Most operations are faster than before.
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@492 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
This commit is contained in:
lrn@chromium.org
parent
49c5ed0029
commit
9e0609db8e
282
src/runtime.cc
282
src/runtime.cc
@ -952,6 +952,145 @@ static Object* Runtime_CharFromCode(Arguments args) {
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}
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// Cap on the maximal shift in the Boyer-Moore implementation. By setting a
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// limit, we can fix the size of tables.
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static const int kBMMaxShift = 0xff;
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static const int kBMAlphabetSize = 0x100; // Reduce alphabet to this size.
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// Holds the two buffers used by Boyer-Moore string search's Good Suffix
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// shift. Only allows the last kBMMaxShift characters of the needle
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// to be indexed.
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class BMGoodSuffixBuffers: public AllStatic {
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public:
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BMGoodSuffixBuffers() {}
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inline void init(int needle_length) {
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ASSERT(needle_length > 1);
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int start = needle_length < kBMMaxShift ? 0 : needle_length - kBMMaxShift;
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int len = needle_length - start;
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biased_suffixes_ = suffixes_ - start;
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biased_good_suffix_shift_ = good_suffix_shift_ - start;
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for (int i = 0; i <= len; i++) {
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good_suffix_shift_[i] = len;
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}
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}
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inline int& suffix(int index) {
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ASSERT(biased_suffixes_ + index >= suffixes_);
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return biased_suffixes_[index];
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}
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inline int& shift(int index) {
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ASSERT(biased_good_suffix_shift_ + index >= good_suffix_shift_);
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return biased_good_suffix_shift_[index];
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}
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private:
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int suffixes_[kBMMaxShift + 1];
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int good_suffix_shift_[kBMMaxShift + 1];
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int *biased_suffixes_;
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int *biased_good_suffix_shift_;
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DISALLOW_COPY_AND_ASSIGN(BMGoodSuffixBuffers);
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};
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// buffers reused by BoyerMoore
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static int bad_char_occurence[kBMAlphabetSize];
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static BMGoodSuffixBuffers bmgs_buffers;
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// Restricted Boyer-Moore string matching. Restricts tables to a
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// suffix of long pattern strings and handles only equivalence classes
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// of the full alphabet. This allows us to ensure that tables take only
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// a fixed amount of space.
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template <typename schar, typename pchar>
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static int BoyerMooreIndexOf(Vector<const schar> subject,
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Vector<const pchar> pattern,
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int start_index) {
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int m = pattern.length();
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int n = subject.length();
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// Only preprocess at most kBMMaxShift last characters of pattern.
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int start = m < kBMMaxShift ? 0 : m - kBMMaxShift;
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int len = m - start;
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// Run forwards to populate bad_char_table, so that *last* instance
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// of character equivalence class is the one registered.
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// Notice: Doesn't include last character.
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for (int i = 0; i < kBMAlphabetSize; i++) {
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bad_char_occurence[i] = start - 1;
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}
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for (int i = start; i < m; i++) {
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uc32 c = pattern[i];
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bad_char_occurence[c % kBMAlphabetSize] = i;
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if (sizeof(schar) == 1 &&
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sizeof(pchar) > 1 &&
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c > String::kMaxAsciiCharCode) {
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return -1;
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}
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}
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// End of Bad Char computation.
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// Compute Good Suffix shift table.
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bmgs_buffers.init(m);
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bmgs_buffers.shift(m-1) = 1;
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bmgs_buffers.suffix(m) = m + 1;
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pchar last_char = pattern[m - 1];
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int suffix = m + 1;
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for (int i = m; i > start;) {
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for (pchar c = pattern[i - 1]; suffix <= m && c != pattern[suffix - 1];) {
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if (bmgs_buffers.shift(suffix) == len) {
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bmgs_buffers.shift(suffix) = suffix - i;
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}
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suffix = bmgs_buffers.suffix(suffix);
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}
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i--;
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suffix--;
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bmgs_buffers.suffix(i) = suffix;
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if (suffix == m) {
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// no suffix to extend, so we check against last_char only.
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while (i > start && pattern[i - 1] != last_char) {
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if (bmgs_buffers.shift(m) == len) {
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bmgs_buffers.shift(m) = m - i;
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}
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i--;
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bmgs_buffers.suffix(i) = m;
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}
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if (i > start) {
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i--;
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suffix--;
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bmgs_buffers.suffix(i) = suffix;
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}
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}
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}
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if (suffix < m) {
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for (int i = start; i <= m; i++) {
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if (bmgs_buffers.shift(i) == len) {
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bmgs_buffers.shift(i) = suffix - start;
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}
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if (i == suffix) {
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suffix = bmgs_buffers.suffix(suffix);
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}
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}
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}
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// End of Good Suffix computation.
