like.c

Go to the documentation of this file.

/*-------------------------------------------------------------------------
 *
 * like.c
 *    like expression handling code.
 *
 *   NOTES
 *      A big hack of the regexp.c code!! Contributed by
 *      Keith Parks <emkxp01@mtcc.demon.co.uk> (7/95).
 *
 * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 * IDENTIFICATION
 *  src/backend/utils/adt/like.c
 *
 *-------------------------------------------------------------------------
 */
#include "postgres.h"
 
#include <ctype.h>
 
#include "catalog/pg_collation.h"
#include "mb/pg_wchar.h"
#include "miscadmin.h"
#include "utils/fmgrprotos.h"
#include "utils/pg_locale.h"
#include "varatt.h"
 
 
#define LIKE_TRUE                       1
#define LIKE_FALSE                      0
#define LIKE_ABORT                      (-1)
 
 
static int  SB_MatchText(const char *t, int tlen, const char *p, int plen,
                         pg_locale_t locale);
static text *SB_do_like_escape(text *pat, text *esc);
 
static int  MB_MatchText(const char *t, int tlen, const char *p, int plen,
                         pg_locale_t locale);
static text *MB_do_like_escape(text *pat, text *esc);
 
static int  UTF8_MatchText(const char *t, int tlen, const char *p, int plen,
                           pg_locale_t locale);
 
static int  SB_IMatchText(const char *t, int tlen, const char *p, int plen,
                          pg_locale_t locale);
 
static int  GenericMatchText(const char *s, int slen, const char *p, int plen, Oid collation);
static int  Generic_Text_IC_like(text *str, text *pat, Oid collation);
 
/*--------------------
 * Support routine for MatchText. Compares given multibyte streams
 * as wide characters. If they match, returns 1 otherwise returns 0.
 *--------------------
 */
static inline int
wchareq(const char *p1, const char *p2)
{
    int         p1_len;
 
    /* Optimization:  quickly compare the first byte. */
    if (*p1 != *p2)
        return 0;
 
    p1_len = pg_mblen(p1);
    if (pg_mblen(p2) != p1_len)
        return 0;
 
    /* They are the same length */
    while (p1_len--)
    {
        if (*p1++ != *p2++)
            return 0;
    }
    return 1;
}
 
/*
 * Formerly we had a routine iwchareq() here that tried to do case-insensitive
 * comparison of multibyte characters.  It did not work at all, however,
 * because it relied on tolower() which has a single-byte API ... and
 * towlower() wouldn't be much better since we have no suitably cheap way
 * of getting a single character transformed to the system's wchar_t format.
 * So now, we just downcase the strings using lower() and apply regular LIKE
 * comparison.  This should be revisited when we install better locale support.
 */
 
/*
 * We do handle case-insensitive matching for single-byte encodings using
 * fold-on-the-fly processing, however.
 */
static char
SB_lower_char(unsigned char c, pg_locale_t locale)
{
    if (locale->ctype_is_c)
        return pg_ascii_tolower(c);
    else if (locale->is_default)
        return pg_tolower(c);
    else
        return tolower_l(c, locale->info.lt);
}
 
 
#define NextByte(p, plen)   ((p)++, (plen)--)
 
/* Set up to compile like_match.c for multibyte characters */
#define CHAREQ(p1, p2) wchareq((p1), (p2))
#define NextChar(p, plen) \
    do { int __l = pg_mblen(p); (p) +=__l; (plen) -=__l; } while (0)
#define CopyAdvChar(dst, src, srclen) \
    do { int __l = pg_mblen(src); \
         (srclen) -= __l; \
         while (__l-- > 0) \
             *(dst)++ = *(src)++; \
       } while (0)
 
#define MatchText   MB_MatchText
#define do_like_escape  MB_do_like_escape
 
#include "like_match.c"
 
/* Set up to compile like_match.c for single-byte characters */
#define CHAREQ(p1, p2) (*(p1) == *(p2))
#define NextChar(p, plen) NextByte((p), (plen))
#define CopyAdvChar(dst, src, srclen) (*(dst)++ = *(src)++, (srclen)--)
 
#define MatchText   SB_MatchText
#define do_like_escape  SB_do_like_escape
 
#include "like_match.c"
 
/* setup to compile like_match.c for single byte case insensitive matches */
#define MATCH_LOWER(t, locale) SB_lower_char((unsigned char) (t), locale)
#define NextChar(p, plen) NextByte((p), (plen))
#define MatchText SB_IMatchText
 
#include "like_match.c"
 
/* setup to compile like_match.c for UTF8 encoding, using fast NextChar */
 
#define NextChar(p, plen) \
    do { (p)++; (plen)--; } while ((plen) > 0 && (*(p) & 0xC0) == 0x80 )
#define MatchText   UTF8_MatchText
 
#include "like_match.c"
 
