01 /*
02 * Java Genetic Algorithm Library (jenetics-7.1.0).
03 * Copyright (c) 2007-2022 Franz Wilhelmstötter
04 *
05 * Licensed under the Apache License, Version 2.0 (the "License");
06 * you may not use this file except in compliance with the License.
07 * You may obtain a copy of the License at
08 *
09 * 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 * Author:
18 * Franz Wilhelmstötter (franz.wilhelmstoetter@gmail.com)
19 */
20 package io.jenetics.ext.internal.parser;
21
22 import java.util.stream.Collectors;
23 import java.util.stream.IntStream;
24
25 /**
26 * Ring-buffer for storing lookup tokens.
27 *
28 * @param <V> the token value type
29 *
30 * @author <a href="mailto:franz.wilhelmstoetter@gmail.com">Franz Wilhelmstötter</a>
31 * @since 7.1
32 * @version 7.1
33 */
34 final class TokenRing<V> {
35 private final Object[] _tokens;
36
37 private int _pos = 0;
38
39 TokenRing(final int k) {
40 _tokens = new Object[k];
41 }
42
43 void add(final V token) {
44 _tokens[_pos] = token;
45 _pos = (_pos + 1)%_tokens.length;
46 }
47
48 @SuppressWarnings("unchecked")
49 public V LT(final int i) {
50 return (V)_tokens[(_pos + i - 1)%_tokens.length];
51 }
52
53 @Override
54 public String toString() {
55 return IntStream.rangeClosed(1, _tokens.length)
56 .mapToObj(i -> i + ":'" + LT(i) + "'")
57 .collect(Collectors.joining(", ", "[", "]"));
58 }
59
60 }
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