diff options
Diffstat (limited to 'gnulib/lib/mbsstr.c')
| -rw-r--r-- | gnulib/lib/mbsstr.c | 512 |
1 files changed, 255 insertions, 257 deletions
diff --git a/gnulib/lib/mbsstr.c b/gnulib/lib/mbsstr.c index 35fd02b..24cff25 100644 --- a/gnulib/lib/mbsstr.c +++ b/gnulib/lib/mbsstr.c @@ -1,5 +1,5 @@ /* Searching in a string. - Copyright (C) 2005-2008 Free Software Foundation, Inc. + Copyright (C) 2005-2013 Free Software Foundation, Inc. Written by Bruno Haible <bruno@clisp.org>, 2005. This program is free software: you can redistribute it and/or modify @@ -24,15 +24,13 @@ #include <stddef.h> /* for NULL, in case a nonstandard string.h lacks it */ #include "malloca.h" -#if HAVE_MBRTOWC -# include "mbuiter.h" -#endif +#include "mbuiter.h" /* Knuth-Morris-Pratt algorithm. */ +#define UNIT unsigned char #define CANON_ELEMENT(c) c #include "str-kmp.h" -#if HAVE_MBRTOWC /* Knuth-Morris-Pratt algorithm. See http://en.wikipedia.org/wiki/Knuth-Morris-Pratt_algorithm Return a boolean indicating success: @@ -40,18 +38,19 @@ Return false if it was aborted because not enough memory was available. */ static bool knuth_morris_pratt_multibyte (const char *haystack, const char *needle, - const char **resultp) + const char **resultp) { size_t m = mbslen (needle); mbchar_t *needle_mbchars; size_t *table; /* Allocate room for needle_mbchars and the table. */ - char *memory = (char *) nmalloca (m, sizeof (mbchar_t) + sizeof (size_t)); + void *memory = nmalloca (m, sizeof (mbchar_t) + sizeof (size_t)); + void *table_memory; if (memory == NULL) return false; - needle_mbchars = (mbchar_t *) memory; - table = (size_t *) (memory + m * sizeof (mbchar_t)); + needle_mbchars = memory; + table = table_memory = needle_mbchars + m; /* Fill needle_mbchars. */ { @@ -87,46 +86,46 @@ knuth_morris_pratt_multibyte (const char *haystack, const char *needle, for (i = 2; i < m; i++) { - /* Here: j = i-1 - table[i-1]. - The inequality needle[x..i-1] != needle[0..i-1-x] is known to hold - for x < table[i-1], by induction. - Furthermore, if j>0: needle[i-1-j..i-2] = needle[0..j-1]. */ - mbchar_t *b = &needle_mbchars[i - 1]; - - for (;;) - { - /* Invariants: The inequality needle[x..i-1] != needle[0..i-1-x] - is known to hold for x < i-1-j. - Furthermore, if j>0: needle[i-1-j..i-2] = needle[0..j-1]. */ - if (mb_equal (*b, needle_mbchars[j])) - { - /* Set table[i] := i-1-j. */ - table[i] = i - ++j; - break; - } - /* The inequality needle[x..i-1] != needle[0..i-1-x] also holds - for x = i-1-j, because - needle[i-1] != needle[j] = needle[i-1-x]. */ - if (j == 0) - { - /* The inequality holds for all possible x. */ - table[i] = i; - break; - } - /* The inequality needle[x..i-1] != needle[0..i-1-x] also holds - for i-1-j < x < i-1-j+table[j], because for these x: - needle[x..i-2] - = needle[x-(i-1-j)..j-1] - != needle[0..j-1-(x-(i-1-j))] (by definition of table[j]) - = needle[0..i-2-x], - hence needle[x..i-1] != needle[0..i-1-x]. - Furthermore - needle[i-1-j+table[j]..i-2] - = needle[table[j]..j-1] - = needle[0..j-1-table[j]] (by definition of table[j]). */ - j = j - table[j]; - } - /* Here: j = i - table[i]. */ + /* Here: j = i-1 - table[i-1]. + The inequality needle[x..i-1] != needle[0..i-1-x] is known to hold + for x < table[i-1], by induction. + Furthermore, if j>0: needle[i-1-j..i-2] = needle[0..j-1]. */ + mbchar_t *b = &needle_mbchars[i - 1]; + + for (;;) + { + /* Invariants: The inequality needle[x..i-1] != needle[0..i-1-x] + is known to hold for x < i-1-j. + Furthermore, if j>0: needle[i-1-j..i-2] = needle[0..j-1]. */ + if (mb_equal (*b, needle_mbchars[j])) + { + /* Set table[i] := i-1-j. */ + table[i] = i - ++j; + break; + } + /* The inequality needle[x..i-1] != needle[0..i-1-x] also holds + for x = i-1-j, because + needle[i-1] != needle[j] = needle[i-1-x]. */ + if (j == 0) + { + /* The inequality holds for all possible x. */ + table[i] = i; + break; + } + /* The inequality needle[x..i-1] != needle[0..i-1-x] also holds + for i-1-j < x < i-1-j+table[j], because for these x: + needle[x..i-2] + = needle[x-(i-1-j)..j-1] + != needle[0..j-1-(x-(i-1-j))] (by