pg_locale.h

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/*-----------------------------------------------------------------------
 *
 * PostgreSQL locale utilities
 *
 * src/include/utils/pg_locale.h
 *
 * Copyright (c) 2002-2025, PostgreSQL Global Development Group
 *
 *-----------------------------------------------------------------------
 */
 
#ifndef _PG_LOCALE_
#define _PG_LOCALE_
 
#ifdef USE_ICU
#include <unicode/ucol.h>
#endif
 
/* use for libc locale names */
#define LOCALE_NAME_BUFLEN 128
 
/* GUC settings */
extern PGDLLIMPORT char *locale_messages;
extern PGDLLIMPORT char *locale_monetary;
extern PGDLLIMPORT char *locale_numeric;
extern PGDLLIMPORT char *locale_time;
extern PGDLLIMPORT int icu_validation_level;
 
/* lc_time localization cache */
extern PGDLLIMPORT char *localized_abbrev_days[];
extern PGDLLIMPORT char *localized_full_days[];
extern PGDLLIMPORT char *localized_abbrev_months[];
extern PGDLLIMPORT char *localized_full_months[];
 
/* is the databases's LC_CTYPE the C locale? */
extern PGDLLIMPORT bool database_ctype_is_c;
 
extern bool check_locale(int category, const char *locale, char **canonname);
extern char *pg_perm_setlocale(int category, const char *locale);
 
/*
 * Return the POSIX lconv struct (contains number/money formatting
 * information) with locale information for all categories.
 */
extern struct lconv *PGLC_localeconv(void);
 
extern void cache_locale_time(void);
 
 
struct pg_locale_struct;
typedef struct pg_locale_struct *pg_locale_t;
 
/* methods that define collation behavior */
struct collate_methods
{
    /* required */
    int         (*strncoll) (const char *arg1, ssize_t len1,
                             const char *arg2, ssize_t len2,
                             pg_locale_t locale);
 
    /* required */
    size_t      (*strnxfrm) (char *dest, size_t destsize,
                             const char *src, ssize_t srclen,
                             pg_locale_t locale);
 
    /* optional */
    size_t      (*strnxfrm_prefix) (char *dest, size_t destsize,
                                    const char *src, ssize_t srclen,
                                    pg_locale_t locale);
 
    /*
     * If the strnxfrm method is not trusted to return the correct results,
     * set strxfrm_is_safe to false. It set to false, the method will not be
     * used in most cases, but the planner still expects it to be there for
     * estimation purposes (where incorrect results are acceptable).
     */
    bool        strxfrm_is_safe;
};
 
/*
 * We use a discriminated union to hold either a locale_t or an ICU collator.
 * pg_locale_t is occasionally checked for truth, so make it a pointer.
 *
 * Also, hold two flags: whether the collation's LC_COLLATE or LC_CTYPE is C
 * (or POSIX), so we can optimize a few code paths in various places.  For the
 * built-in C and POSIX collations, we can know that without even doing a
 * cache lookup, but we want to support aliases for C/POSIX too.  For the
 * "default" collation, there are separate static cache variables, since
 * consulting the pg_collation catalog doesn't tell us what we need.
 *
 * Note that some code relies on the flags not reporting false negatives
 * (that is, saying it's not C when it is).  For example, char2wchar()
 * could fail if the locale is C, so str_tolower() shouldn't call it
 * in that case.
 */
struct pg_locale_struct
{
    char        provider;
    bool        deterministic;
    bool        collate_is_c;
    bool        ctype_is_c;
    bool        is_default;
 
    const struct collate_methods *collate;  /* NULL if collate_is_c */
 
    union
    {
        struct
        {
            const char *locale;
            bool        casemap_full;
        }           builtin;
        locale_t    lt;
#ifdef USE_ICU
        struct
        {
            const char *locale;
            UCollator  *ucol;
        }           icu;
#endif
    }           info;
};
 
extern void init_database_collation(void);
extern pg_locale_t pg_newlocale_from_collation(Oid collid);
 
extern char *get_collation_actual_version(char collprovider, const char *collcollate);
extern size_t pg_strlower(char *dest, size_t destsize,
                          const char *src, ssize_t srclen,
                          pg_locale_t locale);
extern size_t pg_strtitle(char *dest, size_t destsize,
                          const char *src, ssize_t srclen,
                          pg_locale_t locale);
extern size_t pg_strupper(char *dest, size_t destsize,
                          const char *src, ssize_t srclen,
                          pg_locale_t locale);
extern size_t pg_strfold(char *dest, size_t destsize,
                         const char *src, ssize_t srclen,
                         pg_locale_t locale);
extern int  pg_strcoll(const char *arg1, const char *arg2, pg_locale_t locale);
extern int  pg_strncoll(const char *arg1, ssize_t len1,
                        const char *arg2, ssize_t len2, pg_locale_t locale);
extern bool pg_strxfrm_enabled(pg_locale_t locale);
extern size_t pg_strxfrm(char *dest, const char *src, size_t destsize,
                         pg_locale_t locale);
extern size_t pg_strnxfrm(char *dest, size_t destsize, const char *src,
                          ssize_t srclen, pg_locale_t locale);
extern bool pg_strxfrm_prefix_enabled(pg_locale_t locale);
extern size_t pg_strxfrm_prefix(char *dest, const char *src, size_t destsize,
                                pg_locale_t locale);
extern size_t pg_strnxfrm_prefix(char *dest, size_t destsize, const char *src,
                                 ssize_t srclen, pg_locale_t locale);
 
extern int  builtin_locale_encoding(const char *locale);
extern const char *builtin_validate_locale(int encoding, const char *locale);
extern void icu_validate_locale(const char *loc_str);
extern char *icu_language_tag(const char *loc_str, int elevel);
 
/* These functions convert from/to libc's wchar_t, *not* pg_wchar_t */
extern size_t wchar2char(char *to, const wchar_t *from, size_t tolen,
                         pg_locale_t locale);
extern size_t char2wchar(wchar_t *to, size_t tolen,
                         const char *from, size_t fromlen, pg_locale_t locale);
 
#endif                          /* _PG_LOCALE_ */