1 /*
2 * Copyright (C) 2009, Google Inc.
3 * Copyright (C) 2008, Shawn O. Pearce <spearce@spearce.org>
4 * and other copyright owners as documented in the project's IP log.
5 *
6 * This program and the accompanying materials are made available
7 * under the terms of the Eclipse Distribution License v1.0 which
8 * accompanies this distribution, is reproduced below, and is
9 * available at http://www.eclipse.org/org/documents/edl-v10.php
10 *
11 * All rights reserved.
12 *
13 * Redistribution and use in source and binary forms, with or
14 * without modification, are permitted provided that the following
15 * conditions are met:
16 *
17 * - Redistributions of source code must retain the above copyright
18 * notice, this list of conditions and the following disclaimer.
19 *
20 * - Redistributions in binary form must reproduce the above
21 * copyright notice, this list of conditions and the following
22 * disclaimer in the documentation and/or other materials provided
23 * with the distribution.
24 *
25 * - Neither the name of the Eclipse Foundation, Inc. nor the
26 * names of its contributors may be used to endorse or promote
27 * products derived from this software without specific prior
28 * written permission.
29 *
30 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
31 * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
32 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
33 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
34 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
35 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
36 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
37 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
38 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
39 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
40 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
41 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
42 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
43 */
44
45 package org.eclipse.jgit.util;
46
47 import org.eclipse.jgit.internal.JGitText;
48 import org.eclipse.jgit.lib.Constants;
49
50 /**
51 * Searches text using only substring search.
52 * <p>
53 * Instances are thread-safe. Multiple concurrent threads may perform matches on
54 * different character sequences at the same time.
55 */
56 public class RawSubStringPattern {
57 private final String needleString;
58
59 private final byte[] needle;
60
61 /**
62 * Construct a new substring pattern.
63 *
64 * @param patternText
65 * text to locate. This should be a literal string, as no
66 * meta-characters are supported by this implementation. The
67 * string may not be the empty string.
68 */
69 public RawSubStringPattern(String patternText) {
70 if (patternText.length() == 0)
71 throw new IllegalArgumentException(JGitText.get().cannotMatchOnEmptyString);
72 needleString = patternText;
73
74 final byte[] b = Constants.encode(patternText);
75 needle = new byte[b.length];
76 for (int i = 0; i < b.length; i++)
77 needle[i] = lc(b[i]);
78 }
79
80 /**
81 * Match a character sequence against this pattern.
82 *
83 * @param rcs
84 * the sequence to match. Must not be null but the length of the
85 * sequence is permitted to be 0.
86 * @return offset within <code>rcs</code> of the first occurrence of this
87 * pattern; -1 if this pattern does not appear at any position of
88 * <code>rcs</code>.
89 */
90 public int match(RawCharSequence rcs) {
91 final int needleLen = needle.length;
92 final byte first = needle[0];
93
94 final byte[] text = rcs.buffer;
95 int matchPos = rcs.startPtr;
96 final int maxPos = rcs.endPtr - needleLen;
97
98 OUTER: for (; matchPos <= maxPos; matchPos++) {
99 if (neq(first, text[matchPos])) {
100 while (++matchPos <= maxPos && neq(first, text[matchPos])) {
101 /* skip */
102 }
103 if (matchPos > maxPos)
104 return -1;
105 }
106
107 int si = matchPos + 1;
108 for (int j = 1; j < needleLen; j++, si++) {
109 if (neq(needle[j], text[si]))
110 continue OUTER;
111 }
112 return matchPos;
113 }
114 return -1;
115 }
116
117 private static final boolean neq(byte a, byte b) {
118 return a != b && a != lc(b);
119 }
120
121 private static final byte lc(byte q) {
122 return (byte) StringUtils.toLowerCase((char) (q & 0xff));
123 }
124
125 /**
126 * Get the literal pattern string this instance searches for.
127 *
128 * @return the pattern string given to our constructor.
129 */
130 public String pattern() {
131 return needleString;
132 }
133
134 /** {@inheritDoc} */
135 @Override
136 public String toString() {
137 return pattern();
138 }
139 }