+  }
+
+  @override
+  DartObject getField(String name) {
+    if (_state is GenericState) {
+      return (_state as GenericState).fields[name];
+    }
+    return null;
+  }
+
+  /**
+   * Return the result of invoking the '&gt;' operator on this object with the
+   * [rightOperand]. The [typeProvider] is the type provider used to find known
+   * types.
+   *
+   * Throws an [EvaluationException] if the operator is not appropriate for an
+   * object of this kind.
+   */
+  DartObjectImpl greaterThan(
+          TypeProvider typeProvider, DartObjectImpl rightOperand) =>
+      new DartObjectImpl(
+          typeProvider.boolType, _state.greaterThan(rightOperand._state));
+
+  /**
+   * Return the result of invoking the '&gt;=' operator on this object with the
+   * [rightOperand]. The [typeProvider] is the type provider used to find known
+   * types.
+   *
+   * Throws an [EvaluationException] if the operator is not appropriate for an
+   * object of this kind.
+   */
+  DartObjectImpl greaterThanOrEqual(
+          TypeProvider typeProvider, DartObjectImpl rightOperand) =>
+      new DartObjectImpl(typeProvider.boolType,
+          _state.greaterThanOrEqual(rightOperand._state));
+
+  /**
+   * Return the result of invoking the '~/' operator on this object with the
+   * [rightOperand]. The [typeProvider] is the type provider used to find known
+   * types.
+   *
+   * Throws an [EvaluationException] if the operator is not appropriate for an
+   * object of this kind.
+   */
+  DartObjectImpl integerDivide(
+          TypeProvider typeProvider, DartObjectImpl rightOperand) =>
+      new DartObjectImpl(
+          typeProvider.intType, _state.integerDivide(rightOperand._state));
+
+  /**
+   * Return the result of invoking the identical function on this object with
+   * the [rightOperand]. The [typeProvider] is the type provider used to find
+   * known types.
+   */
+  DartObjectImpl isIdentical(
+      TypeProvider typeProvider, DartObjectImpl rightOperand) {
+    return new DartObjectImpl(
+        typeProvider.boolType, _state.isIdentical(rightOperand._state));
+  }
+
+  /**
+   * Return the result of invoking the '&lt;' operator on this object with the
+   * [rightOperand]. The [typeProvider] is the type provider used to find known
+   * types.
+   *
+   * Throws an [EvaluationException] if the operator is not appropriate for an
+   * object of this kind.
+   */
+  DartObjectImpl lessThan(
+          TypeProvider typeProvider, DartObjectImpl rightOperand) =>
+      new DartObjectImpl(
+          typeProvider.boolType, _state.lessThan(rightOperand._state));
+
+  /**
+   * Return the result of invoking the '&lt;=' operator on this object with the
+   * [rightOperand]. The [typeProvider] is the type provider used to find known
+   * types.
+   *
+   * Throws an [EvaluationException] if the operator is not appropriate for an
+   * object of this kind.
+   */
+  DartObjectImpl lessThanOrEqual(
+          TypeProvider typeProvider, DartObjectImpl rightOperand) =>
+      new DartObjectImpl(
+          typeProvider.boolType, _state.lessThanOrEqual(rightOperand._state));
+
+  /**
+   * Return the result of invoking the '&&' operator on this object with the
+   * [rightOperand]. The [typeProvider] is the type provider used to find known
+   * types.
+   *
+   * Throws an [EvaluationException] if the operator is not appropriate for an
+   * object of this kind.
+   */
+  DartObjectImpl logicalAnd(
+          TypeProvider typeProvider, DartObjectImpl rightOperand) =>
+      new DartObjectImpl(
+          typeProvider.boolType, _state.logicalAnd(rightOperand._state));
+
+  /**
+   * Return the result of invoking the '!' operator on this object. The
+   * [typeProvider] is the type provider used to find known types.
+   *
+   * Throws an [EvaluationException] if the operator is not appropriate for an
+   * object of this kind.
+   */
+  DartObjectImpl logicalNot(TypeProvider typeProvider) =>
+      new DartObjectImpl(typeProvider.boolType, _state.logicalNot());
+
+  /**
+   * Return the result of invoking the '||' operator on this object with the
+   * [rightOperand]. The [typeProvider] is the type provider used to find known
+   * types.
+   *
+   * Throws an [EvaluationException] if the operator is not appropriate for an
+   * object of this kind.
+   */
+  DartObjectImpl logicalOr(
+          TypeProvider typeProvider, DartObjectImpl rightOperand) =>
+      new DartObjectImpl(
+          typeProvider.boolType, _state.logicalOr(rightOperand._state));
+
+  /**
+   * Return the result of invoking the '-' operator on this object with the
+   * [rightOperand]. The [typeProvider] is the type provider used to find known
+   * types.
+   *
+   * Throws an [EvaluationException] if the operator is not appropriate for an
+   * object of this kind.
+   */
+  DartObjectImpl minus(TypeProvider typeProvider, DartObjectImpl rightOperand) {
+    InstanceState result = _state.minus(rightOperand._state);
+    if (result is IntState) {
+      return new DartObjectImpl(typeProvider.intType, result);
+    } else if (result is DoubleState) {
+      return new DartObjectImpl(typeProvider.doubleType, result);
+    } else if (result is NumState) {
+      return new DartObjectImpl(typeProvider.numType, result);
+    }
+    // We should never get here.
+    throw new IllegalStateException("minus returned a ${result.runtimeType}");
+  }
+
+  /**
+   * Return the result of invoking the '-' operator on this object. The
+   * [typeProvider] is the type provider used to find known types.
+   *
+   * Throws an [EvaluationException] if the operator is not appropriate for an
+   * object of this kind.
+   */
+  DartObjectImpl negated(TypeProvider typeProvider) {
+    InstanceState result = _state.negated();
+    if (result is IntState) {
+      return new DartObjectImpl(typeProvider.intType, result);
+    } else if (result is DoubleState) {
+      return new DartObjectImpl(typeProvider.doubleType, result);
+    } else if (result is NumState) {
+      return new DartObjectImpl(typeProvider.numType, result);
+    }
+    // We should never get here.
+    throw new IllegalStateException("negated returned a ${result.runtimeType}");
+  }
+
+  /**
+   * Return the result of invoking the '!=' operator on this object with the
+   * [rightOperand]. The [typeProvider] is the type provider used to find known
+   * types.
+   *
+   * Throws an [EvaluationException] if the operator is not appropriate for an
+   * object of this kind.
+   */
+  DartObjectImpl notEqual(
+      TypeProvider typeProvider, DartObjectImpl rightOperand) {
+    if (type != rightOperand.type) {
+      String typeName = type.name;
+      if (typeName != "bool" &&
+          typeName != "double" &&
+          typeName != "int" &&
+          typeName != "num" &&
+          typeName != "String") {
+        return new DartObjectImpl(typeProvider.boolType, BoolState.TRUE_STATE);
+      }
+    }
+    return new DartObjectImpl(typeProvider.boolType,
+        _state.equalEqual(rightOperand._state).logicalNot());
+  }
+
+  /**
+   * Return the result of converting this object to a 'String'. The
+   * [typeProvider] is the type provider used to find known types.
+   *
+   * Throws an [EvaluationException] if the object cannot be converted to a
+   * 'String'.
+   */
+  DartObjectImpl performToString(TypeProvider typeProvider) {
+    InterfaceType stringType = typeProvider.stringType;
+    if (identical(type, stringType)) {
+      return this;
+    }
+    return new DartObjectImpl(stringType, _state.convertToString());
+  }
+
+  /**
+   * Return the result of invoking the '%' operator on this object with the
+   * [rightOperand]. The [typeProvider] is the type provider used to find known
+   * types.
+   *
+   * Throws an [EvaluationException] if the operator is not appropriate for an
+   * object of this kind.
+   */
+  DartObjectImpl remainder(
+      TypeProvider typeProvider, DartObjectImpl rightOperand) {
+    InstanceState result = _state.remainder(rightOperand._state);
+    if (result is IntState) {
+      return new DartObjectImpl(typeProvider.intType, result);
+    } else if (result is DoubleState) {
+      return new DartObjectImpl(typeProvider.doubleType, result);
+    } else if (result is NumState) {
+      return new DartObjectImpl(typeProvider.numType, result);
+    }
+    // We should never get here.
+    throw new IllegalStateException(
+        "remainder returned a ${result.runtimeType}");
+  }
+
+  /**
+   * Return the result of invoking the '&lt;&lt;' operator on this object with
+   * the [rightOperand]. The [typeProvider] is the type provider used to find
+   * known types.
+   *
+   * Throws an [EvaluationException] if the operator is not appropriate for an
+   * object of this kind.
+   */
+  DartObjectImpl shiftLeft(
+          TypeProvider typeProvider, DartObjectImpl rightOperand) =>
+      new DartObjectImpl(
+          typeProvider.intType, _state.shiftLeft(rightOperand._state));
+
+  /**
+   * Return the result of invoking the '&gt;&gt;' operator on this object with
+   * the [rightOperand]. The [typeProvider] is the type provider used to find
+   * known types.
+   *
+   * Throws an [EvaluationException] if the operator is not appropriate for an
+   * object of this kind.
+   */
+  DartObjectImpl shiftRight(
+          TypeProvider typeProvider, DartObjectImpl rightOperand) =>
+      new DartObjectImpl(
+          typeProvider.intType, _state.shiftRight(rightOperand._state));
+
+  /**
+   * Return the result of invoking the 'length' getter on this object. The
+   * [typeProvider] is the type provider used to find known types.
+   *
+   * Throws an [EvaluationException] if the operator is not appropriate for an
+   * object of this kind.
