#include "c.h"

static char rcsid[] = "$Id: string.nw,v 1.9 1997/05/02 20:32:31 drh Exp $";

static struct string {
  char *str;
  int len;
  struct string *link;
} *buckets[1024];
static int scatter[] = {  /* map characters to random values */
  2078917053, 143302914, 1027100827, 1953210302, 755253631,
  2002600785, 1405390230, 45248011, 1099951567, 433832350,
  2018585307, 438263339, 813528929, 1703199216, 618906479,
  573714703, 766270699, 275680090, 1510320440, 1583583926,
  1723401032, 1965443329, 1098183682, 1636505764, 980071615,
  1011597961, 643279273, 1315461275, 157584038, 1069844923,
  471560540, 89017443, 1213147837, 1498661368, 2042227746,
  1968401469, 1353778505, 1300134328, 2013649480, 306246424,
  1733966678, 1884751139, 744509763, 400011959, 1440466707,
  1363416242, 973726663, 59253759, 1639096332, 336563455,
  1642837685, 1215013716, 154523136, 593537720, 704035832,
  1134594751, 1605135681, 1347315106, 302572379, 1762719719,
  269676381, 774132919, 1851737163, 1482824219, 125310639,
  1746481261, 1303742040, 1479089144, 899131941, 1169907872,
  1785335569, 485614972, 907175364, 382361684, 885626931,
  200158423, 1745777927, 1859353594, 259412182, 1237390611,
  48433401, 1902249868, 304920680, 202956538, 348303940,
  1008956512, 1337551289, 1953439621, 208787970, 1640123668,
  1568675693, 478464352, 266772940, 1272929208, 1961288571,
  392083579, 871926821, 1117546963, 1871172724, 1771058762,
  139971187, 1509024645, 109190086, 1047146551, 1891386329,
  994817018, 1247304975, 1489680608, 706686964, 1506717157,
  579587572, 755120366, 1261483377, 884508252, 958076904,
  1609787317, 1893464764, 148144545, 1415743291, 2102252735,
  1788268214, 836935336, 433233439, 2055041154, 2109864544,
  247038362, 299641085, 834307717, 1364585325, 23330161,
  457882831, 1504556512, 1532354806, 567072918, 404219416,
  1276257488, 1561889936, 1651524391, 618454448, 121093252,
  1010757900, 1198042020, 876213618, 124757630, 2082550272,
  1834290522, 1734544947, 1828531389, 1982435068, 1002804590,
  1783300476, 1623219634, 1839739926, 69050267, 1530777140,
  1802120822, 316088629, 1830418225, 488944891, 1680673954,
  1853748387, 946827723, 1037746818, 1238619545, 1513900641,
  1441966234, 367393385, 928306929, 946006977, 985847834,
  1049400181, 1956764878, 36406206, 1925613800, 2081522508,
  2118956479, 1612420674, 1668583807, 1800004220, 1447372094,
  523904750, 1435821048, 923108080, 216161028, 1504871315,
  306401572, 2018281851, 1820959944, 2136819798, 359743094,
  1354150250, 1843084537, 1306570817, 244413420, 934220434,
  672987810, 1686379655, 1301613820, 1601294739, 484902984,
  139978006, 503211273, 294184214, 176384212, 281341425,
  228223074, 147857043, 1893762099, 1896806882, 1947861263,
  1193650546, 273227984, 1236198663, 2116758626, 489389012,
  593586330, 275676551, 360187215, 267062626, 265012701,
  719930310, 1621212876, 2108097238, 2026501127, 1865626297,
  894834024, 552005290, 1404522304, 48964196, 5816381,
  1889425288, 188942202, 509027654, 36125855, 365326415,
  790369079, 264348929, 513183458, 536647531, 13672163,
  313561074, 1730298077, 286900147, 1549759737, 1699573055,
  776289160, 2143346068, 1975249606, 1136476375, 262925046,
  92778659, 1856406685, 1884137923, 53392249, 1735424165,
  1602280572
};
char *string(const char *str) {
  const char *s;

  for (s = str; *s; s++)
    ;
  return stringn(str, s - str);
}
char *stringd(long n) {
  char str[25], *s = str + sizeof (str);
  unsigned long m;

  if (n == LONG_MIN)
    m = (unsigned long)LONG_MAX + 1;
  else if (n < 0)
    m = -n;
  else
    m = n;
  do
    *--s = m%10 + '0';
  while ((m /= 10) != 0);
  if (n < 0)
    *--s = '-';
  return stringn(s, str + sizeof (str) - s);
}
char *stringn(const char *str, int len) {
  int i;
  unsigned int h;
  const char *end;
  struct string *p;

  assert(str);
  for (h = 0, i = len, end = str; i > 0; i--)
    h = (h<<1) + scatter[*(unsigned char *)end++];
  h &= NELEMS(buckets)-1;
  for (p = buckets[h]; p; p = p->link)
    if (len == p->len) {
      const char *s1 = str;
      char *s2 = p->str;
      do {
        if (s1 == end)
          return p->str;
      } while (*s1++ == *s2++);
    }
  {
    static char *next, *strlimit;
    if (len + 1 >= strlimit - next) {
      int n = len + 4*1024;
      next = allocate(n, PERM);
      strlimit = next + n;
    }
    NEW(p, PERM);
    p->len = len;
    for (p->str = next; str < end; )
      *next++ = *str++;
    *next++ = 0;
    p->link = buckets[h];
    buckets[h] = p;
    return p->str;
  }
}