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// Perform search
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for (int i = start_index; i <= n - m;) {
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int j = m - 1;
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schar c;
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while (j >= 0 && pattern[j] == (c = subject[i + j])) j--;
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if (j < 0) {
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return i;
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} else if (j < start) {
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// we have matched more than our tables allow us to be smart about.
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i += 1;
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} else {
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int gs_shift = bmgs_buffers.shift(j + 1);
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int bc_occ = bad_char_occurence[c % kBMAlphabetSize];
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int bc_shift = j - bc_occ;
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i += (gs_shift > bc_shift) ? gs_shift : bc_shift;
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}
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}
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return -1;
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}
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template <typename schar, typename pchar>
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static int SingleCharIndexOf(Vector<const schar> string,
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pchar pattern_char,
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@ -976,124 +1115,12 @@ static int SimpleIndexOf(Vector<const schar> subject,
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pchar pattern_first_char = pattern[0];
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for (int i = start_index, n = subject_length - pattern_length; i <= n; i++) {
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if (subject[i] != pattern_first_char) continue;
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bool failure = false;
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for (int j = 1; j < pattern_length; j++) {
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if (pattern[j] != subject[j+i]) {
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failure = true;
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break;
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}
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}
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if (!failure) {
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return i;
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}
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}
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return -1;
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}
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// Maximal length (+1) of suffix that is indexed. Also the size of the
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// maximal bad-character skip.
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static const int kBMHSignificantSuffixLength = 0xff;
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// Significant bits taken from characters to use in bad-character
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// skips, to reduce size of the table for Unicode letters.
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static const int kBMHSignificantBitsMask = 0xff;
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// Number of elements in bad-char table.
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static const int kBMHBadCharCount = kBMHSignificantBitsMask + 1;
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// Simplified Boyer-Moore string matching. Only uses bad-char skipping,
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// and restricts table to a suffix of long strings (also restricting
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// the maximum possible skip-length) in order to reduce space.
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template <typename schar, typename pchar>
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static int BoyerMooreHorspoolIndexOf(Vector<const schar> subject,
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Vector<const pchar> pattern,
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int start_index) {
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ASSERT(kBMHSignificantSuffixLength < 0x100); // We can use bytes as skips.
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static byte bad_char_map[kBMHBadCharCount];
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int m = pattern.length();
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int n = subject.length();
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// Cap bad char table to last p chars of pattern. Also max skip value.
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int p = m < kBMHSignificantSuffixLength ? m : kBMHSignificantSuffixLength;
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memset(bad_char_map, p, kBMHBadCharCount);
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// Run forwards to populate bad_char_table, so that *last* instance
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// of character equivalence class is the one registered.
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// Notice: Doesn't include last character.
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for (int i = p < m ? m - p : 0; i < m - 1; i++) {
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uc32 c = pattern[i];
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if (sizeof(schar) == 1 &&
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sizeof(pchar) > 1 &&
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c > String::kMaxAsciiCharCode) {
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return -1;
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}
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bad_char_map[c & kBMHSignificantBitsMask] = m - 1 - i;
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}
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for (int i = start_index + m - 1, j = m - 1; i < n;) {
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schar c = subject[i];
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if (c == pattern[j]) {
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if (j == 0) {
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int j = 1;
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while (pattern[j] == subject[j+i]) {
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j++;
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if (j == pattern_length) {
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return i;
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}
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j--;
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i--;
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} else {
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int skip = bad_char_map[c & kBMHSignificantBitsMask];
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if (skip < (m - j)) {
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skip = m - j;
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}
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i += skip;
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j = m - 1;
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}
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}
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return -1;
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}
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// Full KMP pattern match.
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template <typename schar, typename pchar> // Pattern & subject char types
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static int KMPIndexOf(Vector<const schar> subject,
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Vector<const pchar> pattern,
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int start_index) {
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int subject_length = subject.length();
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int pattern_length = pattern.length();
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SmartPointer<int> next_table(NewArray<int>(pattern_length));
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// Compute KMP "next" table
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int i = 0;
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int j = -1;
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next_table[0] = -1;
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pchar p = pattern[0];
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while (i < pattern_length - 1) {
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while (j > -1 && p != pattern[j]) {
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j = next_table[j];
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}
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i++;
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j++;
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p = pattern[i];
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if (p == pattern[j]) {
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next_table[i] = next_table[j];
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} else {
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next_table[i] = j;
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}
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}
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// Search using the 'next' table.
