static void
cnt_trigram(trgm *tptr, char *str, int bytelen)
{
if (bytelen == 3)
{
CPTRGM(tptr, str);
}
else
{
pg_crc32 crc;
INIT_CRC32(crc);
COMP_CRC32(crc, str, bytelen);
FIN_CRC32(crc);
/*
* use only 3 upper bytes from crc, hope, it's good enough hashing
*/
CPTRGM(tptr, &crc);
}
}
Datum
show_trgm(PG_FUNCTION_ARGS)
{
text *in = PG_GETARG_TEXT_P(0);
TRGM *trg;
Datum *d;
ArrayType *a;
trgm *ptr;
int i;
trg = generate_trgm(VARDATA(in), VARSIZE(in) - VARHDRSZ);
d = (Datum *) palloc(sizeof(Datum) * (1 + ARRNELEM(trg)));
for (i = 0, ptr = GETARR(trg); i < ARRNELEM(trg); i++, ptr++)
{
text *item = (text *) palloc(VARHDRSZ + Max(12, pg_database_encoding_max_length() * 3));
if (pg_database_encoding_max_length() > 1 && !ISPRINTABLETRGM(ptr))
{
snprintf(VARDATA(item), 12, "0x%06x", trgm2int(ptr));
SET_VARSIZE(item, VARHDRSZ + strlen(VARDATA(item)));
}
else
{
SET_VARSIZE(item, VARHDRSZ + 3);
CPTRGM(VARDATA(item), ptr);
}
d[i] = PointerGetDatum(item);
}
a = construct_array(
d,
ARRNELEM(trg),
TEXTOID,
-1,
false,
'i'
);
for (i = 0; i < ARRNELEM(trg); i++)
pfree(DatumGetPointer(d[i]));
pfree(d);
pfree(trg);
PG_FREE_IF_COPY(in, 0);
PG_RETURN_POINTER(a);
}
static void
makesign(BITVECP sign, TRGM *a)
{
int32 k,
len = ARRNELEM(a);
trgm *ptr = GETARR(a);
int32 tmp = 0;
MemSet((void *) sign, 0, sizeof(BITVEC));
SETBIT(sign, SIGLENBIT); /* set last unused bit */
for (k = 0; k < len; k++)
{
CPTRGM(((char *) &tmp), ptr + k);
HASH(sign, tmp);
}
}
static int
unique_array(trgm *a, int len)
{
trgm *curend,
*tmp;
curend = tmp = a;
while (tmp - a < len)
if (CMPTRGM(tmp, curend))
{
curend++;
CPTRGM(curend, tmp);
tmp++;
}
else
tmp++;
return curend + 1 - a;
}
/*
* Adds trigrams from words (already padded).
*/
static trgm *
make_trigrams(trgm *tptr, char *str, int bytelen, int charlen)
{
char *ptr = str;
if (charlen < 3)
return tptr;
#ifdef USE_WIDE_UPPER_LOWER
if (pg_database_encoding_max_length() > 1)
{
int lenfirst = pg_mblen(str),
lenmiddle = pg_mblen(str + lenfirst),
lenlast = pg_mblen(str + lenfirst + lenmiddle);
while ((ptr - str) + lenfirst + lenmiddle + lenlast <= bytelen)
{
cnt_trigram(tptr, ptr, lenfirst + lenmiddle + lenlast);
ptr += lenfirst;
tptr++;
lenfirst = lenmiddle;
lenmiddle = lenlast;
lenlast = pg_mblen(ptr + lenfirst + lenmiddle);
}
}
else
#endif
{
Assert(bytelen == charlen);
while (ptr - str < bytelen - 2 /* number of trigrams = strlen - 2 */ )
{
CPTRGM(tptr, ptr);
ptr++;
tptr++;
}
}
return tptr;
}
/*
* Adds trigrams from words (already padded).
*/
static trgm *
make_trigrams(trgm *tptr, char *str, int bytelen, int charlen)
{
char *ptr = str;
if (charlen < 3)
return tptr;
if (bytelen > charlen)
{
/* Find multibyte character boundaries and apply compact_trigram */
int lenfirst = pg_mblen(str),
lenmiddle = pg_mblen(str + lenfirst),
lenlast = pg_mblen(str + lenfirst + lenmiddle);
while ((ptr - str) + lenfirst + lenmiddle + lenlast <= bytelen)
{
compact_trigram(tptr, ptr, lenfirst + lenmiddle + lenlast);
ptr += lenfirst;
tptr++;
lenfirst = lenmiddle;
lenmiddle = lenlast;
lenlast = pg_mblen(ptr + lenfirst + lenmiddle);
}
}
else
{
/* Fast path when there are no multibyte characters */
Assert(bytelen == charlen);
while (ptr - str < bytelen - 2 /* number of trigrams = strlen - 2 */ )
{
CPTRGM(tptr, ptr);
ptr++;
tptr++;
}
}
return tptr;
}
