Author: [EMAIL PROTECTED]
Date: Tue Oct 14 01:57:31 2008
New Revision: 492
Modified:
branches/bleeding_edge/src/runtime.cc
branches/bleeding_edge/test/mjsunit/string-indexof.js
Log:
Most operations are faster than before.
Modified: branches/bleeding_edge/src/runtime.cc
==============================================================================
--- branches/bleeding_edge/src/runtime.cc (original)
+++ branches/bleeding_edge/src/runtime.cc Tue Oct 14 01:57:31 2008
@@ -952,148 +952,175 @@
}
+// Cap on the maximal shift in the Boyer-Moore implementation. By setting a
+// limit, we can fix the size of tables.
+static const int kBMMaxShift = 0xff;
+static const int kBMAlphabetSize = 0x100; // Reduce alphabet to this size.
+
+// Holds the two buffers used by Boyer-Moore string search's Good Suffix
+// shift. Only allows the last kBMMaxShift characters of the needle
+// to be indexed.
+class BMGoodSuffixBuffers: public AllStatic {
+ public:
+ BMGoodSuffixBuffers() {}
+ inline void init(int needle_length) {
+ ASSERT(needle_length > 1);
+ int start = needle_length < kBMMaxShift ? 0 : needle_length -
kBMMaxShift;
+ int len = needle_length - start;
+ biased_suffixes_ = suffixes_ - start;
+ biased_good_suffix_shift_ = good_suffix_shift_ - start;
+ for (int i = 0; i <= len; i++) {
+ good_suffix_shift_[i] = len;
+ }
+ }
+ inline int& suffix(int index) {
+ ASSERT(biased_suffixes_ + index >= suffixes_);
+ return biased_suffixes_[index];
+ }
+ inline int& shift(int index) {
+ ASSERT(biased_good_suffix_shift_ + index >= good_suffix_shift_);
+ return biased_good_suffix_shift_[index];
+ }
+ private:
+ int suffixes_[kBMMaxShift + 1];
+ int good_suffix_shift_[kBMMaxShift + 1];
+ int *biased_suffixes_;
+ int *biased_good_suffix_shift_;
+ DISALLOW_COPY_AND_ASSIGN(BMGoodSuffixBuffers);
+};
+
+// buffers reused by BoyerMoore
+static int bad_char_occurence[kBMAlphabetSize];
+static BMGoodSuffixBuffers bmgs_buffers;
+
+// Restricted Boyer-Moore string matching. Restricts tables to a
+// suffix of long pattern strings and handles only equivalence classes
+// of the full alphabet. This allows us to ensure that tables take only
+// a fixed amount of space.
template <typename schar, typename pchar>
-static int SingleCharIndexOf(Vector<const schar> string,
- pchar pattern_char,
+static int BoyerMooreIndexOf(Vector<const schar> subject,
+ Vector<const pchar> pattern,
int start_index) {
- for (int i = start_index, n = string.length(); i < n; i++) {
- if (pattern_char == string[i]) {
- return i;
- }
- }
- return -1;
-}
-
-// Trivial string search for shorter strings.
-template <typename pchar, typename schar>
-static int SimpleIndexOf(Vector<const schar> subject,
- Vector<const pchar> pattern,
- int start_index) {
- int pattern_length = pattern.length();
- int subject_length = subject.length();
- // We know our pattern is at least 2 characters, we cache the first so
- // the common case of the first character not matching is faster.
- pchar pattern_first_char = pattern[0];
- for (int i = start_index, n = subject_length - pattern_length; i <= n;
i++) {
- if (subject[i] != pattern_first_char) continue;
-
- bool failure = false;
- for (int j = 1; j < pattern_length; j++) {
- if (pattern[j] != subject[j+i]) {
- failure = true;
- break;
- }
- }
- if (!failure) {
- return i;
- }
- }
- return -1;
-}
-
-// Maximal length (+1) of suffix that is indexed. Also the size of the
-// maximal bad-character skip.