+   */
+  DartObjectImpl stringLength(TypeProvider typeProvider) =>
+      new DartObjectImpl(typeProvider.intType, _state.stringLength());
+
+  /**
+   * Return the result of invoking the '*' operator on this object with the
+   * [rightOperand]. The [typeProvider] is the type provider used to find known
+   * types.
+   *
+   * Throws an [EvaluationException] if the operator is not appropriate for an
+   * object of this kind.
+   */
+  DartObjectImpl times(TypeProvider typeProvider, DartObjectImpl rightOperand) {
+    InstanceState result = _state.times(rightOperand._state);
+    if (result is IntState) {
+      return new DartObjectImpl(typeProvider.intType, result);
+    } else if (result is DoubleState) {
+      return new DartObjectImpl(typeProvider.doubleType, result);
+    } else if (result is NumState) {
+      return new DartObjectImpl(typeProvider.numType, result);
+    }
+    // We should never get here.
+    throw new IllegalStateException("times returned a ${result.runtimeType}");
+  }
+
+  @override
+  bool toBoolValue() {
+    if (_state is BoolState) {
+      return (_state as BoolState).value;
+    }
+    return null;
+  }
+
+  @override
+  double toDoubleValue() {
+    if (_state is DoubleState) {
+      return (_state as DoubleState).value;
+    }
+    return null;
+  }
+
+  @override
+  int toIntValue() {
+    if (_state is IntState) {
+      return (_state as IntState).value;
+    }
+    return null;
+  }
+
+  @override
+  List<DartObject> toListValue() {
+    if (_state is ListState) {
+      return (_state as ListState)._elements;
+    }
+    return null;
+  }
+
+  @override
+  Map<DartObject, DartObject> toMapValue() {
+    if (_state is MapState) {
+      return (_state as MapState)._entries;
+    }
+    return null;
+  }
+
+  @override
+  String toString() => "${type.displayName} ($_state)";
+
+  @override
+  String toStringValue() {
+    if (_state is StringState) {
+      return (_state as StringState).value;
+    }
+    return null;
+  }
+
+  @override
+  String toSymbolValue() {
+    if (_state is SymbolState) {
+      return (_state as SymbolState).value;
+    }
+    return null;
+  }
+
+  @override
+  DartType toTypeValue() {
+    if (_state is TypeState) {
+      Element element = (_state as TypeState)._element;
+      if (element is TypeDefiningElement) {
+        return element.type;
+      }
+    }
+    return null;
+  }
+}
+
+/**
+ * The state of an object representing a double.
+ */
+class DoubleState extends NumState {
+  /**
+   * A state that can be used to represent a double whose value is not known.
+   */
+  static DoubleState UNKNOWN_VALUE = new DoubleState(null);
+
+  /**
+   * The value of this instance.
+   */
+  final double value;
+
+  /**
+   * Initialize a newly created state to represent a double with the given
+   * [value].
+   */
+  DoubleState(this.value);
+
+  @override
+  int get hashCode => value == null ? 0 : value.hashCode;
+
+  @override
+  bool get isBoolNumStringOrNull => true;
+
+  @override
+  bool get isUnknown => value == null;
+
+  @override
+  String get typeName => "double";
+
+  @override
+  bool operator ==(Object object) =>
+      object is DoubleState && (value == object.value);
+
+  @override
+  NumState add(InstanceState rightOperand) {
+    assertNumOrNull(rightOperand);
+    if (value == null) {
+      return UNKNOWN_VALUE;
+    }
+    if (rightOperand is IntState) {
+      int rightValue = rightOperand.value;
+      if (rightValue == null) {
+        return UNKNOWN_VALUE;
+      }
+      return new DoubleState(value + rightValue.toDouble());
+    } else if (rightOperand is DoubleState) {
+      double rightValue = rightOperand.value;
+      if (rightValue == null) {
+        return UNKNOWN_VALUE;
+      }
+      return new DoubleState(value + rightValue);
+    } else if (rightOperand is DynamicState || rightOperand is NumState) {
+      return UNKNOWN_VALUE;
+    }
+    throw new EvaluationException(
+        CompileTimeErrorCode.CONST_EVAL_THROWS_EXCEPTION);
+  }
+
+  @override
+  StringState convertToString() {
+    if (value == null) {
+      return StringState.UNKNOWN_VALUE;
+    }
+    return new StringState(value.toString());
+  }
+
+  @override
+  NumState divide(InstanceState rightOperand) {
+    assertNumOrNull(rightOperand);
+    if (value == null) {
+      return UNKNOWN_VALUE;
+    }
+    if (rightOperand is IntState) {
+      int rightValue = rightOperand.value;
+      if (rightValue == null) {
+        return UNKNOWN_VALUE;
+      }
+      return new DoubleState(value / rightValue.toDouble());
+    } else if (rightOperand is DoubleState) {
+      double rightValue = rightOperand.value;
+      if (rightValue == null) {
+        return UNKNOWN_VALUE;
+      }
+      return new DoubleState(value / rightValue);
+    } else if (rightOperand is DynamicState || rightOperand is NumState) {
+      return UNKNOWN_VALUE;
+    }
+    throw new EvaluationException(
+        CompileTimeErrorCode.CONST_EVAL_THROWS_EXCEPTION);
+  }
+
+  @override
+  BoolState equalEqual(InstanceState rightOperand) {
+    assertBoolNumStringOrNull(rightOperand);
+    return isIdentical(rightOperand);
+  }
+
+  @override
+  BoolState greaterThan(InstanceState rightOperand) {
+    assertNumOrNull(rightOperand);
+    if (value == null) {
+      return BoolState.UNKNOWN_VALUE;
+    }
+    if (rightOperand is IntState) {
+      int rightValue = rightOperand.value;
+      if (rightValue == null) {
+        return BoolState.UNKNOWN_VALUE;
+      }
+      return BoolState.from(value > rightValue.toDouble());
+    } else if (rightOperand is DoubleState) {
+      double rightValue = rightOperand.value;
+      if (rightValue == null) {
+        return BoolState.UNKNOWN_VALUE;
+      }
+      return BoolState.from(value > rightValue);
+    } else if (rightOperand is DynamicState || rightOperand is NumState) {
+      return BoolState.UNKNOWN_VALUE;
+    }
+    throw new EvaluationException(
+        CompileTimeErrorCode.CONST_EVAL_THROWS_EXCEPTION);
+  }
+
+  @override
+  BoolState greaterThanOrEqual(InstanceState rightOperand) {
+    assertNumOrNull(rightOperand);
+    if (value == null) {
+      return BoolState.UNKNOWN_VALUE;
+    }
+    if (rightOperand is IntState) {
+      int rightValue = rightOperand.value;
+      if (rightValue == null) {
+        return BoolState.UNKNOWN_VALUE;
+      }
+      return BoolState.from(value >= rightValue.toDouble());
+    } else if (rightOperand is DoubleState) {
+      double rightValue = rightOperand.value;
+      if (rightValue == null) {
+        return BoolState.UNKNOWN_VALUE;
+      }
+      return BoolState.from(value >= rightValue);
+    } else if (rightOperand is DynamicState || rightOperand is NumState) {
+      return BoolState.UNKNOWN_VALUE;
+    }
+    throw new EvaluationException(
+        CompileTimeErrorCode.CONST_EVAL_THROWS_EXCEPTION);
+  }
+
+  @override
+  IntState integerDivide(InstanceState rightOperand) {
+    assertNumOrNull(rightOperand);
+    if (value == null) {
+      return IntState.UNKNOWN_VALUE;
+    }
+    if (rightOperand is IntState) {
+      int rightValue = rightOperand.value;
+      if (rightValue == null) {
+        return IntState.UNKNOWN_VALUE;
+      }
+      double result = value / rightValue.toDouble();
+      return new IntState(result.toInt());
+    } else if (rightOperand is DoubleState) {
+      double rightValue = rightOperand.value;
+      if (rightValue == null) {
+        return IntState.UNKNOWN_VALUE;
+      }
+      double result = value / rightValue;
+      return new IntState(result.toInt());
+    } else if (rightOperand is DynamicState || rightOperand is NumState) {
+      return IntState.UNKNOWN_VALUE;
+    }
+    throw new EvaluationException(
+        CompileTimeErrorCode.CONST_EVAL_THROWS_EXCEPTION);
+  }
+
+  @override
+  BoolState isIdentical(InstanceState rightOperand) {
+    if (value == null) {
+      return BoolState.UNKNOWN_VALUE;
+    }
+    if (rightOperand is DoubleState) {
+      double rightValue = rightOperand.value;
+      if (rightValue == null) {
+        return BoolState.UNKNOWN_VALUE;
+      }
+      return BoolState.from(value == rightValue);
+    } else if (rightOperand is IntState) {
+      int rightValue = rightOperand.value;
+      if (rightValue == null) {
+        return BoolState.UNKNOWN_VALUE;
+      }
+      return BoolState.from(value == rightValue.toDouble());
+    } else if (rightOperand is DynamicState || rightOperand is NumState) {
+      return BoolState.UNKNOWN_VALUE;
+    }
+    return BoolState.FALSE_STATE;
+  }
+
+  @override
+  BoolState lessThan(InstanceState rightOperand) {
+    assertNumOrNull(rightOperand);
+    if (value == null) {
+      return BoolState.UNKNOWN_VALUE;
