1 | /****************************************************************************
|
---|
2 | **
|
---|
3 | ** Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies).
|
---|
4 | ** All rights reserved.
|
---|
5 | ** Contact: Nokia Corporation ([email protected])
|
---|
6 | **
|
---|
7 | ** This file is part of the QtCore module of the Qt Toolkit.
|
---|
8 | **
|
---|
9 | ** $QT_BEGIN_LICENSE:LGPL$
|
---|
10 | ** Commercial Usage
|
---|
11 | ** Licensees holding valid Qt Commercial licenses may use this file in
|
---|
12 | ** accordance with the Qt Commercial License Agreement provided with the
|
---|
13 | ** Software or, alternatively, in accordance with the terms contained in
|
---|
14 | ** a written agreement between you and Nokia.
|
---|
15 | **
|
---|
16 | ** GNU Lesser General Public License Usage
|
---|
17 | ** Alternatively, this file may be used under the terms of the GNU Lesser
|
---|
18 | ** General Public License version 2.1 as published by the Free Software
|
---|
19 | ** Foundation and appearing in the file LICENSE.LGPL included in the
|
---|
20 | ** packaging of this file. Please review the following information to
|
---|
21 | ** ensure the GNU Lesser General Public License version 2.1 requirements
|
---|
22 | ** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
|
---|
23 | **
|
---|
24 | ** In addition, as a special exception, Nokia gives you certain additional
|
---|
25 | ** rights. These rights are described in the Nokia Qt LGPL Exception
|
---|
26 | ** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
|
---|
27 | **
|
---|
28 | ** GNU General Public License Usage
|
---|
29 | ** Alternatively, this file may be used under the terms of the GNU
|
---|
30 | ** General Public License version 3.0 as published by the Free Software
|
---|
31 | ** Foundation and appearing in the file LICENSE.GPL included in the
|
---|
32 | ** packaging of this file. Please review the following information to
|
---|
33 | ** ensure the GNU General Public License version 3.0 requirements will be
|
---|
34 | ** met: http://www.gnu.org/copyleft/gpl.html.
|
---|
35 | **
|
---|
36 | ** If you have questions regarding the use of this file, please contact
|
---|
37 | ** Nokia at [email protected].
|
---|
38 | ** $QT_END_LICENSE$
|
---|
39 | **
|
---|
40 | ****************************************************************************/
|
---|
41 |
|
---|
42 | #include "qbytearraymatcher.h"
|
---|
43 |
|
---|
44 | #include <limits.h>
|
---|
45 |
|
---|
46 | QT_BEGIN_NAMESPACE
|
---|
47 |
|
---|
48 | static inline void bm_init_skiptable(const uchar *cc, int len, uchar *skiptable)
|
---|
49 | {
|
---|
50 | int l = qMin(len, 255);
|
---|
51 | memset(skiptable, l, 256*sizeof(uchar));
|
---|
52 | cc += len - l;
|
---|
53 | while (l--)
|
---|
54 | skiptable[*cc++] = l;
|
---|
55 | }
|
---|
56 |
|
---|
57 | static inline int bm_find(const uchar *cc, int l, int index, const uchar *puc, uint pl,
|
---|
58 | const uchar *skiptable)
|
---|
59 | {
|
---|
60 | if (pl == 0)
|
---|
61 | return index > l ? -1 : index;
|
---|
62 | const uint pl_minus_one = pl - 1;
|
---|
63 |
|
---|
64 | register const uchar *current = cc + index + pl_minus_one;
|
---|
65 | const uchar *end = cc + l;
|
---|
66 | while (current < end) {
|
---|
67 | uint skip = skiptable[*current];
|
---|
68 | if (!skip) {
|
---|
69 | // possible match
|
---|
70 | while (skip < pl) {
|
---|
71 | if (*(current - skip) != puc[pl_minus_one - skip])
|
---|
72 | break;
|
---|
73 | skip++;
|
---|
74 | }
|
---|
75 | if (skip > pl_minus_one) // we have a match
|
---|
76 | return (current - cc) - skip + 1;
|
---|
77 |
|
---|
78 | // in case we don't have a match we are a bit inefficient as we only skip by one
|
---|
79 | // when we have the non matching char in the string.
