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1/*******************************************************************************
2 * Copyright (c) 2010-2015, Andras Szabolcs Nagy, Abel Hegedus, Akos Horvath, Zoltan Ujhelyi and Daniel Varro
3 * This program and the accompanying materials are made available under the
4 * terms of the Eclipse Public License v. 2.0 which is available at
5 * http://www.eclipse.org/legal/epl-v20.html.
6 *
7 * SPDX-License-Identifier: EPL-2.0
8 *******************************************************************************/
9package org.eclipse.viatra.dse.objectives.impl;
10
11import java.util.Comparator;
12import java.util.Objects;
13
14import org.eclipse.viatra.dse.base.ThreadContext;
15import org.eclipse.viatra.dse.objectives.Comparators;
16import org.eclipse.viatra.dse.objectives.IObjective;
17
18/**
19 * This abstract class implements the basic functionality of an objective ({@link IObjective} namely its name,
20 * comparator, level and fitness hard constraint.
21 *
22 * @author Andras Szabolcs Nagy
23 *
24 */
25public abstract class BaseObjective implements IObjective {
26
27 protected final String name;
28 protected Comparator<Double> comparator = Comparators.HIGHER_IS_BETTER;
29 protected int level = 0;
30
31 protected double fitnessConstraint;
32 protected boolean isThereFitnessConstraint = false;
33 protected Comparator<Double> fitnessConstraintComparator;
34
35 public BaseObjective(String name) {
36 Objects.requireNonNull(name, "Name of the objective cannot be null.");
37 this.name = name;
38 }
39
40 @Override
41 public String getName() {
42 return name;
43 }
44
45 @Override
46 public void setComparator(Comparator<Double> comparator) {
47 this.comparator = comparator;
48 }
49
50 @Override
51 public Comparator<Double> getComparator() {
52 return comparator;
53 }
54
55 @Override
56 public void setLevel(int level) {
57 this.level = level;
58 }
59
60 @Override
61 public int getLevel() {
62 return level;
63 }
64
65 public BaseObjective withLevel(int level) {
66 setLevel(level);
67 return this;
68 }
69
70 public BaseObjective withComparator(Comparator<Double> comparator) {
71 setComparator(comparator);
72 return this;
73 }
74
75 /**
76 * Adds a hard constraint on the fitness value. For example, the fitness value must be better than 10 to accept the
77 * current state as a solution.
78 *
79 * @param fitnessConstraint
80 * Solutions should be better than this value.
81 * @param fitnessConstraintComparator
82 * {@link Comparator} to determine if the current state is better than the given value.
83 * @return The actual instance to enable builder pattern like usage.
84 */
85 public BaseObjective withHardConstraintOnFitness(double fitnessConstraint,
86 Comparator<Double> fitnessConstraintComparator) {
87 this.fitnessConstraint = fitnessConstraint;
88 this.fitnessConstraintComparator = fitnessConstraintComparator;
89 this.isThereFitnessConstraint = true;
90 return this;
91 }
92
93 /**
94 * Adds a hard constraint on the fitness value. For example, the fitness value must be better than 10 to accept the
95 * current state as a solution. The provided comparator will be used.
96 *
97 * @param fitnessConstraint
98 * Solutions should be better than this value.
99 * @return The actual instance to enable builder pattern like usage.
100 */
101 public BaseObjective withHardConstraintOnFitness(double fitnessConstraint) {
102 return withHardConstraintOnFitness(fitnessConstraint, null);
103 }
104
105 @Override
106 public void init(ThreadContext context) {
107 if (fitnessConstraintComparator == null) {
108 fitnessConstraintComparator = comparator;
109 }
110 }
111
112 @Override
113 public boolean isHardObjective() {
114 return isThereFitnessConstraint;
115 }
116
117 @Override
118 public boolean satisifiesHardObjective(Double fitness) {
119 if (isThereFitnessConstraint) {
120 int compare = fitnessConstraintComparator.compare(fitness, fitnessConstraint);
121 if (compare < 0) {
122 return false;
123 }
124 }
125 return true;
126 }
127
128 @Override
129 public int hashCode() {
130 return name.hashCode();
131 }
132
133 @Override
134 public boolean equals(Object obj) {
135 if (this == obj) {
136 return true;
137 }
138 if (obj instanceof BaseObjective) {
139 BaseObjective baseObjective = (BaseObjective) obj;
140 return name.equals(baseObjective.getName());
141 }
142 return false;
143 }
144
145 @Override
146 public String toString() {
147 return name;
148 }
149
150}