org.openl.ie.constrainer.GoalInstantiate Maven / Gradle / Ivy
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package org.openl.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 a Selector 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.
*
*/
public class GoalInstantiate extends GoalImpl {
/**
* An internal interface for the instantiation of the variable.
*/
interface Impl extends java.io.Serializable {
/**
* Instantiate variable with a chosen_value.
*/
Goal instantiate(int chosen_value) throws Failure;
}
/**
* Recursive instantiation.
*/
class RecursiveImpl implements Impl {
private final 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);
}
}
@Override
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
private final IntVar _intvar;
private final Impl _impl;
/**
* Creates GoalInstantiate using IntValueSelectorMin as a default ValueSelector. The goal constructed
* that way uses a recursive search algorithm.
*/
public GoalInstantiate(IntVar intvar) {
super(intvar.constrainer(), "");// "Instantiate("+intvar.name()+")");
_intvar = intvar;
_impl = new RecursiveImpl();
}
/**
* An implementation of the instantiation algorithm for the integer variable using value selector.
*/
@Override
public Goal execute() throws Failure {
if (_intvar.size() == 1) {
return null;
}
int chosen_value = _intvar.min();
return _impl.instantiate(chosen_value);
}
/**
* Returns a String representation of this goal.
*
* @return a String representation of this goal.
*/
@Override
public String toString() {
return "Instantiate(" + _intvar.name() + ")";
}
} // ~GoalInstantiate