/*
 * Copyright 2007 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.jjs.ast;

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

/**
 * Binary operator expression.
 */
public class JBinaryOperation extends JExpression {

  private JExpression lhs;
  private final JBinaryOperator op;
  private JExpression rhs;
  private JType type;

  public JBinaryOperation(SourceInfo info, JType type, JBinaryOperator op, JExpression lhs,
      JExpression rhs) {
    super(info);
    this.op = op;
    this.type = type;
    this.lhs = lhs;
    this.rhs = rhs;
  }

  public JExpression getLhs() {
    return lhs;
  }

  public JBinaryOperator getOp() {
    return op;
  }

  public JExpression getRhs() {
    return rhs;
  }

  @Override
  public JType getType() {
    JType resultType = this.type;
    if (isAssignment()) {
      // Use the type of the lhs
      resultType = getLhs().getType();
    }

    if (op != JBinaryOperator.ASG
         && !resultType.isNullType()
         && resultType instanceof JReferenceType) {
      // Except the = operation all other binary operations return a non-nullable exact type.
      resultType = ((JReferenceType) resultType).strengthenToNonNull().strengthenToExact();
    }
    return resultType;
  }

  @Override
  public boolean hasSideEffects() {
    return op.isAssignment() || getLhs().hasSideEffects() || getRhs().hasSideEffects();
  }

  public boolean isAssignment() {
    return op.isAssignment();
  }

  public void setType(JType newType) {
    type = newType;
  }

  @Override
  public void traverse(JVisitor visitor, Context ctx) {
    if (visitor.visit(this, ctx)) {
      if (isAssignment()) {
        lhs = visitor.acceptLvalue(lhs);
      } else {
        lhs = visitor.accept(lhs);
      }
      rhs = visitor.accept(rhs);
    }
    visitor.endVisit(this, ctx);
  }

}