/**
* =========================================
* LibFormula : a free Java formula library
* =========================================
*
* Project Info: http://reporting.pentaho.org/libformula/
*
* (C) Copyright 2006-2007, by Pentaho Corporation and Contributors.
*
* 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.
*
* [Java is a trademark or registered trademark of Sun Microsystems, Inc.
* in the United States and other countries.]
*
*
* ------------
* $Id: Term.java,v 1.10 2007/06/10 13:35:47 taqua Exp $
* ------------
* (C) Copyright 2006-2007, by Pentaho Corporation.
*/
package org.jfree.formula.lvalues;
import java.util.ArrayList;
import org.jfree.formula.EvaluationException;
import org.jfree.formula.FormulaContext;
import org.jfree.formula.operators.InfixOperator;
/**
* An term is a list of LValues connected by operators. For the sake of
* efficiency, this is not stored as tree. We store the term as a list in the
* following format: (headValue)(OP value)* ...
*
* @author Thomas Morgner
*/
public class Term extends AbstractLValue
{
private LValue optimizedHeadValue;
private LValue headValue;
private ArrayList operators;
private ArrayList operands;
private InfixOperator[] operatorArray;
private LValue[] operandsArray;
private boolean initialized;
public Term(final LValue headValue)
{
if (headValue == null)
{
throw new NullPointerException();
}
this.headValue = headValue;
}
public TypeValuePair evaluate() throws EvaluationException
{
TypeValuePair result = optimizedHeadValue.evaluate();
for (int i = 0; i < operandsArray.length; i++)
{
final LValue value = operandsArray[i];
final InfixOperator op = operatorArray[i];
result = op.evaluate(getContext(), result, value.evaluate());
}
return result;
}
public void add(InfixOperator operator, LValue operand)
{
if (operator == null)
{
throw new NullPointerException();
}
if (operand == null)
{
throw new NullPointerException();
}
if (operands == null || operators == null)
{
this.operands = new ArrayList();
this.operators = new ArrayList();
}
operands.add(operand);
operators.add(operator);
initialized = false;
}
public void initialize(FormulaContext context) throws EvaluationException
{
super.initialize(context);
if (operands == null || operators == null)
{
this.optimizedHeadValue = headValue;
this.optimizedHeadValue.initialize(context);
this.operandsArray = new LValue[0];
this.operatorArray = new InfixOperator[0];
return;
}
if (initialized)
{
optimizedHeadValue.initialize(context);
for (int i = 0; i < operandsArray.length; i++)
{
LValue lValue = operandsArray[i];
lValue.initialize(context);
}
return;
}
optimize(context);
}
private void optimize(FormulaContext context) throws EvaluationException
{
ArrayList operators = (ArrayList) this.operators.clone();
ArrayList operands = (ArrayList) this.operands.clone();
this.optimizedHeadValue = headValue;
while (true)
{
// now start to optimize everything.
// first, search the operator with the highest priority..
final InfixOperator op = (InfixOperator) operators.get(0);
int level = op.getLevel();
boolean moreThanOne = false;
for (int i = 1; i < operators.size(); i++)
{
final InfixOperator operator = (InfixOperator) operators.get(i);
final int opLevel = operator.getLevel();
if (opLevel != level)
{
moreThanOne = true;
level = Math.min(opLevel, level);
}
}
if (moreThanOne == false)
{
// No need to optimize the operators ..
break;
}
// There are at least two op-levels in this term.
Term subTerm = null;
for (int i = 0; i < operators.size(); i++)
{
final InfixOperator operator = (InfixOperator) operators.get(i);
if (operator.getLevel() != level)
{
subTerm = null;
continue;
}
if (subTerm == null)
{
if (i == 0)
{
subTerm = new Term(optimizedHeadValue);
optimizedHeadValue = subTerm;
}
else
{
final LValue lval = (LValue) operands.get(i - 1);
subTerm = new Term(lval);
operands.set(i - 1, subTerm);
}
}
// OK, now a term exists, and we should join it.
final LValue operand = (LValue) operands.get(i);
subTerm.add(operator, operand);
operands.remove(i);
operators.remove(i);
// Rollback the current index ..
//noinspection AssignmentToForLoopParameter
i -= 1;
}
}
this.operatorArray = (InfixOperator[])
operators.toArray(new InfixOperator[operators.size()]);
this.operandsArray = (LValue[])
operands.toArray(new LValue[operands.size()]);
this.optimizedHeadValue.initialize(context);
for (int i = 0; i < operandsArray.length; i++)
{
final LValue value = operandsArray[i];
value.initialize(context);
}
}
/**
* Returns any dependent lvalues (parameters and operands, mostly).
*
* @return
*/
public LValue[] getChildValues()
{
final LValue[] values = new LValue[operandsArray.length + 1];
values[0] = headValue;
System.arraycopy(operandsArray, 0, values, 1, operandsArray.length);
return values;
}
public String toString()
{
StringBuffer b = new StringBuffer();
b.append("(");
b.append(headValue);
if (operands != null && operators != null)
{
for (int i = 0; i < operands.size(); i++)
{
InfixOperator op = (InfixOperator) operators.get(i);
LValue value = (LValue) operands.get(i);
b.append(op);
b.append(value);
}
}
b.append(")");
//
// b.append(";OPTIMIZED(");
// b.append(optimizedHeadValue);
// if (operandsArray != null && operatorArray != null)
// {
// for (int i = 0; i < operandsArray.length; i++)
// {
// final InfixOperator op = operatorArray[i];
// final LValue value = operandsArray[i];
// b.append(op);
// b.append(value);
// }
// }
// b.append(")");
return b.toString();
}
/**
* Checks, whether the LValue is constant. Constant lvalues always return the
* same value.
*
* @return
*/
public boolean isConstant()
{
if (headValue.isConstant() == false)
{
return false;
}
for (int i = 0; i < operands.size(); i++)
{
LValue value = (LValue) operands.get(i);
if (value.isConstant() == false)
{
return false;
}
}
return true;
}
public Object clone() throws CloneNotSupportedException
{
final Term o = (Term) super.clone();
if (operands != null)
{
o.operands = (ArrayList) operands.clone();
}
if (operators != null)
{
o.operators = (ArrayList) operators.clone();
}
o.headValue = (LValue) headValue.clone();
o.optimizedHeadValue = null;
o.operandsArray = null;
o.operatorArray = null;
o.initialized = false;
return o;
}
public InfixOperator[] getOperands ()
{
return (InfixOperator[]) operands.toArray(new InfixOperator[operands.size()]);
}
public LValue[] getOperators ()
{
return (LValue[]) operators.toArray(new LValue[operators.size()]);
}
public LValue getHeadValue()
{
return headValue;
}
/**
* Allows access to the post optimized head value
* note that without the optimization, it's difficult to traverse
* libformula's object model.
*
* @return optimized head value
*/
public LValue getOptimizedHeadValue()
{
return optimizedHeadValue;
}
/**
* Allows access to the post optimized operator array
*
* @return optimized operator array
*/
public InfixOperator[] getOptimizedOperators()
{
return operatorArray;
}
/**
* Allows access to the post optimized operand array
*
* @return optimized operand array
*/
public LValue[] getOptimizedOperands()
{
return operandsArray;
}
}