/* Generic for all cases not requiring inline case-folding */
static inline int
GenericMatchText(const char *s, int slen, const char *p, int plen, Oid collation)
{
    pg_locale_t locale;
 
    if (!OidIsValid(collation))
    {
        /*
         * This typically means that the parser could not resolve a conflict
         * of implicit collations, so report it that way.
         */
        ereport(ERROR,
                (errcode(ERRCODE_INDETERMINATE_COLLATION),
                 errmsg("could not determine which collation to use for LIKE"),
                 errhint("Use the COLLATE clause to set the collation explicitly.")));
    }
 
    locale = pg_newlocale_from_collation(collation);
 
    if (pg_database_encoding_max_length() == 1)
        return SB_MatchText(s, slen, p, plen, locale);
    else if (GetDatabaseEncoding() == PG_UTF8)
        return UTF8_MatchText(s, slen, p, plen, locale);
    else
        return MB_MatchText(s, slen, p, plen, locale);
}
 
static inline int
Generic_Text_IC_like(text *str, text *pat, Oid collation)
{
    char       *s,
               *p;
    int         slen,
                plen;
    pg_locale_t locale;
 
    if (!OidIsValid(collation))
    {
        /*
         * This typically means that the parser could not resolve a conflict
         * of implicit collations, so report it that way.
         */
        ereport(ERROR,
                (errcode(ERRCODE_INDETERMINATE_COLLATION),
                 errmsg("could not determine which collation to use for ILIKE"),
                 errhint("Use the COLLATE clause to set the collation explicitly.")));
    }
 
    locale = pg_newlocale_from_collation(collation);
 
    if (!locale->deterministic)
        ereport(ERROR,
                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                 errmsg("nondeterministic collations are not supported for ILIKE")));
 
    /*
     * For efficiency reasons, in the single byte case we don't call lower()
     * on the pattern and text, but instead call SB_lower_char on each
     * character.  In the multi-byte case we don't have much choice :-(. Also,
     * ICU does not support single-character case folding, so we go the long
     * way.
     */
 
    if (pg_database_encoding_max_length() > 1 || (locale->provider == COLLPROVIDER_ICU))
    {
        pat = DatumGetTextPP(DirectFunctionCall1Coll(lower, collation,
                                                     PointerGetDatum(pat)));
        p = VARDATA_ANY(pat);
        plen = VARSIZE_ANY_EXHDR(pat);
        str = DatumGetTextPP(DirectFunctionCall1Coll(lower, collation,
                                                     PointerGetDatum(str)));
        s = VARDATA_ANY(str);
        slen = VARSIZE_ANY_EXHDR(str);
        if (GetDatabaseEncoding() == PG_UTF8)
            return UTF8_MatchText(s, slen, p, plen, 0);
        else
            return MB_MatchText(s, slen, p, plen, 0);
    }
    else
    {
        p = VARDATA_ANY(pat);
        plen = VARSIZE_ANY_EXHDR(pat);
        s = VARDATA_ANY(str);
        slen = VARSIZE_ANY_EXHDR(str);
        return SB_IMatchText(s, slen, p, plen, locale);
    }
}
 
/*
 *  interface routines called by the function manager
 */
 
Datum
namelike(PG_FUNCTION_ARGS)
{
    Name        str = PG_GETARG_NAME(0);
    text       *pat = PG_GETARG_TEXT_PP(1);
    bool        result;
    char       *s,
               *p;
    int         slen,
                plen;
 
    s = NameStr(*str);
    slen = strlen(s);
    p = VARDATA_ANY(pat);
    plen = VARSIZE_ANY_EXHDR(pat);
 
    result = (GenericMatchText(s, slen, p, plen, PG_GET_COLLATION()) == LIKE_TRUE);
 
    PG_RETURN_BOOL(result);
}
 
Datum
namenlike(PG_FUNCTION_ARGS)
{
    Name        str = PG_GETARG_NAME(0);
    text       *pat = PG_GETARG_TEXT_PP(1);
    bool        result;
    char       *s,
               *p;
    int         slen,
                plen;
 
    s = NameStr(*str);
    slen = strlen(s);
    p = VARDATA_ANY(pat);
    plen = VARSIZE_ANY_EXHDR(pat);
 
    result = (GenericMatchText(s, slen, p, plen, PG_GET_COLLATION()) != LIKE_TRUE);
 
    PG_RETURN_BOOL(result);
}
 
Datum
textlike(PG_FUNCTION_ARGS)
{
    text       *str = PG_GETARG_TEXT_PP(0);
    text       *pat = PG_GETARG_TEXT_PP(1);
    bool        result;
    char       *s,
               *p;
    int         slen,
                plen;
 
    s = VARDATA_ANY(str);
    slen = VARSIZE_ANY_EXHDR(str);
    p = VARDATA_ANY(pat);
    plen = VARSIZE_ANY_EXHDR(pat);
 
    result = (GenericMatchText(s, slen, p, plen, PG_GET_COLLATION()) == LIKE_TRUE);
 
