postgresql/contrib/dict_xsyn/dict_xsyn.c

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2023-05-09 21:11:15 +00:00
/*-------------------------------------------------------------------------
*
* dict_xsyn.c
* Extended synonym dictionary
*
* Copyright (c) 2007-2022, PostgreSQL Global Development Group
*
* IDENTIFICATION
* contrib/dict_xsyn/dict_xsyn.c
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include <ctype.h>
#include "commands/defrem.h"
#include "tsearch/ts_locale.h"
#include "tsearch/ts_utils.h"
PG_MODULE_MAGIC;
typedef struct
{
char *key; /* Word */
char *value; /* Unparsed list of synonyms, including the
* word itself */
} Syn;
typedef struct
{
int len;
Syn *syn;
bool matchorig;
bool keeporig;
bool matchsynonyms;
bool keepsynonyms;
} DictSyn;
PG_FUNCTION_INFO_V1(dxsyn_init);
PG_FUNCTION_INFO_V1(dxsyn_lexize);
static char *
find_word(char *in, char **end)
{
char *start;
*end = NULL;
while (*in && t_isspace(in))
in += pg_mblen(in);
if (!*in || *in == '#')
return NULL;
start = in;
while (*in && !t_isspace(in))
in += pg_mblen(in);
*end = in;
return start;
}
static int
compare_syn(const void *a, const void *b)
{
return strcmp(((const Syn *) a)->key, ((const Syn *) b)->key);
}
static void
read_dictionary(DictSyn *d, const char *filename)
{
char *real_filename = get_tsearch_config_filename(filename, "rules");
tsearch_readline_state trst;
char *line;
int cur = 0;
if (!tsearch_readline_begin(&trst, real_filename))
ereport(ERROR,
(errcode(ERRCODE_CONFIG_FILE_ERROR),
errmsg("could not open synonym file \"%s\": %m",
real_filename)));
while ((line = tsearch_readline(&trst)) != NULL)
{
char *value;
char *key;
char *pos;
char *end;
if (*line == '\0')
continue;
value = lowerstr(line);
pfree(line);
pos = value;
while ((key = find_word(pos, &end)) != NULL)
{
/* Enlarge syn structure if full */
if (cur == d->len)
{
d->len = (d->len > 0) ? 2 * d->len : 16;
if (d->syn)
d->syn = (Syn *) repalloc(d->syn, sizeof(Syn) * d->len);
else
d->syn = (Syn *) palloc(sizeof(Syn) * d->len);
}
/* Save first word only if we will match it */
if (pos != value || d->matchorig)
{
d->syn[cur].key = pnstrdup(key, end - key);
d->syn[cur].value = pstrdup(value);
cur++;
}
pos = end;
/* Don't bother scanning synonyms if we will not match them */
if (!d->matchsynonyms)
break;
}
pfree(value);
}
tsearch_readline_end(&trst);
d->len = cur;
if (cur > 1)
qsort(d->syn, d->len, sizeof(Syn), compare_syn);
pfree(real_filename);
}
Datum
dxsyn_init(PG_FUNCTION_ARGS)
{
List *dictoptions = (List *) PG_GETARG_POINTER(0);
DictSyn *d;
ListCell *l;
char *filename = NULL;
d = (DictSyn *) palloc0(sizeof(DictSyn));
d->len = 0;
d->syn = NULL;
d->matchorig = true;
d->keeporig = true;
d->matchsynonyms = false;
d->keepsynonyms = true;
foreach(l, dictoptions)
{
DefElem *defel = (DefElem *) lfirst(l);
if (strcmp(defel->defname, "matchorig") == 0)
{
d->matchorig = defGetBoolean(defel);
}
else if (strcmp(defel->defname, "keeporig") == 0)
{
d->keeporig = defGetBoolean(defel);
}
else if (strcmp(defel->defname, "matchsynonyms") == 0)
{
d->matchsynonyms = defGetBoolean(defel);
}
else if (strcmp(defel->defname, "keepsynonyms") == 0)
{
d->keepsynonyms = defGetBoolean(defel);
}
else if (strcmp(defel->defname, "rules") == 0)
{
/* we can't read the rules before parsing all options! */
filename = defGetString(defel);
}
else
{
ereport(ERROR,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("unrecognized xsyn parameter: \"%s\"",
defel->defname)));
}
}
if (filename)
read_dictionary(d, filename);
PG_RETURN_POINTER(d);
}
Datum
dxsyn_lexize(PG_FUNCTION_ARGS)
{
DictSyn *d = (DictSyn *) PG_GETARG_POINTER(0);
char *in = (char *) PG_GETARG_POINTER(1);
int length = PG_GETARG_INT32(2);
Syn word;
Syn *found;
TSLexeme *res = NULL;
if (!length || d->len == 0)
PG_RETURN_POINTER(NULL);
/* Create search pattern */
{
char *temp = pnstrdup(in, length);
word.key = lowerstr(temp);
pfree(temp);
word.value = NULL;
}
/* Look for matching syn */
found = (Syn *) bsearch(&word, d->syn, d->len, sizeof(Syn), compare_syn);
pfree(word.key);
if (!found)
PG_RETURN_POINTER(NULL);
/* Parse string of synonyms and return array of words */
{
char *value = found->value;
char *syn;
char *pos;
char *end;
int nsyns = 0;
res = palloc(sizeof(TSLexeme));
pos = value;
while ((syn = find_word(pos, &end)) != NULL)
{
res = repalloc(res, sizeof(TSLexeme) * (nsyns + 2));
/* The first word is output only if keeporig=true */
if (pos != value || d->keeporig)
{
res[nsyns].lexeme = pnstrdup(syn, end - syn);
res[nsyns].nvariant = 0;
res[nsyns].flags = 0;
nsyns++;
}
pos = end;
/* Stop if we are not to output the synonyms */
if (!d->keepsynonyms)
break;
}
res[nsyns].lexeme = NULL;
}
PG_RETURN_POINTER(res);
}