/*********************************************************************
*
* Copyright (C) 2007 Andrew Khan
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
***************************************************************************/
package jxl.biff.formula;
import java.util.Stack;
import jxl.biff.IntegerHelper;
/**
* Base class for those tokens which encapsulate a subexpression
*/
abstract class SubExpression extends Operand implements ParsedThing
{
/**
* The number of bytes in the subexpression
*/
private int length;
/**
* The sub expression
*/
private ParseItem[] subExpression;
/**
* Constructor
*/
protected SubExpression()
{
}
/**
* Reads the ptg data from the array starting at the specified position
*
* @param data the RPN array
* @param pos the current position in the array, excluding the ptg identifier
* @return the number of bytes read
*/
public int read(byte[] data, int pos)
{
length = IntegerHelper.getInt(data[pos], data[pos+1]);
return 2;
}
/**
* Gets the operands for this operator from the stack
*/
public void getOperands(Stack s)
{
}
/**
* Gets the token representation of this item in RPN. The Attribute
* token is a special case, which overrides anything useful we could do
* in the base class
*
* @return the bytes applicable to this formula
*/
byte[] getBytes()
{
return null;
}
/**
* Gets the precedence for this operator. Operator precedents run from
* 1 to 5, one being the highest, 5 being the lowest
*
* @return the operator precedence
*/
int getPrecedence()
{
return 5;
}
/**
* Accessor for the length
*
* @return the length of the subexpression
*/
public int getLength()
{
return length;
}
protected final void setLength(int l)
{
length = l;
}
public void setSubExpression(ParseItem[] pi)
{
subExpression = pi;
}
protected ParseItem[] getSubExpression()
{
return subExpression;
}
}
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