+    }
+    if (rightOperand is IntState) {
+      int rightValue = rightOperand.value;
+      if (rightValue == null) {
+        return BoolState.UNKNOWN_VALUE;
+      }
+      return BoolState.from(value < rightValue.toDouble());
+    } else if (rightOperand is DoubleState) {
+      double rightValue = rightOperand.value;
+      if (rightValue == null) {
+        return BoolState.UNKNOWN_VALUE;
+      }
+      return BoolState.from(value < rightValue);
+    } else if (rightOperand is DynamicState || rightOperand is NumState) {
+      return BoolState.UNKNOWN_VALUE;
+    }
+    throw new EvaluationException(
+        CompileTimeErrorCode.CONST_EVAL_THROWS_EXCEPTION);
+  }
+
+  @override
+  BoolState lessThanOrEqual(InstanceState rightOperand) {
+    assertNumOrNull(rightOperand);
+    if (value == null) {
+      return BoolState.UNKNOWN_VALUE;
+    }
+    if (rightOperand is IntState) {
+      int rightValue = rightOperand.value;
+      if (rightValue == null) {
+        return BoolState.UNKNOWN_VALUE;
+      }
+      return BoolState.from(value <= rightValue.toDouble());
+    } else if (rightOperand is DoubleState) {
+      double rightValue = rightOperand.value;
+      if (rightValue == null) {
+        return BoolState.UNKNOWN_VALUE;
+      }
+      return BoolState.from(value <= rightValue);
+    } else if (rightOperand is DynamicState || rightOperand is NumState) {
+      return BoolState.UNKNOWN_VALUE;
+    }
+    throw new EvaluationException(
+        CompileTimeErrorCode.CONST_EVAL_THROWS_EXCEPTION);
+  }
+
+  @override
+  NumState minus(InstanceState rightOperand) {
+    assertNumOrNull(rightOperand);
+    if (value == null) {
+      return UNKNOWN_VALUE;
+    }
+    if (rightOperand is IntState) {
+      int rightValue = rightOperand.value;
+      if (rightValue == null) {
+        return UNKNOWN_VALUE;
+      }
+      return new DoubleState(value - rightValue.toDouble());
+    } else if (rightOperand is DoubleState) {
+      double rightValue = rightOperand.value;
+      if (rightValue == null) {
+        return UNKNOWN_VALUE;
+      }
+      return new DoubleState(value - rightValue);
+    } else if (rightOperand is DynamicState || rightOperand is NumState) {
+      return UNKNOWN_VALUE;
+    }
+    throw new EvaluationException(
+        CompileTimeErrorCode.CONST_EVAL_THROWS_EXCEPTION);
+  }
+
+  @override
+  NumState negated() {
+    if (value == null) {
+      return UNKNOWN_VALUE;
+    }
+    return new DoubleState(-(value));
+  }
+
+  @override
+  NumState remainder(InstanceState rightOperand) {
+    assertNumOrNull(rightOperand);
+    if (value == null) {
+      return UNKNOWN_VALUE;
+    }
+    if (rightOperand is IntState) {
+      int rightValue = rightOperand.value;
+      if (rightValue == null) {
+        return UNKNOWN_VALUE;
+      }
+      return new DoubleState(value % rightValue.toDouble());
+    } else if (rightOperand is DoubleState) {
+      double rightValue = rightOperand.value;
+      if (rightValue == null) {
+        return UNKNOWN_VALUE;
+      }
+      return new DoubleState(value % rightValue);
+    } else if (rightOperand is DynamicState || rightOperand is NumState) {
+      return UNKNOWN_VALUE;
+    }
+    throw new EvaluationException(
+        CompileTimeErrorCode.CONST_EVAL_THROWS_EXCEPTION);
+  }
+
+  @override
+  NumState times(InstanceState rightOperand) {
+    assertNumOrNull(rightOperand);
+    if (value == null) {
+      return UNKNOWN_VALUE;
+    }
+    if (rightOperand is IntState) {
+      int rightValue = rightOperand.value;
+      if (rightValue == null) {
+        return UNKNOWN_VALUE;
+      }
+      return new DoubleState(value * rightValue.toDouble());
+    } else if (rightOperand is DoubleState) {
+      double rightValue = rightOperand.value;
+      if (rightValue == null) {
+        return UNKNOWN_VALUE;
+      }
+      return new DoubleState(value * rightValue);
+    } else if (rightOperand is DynamicState || rightOperand is NumState) {
+      return UNKNOWN_VALUE;
+    }
+    throw new EvaluationException(
+        CompileTimeErrorCode.CONST_EVAL_THROWS_EXCEPTION);
+  }
+
+  @override
+  String toString() => value == null ? "-unknown-" : value.toString();
+}
+
+/**
+ * The state of an object representing a Dart object for which there is no type
+ * information.
+ */
+class DynamicState extends InstanceState {
+  /**
+   * The unique instance of this class.
+   */
+  static DynamicState DYNAMIC_STATE = new DynamicState();
+
+  @override
+  bool get isBool => true;
+
+  @override
+  bool get isBoolNumStringOrNull => true;
+
+  @override
+  String get typeName => "dynamic";
+
+  @override
+  NumState add(InstanceState rightOperand) {
+    assertNumOrNull(rightOperand);
+    return _unknownNum(rightOperand);
+  }
+
+  @override
+  IntState bitAnd(InstanceState rightOperand) {
+    assertIntOrNull(rightOperand);
+    return IntState.UNKNOWN_VALUE;
+  }
+
+  @override
+  IntState bitNot() => IntState.UNKNOWN_VALUE;
+
+  @override
+  IntState bitOr(InstanceState rightOperand) {
+    assertIntOrNull(rightOperand);
+    return IntState.UNKNOWN_VALUE;
+  }
+
+  @override
+  IntState bitXor(InstanceState rightOperand) {
+    assertIntOrNull(rightOperand);
+    return IntState.UNKNOWN_VALUE;
+  }
+
+  @override
+  StringState concatenate(InstanceState rightOperand) {
+    assertString(rightOperand);
+    return StringState.UNKNOWN_VALUE;
+  }
+
+  @override
+  BoolState convertToBool() => BoolState.UNKNOWN_VALUE;
+
+  @override
+  StringState convertToString() => StringState.UNKNOWN_VALUE;
+
+  @override
+  NumState divide(InstanceState rightOperand) {
+    assertNumOrNull(rightOperand);
+    return _unknownNum(rightOperand);
+  }
+
+  @override
+  BoolState equalEqual(InstanceState rightOperand) {
+    assertBoolNumStringOrNull(rightOperand);
+    return BoolState.UNKNOWN_VALUE;
+  }
+
+  @override
+  BoolState greaterThan(InstanceState rightOperand) {
+    assertNumOrNull(rightOperand);
+    return BoolState.UNKNOWN_VALUE;
+  }
+
+  @override
+  BoolState greaterThanOrEqual(InstanceState rightOperand) {
+    assertNumOrNull(rightOperand);
+    return BoolState.UNKNOWN_VALUE;
+  }
+
+  @override
+  IntState integerDivide(InstanceState rightOperand) {
+    assertNumOrNull(rightOperand);
+    return IntState.UNKNOWN_VALUE;
+  }
+
+  @override
+  BoolState isIdentical(InstanceState rightOperand) {
+    return BoolState.UNKNOWN_VALUE;
+  }
+
+  @override
+  BoolState lessThan(InstanceState rightOperand) {
+    assertNumOrNull(rightOperand);
+    return BoolState.UNKNOWN_VALUE;
+  }
+
+  @override
+  BoolState lessThanOrEqual(InstanceState rightOperand) {
+    assertNumOrNull(rightOperand);
+    return BoolState.UNKNOWN_VALUE;
+  }
+
+  @override
+  BoolState logicalAnd(InstanceState rightOperand) {
+    assertBool(rightOperand);
+    return BoolState.UNKNOWN_VALUE;
+  }
+
+  @override
+  BoolState logicalNot() => BoolState.UNKNOWN_VALUE;
+
+  @override
+  BoolState logicalOr(InstanceState rightOperand) {
+    assertBool(rightOperand);
+    return rightOperand.convertToBool();
+  }
+
+  @override
+  NumState minus(InstanceState rightOperand) {
+    assertNumOrNull(rightOperand);
+    return _unknownNum(rightOperand);
+  }
+
+  @override
+  NumState negated() => NumState.UNKNOWN_VALUE;
+
+  @override
+  NumState remainder(InstanceState rightOperand) {
+    assertNumOrNull(rightOperand);
+    return _unknownNum(rightOperand);
+  }
+
+  @override
+  IntState shiftLeft(InstanceState rightOperand) {
+    assertIntOrNull(rightOperand);
+    return IntState.UNKNOWN_VALUE;
+  }
+
+  @override
+  IntState shiftRight(InstanceState rightOperand) {
+    assertIntOrNull(rightOperand);
+    return IntState.UNKNOWN_VALUE;
+  }
+
+  @override
+  NumState times(InstanceState rightOperand) {
+    assertNumOrNull(rightOperand);
+    return _unknownNum(rightOperand);
+  }
+
+  /**
+   * Return an object representing an unknown numeric value whose type is based
+   * on the type of the [rightOperand].
+   */
+  NumState _unknownNum(InstanceState rightOperand) {
+    if (rightOperand is IntState) {
+      return IntState.UNKNOWN_VALUE;
+    } else if (rightOperand is DoubleState) {
+      return DoubleState.UNKNOWN_VALUE;
+    }
+    return NumState.UNKNOWN_VALUE;
+  }
+}
+
+/**
+ * A run-time exception that would be thrown during the evaluation of Dart code.
+ */
+class EvaluationException extends JavaException {
+  /**
+   * The error code associated with the exception.
+   */
+  final ErrorCode errorCode;
+
+  /**
+   * Initialize a newly created exception to have the given [errorCode].
+   */
+  EvaluationException(this.errorCode);
+}
+
+/**
+ * The state of an object representing a function.
