Constant evaluation support

editor/tools/plugins/com.google.dart.engine/src/com/google/dart/engine/internal/object/BoolState.java

Index: editor/tools/plugins/com.google.dart.engine/src/com/google/dart/engine/internal/object/BoolState.java
diff --git a/editor/tools/plugins/com.google.dart.engine/src/com/google/dart/engine/internal/object/BoolState.java b/editor/tools/plugins/com.google.dart.engine/src/com/google/dart/engine/internal/object/BoolState.java
new file mode 100644
index 0000000000000000000000000000000000000000..d13ad68ef777a07251cfbbccd6ccd822a48c2237
--- /dev/null
+++ b/editor/tools/plugins/com.google.dart.engine/src/com/google/dart/engine/internal/object/BoolState.java
@@ -0,0 +1,160 @@
+/*
+ * Copyright (c) 2013, the Dart project authors.
+ * 
+ * Licensed under the Eclipse Public License v1.0 (the "License"); you may not use this file except
+ * in compliance with the License. You may obtain a copy of the License at
+ * 
+ * http://www.eclipse.org/legal/epl-v10.html
+ * 
+ * Unless required by applicable law or agreed to in writing, software distributed under the License
+ * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
+ * or implied. See the License for the specific language governing permissions and limitations under
+ * the License.
+ */
+package com.google.dart.engine.internal.object;
+
+/**
+ * Instances of the class {@code BoolState} represent the state of an object representing a boolean
+ * value.
+ */
+public class BoolState extends InstanceState {
+  /**
+   * The value of this instance.
+   */
+  private Boolean value;
+
+  /**
+   * An instance representing the boolean value 'false'.
+   */
+  public static final BoolState FALSE_STATE = new BoolState(Boolean.FALSE);
+
+  /**
+   * An instance representing the boolean value 'true'.
+   */
+  public static final BoolState TRUE_STATE = new BoolState(Boolean.TRUE);
+
+  /**
+   * A state that can be used to represent a boolean whose value is not known.
+   */
+  public static final BoolState UNKNOWN_VALUE = new BoolState(null);
+
+  /**
+   * Return the boolean state representing the given boolean value.
+   * 
+   * @param value the value to be represented
+   * @return the boolean state representing the given boolean value
+   */
+  public static BoolState from(boolean value) {
+    return value ? BoolState.TRUE_STATE : BoolState.FALSE_STATE;
+  }
+
+  /**
+   * Initialize a newly created state to represent the given value.
+   * 
+   * @param value the value of this instance
+   */
+  private BoolState(Boolean value) {
+    this.value = value;
+  }
+
+  @Override
+  public BoolState convertToBool() {
+    return this;
+  }
+
+  @Override
+  public StringState convertToString() {
+    if (value == null) {
+      return StringState.UNKNOWN_VALUE;
+    }
+    return new StringState(value ? "true" : "false");
+  }
+
+  @Override
+  public BoolState equalEqual(InstanceState rightOperand) throws EvaluationException {
+    assertBoolNumStringOrNull(rightOperand);
+    if (value == null) {
+      return UNKNOWN_VALUE;
+    }
+    if (rightOperand instanceof BoolState) {
+      Boolean rightValue = ((BoolState) rightOperand).getValue();
+      if (rightValue == null) {
+        return UNKNOWN_VALUE;
+      }
+      return BoolState.from(value == rightValue);
+    } else if (rightOperand instanceof DynamicState) {
+      return UNKNOWN_VALUE;
+    }
+    return FALSE_STATE;
+  }
+
+  @Override
+  public boolean equals(Object object) {
+    return object instanceof BoolState && value == ((BoolState) object).value;
+  }
+
+  @Override
+  public String getTypeName() {
+    return "bool"; //$NON-NLS-0$
+  }
+
+  /**
+   * Return the value of this instance.
+   * 
+   * @return the value of this instance
+   */
+  public Boolean getValue() {
+    return value;
+  }
+
+  @Override
+  public int hashCode() {
+    return value == null ? 0 : (value ? 2 : 3);
+  }
+
+  /**
+   * Return {@code true} if this object represents an object whose type is 'bool'.
+   * 
+   * @return {@code true} if this object represents a boolean value
+   */
+  @Override
+  public boolean isBool() {
+    return true;
+  }
+
+  @Override
+  public boolean isBoolNumStringOrNull() {
+    return true;
+  }
+
+  @Override
+  public BoolState logicalAnd(InstanceState rightOperand) throws EvaluationException {
+    assertBool(rightOperand);
+    if (value == null) {
+      return UNKNOWN_VALUE;
+    }
+    return value ? rightOperand.convertToBool() : FALSE_STATE;
+  }
+
+  @Override
+  public BoolState logicalNot() {
+    if (value == null) {
+      return UNKNOWN_VALUE;
+    }
+    return value ? FALSE_STATE : TRUE_STATE;
+  }
+
+  @Override
+  public BoolState logicalOr(InstanceState rightOperand) throws EvaluationException {
+    assertBool(rightOperand);
+    if (value == null) {
+      return UNKNOWN_VALUE;
+    }
+    return value ? TRUE_STATE : rightOperand.convertToBool();
+  }
+
+  @Override
+  public String toString() {
+    return value == null ? "-unknown-" : (value ? "true" : "false");
+  }
+}