diff options
Diffstat (limited to 'Objects/stringlib/fastsearch.h')
| -rw-r--r-- | Objects/stringlib/fastsearch.h | 150 |
1 files changed, 87 insertions, 63 deletions
diff --git a/Objects/stringlib/fastsearch.h b/Objects/stringlib/fastsearch.h index cda68e77c8..98165ad114 100644 --- a/Objects/stringlib/fastsearch.h +++ b/Objects/stringlib/fastsearch.h @@ -32,52 +32,98 @@ #define STRINGLIB_BLOOM(mask, ch) \ ((mask & (1UL << ((ch) & (STRINGLIB_BLOOM_WIDTH -1))))) - Py_LOCAL_INLINE(Py_ssize_t) -STRINGLIB(fastsearch_memchr_1char)(const STRINGLIB_CHAR* s, Py_ssize_t n, - STRINGLIB_CHAR ch, unsigned char needle, - int mode) +STRINGLIB(find_char)(const STRINGLIB_CHAR* s, Py_ssize_t n, STRINGLIB_CHAR ch) { - if (mode == FAST_SEARCH) { - const STRINGLIB_CHAR *ptr = s; - const STRINGLIB_CHAR *e = s + n; - while (ptr < e) { - void *candidate = memchr((const void *) ptr, needle, (e - ptr) * sizeof(STRINGLIB_CHAR)); - if (candidate == NULL) - return -1; - ptr = (const STRINGLIB_CHAR *) _Py_ALIGN_DOWN(candidate, sizeof(STRINGLIB_CHAR)); - if (sizeof(STRINGLIB_CHAR) == 1 || *ptr == ch) - return (ptr - s); - /* False positive */ - ptr++; - } + const STRINGLIB_CHAR *p, *e; + + p = s; + e = s + n; + if (n > 10) { +#if STRINGLIB_SIZEOF_CHAR == 1 + p = memchr(s, ch, n); + if (p != NULL) + return (p - s); return -1; +#else + /* use memchr if we can choose a needle without two many likely + false positives */ + unsigned char needle = ch & 0xff; + /* If looking for a multiple of 256, we'd have too + many false positives looking for the '\0' byte in UCS2 + and UCS4 representations. */ + if (needle != 0) { + while (p < e) { + void *candidate = memchr(p, needle, + (e - p) * sizeof(STRINGLIB_CHAR)); + if (candidate == NULL) + return -1; + p = (const STRINGLIB_CHAR *) + _Py_ALIGN_DOWN(candidate, sizeof(STRINGLIB_CHAR)); + if (*p == ch) + return (p - s); + /* False positive */ + p++; + } + return -1; + } +#endif } + while (p < e) { + if (*p == ch) + return (p - s); + p++; + } + return -1; +} + +Py_LOCAL_INLINE(Py_ssize_t) +STRINGLIB(rfind_char)(const STRINGLIB_CHAR* s, Py_ssize_t n, STRINGLIB_CHAR ch) +{ + const STRINGLIB_CHAR *p; #ifdef HAVE_MEMRCHR /* memrchr() is a GNU extension, available since glibc 2.1.91. it doesn't seem as optimized as memchr(), but is still quite - faster than our hand-written loop in FASTSEARCH below */ - else if (mode == FAST_RSEARCH) { - while (n > 0) { - const STRINGLIB_CHAR *found; - void *candidate = memrchr((const void *) s, needle, n * sizeof(STRINGLIB_CHAR)); - if (candidate == NULL) - return -1; - found = (const STRINGLIB_CHAR *) _Py_ALIGN_DOWN(candidate, sizeof(STRINGLIB_CHAR)); - n = found - s; - if (sizeof(STRINGLIB_CHAR) == 1 || *found == ch) - return n; - /* False positive */ - } + faster than our hand-written loop below */ + + if (n > 10) { +#if STRINGLIB_SIZEOF_CHAR == 1 + p = memrchr(s, ch, n); + if (p != NULL) + return (p - s); return -1; - } +#else + /* use memrchr if we can choose a needle without two many likely + false positives */ + unsigned char needle = ch & 0xff; + /* If looking for a multiple of 256, we'd have too + many false positives looking for the '\0' byte in UCS2 + and UCS4 representations. */ + if (needle != 0) { + while (n > 0) { + void *candidate = memrchr(s, needle, + n * sizeof(STRINGLIB_CHAR)); + if (candidate == NULL) + return -1; + p = (const STRINGLIB_CHAR *) + _Py_ALIGN_DOWN(candidate, sizeof(STRINGLIB_CHAR)); + n = p - s; + if (*p == ch) + return n; + /* False positive */ + } + return -1; + } #endif - else { - assert(0); /* Should never get here */ - return 0; } - -#undef DO_MEMCHR +#endif /* HAVE_MEMRCHR */ + p = s + n; + while (p > s) { + p--; + if (*p == ch) + return (p - s); + } + return -1; } Py_LOCAL_INLINE(Py_ssize_t) @@ -99,25 +145,11 @@ FASTSEARCH(const STRINGLIB_CHAR* s, Py_ssize_t n, if (m <= 0) return -1; /* use special case for 1-character strings */ - if (n > 10 && (mode == FAST_SEARCH -#ifdef HAVE_MEMRCHR - || mode == FAST_RSEARCH -#endif - )) { - /* use memchr if we can choose a needle without two many likely - false positives */ - unsigned char needle; - needle = p[0] & 0xff; -#if STRINGLIB_SIZEOF_CHAR > 1 - /* If looking for a multiple of 256, we'd have too - many false positives looking for the '\0' byte in UCS2 - and UCS4 representations. */ - if (needle != 0) -#endif - return STRINGLIB(fastsearch_memchr_1char) - (s, n, p[0], needle, mode); - } - if (mode == FAST_COUNT) { + if (mode == FAST_SEARCH) + return STRINGLIB(find_char)(s, n, p[0]); + else if (mode == FAST_RSEARCH) + return STRINGLIB(rfind_char)(s, n, p[0]); + else { /* FAST_COUNT */ for (i = 0; i < n; i++) if (s[i] == p[0]) { count++; @@ -125,14 +157,6 @@ FASTSEARCH(const STRINGLIB_CHAR* s, Py_ssize_t n, return maxcount; } return count; - } else if (mode == FAST_SEARCH) { - for (i = 0; i < n; i++) - if (s[i] == p[0]) - return i; - } else { /* FAST_RSEARCH */ - for (i = n - 1; i > -1; i--) - if (s[i] == p[0]) - return i; } return -1; } |