definition of table[j]) + = needle[0..i-2-x], + hence needle[x..i-1] != needle[0..i-1-x]. + Furthermore + needle[i-1-j+table[j]..i-2] + = needle[table[j]..j-1] + = needle[0..j-1-table[j]] (by definition of table[j]). */ + j = j - table[j]; + } + /* Here: j = i - table[i]. */ } } @@ -143,42 +142,41 @@ knuth_morris_pratt_multibyte (const char *haystack, const char *needle, /* Invariant: phaystack = rhaystack + j. */ while (mbui_avail (phaystack)) if (mb_equal (needle_mbchars[j], mbui_cur (phaystack))) - { - j++; - mbui_advance (phaystack); - if (j == m) - { - /* The entire needle has been found. */ - *resultp = mbui_cur_ptr (rhaystack); - break; - } - } + { + j++; + mbui_advance (phaystack); + if (j == m) + { + /* The entire needle has been found. */ + *resultp = mbui_cur_ptr (rhaystack); + break; + } + } else if (j > 0) - { - /* Found a match of needle[0..j-1], mismatch at needle[j]. */ - size_t count = table[j]; - j -= count; - for (; count > 0; count--) - { - if (!mbui_avail (rhaystack)) - abort (); - mbui_advance (rhaystack); - } - } + { + /* Found a match of needle[0..j-1], mismatch at needle[j]. */ + size_t count = table[j]; + j -= count; + for (; count > 0; count--) + { + if (!mbui_avail (rhaystack)) + abort (); + mbui_advance (rhaystack); + } + } else - { - /* Found a mismatch at needle[0] already. */ - if (!mbui_avail (rhaystack)) - abort (); - mbui_advance (rhaystack); - mbui_advance (phaystack); - } + { + /* Found a mismatch at needle[0] already. */ + if (!mbui_avail (rhaystack)) + abort (); + mbui_advance (rhaystack); + mbui_advance (phaystack); + } } freea (memory); return true; } -#endif /* Find the first occurrence of the character string NEEDLE in the character string HAYSTACK. Return NULL if NEEDLE is not found in HAYSTACK. */ @@ -190,196 +188,196 @@ mbsstr (const char *haystack, const char *needle) - haystack may be very long, and a match of needle found early, - needle may be very long, and not even a short initial segment of needle may be found in haystack. */ -#if HAVE_MBRTOWC if (MB_CUR_MAX > 1) { mbui_iterator_t iter_needle; mbui_init (iter_needle, needle); if (mbui_avail (iter_needle)) - { - /* Minimizing the worst-case complexity: - Let n = mbslen(haystack), m = mbslen(needle). - The naïve algorithm is O(n*m) worst-case. - The Knuth-Morris-Pratt algorithm is O(n) worst-case but it needs a - memory allocation. - To achieve linear complexity and yet amortize the cost of the - memory allocation, we activate the Knuth-Morris-Pratt algorithm - only once the naïve algorithm has already run for some time; more - precisely, when - - the outer loop count is >= 10, - - the average number of comparisons per outer loop is >= 5, - - the total number of comparisons is >= m. - But we try it only once. If the memory allocation attempt failed, - we don't retry it. */ - bool try_kmp = true; - size_t outer_loop_count = 0; - size_t comparison_count = 0; - size_t last_ccount = 0; /* last comparison count */ - mbui_iterator_t iter_needle_last_ccount; /* = needle + last_ccount */ - - mbui_iterator_t iter_haystack; - - mbui_init (iter_needle_last_ccount, needle); - mbui_init (iter_haystack, haystack); - for (;; mbui_advance (iter_haystack)) - { - if (!mbui_avail (iter_haystack)) - /* No match. */ - return NULL; - - /* See whether it's advisable to use an asymptotically faster - algorithm. */ - if (try_kmp - && outer_loop_count >= 10 - && comparison_count >= 5 * outer_loop_count) - { - /* See if needle + comparison_count now reaches the end of - needle. */ - size_t count = comparison_count - last_ccount; - for (; - count > 0 && mbui_avail (iter_needle_last_ccount); - count--) - mbui_advance (iter_needle_last_ccount); - last_ccount = comparison_count; - if (!mbui_avail (iter_needle_last_ccount)) - { - /* Try the Knuth-Morris-Pratt algorithm. */ - const char *result; - bool success = - knuth_morris_pratt_multibyte (haystack, needle, - &result); - if (success) - return (char *) result; - try_kmp = false; - } - } - - outer_loop_count++; - comparison_count++; - if (mb_equal (mbui_cur (iter_haystack), mbui_cur (iter_needle))) - /* The first character matches. */ - { - mbui_iterator_t rhaystack; - mbui_iterator_t rneedle; - - memcpy (&rhaystack, &iter_haystack, sizeof (mbui_iterator_t)); - mbui_advance (rhaystack); - - mbui_init (rneedle, needle); - if (!mbui_avail (rneedle)) - abort (); - mbui_advance (rneedle); - - for (;; mbui_advance (rhaystack), mbui_advance (rneedle)) - { - if (!mbui_avail (rneedle)) - /* Found a match. */ - return (char *) mbui_cur_ptr (iter_haystack); - if (!mbui_avail (rhaystack)) - /* No match. */ - return NULL; - comparison_count++; - if (!mb_equal (mbui_cur (rhaystack), mbui_cur (rneedle))) - /* Nothing in this round. */ - break; - } - } - } - } + { + /* Minimizing the worst-case complexity: + Let n = mbslen(haystack), m = mbslen(needle). + The naïve algorithm is O(n*m) worst-case. + The Knuth-Morris-Pratt algorithm is O(n) worst-case but it needs a + memory allocation. + To achieve linear complexity and yet amortize the cost of the + memory allocation, we activate the Knuth-Morris-Pratt algorithm + only once the naïve algorithm has already run for some time; more + precisely, when + - the outer loop count is >= 10, + - the average number of comparisons per outer loop is >= 5, + - the total number of comparisons is >= m. + But we try it only once. If the memory allocation attempt failed, + we don't retry it. */ + bool try_kmp = true; + size_t outer_loop_count = 0; + size_t comparison_count = 0; + size_t last_ccount = 0; /* last comparison count */ + mbui_iterator_t iter_needle_last_ccount; /* = needle + last_ccount */ + + mbui_iterator_t iter_haystack; + + mbui_init (iter_needle_last_ccount, needle); + mbui_init (iter_haystack, haystack); + for (;; mbui_advance (iter_haystack)) + { + if (!mbui_avail (iter_haystack)) + /* No match. */ + return NULL; + + /* See whether it's advisable to use an asymptotically faster + algorithm. */ + if (try_kmp + && outer_loop_count >= 10 + && comparison_count >= 5 * outer_loop_count) + { + /* See if needle + comparison_count now reaches the end of + needle. */ + size_t count = comparison_count - last_ccount; + for (; + count > 0 && mbui_avail (iter_needle_last_ccount); + count--) + mbui_advance (iter_needle_last_ccount); + last_ccount = comparison_count; + if (!mbui_avail (iter_needle_last_ccount)) + { + /* Try the Knuth-Morris-Pratt algorithm. */ + const char *result; + bool success = + knuth_morris_pratt_multibyte (haystack, needle, + &result); + if (success) + return (char *) result; + try_kmp = false; + } + } + + outer_loop_count++; + comparison_count++; + if (mb_equal (mbui_cur (iter_haystack), mbui_cur (iter_needle))) + /* The first character matches. */ + { + mbui_iterator_t rhaystack; + mbui_iterator_t rneedle; + + memcpy (&rhaystack, &iter_haystack, sizeof (mbui_iterator_t)); + mbui_advance (rhaystack); + + mbui_init (rneedle, needle); + if (!mbui_avail (rneedle)) + abort (); + mbui_advance (rneedle); + + for (;; mbui_advance (rhaystack), mbui_advance (rneedle)) + { + if (!mbui_avail (rneedle)) + /* Found a match. */ + return (char *) mbui_cur_ptr (iter_haystack); + if (!mbui_avail (rhaystack)) + /* No match. */ + return NULL; + comparison_count++; + if (!mb_equal (mbui_cur (rhaystack), mbui_cur (rneedle))) + /* Nothing in this round. */ + break; + } + } + } + } else - return (char *) haystack; + return (char *) haystack; } else -#endif { if (*needle != '\0') - { - /* Minimizing the worst-case complexity: - Let n = strlen(haystack), m = strlen(needle). - The naïve algorithm is O(n*m) worst-case. - The Knuth-Morris-Pratt algorithm is O(n) worst-case but it needs a - memory allocation. - To achieve linear complexity and yet amortize the cost of the - memory allocation, we activate the Knuth-Morris-Pratt algorithm - only once the naïve algorithm has already run for some time; more - precisely, when - - the outer loop count is >= 10, - - the average number of comparisons per outer loop is >= 5, - - the total number of comparisons is >= m. - But we try it only once. If the memory allocation