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postgresql/src/backend/snowball/dict_snowball.c

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/*-------------------------------------------------------------------------
*
* dict_snowball.c
* Snowball dictionary
*
* Portions Copyright (c) 1996-2024, PostgreSQL Global Development Group
*
* IDENTIFICATION
* src/backend/snowball/dict_snowball.c
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "commands/defrem.h"
#include "tsearch/ts_locale.h"
#include "tsearch/ts_public.h"
/* Some platforms define MAXINT and/or MININT, causing conflicts */
#ifdef MAXINT
#undef MAXINT
#endif
#ifdef MININT
#undef MININT
#endif
/* Now we can include the original Snowball header.h */
#include "snowball/libstemmer/header.h"
#include "snowball/libstemmer/stem_ISO_8859_1_basque.h"
#include "snowball/libstemmer/stem_ISO_8859_1_catalan.h"
#include "snowball/libstemmer/stem_ISO_8859_1_danish.h"
#include "snowball/libstemmer/stem_ISO_8859_1_dutch.h"
#include "snowball/libstemmer/stem_ISO_8859_1_english.h"
#include "snowball/libstemmer/stem_ISO_8859_1_finnish.h"
#include "snowball/libstemmer/stem_ISO_8859_1_french.h"
#include "snowball/libstemmer/stem_ISO_8859_1_german.h"
#include "snowball/libstemmer/stem_ISO_8859_1_indonesian.h"
#include "snowball/libstemmer/stem_ISO_8859_1_irish.h"
#include "snowball/libstemmer/stem_ISO_8859_1_italian.h"
#include "snowball/libstemmer/stem_ISO_8859_1_norwegian.h"
#include "snowball/libstemmer/stem_ISO_8859_1_porter.h"
#include "snowball/libstemmer/stem_ISO_8859_1_portuguese.h"
#include "snowball/libstemmer/stem_ISO_8859_1_spanish.h"
#include "snowball/libstemmer/stem_ISO_8859_1_swedish.h"
#include "snowball/libstemmer/stem_ISO_8859_2_hungarian.h"
#include "snowball/libstemmer/stem_ISO_8859_2_romanian.h"
#include "snowball/libstemmer/stem_KOI8_R_russian.h"
#include "snowball/libstemmer/stem_UTF_8_arabic.h"
#include "snowball/libstemmer/stem_UTF_8_armenian.h"
#include "snowball/libstemmer/stem_UTF_8_basque.h"
#include "snowball/libstemmer/stem_UTF_8_catalan.h"
#include "snowball/libstemmer/stem_UTF_8_danish.h"
#include "snowball/libstemmer/stem_UTF_8_dutch.h"
#include "snowball/libstemmer/stem_UTF_8_english.h"
#include "snowball/libstemmer/stem_UTF_8_finnish.h"
#include "snowball/libstemmer/stem_UTF_8_french.h"
#include "snowball/libstemmer/stem_UTF_8_german.h"
#include "snowball/libstemmer/stem_UTF_8_greek.h"
#include "snowball/libstemmer/stem_UTF_8_hindi.h"
#include "snowball/libstemmer/stem_UTF_8_hungarian.h"
#include "snowball/libstemmer/stem_UTF_8_indonesian.h"
#include "snowball/libstemmer/stem_UTF_8_irish.h"
#include "snowball/libstemmer/stem_UTF_8_italian.h"
#include "snowball/libstemmer/stem_UTF_8_lithuanian.h"
#include "snowball/libstemmer/stem_UTF_8_nepali.h"
#include "snowball/libstemmer/stem_UTF_8_norwegian.h"
#include "snowball/libstemmer/stem_UTF_8_porter.h"
#include "snowball/libstemmer/stem_UTF_8_portuguese.h"
#include "snowball/libstemmer/stem_UTF_8_romanian.h"
#include "snowball/libstemmer/stem_UTF_8_russian.h"
#include "snowball/libstemmer/stem_UTF_8_serbian.h"
#include "snowball/libstemmer/stem_UTF_8_spanish.h"
#include "snowball/libstemmer/stem_UTF_8_swedish.h"
#include "snowball/libstemmer/stem_UTF_8_tamil.h"
#include "snowball/libstemmer/stem_UTF_8_turkish.h"
#include "snowball/libstemmer/stem_UTF_8_yiddish.h"
PG_MODULE_MAGIC;
PG_FUNCTION_INFO_V1(dsnowball_init);
PG_FUNCTION_INFO_V1(dsnowball_lexize);
/* List of supported modules */
typedef struct stemmer_module
{
const char *name;
pg_enc enc;
struct SN_env *(*create) (void);
