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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  }