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package org.apache.velocity.runtime.parser.node;
/*
* 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.
*/
import org.apache.velocity.context.InternalContextAdapter;
import org.apache.velocity.exception.MathException;
import org.apache.velocity.exception.MethodInvocationException;
import org.apache.velocity.exception.TemplateInitException;
import org.apache.velocity.runtime.RuntimeConstants;
import org.apache.velocity.runtime.parser.Parser;
import org.apache.velocity.util.DuckType;
/**
* Helps handle math<br><br>
*
* Please look at the Parser.jjt file which is
* what controls the generation of this class.
*
* @author <a href="mailto:wglass@forio.com">Will Glass-Husain</a>
* @author <a href="mailto:pero@antaramusic.de">Peter Romianowski</a>
* @author <a href="mailto:jvanzyl@apache.org">Jason van Zyl</a>
* @author <a href="mailto:geirm@optonline.net">Geir Magnusson Jr.</a>
* @author Nathan Bubna
* @version $Id: ASTMathNode.java 517553 2007-03-13 06:09:58Z wglass $
*/
public abstract class ASTMathNode extends ASTBinaryOperator
{
protected boolean strictMode = false;
public ASTMathNode(int id)
{
super(id);
}
public ASTMathNode(Parser p, int id)
{
super(p, id);
}
/**
* {@inheritDoc}
*/
@Override
public Object init(InternalContextAdapter context, Object data) throws TemplateInitException
{
super.init(context, data);
strictMode = rsvc.getBoolean(RuntimeConstants.STRICT_MATH, false);
cleanupParserAndTokens();
return data;
}
/**
* {@inheritDoc}
*/
@Override
public Object jjtAccept(ParserVisitor visitor, Object data)
{
return visitor.visit(this, data);
}
/**
* gets the two args and performs the operation on them
*
* @param context
* @return result or null
* @throws MethodInvocationException
*/
@Override
public Object value(InternalContextAdapter context) throws MethodInvocationException
{
Object left = jjtGetChild(0).value(context);
Object right = jjtGetChild(1).value(context);
/*
* should we do anything special here?
*/
Object special = handleSpecial(left, right, context);
if (special != null)
{
return special;
}
// coerce to Number type, if possible
try
{
left = DuckType.asNumber(left);
}
catch (NumberFormatException nfe) {}
try
{
right = DuckType.asNumber(right);
}
catch (NumberFormatException nfe) {}
/*
* if not a Number, not much we can do
*/
if (!(left instanceof Number) || !(right instanceof Number))
{
boolean wrongright = (left instanceof Number);
boolean wrongtype = wrongright ? right != null : left != null;
String msg = (wrongright ? "Right" : "Left")
+ " side of math operation ("
+ jjtGetChild(wrongright ? 1 : 0).literal() + ") "
+ (wrongtype ? "is not a Number. " : "has a null value. ")
+ getLocation(context);
if (strictMode)
{
log.error(msg);
throw new MathException(msg, rsvc.getLogContext().getStackTrace());
}
else
{
log.debug(msg);
return null;
}
}
return perform((Number)left, (Number)right, context);
}
/**
* Extension hook to allow special behavior by subclasses
* If this method returns a non-null value, that is returned,
* rather than the result of the math operation.
* @param left
* @param right
* @param context
* @return special value
* @see ASTAddNode#handleSpecial
*/
protected Object handleSpecial(Object left, Object right, InternalContextAdapter context)
{
// do nothing, this is an extension hook
return null;
}
/**
* Performs the math operation represented by this node.
* @param left
* @param right
* @param context
* @return computed value
* @see ASTAddNode#perform(Number, Number, InternalContextAdapter)
*/
public abstract Number perform(Number left, Number right, InternalContextAdapter context);
}
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