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int pattern_index = 0;
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int subject_index = start_index;
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while (subject_index < subject_length) {
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schar subject_char = subject[subject_index];
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while (pattern_index > -1 && pattern[pattern_index] != subject_char) {
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pattern_index = next_table[pattern_index];
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}
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pattern_index++;
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subject_index++;
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if (pattern_index >= pattern_length) {
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return subject_index - pattern_index;
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}
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}
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return -1;
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@ -1105,19 +1132,15 @@ static int StringMatchStrategy(Vector<const schar> sub,
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Vector<const pchar> pat,
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int start_index) {
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int pattern_length = pat.length();
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// Searching for one specific character is common. For one
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// character patterns the KMP algorithm is guaranteed to slow down
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// the search, so we just run through the subject string.
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if (pattern_length == 1) {
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return SingleCharIndexOf(sub, pat[0], start_index);
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}
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ASSERT(pattern_length > 1);
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// For small searches, a complex sort is not worth the setup overhead.
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if (sub.length() - start_index < 25) {
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int subject_length = sub.length() - start_index;
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if (subject_length < 100 || pattern_length < 4) {
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return SimpleIndexOf(sub, pat, start_index);
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}
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return BoyerMooreHorspoolIndexOf(sub, pat, start_index);
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return BoyerMooreIndexOf(sub, pat, start_index);
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}
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// Perform string match of pattern on subject, starting at start index.
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@ -1136,6 +1159,17 @@ int Runtime::StringMatch(Handle<String> sub,
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if (start_index + pattern_length > subject_length) return -1;
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FlattenString(sub);
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// Searching for one specific character is common. For one
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// character patterns linear search is necessary, so any smart
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// algorithm is unnecessary overhead.
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if (pattern_length == 1) {
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AssertNoAllocation no_heap_allocation; // ensure vectors stay valid
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if (sub->is_ascii_representation()) {
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return SingleCharIndexOf(sub->ToAsciiVector(), pat->Get(0), start_index);
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}
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return SingleCharIndexOf(sub->ToUC16Vector(), pat->Get(0), start_index);
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}
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FlattenString(pat);
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AssertNoAllocation no_heap_allocation; // ensure vectors stay valid
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@ -27,6 +27,12 @@
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var s = "test test test";
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assertEquals(0, s.indexOf("t"));
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assertEquals(3, s.indexOf("t", 1));
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assertEquals(5, s.indexOf("t", 4));
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assertEquals(1, s.indexOf("e"));
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assertEquals(2, s.indexOf("s"));
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assertEquals(5, s.indexOf("test", 4));
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assertEquals(5, s.indexOf("test", 5));
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assertEquals(10, s.indexOf("test", 6));
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@ -47,3 +53,104 @@ assertEquals(4, reString.indexOf("[a-z]+"));
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assertEquals(10, reString.indexOf("(asdf)?"));
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assertEquals(1, String.prototype.indexOf.length);
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// Random greek letters
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var twoByteString = "\u039a\u0391\u03a3\u03a3\u0395";
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// Test single char pattern
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assertEquals(0, twoByteString.indexOf("\u039a"), "Lamda");
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assertEquals(1, twoByteString.indexOf("\u0391"), "Alpha");
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assertEquals(2, twoByteString.indexOf("\u03a3"), "First Sigma");
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assertEquals(3, twoByteString.indexOf("\u03a3",3), "Second Sigma");
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assertEquals(4, twoByteString.indexOf("\u0395"), "Epsilon");
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assertEquals(-1, twoByteString.indexOf("\u0392"), "Not beta");
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// Test multi-char pattern
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assertEquals(0, twoByteString.indexOf("\u039a\u0391"), "lambda Alpha");
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assertEquals(1, twoByteString.indexOf("\u0391\u03a3"), "Alpha Sigma");
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assertEquals(2, twoByteString.indexOf("\u03a3\u03a3"), "Sigma Sigma");
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assertEquals(3, twoByteString.indexOf("\u03a3\u0395"), "Sigma Epsilon");
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assertEquals(-1, twoByteString.indexOf("\u0391\u03a3\u0395"),
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"Not Alpha Sigma Epsilon");
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//single char pattern
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assertEquals(4, twoByteString.indexOf("\u0395"));
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// Test complex string indexOf algorithms. Only trigger for long strings.