+ */
+class FunctionState extends InstanceState {
+  /**
+   * The element representing the function being modeled.
+   */
+  final ExecutableElement _element;
+
+  /**
+   * Initialize a newly created state to represent the function with the given
+   * [element].
+   */
+  FunctionState(this._element);
+
+  @override
+  int get hashCode => _element == null ? 0 : _element.hashCode;
+
+  @override
+  String get typeName => "Function";
+
+  @override
+  bool operator ==(Object object) =>
+      object is FunctionState && (_element == object._element);
+
+  @override
+  StringState convertToString() {
+    if (_element == null) {
+      return StringState.UNKNOWN_VALUE;
+    }
+    return new StringState(_element.name);
+  }
+
+  @override
+  BoolState equalEqual(InstanceState rightOperand) {
+    return isIdentical(rightOperand);
+  }
+
+  @override
+  BoolState isIdentical(InstanceState rightOperand) {
+    if (_element == null) {
+      return BoolState.UNKNOWN_VALUE;
+    }
+    if (rightOperand is FunctionState) {
+      ExecutableElement rightElement = rightOperand._element;
+      if (rightElement == null) {
+        return BoolState.UNKNOWN_VALUE;
+      }
+      return BoolState.from(_element == rightElement);
+    } else if (rightOperand is DynamicState) {
+      return BoolState.UNKNOWN_VALUE;
+    }
+    return BoolState.FALSE_STATE;
+  }
+
+  @override
+  String toString() => _element == null ? "-unknown-" : _element.name;
+}
+
+/**
+ * The state of an object representing a Dart object for which there is no more
+ * specific state.
+ */
+class GenericState extends InstanceState {
+  /**
+   * Pseudo-field that we use to represent fields in the superclass.
+   */
+  static String SUPERCLASS_FIELD = "(super)";
+
+  /**
+   * A state that can be used to represent an object whose state is not known.
+   */
+  static GenericState UNKNOWN_VALUE =
+      new GenericState(new HashMap<String, DartObjectImpl>());
+
+  /**
+   * The values of the fields of this instance.
+   */
+  final HashMap<String, DartObjectImpl> _fieldMap;
+
+  /**
+   * Initialize a newly created state to represent a newly created object. The
+   * [fieldMap] contains the values of the fields of the instance.
+   */
+  GenericState(this._fieldMap);
+
+  @override
+  HashMap<String, DartObjectImpl> get fields => _fieldMap;
+
+  @override
+  int get hashCode {
+    int hashCode = 0;
+    for (DartObjectImpl value in _fieldMap.values) {
+      hashCode += value.hashCode;
+    }
+    return hashCode;
+  }
+
+  @override
+  bool get isUnknown => identical(this, UNKNOWN_VALUE);
+
+  @override
+  String get typeName => "user defined type";
+
+  @override
+  bool operator ==(Object object) {
+    if (object is! GenericState) {
+      return false;
+    }
+    GenericState state = object as GenericState;
+    HashSet<String> otherFields =
+        new HashSet<String>.from(state._fieldMap.keys.toSet());
+    for (String fieldName in _fieldMap.keys.toSet()) {
+      if (_fieldMap[fieldName] != state._fieldMap[fieldName]) {
+        return false;
+      }
+      otherFields.remove(fieldName);
+    }
+    for (String fieldName in otherFields) {
+      if (state._fieldMap[fieldName] != _fieldMap[fieldName]) {
+        return false;
+      }
+    }
+    return true;
+  }
+
+  @override
+  StringState convertToString() => StringState.UNKNOWN_VALUE;
+
+  @override
+  BoolState equalEqual(InstanceState rightOperand) {
+    assertBoolNumStringOrNull(rightOperand);
+    return isIdentical(rightOperand);
+  }
+
+  @override
+  BoolState isIdentical(InstanceState rightOperand) {
+    if (rightOperand is DynamicState) {
+      return BoolState.UNKNOWN_VALUE;
+    }
+    return BoolState.from(this == rightOperand);
+  }
+
+  @override
+  String toString() {
+    StringBuffer buffer = new StringBuffer();
+    List<String> fieldNames = _fieldMap.keys.toList();
+    fieldNames.sort();
+    bool first = true;
+    for (String fieldName in fieldNames) {
+      if (first) {
+        first = false;
+      } else {
+        buffer.write('; ');
+      }
+      buffer.write(fieldName);
+      buffer.write(' = ');
+      buffer.write(_fieldMap[fieldName]);
+    }
+    return buffer.toString();
+  }
+}
+
+/**
+ * The state of an object representing a Dart object.
+ */
+abstract class InstanceState {
+  /**
+   * If this represents a generic dart object, return a map from its field names
+   * to their values. Otherwise return null.
+   */
+  HashMap<String, DartObjectImpl> get fields => null;
+
+  /**
+   * Return `true` if this object represents an object whose type is 'bool'.
+   */
+  bool get isBool => false;
+
+  /**
+   * Return `true` if this object represents an object whose type is either
+   * 'bool', 'num', 'String', or 'Null'.
+   */
+  bool get isBoolNumStringOrNull => false;
+
+  /**
+   * Return `true` if this object represents an unknown value.
+   */
+  bool get isUnknown => false;
+
+  /**
+   * Return the name of the type of this value.
+   */
+  String get typeName;
+
+  /**
+   * Return the result of invoking the '+' operator on this object with the
+   * [rightOperand].
+   *
+   * Throws an [EvaluationException] if the operator is not appropriate for an
+   * object of this kind.
+   */
+  InstanceState add(InstanceState rightOperand) {
+    if (this is StringState && rightOperand is StringState) {
+      return concatenate(rightOperand);
+    }
+    assertNumOrNull(this);
+    assertNumOrNull(rightOperand);
+    throw new EvaluationException(CompileTimeErrorCode.INVALID_CONSTANT);
+  }
+
+  /**
+   * Throw an exception if the given [state] does not represent a boolean value.
+   */
+  void assertBool(InstanceState state) {
+    if (!(state is BoolState || state is DynamicState)) {
+      throw new EvaluationException(CompileTimeErrorCode.CONST_EVAL_TYPE_BOOL);
+    }
+  }
+
+  /**
+   * Throw an exception if the given [state] does not represent a boolean,
+   * numeric, string or null value.
+   */
+  void assertBoolNumStringOrNull(InstanceState state) {
+    if (!(state is BoolState ||
+        state is DoubleState ||
+        state is IntState ||
+        state is NumState ||
+        state is StringState ||
+        state is NullState ||
+        state is DynamicState)) {
+      throw new EvaluationException(
+          CompileTimeErrorCode.CONST_EVAL_TYPE_BOOL_NUM_STRING);
+    }
+  }
+
+  /**
+   * Throw an exception if the given [state] does not represent an integer or
+   * null value.
+   */
+  void assertIntOrNull(InstanceState state) {
+    if (!(state is IntState ||
+        state is NumState ||
+        state is NullState ||
+        state is DynamicState)) {
+      throw new EvaluationException(CompileTimeErrorCode.CONST_EVAL_TYPE_INT);
+    }
+  }
+
+  /**
+   * Throw an exception if the given [state] does not represent a boolean,
+   * numeric, string or null value.
+   */
+  void assertNumOrNull(InstanceState state) {
+    if (!(state is DoubleState ||
+        state is IntState ||
+        state is NumState ||
+        state is NullState ||
+        state is DynamicState)) {
+      throw new EvaluationException(CompileTimeErrorCode.CONST_EVAL_TYPE_NUM);
+    }
+  }
+
+  /**
+   * Throw an exception if the given [state] does not represent a String value.
+   */
+  void assertString(InstanceState state) {
+    if (!(state is StringState || state is DynamicState)) {
+      throw new EvaluationException(CompileTimeErrorCode.CONST_EVAL_TYPE_BOOL);
+    }
+  }
+
+  /**
+   * Return the result of invoking the '&' operator on this object with the
+   * [rightOperand].
+   *
+   * Throws an [EvaluationException] if the operator is not appropriate for an
+   * object of this kind.
+   */
+  IntState bitAnd(InstanceState rightOperand) {
+    assertIntOrNull(this);
+    assertIntOrNull(rightOperand);
+    throw new EvaluationException(CompileTimeErrorCode.INVALID_CONSTANT);
+  }
+
+  /**
+   * Return the result of invoking the '~' operator on this object.
+   *
+   * Throws an [EvaluationException] if the operator is not appropriate for an
+   * object of this kind.
+   */
+  IntState bitNot() {
+    assertIntOrNull(this);
+    throw new EvaluationException(CompileTimeErrorCode.INVALID_CONSTANT);
+  }
+
+  /**
+   * Return the result of invoking the '|' operator on this object with the
+   * [rightOperand].
+   *
+   * Throws an [EvaluationException] if the operator is not appropriate for an
+   * object of this kind.
+   */
+  IntState bitOr(InstanceState rightOperand) {
+    assertIntOrNull(this);
+    assertIntOrNull(rightOperand);
+    throw new EvaluationException(CompileTimeErrorCode.INVALID_CONSTANT);
+  }
+
+  /**
+   * Return the result of invoking the '^' operator on this object with the
+   * [rightOperand].
+   *
+   * Throws an [EvaluationException] if the operator is not appropriate for an
+   * object of this kind.
+   */
+  IntState bitXor(InstanceState rightOperand) {
+    assertIntOrNull(this);
+    assertIntOrNull(rightOperand);
+    throw new EvaluationException(CompileTimeErrorCode.INVALID_CONSTANT);
+  }
+
+  /**
+   * Return the result of invoking the ' ' operator on this object with the
+   * [rightOperand].