-static const int kBMHSignificantSuffixLength = 0xff;
-
-// Significant bits taken from characters to use in bad-character
-// skips, to reduce size of the table for Unicode letters.
-static const int kBMHSignificantBitsMask = 0xff;
-
-// Number of elements in bad-char table.
-static const int kBMHBadCharCount = kBMHSignificantBitsMask + 1;
-
-// Simplified Boyer-Moore string matching. Only uses bad-char skipping,
-// and restricts table to a suffix of long strings (also restricting
-// the maximum possible skip-length) in order to reduce space.
-template <typename schar, typename pchar>
-static int BoyerMooreHorspoolIndexOf(Vector<const schar> subject,
- Vector<const pchar> pattern,
- int start_index) {
- ASSERT(kBMHSignificantSuffixLength < 0x100); // We can use bytes as
skips.
- static byte bad_char_map[kBMHBadCharCount];
-
int m = pattern.length();
int n = subject.length();
- // Cap bad char table to last p chars of pattern. Also max skip value.
- int p = m < kBMHSignificantSuffixLength ? m :
kBMHSignificantSuffixLength;
- memset(bad_char_map, p, kBMHBadCharCount);
+ // Only preprocess at most kBMMaxShift last characters of pattern.
+ int start = m < kBMMaxShift ? 0 : m - kBMMaxShift;
+ int len = m - start;
// Run forwards to populate bad_char_table, so that *last* instance
// of character equivalence class is the one registered.
// Notice: Doesn't include last character.
- for (int i = p < m ? m - p : 0; i < m - 1; i++) {
+ for (int i = 0; i < kBMAlphabetSize; i++) {
+ bad_char_occurence[i] = start - 1;
+ }
+ for (int i = start; i < m; i++) {
uc32 c = pattern[i];
+ bad_char_occurence[c % kBMAlphabetSize] = i;
if (sizeof(schar) == 1 &&
sizeof(pchar) > 1 &&
c > String::kMaxAsciiCharCode) {
return -1;
}
- bad_char_map[c & kBMHSignificantBitsMask] = m - 1 - i;
}
+ // End of Bad Char computation.
- for (int i = start_index + m - 1, j = m - 1; i < n;) {
- schar c = subject[i];
- if (c == pattern[j]) {
- if (j == 0) {
- return i;
+ // Compute Good Suffix shift table.
+ bmgs_buffers.init(m);
+
+ bmgs_buffers.shift(m-1) = 1;
+ bmgs_buffers.suffix(m) = m + 1;
+ pchar last_char = pattern[m - 1];
+ int suffix = m + 1;
+ for (int i = m; i > start;) {
+ for (pchar c = pattern[i - 1]; suffix <= m && c != pattern[suffix -
1];) {
+ if (bmgs_buffers.shift(suffix) == len) {
+ bmgs_buffers.shift(suffix) = suffix - i;
}
- j--;
- i--;
- } else {
- int skip = bad_char_map[c & kBMHSignificantBitsMask];
- if (skip < (m - j)) {
- skip = m - j;
+ suffix = bmgs_buffers.suffix(suffix);
+ }
+ i--;
+ suffix--;
+ bmgs_buffers.suffix(i) = suffix;
+ if (suffix == m) {
+ // no suffix to extend, so we check against last_char only.
+ while (i > start && pattern[i - 1] != last_char) {
+ if (bmgs_buffers.shift(m) == len) {
+ bmgs_buffers.shift(m) = m - i;
+ }
+ i--;
+ bmgs_buffers.suffix(i) = m;
+ }
+ if (i > start) {
+ i--;
+ suffix--;
+ bmgs_buffers.suffix(i) = suffix;
}
- i += skip;
- j = m - 1;
}
}
- return -1;
-}
-
+ if (suffix < m) {
+ for (int i = start; i <= m; i++) {
+ if (bmgs_buffers.shift(i) == len) {
+ bmgs_buffers.shift(i) = suffix - start;
+ }
+ if (i == suffix) {
+ suffix = bmgs_buffers.suffix(suffix);
+ }
+ }
+ }
+ // End of Good Suffix computation.
