package com.exigen.ie.constrainer;
///////////////////////////////////////////////////////////////////////////////
/*
* 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.
*/
///////////////////////////////////////////////////////////////////////////////
import com.exigen.ie.tools.FastVector;
/**
* An implementation of a {@link Goal} that generates a solution
* for the problem with the unknown integer variables.
* <p>
* This goal:
* <ul>
* <li>Selects the variable using {@link IntVarSelector}.
* <li>Tries to instantiate it using {@link GoalInstantiate}.
* GoalInstantiate make use of IntValueSelector taken from a constructor of GoalGenerate
* to work with the domain of a variable.
* </ul>
* @see IntVarSelector
* @see IntValueSelector
* @see GoalInstantiate
*/
public class GoalGenerate extends GoalImpl
{
private IntExpArray _intvars;
private IntVarSelector _var_selector;
private boolean _dichotomize;
private IntValueSelector _value_selector;
private boolean _recursiveInstantiate = true;
/**
* Returns true if the instantiation goals are recursive.
*/
public boolean recursiveInstantiate()
{
return _recursiveInstantiate;
}
/**
* Sets the recursive flag for the instantiation goals.
*/
public void recursiveInstantiate(boolean recursive)
{
_recursiveInstantiate = recursive;
initGoals();
}
/**
* The search goals that instantiate each variable.
*/
private FastVector _goals;
/**
* Constructor with a given array of variables.
* GoalGenerate will be constructed with <code>IntVarSelectorFirstUnbound<code>
* as a default variable selector and <code>IntValueSelectorMin</code> as a
* default value selector and it won't use dichotomize.
*/
public GoalGenerate(IntExpArray intvars)
{
this(intvars, null, null, false);
}
/**
* GoalGenerate will be constructed with <code>IntVarSelectorFirstUnbound<code>
* as a default variable selector and <code>IntValueSelectorMin</code> as a
* default value selector.
*/
public GoalGenerate(IntExpArray intvars, boolean dichotomize)
{
this(intvars, null, null, dichotomize);
}
/**
* Constructor with a given array of variables, variable selector, and value selector.
* GoalGenerate constructed that way won't use dichotomize procedure.
*/
public GoalGenerate(IntExpArray intvars, IntVarSelector var_selector, IntValueSelector value_selector)
{
this(intvars, var_selector, value_selector, false);
}
/**
* Constructor with a given array of variables, variable selector, and "dichotomize" parameter.
*/
public GoalGenerate(IntExpArray intvars, IntVarSelector var_selector, boolean dichotomize)
{
this(intvars, var_selector, null, dichotomize);
}
/**
* Constructor with full (and redundant) set of parameters.
*/
GoalGenerate(IntExpArray intvars, IntVarSelector var_selector, IntValueSelector value_selector, boolean dichotomize)
{
super(intvars.constrainer(), "Generate");
_intvars = intvars;
_dichotomize = dichotomize;
_var_selector = ( var_selector != null ? var_selector :
new IntVarSelectorFirstUnbound(intvars) );
_value_selector = ( dichotomize ? null :
value_selector != null ? value_selector :
new IntValueSelectorMin() );
initGoals();
}
/**
* Returns the array of the variables for this goal.
*/
public IntExpArray vars()
{
return _intvars;
}
/**
* Initializes an array of instantiation goals for the variables.
*/
void initGoals()
{
int size = _intvars.size();
_goals = new FastVector(size);
for(int i=0; i < size; i++)
{
IntVar var = (IntVar)_intvars.elementAt(i);
Goal goal;
if (_dichotomize)
{
goal = new GoalDichotomize(var,_recursiveInstantiate);
}
else
{
goal = new GoalInstantiate(var,_value_selector,_recursiveInstantiate);
}
_goals.addElement(goal);
}
}
/**
* Returns a String representation of this goal.
* @return a String representation of this goal.
*/
public String toString()
{
return "Generate("+_intvars.size()+")";
}
/**
* Instantiates all variables in the order defined by the IntVarSelector.
*/
public Goal execute() throws Failure
{
//Debug.on();Debug.print("Generate"+_intvars);Debug.off();
int index = _var_selector.select();
if (index == -1)
return null; // all vars are instantiated
// IntVar var = (IntVar)_intvars.elementAt(index);
// Debug.on();Debug.print("Var Selected:"+var);Debug.off();
Goal search_goal = (Goal)_goals.elementAt(index);
return new GoalAnd(search_goal,this);
}
} // ~GoalGenerate