void (*close) (struct SN_env *);
int (*stem) (struct SN_env *);
} stemmer_module;
/* Args: stemmer name, PG code for encoding, Snowball's name for encoding */
#define STEMMER_MODULE(name,enc,senc) \
{#name, enc, name##_##senc##_create_env, name##_##senc##_close_env, name##_##senc##_stem}
static const stemmer_module stemmer_modules[] =
{
/*
* Stemmers list from Snowball distribution
*/
STEMMER_MODULE(basque, PG_LATIN1, ISO_8859_1),
STEMMER_MODULE(catalan, PG_LATIN1, ISO_8859_1),
STEMMER_MODULE(danish, PG_LATIN1, ISO_8859_1),
STEMMER_MODULE(dutch, PG_LATIN1, ISO_8859_1),
STEMMER_MODULE(english, PG_LATIN1, ISO_8859_1),
STEMMER_MODULE(finnish, PG_LATIN1, ISO_8859_1),
STEMMER_MODULE(french, PG_LATIN1, ISO_8859_1),
STEMMER_MODULE(german, PG_LATIN1, ISO_8859_1),
STEMMER_MODULE(indonesian, PG_LATIN1, ISO_8859_1),
STEMMER_MODULE(irish, PG_LATIN1, ISO_8859_1),
STEMMER_MODULE(italian, PG_LATIN1, ISO_8859_1),
STEMMER_MODULE(norwegian, PG_LATIN1, ISO_8859_1),
STEMMER_MODULE(porter, PG_LATIN1, ISO_8859_1),
STEMMER_MODULE(portuguese, PG_LATIN1, ISO_8859_1),
STEMMER_MODULE(spanish, PG_LATIN1, ISO_8859_1),
STEMMER_MODULE(swedish, PG_LATIN1, ISO_8859_1),
STEMMER_MODULE(hungarian, PG_LATIN2, ISO_8859_2),
STEMMER_MODULE(romanian, PG_LATIN2, ISO_8859_2),
STEMMER_MODULE(russian, PG_KOI8R, KOI8_R),
STEMMER_MODULE(arabic, PG_UTF8, UTF_8),
STEMMER_MODULE(armenian, PG_UTF8, UTF_8),
STEMMER_MODULE(basque, PG_UTF8, UTF_8),
STEMMER_MODULE(catalan, PG_UTF8, UTF_8),
STEMMER_MODULE(danish, PG_UTF8, UTF_8),
STEMMER_MODULE(dutch, PG_UTF8, UTF_8),
STEMMER_MODULE(english, PG_UTF8, UTF_8),
STEMMER_MODULE(finnish, PG_UTF8, UTF_8),
STEMMER_MODULE(french, PG_UTF8, UTF_8),
STEMMER_MODULE(german, PG_UTF8, UTF_8),
STEMMER_MODULE(greek, PG_UTF8, UTF_8),
STEMMER_MODULE(hindi, PG_UTF8, UTF_8),
STEMMER_MODULE(hungarian, PG_UTF8, UTF_8),
STEMMER_MODULE(indonesian, PG_UTF8, UTF_8),
STEMMER_MODULE(irish, PG_UTF8, UTF_8),
STEMMER_MODULE(italian, PG_UTF8, UTF_8),
STEMMER_MODULE(lithuanian, PG_UTF8, UTF_8),
STEMMER_MODULE(nepali, PG_UTF8, UTF_8),
STEMMER_MODULE(norwegian, PG_UTF8, UTF_8),
STEMMER_MODULE(porter, PG_UTF8, UTF_8),
STEMMER_MODULE(portuguese, PG_UTF8, UTF_8),
STEMMER_MODULE(romanian, PG_UTF8, UTF_8),
STEMMER_MODULE(russian, PG_UTF8, UTF_8),
STEMMER_MODULE(serbian, PG_UTF8, UTF_8),
STEMMER_MODULE(spanish, PG_UTF8, UTF_8),
STEMMER_MODULE(swedish, PG_UTF8, UTF_8),
STEMMER_MODULE(tamil, PG_UTF8, UTF_8),
STEMMER_MODULE(turkish, PG_UTF8, UTF_8),
STEMMER_MODULE(yiddish, PG_UTF8, UTF_8),
/*
* Stemmer with PG_SQL_ASCII encoding should be valid for any server
* encoding
*/
STEMMER_MODULE(english, PG_SQL_ASCII, ISO_8859_1),
{NULL, 0, NULL, NULL, NULL} /* list end marker */
};
typedef struct DictSnowball
{
struct SN_env *z;
StopList stoplist;
bool needrecode; /* needs recoding before/after call stem */
int (*stem) (struct SN_env *z);
/*
* snowball saves alloced memory between calls, so we should run it in our
* private memory context. Note, init function is executed in long lived
* context, so we just remember CurrentMemoryContext
*/
MemoryContext dictCtx;
} DictSnowball;
static void
locate_stem_module(DictSnowball *d, const char *lang)
{
const stemmer_module *m;
/*
* First, try to find exact match of stemmer module. Stemmer with
* PG_SQL_ASCII encoding is treated as working with any server encoding
*/
for (m = stemmer_modules; m->name; m++)
{
if ((m->enc == PG_SQL_ASCII || m->enc == GetDatabaseEncoding()) &&
pg_strcasecmp(m->name, lang) == 0)
{
d->stem = m->stem;
d->z = m->create();
d->needrecode = false;
return;
}
}
/*
* Second, try to find stemmer for needed language for UTF8 encoding.
