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kstring.c

#include <stdarg.h>
#include <stdio.h>
#include <ctype.h>
#include <string.h>
#include <stdint.h>
#include "kstring.h"

int ksprintf(kstring_t *s, const char *fmt, ...)
{
      va_list ap;
      int l;
      va_start(ap, fmt);
      l = vsnprintf(s->s + s->l, s->m - s->l, fmt, ap); // This line does not work with glibc 2.0. See `man snprintf'.
      va_end(ap);
      if (l + 1 > s->m - s->l) {
            s->m = s->l + l + 2;
            kroundup32(s->m);
            s->s = (char*)realloc(s->s, s->m);
            va_start(ap, fmt);
            l = vsnprintf(s->s + s->l, s->m - s->l, fmt, ap);
      }
      va_end(ap);
      s->l += l;
      return l;
}

char *kstrtok(const char *str, const char *sep, ks_tokaux_t *aux)
{
      const char *p, *start;
      if (sep) { // set up the table
            if (str == 0 && (aux->tab[0]&1)) return 0; // no need to set up if we have finished
            aux->tab[0] = aux->tab[1] = aux->tab[2] = aux->tab[3] = 0;
            for (p = sep; *p; ++p)
                  aux->tab[*p/64] |= 1ull<<(*p%64);
      }
      if (str) aux->p = str - 1, aux->tab[0] &= ~1ull;
      else if (aux->tab[0]&1) return 0;
      for (p = start = aux->p + 1; *p; ++p)
            if (aux->tab[*p/64]>>(*p%64)&1) break;
      aux->p = p; // end of token
      if (*p == 0) aux->tab[0] |= 1; // no more tokens
      return (char*)start;
}

// s MUST BE a null terminated string; l = strlen(s)
int ksplit_core(char *s, int delimiter, int *_max, int **_offsets)
{
      int i, n, max, last_char, last_start, *offsets, l;
      n = 0; max = *_max; offsets = *_offsets;
      l = strlen(s);
      
#define __ksplit_aux do {                                                                       \
            if (_offsets) {                                                                           \
                  s[i] = 0;                                                                           \
                  if (n == max) {                                                                     \
                        max = max? max<<1 : 2;                                                  \
                        offsets = (int*)realloc(offsets, sizeof(int) * max);  \
                  }                                                                                         \
                  offsets[n++] = last_start;                                                    \
            } else ++n;                                                                               \
      } while (0)

      for (i = 0, last_char = last_start = 0; i <= l; ++i) {
            if (delimiter == 0) {
                  if (isspace(s[i]) || s[i] == 0) {
                        if (isgraph(last_char)) __ksplit_aux; // the end of a field
                  } else {
                        if (isspace(last_char) || last_char == 0) last_start = i;
                  }
            } else {
                  if (s[i] == delimiter || s[i] == 0) {
                        if (last_char != 0 && last_char != delimiter) __ksplit_aux; // the end of a field
                  } else {
                        if (last_char == delimiter || last_char == 0) last_start = i;
                  }
            }
            last_char = s[i];
      }
      *_max = max; *_offsets = offsets;
      return n;
}

/**********************
 * Boyer-Moore search *
 **********************/

typedef unsigned char ubyte_t;

// reference: http://www-igm.univ-mlv.fr/~lecroq/string/node14.html
static int *ksBM_prep(const ubyte_t *pat, int m)
{
      int i, *suff, *prep, *bmGs, *bmBc;
      prep = calloc(m + 256, sizeof(int));
      bmGs = prep; bmBc = prep + m;
      { // preBmBc()
            for (i = 0; i < 256; ++i) bmBc[i] = m;
            for (i = 0; i < m - 1; ++i) bmBc[pat[i]] = m - i - 1;
      }
      suff = calloc(m, sizeof(int));
      { // suffixes()
            int f = 0, g;
            suff[m - 1] = m;
            g = m - 1;
            for (i = m - 2; i >= 0; --i) {
                  if (i > g && suff[i + m - 1 - f] < i - g)
                        suff[i] = suff[i + m - 1 - f];
                  else {
                        if (i < g) g = i;
                        f = i;
                        while (g >= 0 && pat[g] == pat[g + m - 1 - f]) --g;
                        suff[i] = f - g;
                  }
            }
      }
      { // preBmGs()
            int j = 0;
            for (i = 0; i < m; ++i) bmGs[i] = m;
            for (i = m - 1; i >= 0; --i)
                  if (suff[i] == i + 1)
                        for (; j < m - 1 - i; ++j)
                              if (bmGs[j] == m)
                                    bmGs[j] = m - 1 - i;
            for (i = 0; i <= m - 2; ++i)
                  bmGs[m - 1 - suff[i]] = m - 1 - i;
      }
      free(suff);
      return prep;
}

void *kmemmem(const void *_str, int n, const void *_pat, int m, int **_prep)
{
      int i, j, *prep = 0, *bmGs, *bmBc;
      const ubyte_t *str, *pat;
      str = (const ubyte_t*)_str; pat = (const ubyte_t*)_pat;
      prep = (_prep == 0 || *_prep == 0)? ksBM_prep(pat, m) : *_prep;
      if (_prep && *_prep == 0) *_prep = prep;
      bmGs = prep; bmBc = prep + m;
      j = 0;
      while (j <= n - m) {
            for (i = m - 1; i >= 0 && pat[i] == str[i+j]; --i);
            if (i >= 0) {
                  int max = bmBc[str[i+j]] - m + 1 + i;
                  if (max < bmGs[i]) max = bmGs[i];
                  j += max;
            } else return (void*)(str + j);
      }
      if (_prep == 0) free(prep);
      return 0;
}

char *kstrstr(const char *str, const char *pat, int **_prep)
{
      return (char*)kmemmem(str, strlen(str), pat, strlen(pat), _prep);
}

char *kstrnstr(const char *str, const char *pat, int n, int **_prep)
{
      return (char*)kmemmem(str, n, pat, strlen(pat), _prep);
}

/***********************
 * The main() function *
 ***********************/

#ifdef KSTRING_MAIN
#include <stdio.h>
int main()
{
      kstring_t *s;
      int *fields, n, i;
      ks_tokaux_t aux;
      char *p;
      s = (kstring_t*)calloc(1, sizeof(kstring_t));
      // test ksprintf()
      ksprintf(s, " abcdefg:    %d ", 100);
      printf("'%s'\n", s->s);
      // test ksplit()
      fields = ksplit(s, 0, &n);
      for (i = 0; i < n; ++i)
            printf("field[%d] = '%s'\n", i, s->s + fields[i]);
      // test kstrtok()
      s->l = 0;
      for (p = kstrtok("ab:cde:fg/hij::k", ":/", &aux); p; p = kstrtok(0, 0, &aux)) {
            kputsn(p, aux.p - p, s);
            kputc('\n', s);
      }
      printf("%s", s->s);
      // free
      free(s->s); free(s); free(fields);

      {
            static char *str = "abcdefgcdgcagtcakcdcd";
            static char *pat = "cd";
            char *ret, *s = str;
            int *prep = 0;
            while ((ret = kstrstr(s, pat, &prep)) != 0) {
                  printf("match: %s\n", ret);
                  s = ret + prep[0];
            }
            free(prep);
      }
      return 0;
}
#endif

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