package com.exigen.ie.constrainer.impl;
import com.exigen.ie.constrainer.ConstraintImpl;
import com.exigen.ie.constrainer.EventOfInterest;
import com.exigen.ie.constrainer.Failure;
import com.exigen.ie.constrainer.Goal;
import com.exigen.ie.constrainer.IntExp;
import com.exigen.ie.constrainer.IntExpArray;
import com.exigen.ie.constrainer.Observer;
import com.exigen.ie.constrainer.Subject;
///////////////////////////////////////////////////////////////////////////////
/*
* Copyright Exigen Group 1998, 1999, 2000
* 320 Amboy Ave., Metuchen, NJ, 08840, USA, www.exigengroup.com
*
* The copyright to the computer program(s) herein
* is the property of Exigen Group, USA. All rights reserved.
* The program(s) may be used and/or copied only with
* the written permission of Exigen Group
* or in accordance with the terms and conditions
* stipulated in the agreement/contract under which
* the program(s) have been supplied.
*/
///////////////////////////////////////////////////////////////////////////////
//
//: ConstraintAllDiff.java
//
/**
* An implementation of the constraint "All Different".
*
* Any two constrained integer expressions from the array (parameter of this
* constraint) should not be instantiated with the same value.
*/
public final class ConstraintAllDiff extends ConstraintImpl
{
// PRIVATE MEMBERS
private IntExpArray _intvars;
private UndoableBits _bits; // one bit for every possible values among all _intvars
//////////////////////////////////////////////// inner class AllDiffObserver
class AllDiffObserver extends Observer
{
public void update(Subject var, EventOfInterest interest)
throws Failure
{
IntExp event_var = (IntExp)var;
//Debug.on(); Debug.print("AllDiffObserver("+var+") "+interest+" "+_bits); Debug.off();
int size = _intvars.size();
int value = event_var.value();
boolean bit = _bits.bit(value);
// check for failure
if (bit)
{
//Debug.on();Debug.print("diff fail: "+interest+_intvars+_bits);Debug.off();
var.constrainer().fail("AllDiff"); //+_bits +" "+_intvars);
}
// set the bit
_bits.bit(value,true); //Debug.on();Debug.print(" "+this+": "+_bits);Debug.off();
var.constrainer().addUndo(UndoBits.getUndo(_bits,value));
// additional propagation
IntExp[] data = _intvars.data();
for(int i=0; i < size; i++)
{
IntExp vari = data[i];
if (vari!=event_var)
{
//Debug.on();Debug.print("alldiff remove "+value+" from "+vari);Debug.off();
vari.removeValue(value); // may fail
}
}
}
public int subscriberMask()
{
return EventOfInterest.VALUE;
}
public String toString()
{
return "AllDiff";//+_intvars;
}
public Object master()
{
return ConstraintAllDiff.this;
}
} //~ AllDiffObserver
///////////////////////////////////// inner class AllDiffMinMaxObserver
class AllDiffMinMaxObserver extends Observer
{
public void update(Subject var, EventOfInterest interest)
throws Failure
{
int min = _bits.min();
int max = _bits.max();
//Debug.on();Debug.print("alldiff minmax "+interest+": "+_bits);Debug.off();
for(int i=0; i<_intvars.size(); i++)
{
IntExp vari = (IntExp)_intvars.elementAt(i);
if (!vari.bound())
{
for(int v=min; v <=max; v++)
{
if (_bits.bit(v) && vari.contains(v))//(v==vari.min() || v==vari.max()))
{
//Debug.on();Debug.print("alldiff minmax remove "+v+" from "+vari);Debug.off();
vari.removeValue(v); // may fail
if (vari.bound())
break;
}
}
}
}
}
public int subscriberMask()
{
return EventOfInterest.MINMAX;
}
public Object master()
{
return ConstraintAllDiff.this;
}
} //~ AllDiffMinMaxObserver
public ConstraintAllDiff(IntExpArray intvars)
{
super(intvars.constrainer(),"AllDiff");
_intvars = intvars;
int min = intvars.min();
int max = intvars.max();
_bits = new UndoableBits(constrainer(), min,max);
_bits.object(this);
}
void bits(UndoableBits b)
{
_bits = b;
}
UndoableBits bits()
{
return _bits;
}
public Goal execute() throws Failure
{
// initial propagation
int size = _intvars.size();
for(int i=0; i<size; i++)
{
IntExp vari = (IntExp)_intvars.elementAt(i);
if (vari.bound())
{
int value = vari.value();
boolean bit = _bits.bit(value);
// check for failure
if (bit)
{
constrainer().fail("Diff");
}
_bits.bit(value,true);
constrainer().addUndo(UndoBits.getUndo(_bits,value));
}
}
// attach observers
Observer value_observer = new AllDiffObserver();
Observer minmax_observer = new AllDiffMinMaxObserver();
for(int i=0; i<size; i++)
{
IntExp vari = (IntExp)_intvars.elementAt(i);
vari.attachObserver(value_observer);
}
return null;
} // end of execute
} // ~ConstraintAllDiff