+   *
+   * Throws an [EvaluationException] if the operator is not appropriate for an
+   * object of this kind.
+   */
+  StringState concatenate(InstanceState rightOperand) {
+    assertString(rightOperand);
+    throw new EvaluationException(CompileTimeErrorCode.INVALID_CONSTANT);
+  }
+
+  /**
+   * Return the result of applying boolean conversion to this object.
+   *
+   * Throws an [EvaluationException] if the operator is not appropriate for an
+   * object of this kind.
+   */
+  BoolState convertToBool() => BoolState.FALSE_STATE;
+
+  /**
+   * Return the result of converting this object to a String.
+   *
+   * Throws an [EvaluationException] if the operator is not appropriate for an
+   * object of this kind.
+   */
+  StringState convertToString();
+
+  /**
+   * Return the result of invoking the '/' operator on this object with the
+   * [rightOperand].
+   *
+   * Throws an [EvaluationException] if the operator is not appropriate for an
+   * object of this kind.
+   */
+  NumState divide(InstanceState rightOperand) {
+    assertNumOrNull(this);
+    assertNumOrNull(rightOperand);
+    throw new EvaluationException(CompileTimeErrorCode.INVALID_CONSTANT);
+  }
+
+  /**
+   * Return the result of invoking the '==' operator on this object with the
+   * [rightOperand].
+   *
+   * Throws an [EvaluationException] if the operator is not appropriate for an
+   * object of this kind.
+   */
+  BoolState equalEqual(InstanceState rightOperand);
+
+  /**
+   * Return the result of invoking the '&gt;' operator on this object with the
+   * [rightOperand].
+   *
+   * Throws an [EvaluationException] if the operator is not appropriate for an
+   * object of this kind.
+   */
+  BoolState greaterThan(InstanceState rightOperand) {
+    assertNumOrNull(this);
+    assertNumOrNull(rightOperand);
+    throw new EvaluationException(CompileTimeErrorCode.INVALID_CONSTANT);
+  }
+
+  /**
+   * Return the result of invoking the '&gt;=' operator on this object with the
+   * [rightOperand].
+   *
+   * Throws an [EvaluationException] if the operator is not appropriate for an
+   * object of this kind.
+   */
+  BoolState greaterThanOrEqual(InstanceState rightOperand) {
+    assertNumOrNull(this);
+    assertNumOrNull(rightOperand);
+    throw new EvaluationException(CompileTimeErrorCode.INVALID_CONSTANT);
+  }
+
+  /**
+   * Return the result of invoking the '~/' operator on this object with the
+   * [rightOperand].
+   *
+   * Throws an [EvaluationException] if the operator is not appropriate for an
+   * object of this kind.
+   */
+  IntState integerDivide(InstanceState rightOperand) {
+    assertNumOrNull(this);
+    assertNumOrNull(rightOperand);
+    throw new EvaluationException(CompileTimeErrorCode.INVALID_CONSTANT);
+  }
+
+  /**
+   * Return the result of invoking the identical function on this object with
+   * the [rightOperand].
+   */
+  BoolState isIdentical(InstanceState rightOperand);
+
+  /**
+   * Return the result of invoking the '&lt;' operator on this object with the
+   * [rightOperand].
+   *
+   * Throws an [EvaluationException] if the operator is not appropriate for an
+   * object of this kind.
+   */
+  BoolState lessThan(InstanceState rightOperand) {
+    assertNumOrNull(this);
+    assertNumOrNull(rightOperand);
+    throw new EvaluationException(CompileTimeErrorCode.INVALID_CONSTANT);
+  }
+
+  /**
+   * Return the result of invoking the '&lt;=' operator on this object with the
+   * [rightOperand].
+   *
+   * Throws an [EvaluationException] if the operator is not appropriate for an
+   * object of this kind.
+   */
+  BoolState lessThanOrEqual(InstanceState rightOperand) {
+    assertNumOrNull(this);
+    assertNumOrNull(rightOperand);
+    throw new EvaluationException(CompileTimeErrorCode.INVALID_CONSTANT);
+  }
+
+  /**
+   * Return the result of invoking the '&&' operator on this object with the
+   * [rightOperand].
+   *
+   * Throws an [EvaluationException] if the operator is not appropriate for an
+   * object of this kind.
+   */
+  BoolState logicalAnd(InstanceState rightOperand) {
+    assertBool(this);
+    assertBool(rightOperand);
+    return BoolState.FALSE_STATE;
+  }
+
+  /**
+   * Return the result of invoking the '!' operator on this object.
+   *
+   * Throws an [EvaluationException] if the operator is not appropriate for an
+   * object of this kind.
+   */
+  BoolState logicalNot() {
+    assertBool(this);
+    return BoolState.TRUE_STATE;
+  }
+
+  /**
+   * Return the result of invoking the '||' operator on this object with the
+   * [rightOperand].
+   *
+   * Throws an [EvaluationException] if the operator is not appropriate for an
+   * object of this kind.
+   */
+  BoolState logicalOr(InstanceState rightOperand) {
+    assertBool(this);
+    assertBool(rightOperand);
+    return rightOperand.convertToBool();
+  }
+
+  /**
+   * Return the result of invoking the '-' operator on this object with the
+   * [rightOperand].
+   *
+   * Throws an [EvaluationException] if the operator is not appropriate for an
+   * object of this kind.
+   */
+  NumState minus(InstanceState rightOperand) {
+    assertNumOrNull(this);
+    assertNumOrNull(rightOperand);
+    throw new EvaluationException(CompileTimeErrorCode.INVALID_CONSTANT);
+  }
+
+  /**
+   * Return the result of invoking the '-' operator on this object.
+   *
+   * Throws an [EvaluationException] if the operator is not appropriate for an
+   * object of this kind.
+   */
+  NumState negated() {
+    assertNumOrNull(this);
+    throw new EvaluationException(CompileTimeErrorCode.INVALID_CONSTANT);
+  }
+
+  /**
+   * Return the result of invoking the '%' operator on this object with the
+   * [rightOperand].
+   *
+   * Throws an [EvaluationException] if the operator is not appropriate for an
+   * object of this kind.
+   */
+  NumState remainder(InstanceState rightOperand) {
+    assertNumOrNull(this);
+    assertNumOrNull(rightOperand);
+    throw new EvaluationException(CompileTimeErrorCode.INVALID_CONSTANT);
+  }
+
+  /**
+   * Return the result of invoking the '&lt;&lt;' operator on this object with
+   * the [rightOperand].
+   *
+   * Throws an [EvaluationException] if the operator is not appropriate for an
+   * object of this kind.
+   */
+  IntState shiftLeft(InstanceState rightOperand) {
+    assertIntOrNull(this);
+    assertIntOrNull(rightOperand);
+    throw new EvaluationException(CompileTimeErrorCode.INVALID_CONSTANT);
+  }
+
+  /**
+   * Return the result of invoking the '&gt;&gt;' operator on this object with
+   * the [rightOperand].
+   *
+   * Throws an [EvaluationException] if the operator is not appropriate for an
+   * object of this kind.
+   */
+  IntState shiftRight(InstanceState rightOperand) {
+    assertIntOrNull(this);
+    assertIntOrNull(rightOperand);
+    throw new EvaluationException(CompileTimeErrorCode.INVALID_CONSTANT);
+  }
+
+  /**
+   * Return the result of invoking the 'length' getter on this object.
+   *
+   * Throws an [EvaluationException] if the operator is not appropriate for an
+   * object of this kind.
+   */
+  IntState stringLength() {
+    assertString(this);
+    throw new EvaluationException(CompileTimeErrorCode.INVALID_CONSTANT);
+  }
+
+  /**
+   * Return the result of invoking the '*' operator on this object with the
+   * [rightOperand].
+   *
+   * Throws an [EvaluationException] if the operator is not appropriate for an
+   * object of this kind.
+   */
+  NumState times(InstanceState rightOperand) {
+    assertNumOrNull(this);
+    assertNumOrNull(rightOperand);
+    throw new EvaluationException(CompileTimeErrorCode.INVALID_CONSTANT);
+  }
+}
+
+/**
+ * The state of an object representing an int.
+ */
+class IntState extends NumState {
+  /**
+   * A state that can be used to represent an int whose value is not known.
+   */
+  static IntState UNKNOWN_VALUE = new IntState(null);
+
+  /**
+   * The value of this instance.
+   */
+  final int value;
+
+  /**
+   * Initialize a newly created state to represent an int with the given
+   * [value].
