/*
 * Copyright 2008 Google Inc.
 * 
 * Licensed under the Apache License, Version 2.0 (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.apache.org/licenses/LICENSE-2.0
 * 
 * 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.gwt.dev.js.ast;

import com.google.gwt.dev.jjs.SourceInfo;
import com.google.gwt.dev.jjs.SourceOrigin;

/**
 * Represents a JavaScript literal boolean expression.
 */
public final class JsBooleanLiteral extends JsValueLiteral {

  public static final JsBooleanLiteral FALSE = new JsBooleanLiteral(
      SourceOrigin.UNKNOWN, false);

  public static final JsBooleanLiteral TRUE = new JsBooleanLiteral(
      SourceOrigin.UNKNOWN, true);

  public static JsBooleanLiteral get(boolean value) {
    return value ? TRUE : FALSE;
  }

  private final boolean value;

  private JsBooleanLiteral(SourceInfo sourceInfo, boolean value) {
    super(sourceInfo);
    this.value = value;
  }

  public boolean getValue() {
    return value;
  }

  public boolean isBooleanFalse() {
    return value == false;
  }

  public boolean isBooleanTrue() {
    return value == true;
  }

  @Override
  public boolean isDefinitelyNotNull() {
    return true;
  }

  @Override
  public boolean isDefinitelyNull() {
    return false;
  }

  public void traverse(JsVisitor v, JsContext ctx) {
    v.visit(this, ctx);
    v.endVisit(this, ctx);
  }

  private Object readResolve() {
    return get(value);
  }
}