-// Full KMP pattern match.
-template <typename schar, typename pchar> // Pattern & subject char types
-static int KMPIndexOf(Vector<const schar> subject,
- Vector<const pchar> pattern,
- int start_index) {
- int subject_length = subject.length();
- int pattern_length = pattern.length();
- SmartPointer<int> next_table(NewArray<int>(pattern_length));
- // Compute KMP "next" table
- int i = 0;
- int j = -1;
- next_table[0] = -1;
-
- pchar p = pattern[0];
- while (i < pattern_length - 1) {
- while (j > -1 && p != pattern[j]) {
- j = next_table[j];
- }
- i++;
- j++;
- p = pattern[i];
- if (p == pattern[j]) {
- next_table[i] = next_table[j];
+ // Perform search
+ for (int i = start_index; i <= n - m;) {
+ int j = m - 1;
+ schar c;
+ while (j >= 0 && pattern[j] == (c = subject[i + j])) j--;
+ if (j < 0) {
+ return i;
+ } else if (j < start) {
+ // we have matched more than our tables allow us to be smart about.
+ i += 1;
} else {
- next_table[i] = j;
+ int gs_shift = bmgs_buffers.shift(j + 1);
+ int bc_occ = bad_char_occurence[c % kBMAlphabetSize];
+ int bc_shift = j - bc_occ;
+ i += (gs_shift > bc_shift) ? gs_shift : bc_shift;
}
}
+ return -1;
+}
- // Search using the 'next' table.
- int pattern_index = 0;
- int subject_index = start_index;
- while (subject_index < subject_length) {
- schar subject_char = subject[subject_index];
- while (pattern_index > -1 && pattern[pattern_index] != subject_char) {
- pattern_index = next_table[pattern_index];
- }
- pattern_index++;
- subject_index++;
- if (pattern_index >= pattern_length) {
- return subject_index - pattern_index;
+template <typename schar, typename pchar>
+static int SingleCharIndexOf(Vector<const schar> string,
+ pchar pattern_char,
+ int start_index) {
+ for (int i = start_index, n = string.length(); i < n; i++) {
+ if (pattern_char == string[i]) {
+ return i;
+ }
+ }
+ return -1;
+}
+
+// Trivial string search for shorter strings.
+template <typename pchar, typename schar>
+static int SimpleIndexOf(Vector<const schar> subject,
+ Vector<const pchar> pattern,
+ int start_index) {
+ int pattern_length = pattern.length();
+ int subject_length = subject.length();
+ // We know our pattern is at least 2 characters, we cache the first so
+ // the common case of the first character not matching is faster.
+ pchar pattern_first_char = pattern[0];
+ for (int i = start_index, n = subject_length - pattern_length; i <= n;
i++) {
+ if (subject[i] != pattern_first_char) continue;
+ int j = 1;
+ while (pattern[j] == subject[j+i]) {
+ j++;
+ if (j == pattern_length) {
+ return i;
+ }
}
}
return -1;
@@ -1105,19 +1132,15 @@
Vector<const pchar> pat,
int start_index) {
int pattern_length = pat.length();
- // Searching for one specific character is common. For one
- // character patterns the KMP algorithm is guaranteed to slow down
- // the search, so we just run through the subject string.
- if (pattern_length == 1) {
- return SingleCharIndexOf(sub, pat[0], start_index);
- }
+ ASSERT(pattern_length > 1);
// For small searches, a complex sort is not worth the setup overhead.
- if (sub.length() - start_index < 25) {
+ int subject_length = sub.length() - start_index;
+ if (subject_length < 100 || pattern_length < 4) {
return SimpleIndexOf(sub, pat, start_index);
}
- return BoyerMooreHorspoolIndexOf(sub, pat, start_index);
+ return BoyerMooreIndexOf(sub, pat, start_index);
}
// Perform string match of pattern on subject, starting at start index.