+   */
+  IntState(this.value);
+
+  @override
+  int get hashCode => value == null ? 0 : value.hashCode;
+
+  @override
+  bool get isBoolNumStringOrNull => true;
+
+  @override
+  bool get isUnknown => value == null;
+
+  @override
+  String get typeName => "int";
+
+  @override
+  bool operator ==(Object object) =>
+      object is IntState && (value == object.value);
+
+  @override
+  NumState add(InstanceState rightOperand) {
+    assertNumOrNull(rightOperand);
+    if (value == null) {
+      if (rightOperand is DoubleState) {
+        return DoubleState.UNKNOWN_VALUE;
+      }
+      return UNKNOWN_VALUE;
+    }
+    if (rightOperand is IntState) {
+      int rightValue = rightOperand.value;
+      if (rightValue == null) {
+        return UNKNOWN_VALUE;
+      }
+      return new IntState(value + rightValue);
+    } else if (rightOperand is DoubleState) {
+      double rightValue = rightOperand.value;
+      if (rightValue == null) {
+        return DoubleState.UNKNOWN_VALUE;
+      }
+      return new DoubleState(value.toDouble() + rightValue);
+    } else if (rightOperand is DynamicState || rightOperand is NumState) {
+      return UNKNOWN_VALUE;
+    }
+    throw new EvaluationException(
+        CompileTimeErrorCode.CONST_EVAL_THROWS_EXCEPTION);
+  }
+
+  @override
+  IntState bitAnd(InstanceState rightOperand) {
+    assertIntOrNull(rightOperand);
+    if (value == null) {
+      return UNKNOWN_VALUE;
+    }
+    if (rightOperand is IntState) {
+      int rightValue = rightOperand.value;
+      if (rightValue == null) {
+        return UNKNOWN_VALUE;
+      }
+      return new IntState(value & rightValue);
+    } else if (rightOperand is DynamicState || rightOperand is NumState) {
+      return UNKNOWN_VALUE;
+    }
+    throw new EvaluationException(
+        CompileTimeErrorCode.CONST_EVAL_THROWS_EXCEPTION);
+  }
+
+  @override
+  IntState bitNot() {
+    if (value == null) {
+      return UNKNOWN_VALUE;
+    }
+    return new IntState(~value);
+  }
+
+  @override
+  IntState bitOr(InstanceState rightOperand) {
+    assertIntOrNull(rightOperand);
+    if (value == null) {
+      return UNKNOWN_VALUE;
+    }
+    if (rightOperand is IntState) {
+      int rightValue = rightOperand.value;
+      if (rightValue == null) {
+        return UNKNOWN_VALUE;
+      }
+      return new IntState(value | rightValue);
+    } else if (rightOperand is DynamicState || rightOperand is NumState) {
+      return UNKNOWN_VALUE;
+    }
+    throw new EvaluationException(
+        CompileTimeErrorCode.CONST_EVAL_THROWS_EXCEPTION);
+  }
+
+  @override
+  IntState bitXor(InstanceState rightOperand) {
+    assertIntOrNull(rightOperand);
+    if (value == null) {
+      return UNKNOWN_VALUE;
+    }
+    if (rightOperand is IntState) {
+      int rightValue = rightOperand.value;
+      if (rightValue == null) {
+        return UNKNOWN_VALUE;
+      }
+      return new IntState(value ^ rightValue);
+    } else if (rightOperand is DynamicState || rightOperand is NumState) {
+      return UNKNOWN_VALUE;
+    }
+    throw new EvaluationException(
+        CompileTimeErrorCode.CONST_EVAL_THROWS_EXCEPTION);
+  }
+
+  @override
+  StringState convertToString() {
+    if (value == null) {
+      return StringState.UNKNOWN_VALUE;
+    }
+    return new StringState(value.toString());
+  }
+
+  @override
+  NumState divide(InstanceState rightOperand) {
+    assertNumOrNull(rightOperand);
+    if (value == null) {
+      return DoubleState.UNKNOWN_VALUE;
+    }
+    if (rightOperand is IntState) {
+      int rightValue = rightOperand.value;
+      if (rightValue == null) {
+        return DoubleState.UNKNOWN_VALUE;
+      } else {
+        return new DoubleState(value.toDouble() / rightValue.toDouble());
+      }
+    } else if (rightOperand is DoubleState) {
+      double rightValue = rightOperand.value;
+      if (rightValue == null) {
+        return DoubleState.UNKNOWN_VALUE;
+      }
+      return new DoubleState(value.toDouble() / rightValue);
+    } else if (rightOperand is DynamicState || rightOperand is NumState) {
+      return DoubleState.UNKNOWN_VALUE;
+    }
+    throw new EvaluationException(
+        CompileTimeErrorCode.CONST_EVAL_THROWS_EXCEPTION);
+  }
+
+  @override
+  BoolState equalEqual(InstanceState rightOperand) {
+    assertBoolNumStringOrNull(rightOperand);
+    return isIdentical(rightOperand);
+  }
+
+  @override
+  BoolState greaterThan(InstanceState rightOperand) {
+    assertNumOrNull(rightOperand);
+    if (value == null) {
+      return BoolState.UNKNOWN_VALUE;
+    }
+    if (rightOperand is IntState) {
+      int rightValue = rightOperand.value;
+      if (rightValue == null) {
+        return BoolState.UNKNOWN_VALUE;
+      }
+      return BoolState.from(value.compareTo(rightValue) > 0);
+    } else if (rightOperand is DoubleState) {
+      double rightValue = rightOperand.value;
+      if (rightValue == null) {
+        return BoolState.UNKNOWN_VALUE;
+      }
+      return BoolState.from(value.toDouble() > rightValue);
+    } else if (rightOperand is DynamicState || rightOperand is NumState) {
+      return BoolState.UNKNOWN_VALUE;
+    }
+    throw new EvaluationException(
+        CompileTimeErrorCode.CONST_EVAL_THROWS_EXCEPTION);
+  }
+
+  @override
+  BoolState greaterThanOrEqual(InstanceState rightOperand) {
+    assertNumOrNull(rightOperand);
+    if (value == null) {
+      return BoolState.UNKNOWN_VALUE;
+    }
+    if (rightOperand is IntState) {
+      int rightValue = rightOperand.value;
+      if (rightValue == null) {
+        return BoolState.UNKNOWN_VALUE;
+      }
+      return BoolState.from(value.compareTo(rightValue) >= 0);
+    } else if (rightOperand is DoubleState) {
+      double rightValue = rightOperand.value;
+      if (rightValue == null) {
+        return BoolState.UNKNOWN_VALUE;
+      }
+      return BoolState.from(value.toDouble() >= rightValue);
+    } else if (rightOperand is DynamicState || rightOperand is NumState) {
+      return BoolState.UNKNOWN_VALUE;
+    }
+    throw new EvaluationException(
+        CompileTimeErrorCode.CONST_EVAL_THROWS_EXCEPTION);
+  }
+
+  @override
+  IntState integerDivide(InstanceState rightOperand) {
+    assertNumOrNull(rightOperand);
+    if (value == null) {
+      return UNKNOWN_VALUE;
+    }
+    if (rightOperand is IntState) {
+      int rightValue = rightOperand.value;
+      if (rightValue == null) {
+        return UNKNOWN_VALUE;
+      } else if (rightValue == 0) {
+        throw new EvaluationException(
+            CompileTimeErrorCode.CONST_EVAL_THROWS_IDBZE);
+      }
+      return new IntState(value ~/ rightValue);
+    } else if (rightOperand is DoubleState) {
+      double rightValue = rightOperand.value;
+      if (rightValue == null) {
+        return UNKNOWN_VALUE;
+      }
+      double result = value.toDouble() / rightValue;
+      return new IntState(result.toInt());
+    } else if (rightOperand is DynamicState || rightOperand is NumState) {
+      return UNKNOWN_VALUE;
+    }
+    throw new EvaluationException(
+        CompileTimeErrorCode.CONST_EVAL_THROWS_EXCEPTION);
+  }
+
+  @override
+  BoolState isIdentical(InstanceState rightOperand) {
+    if (value == null) {
+      return BoolState.UNKNOWN_VALUE;
+    }
+    if (rightOperand is IntState) {
+      int rightValue = rightOperand.value;
+      if (rightValue == null) {
+        return BoolState.UNKNOWN_VALUE;
+      }
+      return BoolState.from(value == rightValue);
+    } else if (rightOperand is DoubleState) {
+      double rightValue = rightOperand.value;
+      if (rightValue == null) {
+        return BoolState.UNKNOWN_VALUE;
+      }
+      return BoolState.from(rightValue == value.toDouble());
+    } else if (rightOperand is DynamicState || rightOperand is NumState) {
+      return BoolState.UNKNOWN_VALUE;
+    }
+    return BoolState.FALSE_STATE;
+  }
+
+  @override
+  BoolState lessThan(InstanceState rightOperand) {
+    assertNumOrNull(rightOperand);
+    if (value == null) {
+      return BoolState.UNKNOWN_VALUE;
+    }
+    if (rightOperand is IntState) {
+      int rightValue = rightOperand.value;
+      if (rightValue == null) {
+        return BoolState.UNKNOWN_VALUE;
+      }
+      return BoolState.from(value.compareTo(rightValue) < 0);
+    } else if (rightOperand is DoubleState) {
+      double rightValue = rightOperand.value;
+      if (rightValue == null) {
+        return BoolState.UNKNOWN_VALUE;
+      }
+      return BoolState.from(value.toDouble() < rightValue);
+    } else if (rightOperand is DynamicState || rightOperand is NumState) {
+      return BoolState.UNKNOWN_VALUE;
+    }
+    throw new EvaluationException(
+        CompileTimeErrorCode.CONST_EVAL_THROWS_EXCEPTION);
+  }
+
+  @override
+  BoolState lessThanOrEqual(InstanceState rightOperand) {
+    assertNumOrNull(rightOperand);
+    if (value == null) {
+      return BoolState.UNKNOWN_VALUE;
+    }
+    if (rightOperand is IntState) {
+      int rightValue = rightOperand.value;
+      if (rightValue == null) {
+        return BoolState.UNKNOWN_VALUE;
+      }