|
---|
80 | if (skiptable[*(current - skip)] == pl)
|
---|
81 | skip = pl - skip;
|
---|
82 | else
|
---|
83 | skip = 1;
|
---|
84 | }
|
---|
85 | if (current > end - skip)
|
---|
86 | break;
|
---|
87 | current += skip;
|
---|
88 | }
|
---|
89 | return -1; // not found
|
---|
90 | }
|
---|
91 |
|
---|
92 | /*! \class QByteArrayMatcher
|
---|
93 | \brief The QByteArrayMatcher class holds a sequence of bytes that
|
---|
94 | can be quickly matched in a byte array.
|
---|
95 |
|
---|
96 | \ingroup tools
|
---|
97 | \ingroup string-processing
|
---|
98 |
|
---|
99 | This class is useful when you have a sequence of bytes that you
|
---|
100 | want to repeatedly match against some byte arrays (perhaps in a
|
---|
101 | loop), or when you want to search for the same sequence of bytes
|
---|
102 | multiple times in the same byte array. Using a matcher object and
|
---|
103 | indexIn() is faster than matching a plain QByteArray with
|
---|
104 | QByteArray::indexOf() if repeated matching takes place. This
|
---|
105 | class offers no benefit if you are doing one-off byte array
|
---|
106 | matches.
|
---|
107 |
|
---|
108 | Create the QByteArrayMatcher with the QByteArray you want to
|
---|
109 | search for. Then call indexIn() on the QByteArray that you want to
|
---|
110 | search.
|
---|
111 |
|
---|
112 | \sa QByteArray, QStringMatcher
|
---|
113 | */
|
---|
114 |
|
---|
115 | /*!
|
---|
116 | Constructs an empty byte array matcher that won't match anything.
|
---|
117 | Call setPattern() to give it a pattern to match.
|
---|
118 | */
|
---|
119 | QByteArrayMatcher::QByteArrayMatcher()
|
---|
120 | : d(0)
|
---|
121 | {
|
---|
122 | p.p = 0;
|
---|
123 | p.l = 0;
|
---|
124 | qMemSet(p.q_skiptable, 0, sizeof(p.q_skiptable));
|
---|
125 | }
|
---|
126 |
|
---|
127 | /*!
|
---|
128 | Constructs a byte array matcher from \a pattern. \a pattern
|
---|
129 | has the given \a length. \a pattern must remain in scope, but
|
---|
130 | the destructor does not delete \a pattern.
|
---|
131 | */
|
---|
132 | QByteArrayMatcher::QByteArrayMatcher(const char *pattern, int length)
|
---|
133 | : d(0)
|
---|
134 | {
|
---|
135 | p.p = reinterpret_cast<const uchar *>(pattern);
|
---|
136 | p.l = length;
|
---|
137 | bm_init_skiptable(p.p, p.l, p.q_skiptable);
|
---|
138 | }
|
---|
139 |
|
---|
140 | /*!
|
---|
141 | Constructs a byte array matcher that will search for \a pattern.
|
---|
142 | Call indexIn() to perform a search.
|
---|
143 | */
|
---|
144 | QByteArrayMatcher::QByteArrayMatcher(const QByteArray &pattern)
|
---|
145 | : d(0), q_pattern(pattern)
|
---|
146 | {
|
---|
147 | p.p = reinterpret_cast<const uchar *>(pattern.constData());
|
---|
148 | p.l = pattern.size();
|
---|
149 | bm_init_skiptable(p.p, p.l, p.q_skiptable);
|
---|
150 | }
|
---|
151 |
|
---|
152 | /*!
|
---|
153 | Copies the \a other byte array matcher to this byte array matcher.
|
---|
154 | */
|
---|
155 | QByteArrayMatcher::QByteArrayMatcher(const QByteArrayMatcher &other)
|
---|
156 | : d(0)
|
---|
157 | {
|
---|
158 | operator=(other);
|
---|
159 | }
|
---|
160 |
|
---|
161 | /*!