@@ -1136,6 +1159,17 @@
if (start_index + pattern_length > subject_length) return -1;
FlattenString(sub);
+ // Searching for one specific character is common. For one
+ // character patterns linear search is necessary, so any smart
+ // algorithm is unnecessary overhead.
+ if (pattern_length == 1) {
+ AssertNoAllocation no_heap_allocation; // ensure vectors stay valid
+ if (sub->is_ascii_representation()) {
+ return SingleCharIndexOf(sub->ToAsciiVector(), pat->Get(0),
start_index);
+ }
+ return SingleCharIndexOf(sub->ToUC16Vector(), pat->Get(0),
start_index);
+ }
+
FlattenString(pat);
AssertNoAllocation no_heap_allocation; // ensure vectors stay valid
Modified: branches/bleeding_edge/test/mjsunit/string-indexof.js
==============================================================================
--- branches/bleeding_edge/test/mjsunit/string-indexof.js (original)
+++ branches/bleeding_edge/test/mjsunit/string-indexof.js Tue Oct 14
01:57:31 2008
@@ -27,6 +27,12 @@
var s = "test test test";
+assertEquals(0, s.indexOf("t"));
+assertEquals(3, s.indexOf("t", 1));
+assertEquals(5, s.indexOf("t", 4));
+assertEquals(1, s.indexOf("e"));
+assertEquals(2, s.indexOf("s"));
+
assertEquals(5, s.indexOf("test", 4));
assertEquals(5, s.indexOf("test", 5));
assertEquals(10, s.indexOf("test", 6));
@@ -47,3 +53,104 @@
assertEquals(10, reString.indexOf("(asdf)?"));
assertEquals(1, String.prototype.indexOf.length);
+
+// Random greek letters
+var twoByteString = "\u039a\u0391\u03a3\u03a3\u0395";
+
+// Test single char pattern
+assertEquals(0, twoByteString.indexOf("\u039a"), "Lamda");
+assertEquals(1, twoByteString.indexOf("\u0391"), "Alpha");
+assertEquals(2, twoByteString.indexOf("\u03a3"), "First Sigma");
+assertEquals(3, twoByteString.indexOf("\u03a3",3), "Second Sigma");
+assertEquals(4, twoByteString.indexOf("\u0395"), "Epsilon");
+assertEquals(-1, twoByteString.indexOf("\u0392"), "Not beta");
+
+// Test multi-char pattern
+assertEquals(0, twoByteString.indexOf("\u039a\u0391"), "lambda Alpha");
+assertEquals(1, twoByteString.indexOf("\u0391\u03a3"), "Alpha Sigma");
+assertEquals(2, twoByteString.indexOf("\u03a3\u03a3"), "Sigma Sigma");
+assertEquals(3, twoByteString.indexOf("\u03a3\u0395"), "Sigma Epsilon");
+
+assertEquals(-1, twoByteString.indexOf("\u0391\u03a3\u0395"),
+ "Not Alpha Sigma Epsilon");
+
+//single char pattern
+assertEquals(4, twoByteString.indexOf("\u0395"));
+
+// Test complex string indexOf algorithms. Only trigger for long strings.
+
+// Long string that isn't a simple repeat of a shorter string.
