DiscreteDomain.java

  1. /* Copyright 2015 Laurent COCAULT
  2.  * Licensed to Laurent COCAULT under one or more contributor license agreements.
  3.  * See the NOTICE file distributed with this work for additional information
  4.  * regarding copyright ownership. Laurent COCAULT licenses this file to You
  5.  * under the Apache License, Version 2.0 (the "License"); you may not use this
  6.  * file except in compliance with the License.  You may obtain a copy of the
  7.  * License at
  8.  *
  9.  *   http://www.apache.org/licenses/LICENSE-2.0
  10.  *
  11.  * Unless required by applicable law or agreed to in writing, software
  12.  * distributed under the License is distributed on an "AS IS" BASIS,
  13.  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  14.  * See the License for the specific language governing permissions and
  15.  * limitations under the License.
  16.  */
  17. package org.csp.constraint.model;

  19. import java.util.Iterator;
  20. import java.util.TreeSet;

  22. /**
  23.  * Represents a domain as a set of values.
  24.  */
  25. public class DiscreteDomain<T extends Value<T>> implements Domain<T> {

  27.     /**
  28.      * Values of the domain.
  29.      */
  30.     private TreeSet<T> values_;

  32.     /**
  33.      * Default constructor.
  34.      */
  35.     public DiscreteDomain() {
  36.         values_ = new TreeSet<T>();
  37.     }

  39.     /**
  40.      * Add a value to the domain.
  41.      * @param value
  42.      *            Value to add
  43.      */
  44.     public void addValue(final T value) {
  45.         values_.add(value);
  46.     }

  48.     /**
  49.      * {@inheritDoc}
  50.      */
  51.     @Override
  52.     public boolean contains(final Value<T> value) {
  53.         return values_.contains(value);
  54.     }

  56.     /**
  57.      * {@inheritDoc}
  58.      */
  59.     @Override
  60.     public Domain<T> copy() {
  61.         final DiscreteDomain<T> copy = new DiscreteDomain<T>();
  62.         copy.values_ = new TreeSet<T>(values_);
  63.         return copy;
  64.     }

  66.     /**
  67.      * {@inheritDoc}
  68.      */
  69.     @Override
  70.     public Value<T> getFirstValue() throws EmptyDomainException {
  71.         if (values_.isEmpty()) {
  72.             throw new EmptyDomainException();
  73.         }
  74.         return values_.first();
  75.     }

  77.     /**
  78.      * {@inheritDoc}
  79.      */
  80.     @Override
  81.     public int getSize() {
  82.         return values_.size();
  83.     }

  85.     /**
  86.      * {@inheritDoc}
  87.      */
  88.     @Override
  89.     public Value<T> getValue() throws UnboundDomainException {
  90.         if (!hasSingleValue()) {
  91.             throw new UnboundDomainException();
  92.         }
  93.         return getFirstValue();
  94.     }

  96.     /**
  97.      * {@inheritDoc}
  98.      */
  99.     @Override
  100.     public boolean hasSingleValue() {
  101.         return values_.size() == 1;
  102.     }

  104.     /**
  105.      * {@inheritDoc}
  106.      */
  107.     @Override
  108.     public boolean isEmpty() {
  109.         return values_.isEmpty();
  110.     }

  112.     /**
  113.      * {@inheritDoc}
  114.      */
  115.     @Override
  116.     public boolean isInDomain(final Value<T> value) {
  117.         return values_.contains(value);
  118.     }

  120.     /**
  121.      * {@inheritDoc}
  122.      */
  123.     @Override
  124.     public Iterator<T> iterator() {
  125.         return values_.iterator();
  126.     }

  128.     /**
  129.      * {@inheritDoc}
  130.      */
  131.     @Override
  132.     public boolean reduceToDomainIntersection(final Domain<T> other) {
  133.         boolean domainChanged = false;
  134.         final Iterator<T> values = values_.iterator();
  135.         // Run through the possible values of the domain and check if it also in
  136.         // the other domain. If a value is not found in the other domain it is
  137.         // removed.
  138.         while (values.hasNext()) {
  139.             final Value<T> value = values.next();
  140.             if (!other.isInDomain(value)) {
  141.                 // The value is not in the other domain, remove it
  142.                 values.remove();
  143.                 domainChanged = true;
  144.             }
  145.         }
  146.         return domainChanged;
  147.     }

  149.     /**
  150.      * {@inheritDoc}
  151.      */
  152.     @Override
  153.     public boolean removeValue(final Value<T> value) {
  154.         return values_.remove(value);
  155.     }

  157.     /**
  158.      * {@inheritDoc}
  159.      */
  160.     @Override
  161.     public boolean setValue(final Value<T> value) {
  162.         final boolean domainChanged = !(hasSingleValue() && isInDomain(value));
  163.         if (domainChanged) {
  164.             // The domain is reduced to only one value
  165.             values_.clear();
  166.             values_.add(value.value());
  167.         }
  168.         return domainChanged;
  169.     }

  171.     /**
  172.      * {@inheritDoc}
  173.      */
  174.     @Override
  175.     public String toString() {
  176.         return values_.toString();
  177.     }

  179. }
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