Literal.java

// Copyright (C) 2005 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.caja.parser.js;

import com.google.caja.lexer.FilePosition;
import com.google.caja.reporting.RenderContext;

/**
 * A literal expression whose value does not depend on the environment, and
 * whose evaluation has no side-effect.
 *
 * @author mikesamuel@gmail.com
 */
public abstract class Literal extends AbstractExpression {
  private static final long serialVersionUID = 2713667134417886694L;

  protected Literal(FilePosition pos) { super(pos, NoChildren.class); }

  @Override
  public abstract Object getValue();

  public abstract boolean getValueInBooleanContext();

  @Override
  protected final void childrenChanged() {
    super.childrenChanged();
    if (!children().isEmpty()) { throw new IllegalStateException(); }
  }

  public void render(RenderContext rc) {
    rc.getOut().mark(getFilePosition());
    rc.getOut().consume(getValue().toString());
  }

  @Override
  public Expression simplifyForSideEffect() { return null; }

  @Override
  public Boolean conditionResult() { return getValueInBooleanContext(); }
}