/*

 * Copyright (c) 2017, Oracle and/or its affiliates. All rights reserved.

 */

/*

 * Licensed to the Apache Software Foundation (ASF) under one or more

 * contributor license agreements.  See the NOTICE file distributed with

 * this work for additional information regarding copyright ownership.

 * The ASF licenses this file to You 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.sun.org.apache.xpath.internal.operations;

import com.sun.org.apache.xml.internal.utils.QName;

import com.sun.org.apache.xpath.internal.Expression;

import com.sun.org.apache.xpath.internal.ExpressionOwner;

import com.sun.org.apache.xpath.internal.XPathContext;

import com.sun.org.apache.xpath.internal.XPathVisitor;

import com.sun.org.apache.xpath.internal.objects.XObject;

import java.util.List;

/**

 * The baseclass for a binary operation.

 *

 * @LastModified: Oct 2017

 */

public class Operation extends Expression implements ExpressionOwner

{

    static final long serialVersionUID = -3037139537171050430L;

  /** The left operand expression.

   *  @serial */

  protected Expression m_left;

  /** The right operand expression.

   *  @serial */

  protected Expression m_right;

  /**

   * This function is used to fixup variables from QNames to stack frame

   * indexes at stylesheet build time.

   * @param vars List of QNames that correspond to variables.  This list

   * should be searched backwards for the first qualified name that

   * corresponds to the variable reference qname.  The position of the

   * QName in the vector from the start of the vector will be its position

   * in the stack frame (but variables above the globalsTop value will need

   * to be offset to the current stack frame).

   */

  public void fixupVariables(List<QName> vars, int globalsSize)

  {

    m_left.fixupVariables(vars, globalsSize);

    m_right.fixupVariables(vars, globalsSize);

  }

  /**

   * Tell if this expression or it's subexpressions can traverse outside

   * the current subtree.

   *

   * @return true if traversal outside the context node's subtree can occur.

   */

  public boolean canTraverseOutsideSubtree()

  {

    if (null != m_left && m_left.canTraverseOutsideSubtree())

      return true;

    if (null != m_right && m_right.canTraverseOutsideSubtree())

      return true;

    return false;

  }

  /**

   * Set the left and right operand expressions for this operation.

   *

   *

   * @param l The left expression operand.

   * @param r The right expression operand.

   */

  public void setLeftRight(Expression l, Expression r)

  {

    m_left = l;

    m_right = r;

    l.exprSetParent(this);

    r.exprSetParent(this);

  }

  /**

   * Execute a binary operation by calling execute on each of the operands,

   * and then calling the operate method on the derived class.

   *

   *

   * @param xctxt The runtime execution context.

   *

   * @return The XObject result of the operation.

   *

   * @throws javax.xml.transform.TransformerException

   */

  public XObject execute(XPathContext xctxt)

          throws javax.xml.transform.TransformerException

  {

    XObject left = m_left.execute(xctxt, true);

    XObject right = m_right.execute(xctxt, true);

    XObject result = operate(left, right);

    left.detach();

    right.detach();

    return result;

  }

  /**

   * Apply the operation to two operands, and return the result.

   *

   *

   * @param left non-null reference to the evaluated left operand.

   * @param right non-null reference to the evaluated right operand.

   *

   * @return non-null reference to the XObject that represents the result of the operation.

   *

   * @throws javax.xml.transform.TransformerException

   */

  public XObject operate(XObject left, XObject right)

          throws javax.xml.transform.TransformerException

  {

    return null;  // no-op

  }

  /** @return the left operand of binary operation, as an Expression.

   */

  public Expression getLeftOperand(){

    return m_left;

  }

  /** @return the right operand of binary operation, as an Expression.

   */

  public Expression getRightOperand(){

    return m_right;

  }

  class LeftExprOwner implements ExpressionOwner

  {

    /**

     * @see ExpressionOwner#getExpression()

     */

    public Expression getExpression()

    {

      return m_left;

    }

    /**

     * @see ExpressionOwner#setExpression(Expression)

     */

    public void setExpression(Expression exp)

    {

        exp.exprSetParent(Operation.this);

        m_left = exp;

    }

  }

  /**

   * @see com.sun.org.apache.xpath.internal.XPathVisitable#callVisitors(ExpressionOwner, XPathVisitor)

   */

  public void callVisitors(ExpressionOwner owner, XPathVisitor visitor)

  {

        if(visitor.visitBinaryOperation(owner, this))

        {

                m_left.callVisitors(new LeftExprOwner(), visitor);

                m_right.callVisitors(this, visitor);

        }

  }

  /**

   * @see ExpressionOwner#getExpression()

   */

  public Expression getExpression()

  {

    return m_right;

  }

  /**

   * @see ExpressionOwner#setExpression(Expression)

   */

  public void setExpression(Expression exp)

  {

        exp.exprSetParent(this);

        m_right = exp;

  }

  /**

   * @see Expression#deepEquals(Expression)

   */

  public boolean deepEquals(Expression expr)

  {

        if(!isSameClass(expr))

                return false;

        if(!m_left.deepEquals(((Operation)expr).m_left))

                return false;

        if(!m_right.deepEquals(((Operation)expr).m_right))

                return false;

        return true;

  }

}