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// Long string that isn't a simple repeat of a shorter string.
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var long = "A";
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for(var i = 66; i < 76; i++) { // from 'B' to 'K'
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long = long + String.fromCharCode(i) + long;
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}
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// pattern of 15 chars, repeated every 16 chars in long
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var pattern = "ABACABADABACABA";
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for(var i = 0; i < long.length - pattern.length; i+= 7) {
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var index = long.indexOf(pattern, i);
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assertEquals((i + 15) & ~0xf, index, "Long ABACABA...-string at index " + i);
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}
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assertEquals(510, long.indexOf("AJABACA"), "Long AJABACA, First J");
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assertEquals(1534, long.indexOf("AJABACA", 511), "Long AJABACA, Second J");
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pattern = "JABACABADABACABA";
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assertEquals(511, long.indexOf(pattern), "Long JABACABA..., First J");
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assertEquals(1535, long.indexOf(pattern, 512), "Long JABACABA..., Second J");
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var lipsum = "lorem ipsum per se esse fugiendum. itaque aiunt hanc quasi "
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+ "naturalem atque insitam in animis nostris inesse notionem, ut "
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+ "alterum esse appetendum, alterum aspernandum sentiamus. Alii autem,"
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+ " quibus ego assentior, cum a philosophis compluribus permulta "
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+ "dicantur, cur nec voluptas in bonis sit numeranda nec in malis "
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+ "dolor, non existimant oportere nimium nos causae confidere, sed et"
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+ " argumentandum et accurate disserendum et rationibus conquisitis de"
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+ " voluptate et dolore disputandum putant.\n"
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+ "Sed ut perspiciatis, unde omnis iste natus error sit voluptatem "
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+ "accusantium doloremque laudantium, totam rem aperiam eaque ipsa,"
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+ "quae ab illo inventore veritatis et quasi architecto beatae vitae "
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+ "dicta sunt, explicabo. nemo enim ipsam voluptatem, quia voluptas"
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+ "sit, aspernatur aut odit aut fugit, sed quia consequuntur magni"
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+ " dolores eos, qui ratione voluptatem sequi nesciunt, neque porro"
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+ " quisquam est, qui dolorem ipsum, quia dolor sit, amet, "
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+ "consectetur, adipisci velit, sed quia non numquam eius modi"
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+ " tempora incidunt, ut labore et dolore magnam aliquam quaerat "
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+ "voluptatem. ut enim ad minima veniam, quis nostrum exercitationem "
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+ "ullam corporis suscipit laboriosam, nisi ut aliquid ex ea commodi "
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+ "consequatur? quis autem vel eum iure reprehenderit, qui in ea "
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+ "voluptate velit esse, quam nihil molestiae consequatur, vel illum, "
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+ "qui dolorem eum fugiat, quo voluptas nulla pariatur?\n"
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+ "At vero eos et accusamus et iusto odio dignissimos ducimus, qui "
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+ "blanditiis praesentium voluptatum deleniti atque corrupti, quos "
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+ "dolores et quas molestias excepturi sint, obcaecati cupiditate "
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+ "non provident, similique sunt in culpa, qui officia deserunt "
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+ "mollitia animi, id est laborum et dolorum fuga. et harum quidem "
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+ "rerum facilis est et expedita distinctio. nam libero tempore, "
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+ "cum soluta nobis est eligendi optio, cumque nihil impedit, quo "
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+ "minus id, quod maxime placeat, facere possimus, omnis voluptas "
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+ "assumenda est, omnis dolor repellendus. temporibus autem "
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+ "quibusdam et aut officiis debitis aut rerum necessitatibus "
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+ "saepe eveniet, ut et voluptates repudiandae sint et molestiae "
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+ "non recusandae. itaque earum rerum hic tenetur a sapiente "
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+ "delectus, ut aut reiciendis voluptatibus maiores alias consequatur "
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+ "aut perferendis doloribus asperiores repellat.";
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assertEquals(893, lipsum.indexOf("lorem ipsum, quia dolor sit, amet"),
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"Lipsum");
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// test a lot of substrings of differing length and start-position.
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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));
|
||||
}
|
||||
}
|
||||
|
||||
Loading…
Reference in New Issue
Block a user