+/* Knuth-Morris-Pratt algorithm. */
+#define UNIT unsigned char
+#define CANON_ELEMENT(c) TOLOWER (c)
+#include "str-kmp.h"
+
+/* Knuth-Morris-Pratt algorithm.
+ See http://en.wikipedia.org/wiki/Knuth-Morris-Pratt_algorithm
+ Return a boolean indicating success:
+ Return true and set *RESULTP if the search was completed.
+ 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)
+{
+ 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));
+ if (memory == NULL)
+ return false;
+ needle_mbchars = (mbchar_t *) memory;
+ table = (size_t *) (memory + m * sizeof (mbchar_t));
+
+ /* Fill needle_mbchars. */
+ {
+ mbui_iterator_t iter;
+ size_t j;
+
+ j = 0;
+ for (mbui_init (iter, needle); mbui_avail (iter); mbui_advance (iter), j++)
+ {
+ mb_copy (&needle_mbchars[j], &mbui_cur (iter));
+ if (needle_mbchars[j].wc_valid)
+ needle_mbchars[j].wc = towlower (needle_mbchars[j].wc);
+ }
+ }
+
+ /* Fill the table.
+ For 0 < i < m:
+ 0 < table[i] <= i is defined such that
+ forall 0 < x < table[i]: needle[x..i-1] != needle[0..i-1-x],
+ and table[i] is as large as possible with this property.
+ This implies:
+ 1) For 0 < i < m:
+ If table[i] < i,
+ needle[table[i]..i-1] = needle[0..i-1-table[i]].
+ 2) For 0 < i < m:
+ rhaystack[0..i-1] == needle[0..i-1]
+ and exists h, i <= h < m: rhaystack[h] != needle[h]
+ implies
+ forall 0 <= x < table[i]: rhaystack[x..x+m-1] != needle[0..m-1].
+ table[0] remains uninitialized. */
+ {
+ size_t i, j;
+
+ /* i = 1: Nothing to verify for x = 0. */
+ table[1] = 1;
+ j = 0;
+
+ 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]. */
+ }
+ }
+
+ /* Search, using the table to accelerate the processing. */
+ {
+ size_t j;
+ mbui_iterator_t rhaystack;
+ mbui_iterator_t phaystack;
+
+ *resultp = NULL;
+ j = 0;
+ mbui_init (rhaystack, haystack);
+ mbui_init (phaystack, haystack);
+ /* Invariant: phaystack = rhaystack + j. */
+ while (mbui_avail (phaystack))
+ {
+ mbchar_t c;
+
+ mb_copy (&c, &mbui_cur (phaystack));
+ if (c.wc_valid)
+ c.wc = towlower (c.wc);
+ if (mb_equal (needle_mbchars[j], c))
+ {
+ 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);
+ }
+ }
+ else
+ {
+ /* Found a mismatch at needle[0] already. */
+ if (!mbui_avail (rhaystack))
+ abort ();
+ mbui_advance (rhaystack);
+ mbui_advance (phaystack);
+ }
+ }
+ }
+
+ freea (memory);
+ return true;
+}
+
+/* Find the first occurrence of the character string NEEDLE in the character
+ string HAYSTACK, using case-insensitive comparison.