1 /*
2 * #%L
3 * prolobjectlink-jpi
4 * %%
5 * Copyright (C) 2019 Prolobjectlink Project
6 * %%
7 * Permission is hereby granted, free of charge, to any person obtaining a copy
8 * of this software and associated documentation files (the "Software"), to deal
9 * in the Software without restriction, including without limitation the rights
10 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
11 * copies of the Software, and to permit persons to whom the Software is
12 * furnished to do so, subject to the following conditions:
13 *
14 * The above copyright notice and this permission notice shall be included in
15 * all copies or substantial portions of the Software.
16 *
17 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
18 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
19 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
20 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
21 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
22 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
23 * THE SOFTWARE.
24 * #L%
25 */
26 package io.github.prolobjectlink.prolog;
27
28 import java.util.Collection;
29 import java.util.Iterator;
30 import java.util.NoSuchElementException;
31
32 /**
33 * Iterator class implementation for Prolog Query
34 *
35 * @author Jose Zalacain
36 * @since 1.0
37 */
38 final class PrologQueryIterator extends AbstractIterator<Collection<PrologTerm>>
39 implements Iterator<Collection<PrologTerm>> {
40
41 private final PrologQuery query;
42
43 /**
44 * Create a new query iterator over given PrologQuery.
45 *
46 * @param query PrologQuery to iterate
47 */
48 PrologQueryIterator(PrologQuery query) {
49 this.query = query;
50 }
51
52 /**
53 * True if the current Prolog query has more solution, false if not has more
54 * solution
55 */
56 public boolean hasNext() {
57 return query.hasMoreSolutions();
58 }
59
60 /**
61 * Next Prolog solution terms
62 */
63 public Collection<PrologTerm> next() {
64 if (!query.hasMoreSolutions()) {
65 throw new NoSuchElementException();
66 }
67 return query.nextVariablesSolution().values();
68 }
69
70 /**
71 * Skip the next solution invoking next solution method
72 */
73 @Override
74 public void remove() {
75 query.nextSolution();
76 }
77
78 }