com.exigen.ie.constrainer.GoalInstantiate Maven / Gradle / Ivy
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.
*/
///////////////////////////////////////////////////////////////////////////////
/**
* An implementation of a {@link Goal} that instaintiates the constraint integer variable.
*
* It uses {@link IntValueSelector} to select the next value
* to be removed from the domain of the variable.
*
* The selector should select the values that can be effectively removed
* from the domain of the variable. For example, if the domain type is plain
* then selector should select only min or max values from the domain.
* GoalInstantiate can use both recursive and non-recursive search algorithms.
* Recursive implementation iterates the domain looking for a value that can be
* assigned to a variable by GoalSetValue. Non-recursive implementations invokes
* GoalSetValue ones and removes the given value if it fails.
* @see IntVar
* @see IntValueSelector
*/
public class GoalInstantiate extends GoalImpl
{
private IntVar _intvar;
private IntValueSelector _selector;
private Impl _impl;
/**
* Creates GoalInstantiate using IntValueSelectorMin as
* a default ValueSelector. The goal constructed that way uses a recursive
* search algorithm.
*/
public GoalInstantiate(IntVar intvar)
{
this(intvar, new IntValueSelectorMin(), true);
}
/**
* Constructor with a given variable and value selector.
*/
public GoalInstantiate(IntVar intvar, IntValueSelector selector)
{
this(intvar, selector, true);
}
/**
* Constructor with a given variable, value selector, and recursive flag.
*/
public GoalInstantiate(IntVar intvar, IntValueSelector selector, boolean recursive)
{
super(intvar.constrainer(),"");// "Instantiate("+intvar.name()+")");
_intvar = intvar;
_selector = selector;
if(recursive)
_impl = new RecursiveImpl();
else
_impl = new NonRecursiveImpl();
}
/**
* An implementation of the instantiation algorithm for the integer variable using value selector.
*/
public Goal execute() throws Failure
{
if (_intvar.size()==1)
return null;
int chosen_value = _selector.select(_intvar);
return _impl.instantiate(chosen_value);
}
/**
* Returns a String representation of this goal.
* @return a String representation of this goal.
*/
public String toString()
{
return "Instantiate("+_intvar.name()+")";
}
/**
* An internal interface for the instantiation of the variable.
*/
interface Impl extends java.io.Serializable
{
/**
* Instantiate variable with a chosen_value.
*/
public Goal instantiate(int chosen_value) throws Failure;
}
/**
* Recursive instantiation.
*/
class RecursiveImpl implements Impl
{
private GoalSetValue _goal_value;
private GoalRemoveValue _goal_remove;
private GoalSetMin _goal_min;
private GoalSetMax _goal_max;
public RecursiveImpl()
{
_goal_value = new GoalSetValue(_intvar);
if (_intvar.domainType() != IntVar.DOMAIN_PLAIN)
{
_goal_remove = new GoalRemoveValue(_intvar);
}
else
{
_goal_min = new GoalSetMin(_intvar);
_goal_max = new GoalSetMax(_intvar);
}
}
public Goal instantiate(int chosen_value) throws Failure
{
_goal_value.value(chosen_value);
Goal goal_limit ;
if (_intvar.domainType() != IntVar.DOMAIN_PLAIN)
{
_goal_remove.value(chosen_value);
goal_limit = _goal_remove;
}
else
{
if (chosen_value == _intvar.min())
{
_goal_min.min(chosen_value+1);
goal_limit = _goal_min;
}
else
{
_goal_max.max(chosen_value-1);
goal_limit = _goal_max;
}
}
//Debug.on();Debug.print(this + " by "+chosen_value);Debug.off();
return new GoalOr(_goal_value,
new GoalAnd(goal_limit, GoalInstantiate.this) );
}
} // ~RecursiveImpl
/**
* Non recursive instantiation.
*/
class NonRecursiveImpl implements Impl
{
public NonRecursiveImpl()
{
}
public Goal instantiate(int chosen_value) throws Failure
{
Goal goal_value = new GoalSetValue(_intvar, chosen_value);
Goal goal_limit;
if (_intvar.domainType() != IntVar.DOMAIN_PLAIN)
{
goal_limit = new GoalRemoveValue(_intvar,chosen_value);
}
else
{
if (chosen_value == _intvar.min())
{
goal_limit = new GoalSetMin(_intvar,chosen_value+1);
}
else
{
goal_limit = new GoalSetMax(_intvar,chosen_value-1);
}
}
//Debug.on();Debug.print(this + " by "+chosen_value);Debug.off();
return new GoalOr(goal_value, goal_limit);
}
} // ~NonRecursiveImpl
} // ~GoalInstantiate