*/
for (m = stemmer_modules; m->name; m++)
{
if (m->enc == PG_UTF8 && pg_strcasecmp(m->name, lang) == 0)
{
d->stem = m->stem;
d->z = m->create();
d->needrecode = true;
return;
}
}
ereport(ERROR,
(errcode(ERRCODE_UNDEFINED_OBJECT),
errmsg("no Snowball stemmer available for language \"%s\" and encoding \"%s\"",
lang, GetDatabaseEncodingName())));
}
Datum
dsnowball_init(PG_FUNCTION_ARGS)
{
List *dictoptions = (List *) PG_GETARG_POINTER(0);
DictSnowball *d;
bool stoploaded = false;
ListCell *l;
d = (DictSnowball *) palloc0(sizeof(DictSnowball));
foreach(l, dictoptions)
{
DefElem *defel = (DefElem *) lfirst(l);
if (strcmp(defel->defname, "stopwords") == 0)
{
if (stoploaded)
ereport(ERROR,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("multiple StopWords parameters")));
readstoplist(defGetString(defel), &d->stoplist, lowerstr);
stoploaded = true;
}
else if (strcmp(defel->defname, "language") == 0)
{
if (d->stem)
ereport(ERROR,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("multiple Language parameters")));
locate_stem_module(d, defGetString(defel));
}
else
{
ereport(ERROR,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("unrecognized Snowball parameter: \"%s\"",
defel->defname)));
}
}
if (!d->stem)
ereport(ERROR,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("missing Language parameter")));
d->dictCtx = CurrentMemoryContext;
PG_RETURN_POINTER(d);
}
Datum
dsnowball_lexize(PG_FUNCTION_ARGS)
{
DictSnowball *d = (DictSnowball *) PG_GETARG_POINTER(0);
char *in = (char *) PG_GETARG_POINTER(1);
int32 len = PG_GETARG_INT32(2);
char *txt = lowerstr_with_len(in, len);
TSLexeme *res = palloc0(sizeof(TSLexeme) * 2);
/*
* Do not pass strings exceeding 1000 bytes to the stemmer, as they're
* surely not words in any human language. This restriction avoids
* wasting cycles on stuff like base64-encoded data, and it protects us
* against possible inefficiency or misbehavior in the stemmer. (For
* example, the Turkish stemmer has an indefinite recursion, so it can
* crash on long-enough strings.) However, Snowball dictionaries are
* defined to recognize all strings, so we can't reject the string as an
* unknown word.
*/
if (len > 1000)
{
/* return the lexeme lowercased, but otherwise unmodified */
res->lexeme = txt;
}
else if (*txt == '\0' || searchstoplist(&(d->stoplist), txt))
{
/* empty or stopword, so report as stopword */
pfree(txt);
}
else
{
MemoryContext saveCtx;
/*
* recode to utf8 if stemmer is utf8 and doesn't match server encoding
*/
if (d->needrecode)
{
char *recoded;
recoded = pg_server_to_any(txt, strlen(txt), PG_UTF8);
if (recoded != txt)
{
pfree(txt);
txt = recoded;
}
}
/* see comment about d->dictCtx */
saveCtx = MemoryContextSwitchTo(d->dictCtx);
SN_set_current(d->z, strlen(txt), (symbol *) txt);
d->stem(d->z);
MemoryContextSwitchTo(saveCtx);
if (d->z->p && d->z->l)
{
txt = repalloc(txt, d->z->l + 1);
memcpy(txt, d->z->p, d->z->l);
txt[d->z->l] = '\0';
}
/* back recode if needed */
if (d->needrecode)
{
char *recoded;
recoded = pg_any_to_server(txt, strlen(txt), PG_UTF8);
if (recoded != txt)
{
pfree(txt);
txt = recoded;
}
}
res->lexeme = txt;
}
PG_RETURN_POINTER(res);
}
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