+      return BoolState.from(value.compareTo(rightValue) <= 0);
+    } else if (rightOperand is DoubleState) {
+      double rightValue = rightOperand.value;
+      if (rightValue == null) {
+        return BoolState.UNKNOWN_VALUE;
+      }
+      return BoolState.from(value.toDouble() <= rightValue);
+    } else if (rightOperand is DynamicState || rightOperand is NumState) {
+      return BoolState.UNKNOWN_VALUE;
+    }
+    throw new EvaluationException(
+        CompileTimeErrorCode.CONST_EVAL_THROWS_EXCEPTION);
+  }
+
+  @override
+  NumState minus(InstanceState rightOperand) {
+    assertNumOrNull(rightOperand);
+    if (value == null) {
+      if (rightOperand is DoubleState) {
+        return DoubleState.UNKNOWN_VALUE;
+      }
+      return UNKNOWN_VALUE;
+    }
+    if (rightOperand is IntState) {
+      int rightValue = rightOperand.value;
+      if (rightValue == null) {
+        return UNKNOWN_VALUE;
+      }
+      return new IntState(value - rightValue);
+    } else if (rightOperand is DoubleState) {
+      double rightValue = rightOperand.value;
+      if (rightValue == null) {
+        return DoubleState.UNKNOWN_VALUE;
+      }
+      return new DoubleState(value.toDouble() - rightValue);
+    } else if (rightOperand is DynamicState || rightOperand is NumState) {
+      return UNKNOWN_VALUE;
+    }
+    throw new EvaluationException(
+        CompileTimeErrorCode.CONST_EVAL_THROWS_EXCEPTION);
+  }
+
+  @override
+  NumState negated() {
+    if (value == null) {
+      return UNKNOWN_VALUE;
+    }
+    return new IntState(-value);
+  }
+
+  @override
+  NumState remainder(InstanceState rightOperand) {
+    assertNumOrNull(rightOperand);
+    if (value == null) {
+      if (rightOperand is DoubleState) {
+        return DoubleState.UNKNOWN_VALUE;
+      }
+      return UNKNOWN_VALUE;
+    }
+    if (rightOperand is IntState) {
+      int rightValue = rightOperand.value;
+      if (rightValue == null) {
+        return UNKNOWN_VALUE;
+      } else if (rightValue == 0) {
+        return new DoubleState(value.toDouble() % rightValue.toDouble());
+      }
+      return new IntState(value.remainder(rightValue));
+    } else if (rightOperand is DoubleState) {
+      double rightValue = rightOperand.value;
+      if (rightValue == null) {
+        return DoubleState.UNKNOWN_VALUE;
+      }
+      return new DoubleState(value.toDouble() % rightValue);
+    } else if (rightOperand is DynamicState || rightOperand is NumState) {
+      return UNKNOWN_VALUE;
+    }
+    throw new EvaluationException(
+        CompileTimeErrorCode.CONST_EVAL_THROWS_EXCEPTION);
+  }
+
+  @override
+  IntState shiftLeft(InstanceState rightOperand) {
+    assertIntOrNull(rightOperand);
+    if (value == null) {
+      return UNKNOWN_VALUE;
+    }
+    if (rightOperand is IntState) {
+      int rightValue = rightOperand.value;
+      if (rightValue == null) {
+        return UNKNOWN_VALUE;
+      } else if (rightValue.bitLength > 31) {
+        return UNKNOWN_VALUE;
+      }
+      return new IntState(value << rightValue);
+    } else if (rightOperand is DynamicState || rightOperand is NumState) {
+      return UNKNOWN_VALUE;
+    }
+    throw new EvaluationException(
+        CompileTimeErrorCode.CONST_EVAL_THROWS_EXCEPTION);
+  }
+
+  @override
+  IntState shiftRight(InstanceState rightOperand) {
+    assertIntOrNull(rightOperand);
+    if (value == null) {
+      return UNKNOWN_VALUE;
+    }
+    if (rightOperand is IntState) {
+      int rightValue = rightOperand.value;
+      if (rightValue == null) {
+        return UNKNOWN_VALUE;
+      } else if (rightValue.bitLength > 31) {
+        return UNKNOWN_VALUE;
+      }
+      return new IntState(value >> rightValue);
+    } else if (rightOperand is DynamicState || rightOperand is NumState) {
+      return UNKNOWN_VALUE;
+    }
+    throw new EvaluationException(
+        CompileTimeErrorCode.CONST_EVAL_THROWS_EXCEPTION);
+  }
+
+  @override
+  NumState times(InstanceState rightOperand) {
+    assertNumOrNull(rightOperand);
+    if (value == null) {
+      if (rightOperand is DoubleState) {
+        return DoubleState.UNKNOWN_VALUE;
+      }
+      return UNKNOWN_VALUE;
+    }
+    if (rightOperand is IntState) {
+      int rightValue = rightOperand.value;
+      if (rightValue == null) {
+        return UNKNOWN_VALUE;
+      }
+      return new IntState(value * rightValue);
+    } else if (rightOperand is DoubleState) {
+      double rightValue = rightOperand.value;
+      if (rightValue == null) {
+        return DoubleState.UNKNOWN_VALUE;
+      }
+      return new DoubleState(value.toDouble() * rightValue);
+    } else if (rightOperand is DynamicState || rightOperand is NumState) {
+      return UNKNOWN_VALUE;
+    }
+    throw new EvaluationException(
+        CompileTimeErrorCode.CONST_EVAL_THROWS_EXCEPTION);
+  }
+
+  @override
+  String toString() => value == null ? "-unknown-" : value.toString();
+}
+
+/**
+ * The state of an object representing a list.
+ */
+class ListState extends InstanceState {
+  /**
+   * The elements of the list.
+   */
+  final List<DartObjectImpl> _elements;
+
+  /**
+   * Initialize a newly created state to represent a list with the given
+   * [elements].
+   */
+  ListState(this._elements);
+
+  @override
+  int get hashCode {
+    int value = 0;
+    int count = _elements.length;
+    for (int i = 0; i < count; i++) {
+      value = (value << 3) ^ _elements[i].hashCode;
+    }
+    return value;
+  }
+
+  @override
+  String get typeName => "List";
+
+  @override
+  bool operator ==(Object object) {
+    if (object is! ListState) {
+      return false;
+    }
+    List<DartObjectImpl> otherElements = (object as ListState)._elements;
+    int count = _elements.length;
+    if (otherElements.length != count) {
+      return false;
+    } else if (count == 0) {
+      return true;
+    }
+    for (int i = 0; i < count; i++) {
+      if (_elements[i] != otherElements[i]) {
+        return false;
+      }
+    }
+    return true;
+  }
+
+  @override
+  StringState convertToString() => StringState.UNKNOWN_VALUE;
+
+  @override
+  BoolState equalEqual(InstanceState rightOperand) {
+    assertBoolNumStringOrNull(rightOperand);
+    return isIdentical(rightOperand);
+  }
+
+  @override
+  BoolState isIdentical(InstanceState rightOperand) {
+    if (rightOperand is DynamicState) {
+      return BoolState.UNKNOWN_VALUE;
+    }
+    return BoolState.from(this == rightOperand);
+  }
+
+  @override
+  String toString() {
+    StringBuffer buffer = new StringBuffer();
+    buffer.write('[');
+    bool first = true;
+    _elements.forEach((DartObjectImpl element) {
+      if (first) {
+        first = false;
+      } else {
+        buffer.write(', ');
+      }
+      buffer.write(element);
+    });
+    buffer.write(']');
+    return buffer.toString();
+  }
+}
+
+/**
+ * The state of an object representing a map.
+ */
+class MapState extends InstanceState {
+  /**
+   * The entries in the map.
+   */
+  final HashMap<DartObjectImpl, DartObjectImpl> _entries;
+
+  /**
+   * Initialize a newly created state to represent a map with the given
+   * [entries].
+   */
+  MapState(this._entries);
+
+  @override
+  int get hashCode {
+    int value = 0;
+    for (DartObjectImpl key in _entries.keys.toSet()) {
+      value = (value << 3) ^ key.hashCode;
+    }
+    return value;
+  }
+
+  @override
+  String get typeName => "Map";
+
+  @override
+  bool operator ==(Object object) {
+    if (object is! MapState) {
+      return false;
+    }
+    HashMap<DartObjectImpl, DartObjectImpl> otherElements =
+        (object as MapState)._entries;
+    int count = _entries.length;
+    if (otherElements.length != count) {
+      return false;
+    } else if (count == 0) {
+      return true;
+    }
+    for (DartObjectImpl key in _entries.keys) {
+      DartObjectImpl value = _entries[key];
+      DartObjectImpl otherValue = otherElements[key];
+      if (value != otherValue) {
+        return false;
+      }
+    }
+    return true;
+  }
+
+  @override
+  StringState convertToString() => StringState.UNKNOWN_VALUE;
+
+  @override
+  BoolState equalEqual(InstanceState rightOperand) {
+    assertBoolNumStringOrNull(rightOperand);
+    return isIdentical(rightOperand);
+  }
+
+  @override
+  BoolState isIdentical(InstanceState rightOperand) {
+    if (rightOperand is DynamicState) {
+      return BoolState.UNKNOWN_VALUE;
+    }
+    return BoolState.from(this == rightOperand);
+  }
+
+  @override
+  String toString() {
+    StringBuffer buffer = new StringBuffer();
+    buffer.write('{');
+    bool first = true;
+    _entries.forEach((DartObjectImpl key, DartObjectImpl value) {
+      if (first) {
+        first = false;
+      } else {
+        buffer.write(', ');
+      }
+      buffer.write(key);
+      buffer.write(' = ');
+      buffer.write(value);
+    });
+    buffer.write('}');
+    return buffer.toString();
+  }
+}
+
+/**
+ * The state of an object representing the value 'null'.
+ */
+class NullState extends InstanceState {
+  /**
+   * An instance representing the boolean value 'null'.