    PG_RETURN_BOOL(result);
}
 
Datum
textnlike(PG_FUNCTION_ARGS)
{
    text       *str = PG_GETARG_TEXT_PP(0);
    text       *pat = PG_GETARG_TEXT_PP(1);
    bool        result;
    char       *s,
               *p;
    int         slen,
                plen;
 
    s = VARDATA_ANY(str);
    slen = VARSIZE_ANY_EXHDR(str);
    p = VARDATA_ANY(pat);
    plen = VARSIZE_ANY_EXHDR(pat);
 
    result = (GenericMatchText(s, slen, p, plen, PG_GET_COLLATION()) != LIKE_TRUE);
 
    PG_RETURN_BOOL(result);
}
 
Datum
bytealike(PG_FUNCTION_ARGS)
{
    bytea      *str = PG_GETARG_BYTEA_PP(0);
    bytea      *pat = PG_GETARG_BYTEA_PP(1);
    bool        result;
    char       *s,
               *p;
    int         slen,
                plen;
 
    s = VARDATA_ANY(str);
    slen = VARSIZE_ANY_EXHDR(str);
    p = VARDATA_ANY(pat);
    plen = VARSIZE_ANY_EXHDR(pat);
 
    result = (SB_MatchText(s, slen, p, plen, 0) == LIKE_TRUE);
 
    PG_RETURN_BOOL(result);
}
 
Datum
byteanlike(PG_FUNCTION_ARGS)
{
    bytea      *str = PG_GETARG_BYTEA_PP(0);
    bytea      *pat = PG_GETARG_BYTEA_PP(1);
    bool        result;
    char       *s,
               *p;
    int         slen,
                plen;
 
    s = VARDATA_ANY(str);
    slen = VARSIZE_ANY_EXHDR(str);
    p = VARDATA_ANY(pat);
    plen = VARSIZE_ANY_EXHDR(pat);
 
    result = (SB_MatchText(s, slen, p, plen, 0) != LIKE_TRUE);
 
    PG_RETURN_BOOL(result);
}
 
/*
 * Case-insensitive versions
 */
 
Datum
nameiclike(PG_FUNCTION_ARGS)
{
    Name        str = PG_GETARG_NAME(0);
    text       *pat = PG_GETARG_TEXT_PP(1);
    bool        result;
    text       *strtext;
 
    strtext = DatumGetTextPP(DirectFunctionCall1(name_text,
                                                 NameGetDatum(str)));
    result = (Generic_Text_IC_like(strtext, pat, PG_GET_COLLATION()) == LIKE_TRUE);
 
    PG_RETURN_BOOL(result);
}
 
Datum
nameicnlike(PG_FUNCTION_ARGS)
{
    Name        str = PG_GETARG_NAME(0);
    text       *pat = PG_GETARG_TEXT_PP(1);
    bool        result;
    text       *strtext;
 
    strtext = DatumGetTextPP(DirectFunctionCall1(name_text,
                                                 NameGetDatum(str)));
    result = (Generic_Text_IC_like(strtext, pat, PG_GET_COLLATION()) != LIKE_TRUE);
 
    PG_RETURN_BOOL(result);
}
 
Datum
texticlike(PG_FUNCTION_ARGS)
{
    text       *str = PG_GETARG_TEXT_PP(0);
    text       *pat = PG_GETARG_TEXT_PP(1);
    bool        result;
 
    result = (Generic_Text_IC_like(str, pat, PG_GET_COLLATION()) == LIKE_TRUE);
 
    PG_RETURN_BOOL(result);
}
 
Datum
texticnlike(PG_FUNCTION_ARGS)
{
    text       *str = PG_GETARG_TEXT_PP(0);
    text       *pat = PG_GETARG_TEXT_PP(1);
    bool        result;
 
    result = (Generic_Text_IC_like(str, pat, PG_GET_COLLATION()) != LIKE_TRUE);
 
    PG_RETURN_BOOL(result);
}
 
/*
 * like_escape() --- given a pattern and an ESCAPE string,
 * convert the pattern to use Postgres' standard backslash escape convention.
 */
Datum
like_escape(PG_FUNCTION_ARGS)
{
    text       *pat = PG_GETARG_TEXT_PP(0);
    text       *esc = PG_GETARG_TEXT_PP(1);
    text       *result;
 
    if (pg_database_encoding_max_length() == 1)
        result = SB_do_like_escape(pat, esc);
    else
        result = MB_do_like_escape(pat, esc);
 
    PG_RETURN_TEXT_P(result);
}
 
/*
 * like_escape_bytea() --- given a pattern and an ESCAPE string,
 * convert the pattern to use Postgres' standard backslash escape convention.
 */
Datum
like_escape_bytea(PG_FUNCTION_ARGS)
{
    bytea      *pat = PG_GETARG_BYTEA_PP(0);
    bytea      *esc = PG_GETARG_BYTEA_PP(1);
    bytea      *result = SB_do_like_escape((text *) pat, (text *) esc);
 
    PG_RETURN_BYTEA_P((bytea *) result);
}