attempt failed, - we don't retry it. */ - bool try_kmp = true; - size_t outer_loop_count = 0; - size_t comparison_count = 0; - size_t last_ccount = 0; /* last comparison count */ - const char *needle_last_ccount = needle; /* = needle + last_ccount */ - - /* Speed up the following searches of needle by caching its first - character. */ - char b = *needle++; - - for (;; haystack++) - { - if (*haystack == '\0') - /* No match. */ - return NULL; - - /* See whether it's advisable to use an asymptotically faster - algorithm. */ - if (try_kmp - && outer_loop_count >= 10 - && comparison_count >= 5 * outer_loop_count) - { - /* See if needle + comparison_count now reaches the end of - needle. */ - if (needle_last_ccount != NULL) - { - needle_last_ccount += - strnlen (needle_last_ccount, - comparison_count - last_ccount); - if (*needle_last_ccount == '\0') - needle_last_ccount = NULL; - last_ccount = comparison_count; - } - if (needle_last_ccount == NULL) - { - /* Try the Knuth-Morris-Pratt algorithm. */ - const char *result; - bool success = - knuth_morris_pratt_unibyte (haystack, needle - 1, - &result); - if (success) - return (char *) result; - try_kmp = false; - } - } - - outer_loop_count++; - comparison_count++; - if (*haystack == b) - /* The first character matches. */ - { - const char *rhaystack = haystack + 1; - const char *rneedle = needle; - - for (;; rhaystack++, rneedle++) - { - if (*rneedle == '\0') - /* Found a match. */ - return (char *) haystack; - if (*rhaystack == '\0') - /* No match. */ - return NULL; - comparison_count++; - if (*rhaystack != *rneedle) - /* Nothing in this round. */ - break; - } - } - } - } + { + /* Minimizing the worst-case complexity: + Let n = strlen(haystack), m = strlen(needle). + The naïve algorithm is O(n*m) worst-case. + The Knuth-Morris-Pratt algorithm is O(n) worst-case but it needs a + memory allocation. + To achieve linear complexity and yet amortize the cost of the + memory allocation, we activate the Knuth-Morris-Pratt algorithm + only once the naïve algorithm has already run for some time; more + precisely, when + - the outer loop count is >= 10, + - the average number of comparisons per outer loop is >= 5, + - the total number of comparisons is >= m. + But we try it only once. If the memory allocation attempt failed, + we don't retry it. */ + bool try_kmp = true; + size_t outer_loop_count = 0; + size_t comparison_count = 0; + size_t last_ccount = 0; /* last comparison count */ + const char *needle_last_ccount = needle; /* = needle + last_ccount */ + + /* Speed up the following searches of needle by caching its first + character. */ + char b = *needle++; + + for (;; haystack++) + { + if (*haystack == '\0') + /* No match. */ + return NULL; + + /* See whether it's advisable to use an asymptotically faster + algorithm. */ + if (try_kmp + && outer_loop_count >= 10 + && comparison_count >= 5 * outer_loop_count) + { + /* See if needle + comparison_count now reaches the end of + needle. */ + if (needle_last_ccount != NULL) + { + needle_last_ccount += + strnlen (needle_last_ccount, + comparison_count - last_ccount); + if (*needle_last_ccount == '\0') + needle_last_ccount = NULL; + last_ccount = comparison_count; + } + if (needle_last_ccount == NULL) + { + /* Try the Knuth-Morris-Pratt algorithm. */ + const unsigned char *result; + bool success = + knuth_morris_pratt ((const unsigned char *) haystack, + (const unsigned char *) (needle - 1), + strlen (needle - 1), + &result); + if (success) + return (char *) result; + try_kmp = false; + } + } + + outer_loop_count++; + comparison_count++; + if (*haystack == b) + /* The first character matches. */ + { + const char *rhaystack = haystack + 1; + const char *rneedle = needle; + + for (;; rhaystack++, rneedle++) + { + if (*rneedle == '\0') + /* Found a match. */ + return (char *) haystack; + if (*rhaystack == '\0') + /* No match. */ + return NULL; + comparison_count++; + if (*rhaystack != *rneedle) + /* Nothing in this round. */ + break; + } + } + } + } else - return (char *) haystack; + return (char *) haystack; } } |