+   */
+  static NullState NULL_STATE = new NullState();
+
+  @override
+  int get hashCode => 0;
+
+  @override
+  bool get isBoolNumStringOrNull => true;
+
+  @override
+  String get typeName => "Null";
+
+  @override
+  bool operator ==(Object object) => object is NullState;
+
+  @override
+  BoolState convertToBool() {
+    throw new EvaluationException(
+        CompileTimeErrorCode.CONST_EVAL_THROWS_EXCEPTION);
+  }
+
+  @override
+  StringState convertToString() => new StringState("null");
+
+  @override
+  BoolState equalEqual(InstanceState rightOperand) {
+    assertBoolNumStringOrNull(rightOperand);
+    return isIdentical(rightOperand);
+  }
+
+  @override
+  BoolState isIdentical(InstanceState rightOperand) {
+    if (rightOperand is DynamicState) {
+      return BoolState.UNKNOWN_VALUE;
+    }
+    return BoolState.from(rightOperand is NullState);
+  }
+
+  @override
+  BoolState logicalNot() {
+    throw new EvaluationException(
+        CompileTimeErrorCode.CONST_EVAL_THROWS_EXCEPTION);
+  }
+
+  @override
+  String toString() => "null";
+}
+
+/**
+ * The state of an object representing a number of an unknown type (a 'num').
+ */
+class NumState extends InstanceState {
+  /**
+   * A state that can be used to represent a number whose value is not known.
+   */
+  static NumState UNKNOWN_VALUE = new NumState();
+
+  @override
+  int get hashCode => 7;
+
+  @override
+  bool get isBoolNumStringOrNull => true;
+
+  @override
+  bool get isUnknown => identical(this, UNKNOWN_VALUE);
+
+  @override
+  String get typeName => "num";
+
+  @override
+  bool operator ==(Object object) => object is NumState;
+
+  @override
+  NumState add(InstanceState rightOperand) {
+    assertNumOrNull(rightOperand);
+    return UNKNOWN_VALUE;
+  }
+
+  @override
+  StringState convertToString() => StringState.UNKNOWN_VALUE;
+
+  @override
+  NumState divide(InstanceState rightOperand) {
+    assertNumOrNull(rightOperand);
+    return DoubleState.UNKNOWN_VALUE;
+  }
+
+  @override
+  BoolState equalEqual(InstanceState rightOperand) {
+    assertBoolNumStringOrNull(rightOperand);
+    return BoolState.UNKNOWN_VALUE;
+  }
+
+  @override
+  BoolState greaterThan(InstanceState rightOperand) {
+    assertNumOrNull(rightOperand);
+    return BoolState.UNKNOWN_VALUE;
+  }
+
+  @override
+  BoolState greaterThanOrEqual(InstanceState rightOperand) {
+    assertNumOrNull(rightOperand);
+    return BoolState.UNKNOWN_VALUE;
+  }
+
+  @override
+  IntState integerDivide(InstanceState rightOperand) {
+    assertNumOrNull(rightOperand);
+    if (rightOperand is IntState) {
+      int rightValue = rightOperand.value;
+      if (rightValue == null) {
+        return IntState.UNKNOWN_VALUE;
+      } else if (rightValue == 0) {
+        throw new EvaluationException(
+            CompileTimeErrorCode.CONST_EVAL_THROWS_IDBZE);
+      }
+    } else if (rightOperand is DynamicState) {
+      return IntState.UNKNOWN_VALUE;
+    }
+    return IntState.UNKNOWN_VALUE;
+  }
+
+  @override
+  BoolState isIdentical(InstanceState rightOperand) {
+    return BoolState.UNKNOWN_VALUE;
+  }
+
+  @override
+  BoolState lessThan(InstanceState rightOperand) {
+    assertNumOrNull(rightOperand);
+    return BoolState.UNKNOWN_VALUE;
+  }
+
+  @override
+  BoolState lessThanOrEqual(InstanceState rightOperand) {
+    assertNumOrNull(rightOperand);
+    return BoolState.UNKNOWN_VALUE;
+  }
+
+  @override
+  NumState minus(InstanceState rightOperand) {
+    assertNumOrNull(rightOperand);
+    return UNKNOWN_VALUE;
+  }
+
+  @override
+  NumState negated() => UNKNOWN_VALUE;
+
+  @override
+  NumState remainder(InstanceState rightOperand) {
+    assertNumOrNull(rightOperand);
+    return UNKNOWN_VALUE;
+  }
+
+  @override
+  NumState times(InstanceState rightOperand) {
+    assertNumOrNull(rightOperand);
+    return UNKNOWN_VALUE;
+  }
+
+  @override
+  String toString() => "-unknown-";
+}
+
+/**
+ * The state of an object representing a string.
+ */
+class StringState extends InstanceState {
+  /**
+   * A state that can be used to represent a double whose value is not known.
+   */
+  static StringState UNKNOWN_VALUE = new StringState(null);
+
+  /**
+   * The value of this instance.
+   */
+  final String value;
+
+  /**
+   * Initialize a newly created state to represent the given [value].
+   */
+  StringState(this.value);
+
+  @override
+  int get hashCode => value == null ? 0 : value.hashCode;
+
+  @override
+  bool get isBoolNumStringOrNull => true;
+
+  @override
+  bool get isUnknown => value == null;
+
+  @override
+  String get typeName => "String";
+
+  @override
+  bool operator ==(Object object) =>
+      object is StringState && (value == object.value);
+
+  @override
+  StringState concatenate(InstanceState rightOperand) {
+    if (value == null) {
+      return UNKNOWN_VALUE;
+    }
+    if (rightOperand is StringState) {
+      String rightValue = rightOperand.value;
+      if (rightValue == null) {
+        return UNKNOWN_VALUE;
+      }
+      return new StringState("$value$rightValue");
+    } else if (rightOperand is DynamicState) {
+      return UNKNOWN_VALUE;
+    }
+    return super.concatenate(rightOperand);
+  }
+
+  @override
+  StringState convertToString() => this;
+
+  @override
+  BoolState equalEqual(InstanceState rightOperand) {
+    assertBoolNumStringOrNull(rightOperand);
+    return isIdentical(rightOperand);
+  }
+
+  @override
+  BoolState isIdentical(InstanceState rightOperand) {
+    if (value == null) {
+      return BoolState.UNKNOWN_VALUE;
+    }
+    if (rightOperand is StringState) {
+      String rightValue = rightOperand.value;
+      if (rightValue == null) {
+        return BoolState.UNKNOWN_VALUE;
+      }
+      return BoolState.from(value == rightValue);
+    } else if (rightOperand is DynamicState) {
+      return BoolState.UNKNOWN_VALUE;
+    }
+    return BoolState.FALSE_STATE;
+  }
+
+  @override
+  IntState stringLength() {
+    if (value == null) {
+      return IntState.UNKNOWN_VALUE;
+    }
+    return new IntState(value.length);
+  }
+
+  @override
+  String toString() => value == null ? "-unknown-" : "'$value'";
+}
+
+/**
+ * The state of an object representing a symbol.
+ */
+class SymbolState extends InstanceState {
+  /**
+   * The value of this instance.
+   */
+  final String value;
+
+  /**
+   * Initialize a newly created state to represent the given [value].
+   */
+  SymbolState(this.value);
+
+  @override
+  int get hashCode => value == null ? 0 : value.hashCode;
+
+  @override
+  String get typeName => "Symbol";
+
+  @override
+  bool operator ==(Object object) =>
+      object is SymbolState && (value == object.value);
+
+  @override
+  StringState convertToString() {
+    if (value == null) {
+      return StringState.UNKNOWN_VALUE;
+    }
+    return new StringState(value);
+  }
+
+  @override
+  BoolState equalEqual(InstanceState rightOperand) {
+    assertBoolNumStringOrNull(rightOperand);
+    return isIdentical(rightOperand);
+  }
+
+  @override
+  BoolState isIdentical(InstanceState rightOperand) {
+    if (value == null) {
+      return BoolState.UNKNOWN_VALUE;
+    }
+    if (rightOperand is SymbolState) {
+      String rightValue = rightOperand.value;
+      if (rightValue == null) {
+        return BoolState.UNKNOWN_VALUE;
+      }
+      return BoolState.from(value == rightValue);
+    } else if (rightOperand is DynamicState) {
+      return BoolState.UNKNOWN_VALUE;
+    }
+    return BoolState.FALSE_STATE;
+  }
+
+  @override
+  String toString() => value == null ? "-unknown-" : "#$value";
+}
+
+/**
+ * The state of an object representing a type.
+ */
+class TypeState extends InstanceState {
+  /**
+   * The element representing the type being modeled.
+   */
+  final Element _element;
+
+  /**
+   * Initialize a newly created state to represent the given [value].
+   */
+  TypeState(this._element);
+
+  @override
+  int get hashCode => _element == null ? 0 : _element.hashCode;
+
+  @override
+  String get typeName => "Type";
+
+  @override
+  bool operator ==(Object object) =>
+      object is TypeState && (_element == object._element);
+
+  @override
+  StringState convertToString() {
+    if (_element == null) {
+      return StringState.UNKNOWN_VALUE;
+    }
+    return new StringState(_element.name);
+  }
+
+  @override
+  BoolState equalEqual(InstanceState rightOperand) {
+    assertBoolNumStringOrNull(rightOperand);
+    return isIdentical(rightOperand);
+  }
+
+  @override
+  BoolState isIdentical(InstanceState rightOperand) {
+    if (_element == null) {
+      return BoolState.UNKNOWN_VALUE;
+    }
+    if (rightOperand is TypeState) {
+      Element rightElement = rightOperand._element;
+      if (rightElement == null) {
+        return BoolState.UNKNOWN_VALUE;
+      }
+      return BoolState.from(_element == rightElement);
+    } else if (rightOperand is DynamicState) {
+      return BoolState.UNKNOWN_VALUE;
+    }
+    return BoolState.FALSE_STATE;
+  }
+
+  @override
+  String toString() => _element == null ? "-unknown-" : _element.name;
+}