|
---|
162 | Destroys the byte array matcher.
|
---|
163 | */
|
---|
164 | QByteArrayMatcher::~QByteArrayMatcher()
|
---|
165 | {
|
---|
166 | }
|
---|
167 |
|
---|
168 | /*!
|
---|
169 | Assigns the \a other byte array matcher to this byte array matcher.
|
---|
170 | */
|
---|
171 | QByteArrayMatcher &QByteArrayMatcher::operator=(const QByteArrayMatcher &other)
|
---|
172 | {
|
---|
173 | q_pattern = other.q_pattern;
|
---|
174 | qMemCopy(&p, &other.p, sizeof(p));
|
---|
175 | return *this;
|
---|
176 | }
|
---|
177 |
|
---|
178 | /*!
|
---|
179 | Sets the byte array that this byte array matcher will search for
|
---|
180 | to \a pattern.
|
---|
181 |
|
---|
182 | \sa pattern(), indexIn()
|
---|
183 | */
|
---|
184 | void QByteArrayMatcher::setPattern(const QByteArray &pattern)
|
---|
185 | {
|
---|
186 | q_pattern = pattern;
|
---|
187 | p.p = reinterpret_cast<const uchar *>(pattern.constData());
|
---|
188 | p.l = pattern.size();
|
---|
189 | bm_init_skiptable(p.p, p.l, p.q_skiptable);
|
---|
190 | }
|
---|
191 |
|
---|
192 | /*!
|
---|
193 | Searches the byte array \a ba, from byte position \a from (default
|
---|
194 | 0, i.e. from the first byte), for the byte array pattern() that
|
---|
195 | was set in the constructor or in the most recent call to
|
---|
196 | setPattern(). Returns the position where the pattern() matched in
|
---|
197 | \a ba, or -1 if no match was found.
|
---|
198 | */
|
---|
199 | int QByteArrayMatcher::indexIn(const QByteArray &ba, int from) const
|
---|
200 | {
|
---|
201 | if (from < 0)
|
---|
202 | from = 0;
|
---|
203 | return bm_find(reinterpret_cast<const uchar *>(ba.constData()), ba.size(), from,
|
---|
204 | p.p, p.l, p.q_skiptable);
|
---|
205 | }
|
---|
206 |
|
---|
207 | /*!
|
---|
208 | Searches the char string \a str, which has length \a len, from
|
---|
209 | byte position \a from (default 0, i.e. from the first byte), for
|
---|
210 | the byte array pattern() that was set in the constructor or in the
|
---|
211 | most recent call to setPattern(). Returns the position where the
|
---|
212 | pattern() matched in \a str, or -1 if no match was found.
|
---|
213 | */
|
---|
214 | int QByteArrayMatcher::indexIn(const char *str, int len, int from) const
|
---|
215 | {
|
---|
216 | if (from < 0)
|
---|
217 | from = 0;
|
---|
218 | return bm_find(reinterpret_cast<const uchar *>(str), len, from,
|
---|
219 | p.p, p.l, p.q_skiptable);
|
---|
220 | }
|
---|
221 |
|
---|
222 | /*!
|
---|
223 | \fn QByteArray QByteArrayMatcher::pattern() const
|
---|
224 |
|
---|
225 | Returns the byte array pattern that this byte array matcher will
|
---|
226 | search for.