+var long = "A";
+for(var i = 66; i < 76; i++) { // from 'B' to 'K'
+ long = long + String.fromCharCode(i) + long;
+}
+
+// pattern of 15 chars, repeated every 16 chars in long
+var pattern = "ABACABADABACABA";
+for(var i = 0; i < long.length - pattern.length; i+= 7) {
+ var index = long.indexOf(pattern, i);
+ assertEquals((i + 15) & ~0xf, index, "Long ABACABA...-string at index "
+ i);
+}
+assertEquals(510, long.indexOf("AJABACA"), "Long AJABACA, First J");
+assertEquals(1534, long.indexOf("AJABACA", 511), "Long AJABACA, Second J");
+
+pattern = "JABACABADABACABA";
+assertEquals(511, long.indexOf(pattern), "Long JABACABA..., First J");
+assertEquals(1535, long.indexOf(pattern, 512), "Long JABACABA..., Second
J");
+
+
+var lipsum = "lorem ipsum per se esse fugiendum. itaque aiunt hanc quasi "
+ + "naturalem atque insitam in animis nostris inesse notionem, ut "
+ + "alterum esse appetendum, alterum aspernandum sentiamus. Alii autem,"
+ + " quibus ego assentior, cum a philosophis compluribus permulta "
+ + "dicantur, cur nec voluptas in bonis sit numeranda nec in malis "
+ + "dolor, non existimant oportere nimium nos causae confidere, sed et"
+ + " argumentandum et accurate disserendum et rationibus conquisitis de"
+ + " voluptate et dolore disputandum putant.\n"
+ + "Sed ut perspiciatis, unde omnis iste natus error sit voluptatem "
+ + "accusantium doloremque laudantium, totam rem aperiam eaque ipsa,"
+ + "quae ab illo inventore veritatis et quasi architecto beatae vitae "
+ + "dicta sunt, explicabo. nemo enim ipsam voluptatem, quia voluptas"
+ + "sit, aspernatur aut odit aut fugit, sed quia consequuntur magni"
+ + " dolores eos, qui ratione voluptatem sequi nesciunt, neque porro"
+ + " quisquam est, qui dolorem ipsum, quia dolor sit, amet, "
+ + "consectetur, adipisci velit, sed quia non numquam eius modi"
+ + " tempora incidunt, ut labore et dolore magnam aliquam quaerat "
+ + "voluptatem. ut enim ad minima veniam, quis nostrum exercitationem "
+ + "ullam corporis suscipit laboriosam, nisi ut aliquid ex ea commodi "
+ + "consequatur? quis autem vel eum iure reprehenderit, qui in ea "
+ + "voluptate velit esse, quam nihil molestiae consequatur, vel illum, "
+ + "qui dolorem eum fugiat, quo voluptas nulla pariatur?\n"
+ + "At vero eos et accusamus et iusto odio dignissimos ducimus, qui "
+ + "blanditiis praesentium voluptatum deleniti atque corrupti, quos "
+ + "dolores et quas molestias excepturi sint, obcaecati cupiditate "
+ + "non provident, similique sunt in culpa, qui officia deserunt "
+ + "mollitia animi, id est laborum et dolorum fuga. et harum quidem "
+ + "rerum facilis est et expedita distinctio. nam libero tempore, "
+ + "cum soluta nobis est eligendi optio, cumque nihil impedit, quo "
+ + "minus id, quod maxime placeat, facere possimus, omnis voluptas "
+ + "assumenda est, omnis dolor repellendus. temporibus autem "
+ + "quibusdam et aut officiis debitis aut rerum necessitatibus "
+ + "saepe eveniet, ut et voluptates repudiandae sint et molestiae "
+ + "non recusandae. itaque earum rerum hic tenetur a sapiente "
+ + "delectus, ut aut reiciendis voluptatibus maiores alias consequatur "
+ + "aut perferendis doloribus asperiores repellat.";
+
+assertEquals(893, lipsum.indexOf("lorem ipsum, quia dolor sit, amet"),
+ "Lipsum");
+// test a lot of substrings of differing length and start-position.
+for(var i = 255; i < lipsum.length; i += 3) {
+ for(var len = 661; i + len < lipsum.length; len += 4) {
+ var substring = lipsum.substring(i, i + len);
+ var index = -1;
+ do {
+ index = lipsum.indexOf(substring, index + 1);
+ assertTrue(index != -1,
+ "Lipsum substring " + i + ".." + (i + len-1) + " not
found");
+ assertEquals(lipsum.substring(index, index + len), substring,
+ "Wrong lipsum substring found: " + i + ".." + (i + len - 1)
+ "/" +
+ index + ".." + (index + len - 1));
+ } while (index >= 0 && index < i);
+ assertEquals(i, index, "Lipsum match at " + i + ".." + (i + len - 1));
+ }
+}
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