- /*
- * Copyright 1999-2004 The Apache Software Foundation.
- *
- * 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.
- */
- /*
- * $Id: Operation.java,v 1.12 2004/02/17 04:35:12 minchau Exp $
- */
- package com.sun.org.apache.xpath.internal.operations;
-
- 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;
-
- /**
- * The baseclass for a binary operation.
- */
- public class Operation extends Expression implements ExpressionOwner
- {
-
- /** 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(java.util.Vector 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 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;
- }
- }