|
---|
227 |
|
---|
228 | \sa setPattern()
|
---|
229 | */
|
---|
230 |
|
---|
231 |
|
---|
232 | static int findChar(const char *str, int len, char ch, int from)
|
---|
233 | {
|
---|
234 | const uchar *s = (const uchar *)str;
|
---|
235 | uchar c = (uchar)ch;
|
---|
236 | if (from < 0)
|
---|
237 | from = qMax(from + len, 0);
|
---|
238 | if (from < len) {
|
---|
239 | const uchar *n = s + from - 1;
|
---|
240 | const uchar *e = s + len;
|
---|
241 | while (++n != e)
|
---|
242 | if (*n == c)
|
---|
243 | return n - s;
|
---|
244 | }
|
---|
245 | return -1;
|
---|
246 | }
|
---|
247 |
|
---|
248 | /*! \internal
|
---|
249 | */
|
---|
250 | static int qFindByteArrayBoyerMoore(
|
---|
251 | const char *haystack, int haystackLen, int haystackOffset,
|
---|
252 | const char *needle, int needleLen)
|
---|
253 | {
|
---|
254 | uchar skiptable[256];
|
---|
255 | bm_init_skiptable((const uchar *)needle, needleLen, skiptable);
|
---|
256 | if (haystackOffset < 0)
|
---|
257 | haystackOffset = 0;
|
---|
258 | return bm_find((const uchar *)haystack, haystackLen, haystackOffset,
|
---|
259 | (const uchar *)needle, needleLen, skiptable);
|
---|
260 | }
|
---|
261 |
|
---|
262 | #define REHASH(a) \
|
---|
263 | if (sl_minus_1 < sizeof(uint) * CHAR_BIT) \
|
---|
264 | hashHaystack -= (a) << sl_minus_1; \
|
---|
265 | hashHaystack <<= 1
|
---|
266 |
|
---|
267 | /*! \internal
|
---|
268 | */
|
---|
269 | int qFindByteArray(
|
---|
270 | const char *haystack0, int haystackLen, int from,
|
---|
271 | const char *needle, int needleLen)
|
---|
272 | {
|
---|
273 | const int l = haystackLen;
|
---|
274 | const int sl = needleLen;
|
---|
275 | if (from < 0)
|
---|
276 | from += l;
|
---|
277 | if (uint(sl + from) > (uint)l)
|
---|
278 | return -1;
|
---|
279 | if (!sl)
|
---|
280 | return from;
|
---|
281 | if (!l)
|
---|
282 | return -1;
|
---|
283 |
|
---|
284 | if (sl == 1)
|
---|
285 | return findChar(haystack0, haystackLen, needle[0], from);
|
---|
286 |
|
---|
287 | /*
|
---|
288 | We use the Boyer-Moore algorithm in cases where the overhead
|
---|
289 | for the skip table should pay off, otherwise we use a simple
|
---|
290 | hash function.
|
---|
291 | */
|
---|
292 | if (l > 500 && sl > 5)
|
---|
293 | return qFindByteArrayBoyerMoore(haystack0, haystackLen, from,
|
---|
294 | needle, needleLen);
|
---|
295 |
|
---|
296 | /*
|
---|
297 | We use some hashing for efficiency's sake. Instead of
|
---|
298 | comparing strings, we compare the hash value of str with that
|
---|
299 | of a part of this QString. Only if that matches, we call memcmp().
|
---|
300 | */
|
---|
301 | const char *haystack = haystack0 + from;
|
---|
302 | const char *end = haystack0 + (l - sl);
|
---|
303 | const uint sl_minus_1 = sl - 1;
|
---|
304 | uint hashNeedle = 0, hashHaystack = 0;
|
---|
305 | int idx;
|
---|
306 | for (idx = 0; idx < sl; ++idx) {
|
---|
307 | hashNeedle = ((hashNeedle<<1) + needle[idx]);
|
---|
308 | hashHaystack = ((hashHaystack<<1) + haystack[idx]);
|
---|
309 | }
|
---|
310 | hashHaystack -= *(haystack + sl_minus_1);
|
---|
311 |
|
---|
312 | while (haystack <= end) {
|
---|
313 | hashHaystack += *(haystack + sl_minus_1);
|
---|
314 | if (hashHaystack == hashNeedle && *needle == *haystack
|
---|
315 | && memcmp(needle, haystack, sl) == 0)
|
---|
316 | return haystack - haystack0;
|
---|
317 |
|
---|
318 | REHASH(*haystack);
|
---|
319 | ++haystack;
|
---|
320 | }
|
---|
321 | return -1;
|
---|
322 | }
|
---|
323 |
|
---|
324 | QT_END_NAMESPACE
|
---|