regc_pg_locale.c

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/*-------------------------------------------------------------------------
 *
 * regc_pg_locale.c
 *    ctype functions adapted to work on pg_wchar (a/k/a chr),
 *    and functions to cache the results of wholesale ctype probing.
 *
 * This file is #included by regcomp.c; it's not meant to compile standalone.
 *
 * Portions Copyright (c) 1996-2024, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 * IDENTIFICATION
 *    src/backend/regex/regc_pg_locale.c
 *
 *-------------------------------------------------------------------------
 */
 
#include "catalog/pg_collation.h"
#include "common/unicode_case.h"
#include "common/unicode_category.h"
#include "utils/pg_locale.h"
 
/*
 * To provide as much functionality as possible on a variety of platforms,
 * without going so far as to implement everything from scratch, we use
 * several implementation strategies depending on the situation:
 *
 * 1. In C/POSIX collations, we use hard-wired code.  We can't depend on
 * the <ctype.h> functions since those will obey LC_CTYPE.  Note that these
 * collations don't give a fig about multibyte characters.
 *
 * 2. In the "default" collation (which is supposed to obey LC_CTYPE):
 *
 * 2a. When working in UTF8 encoding, we use the <wctype.h> functions.
 * This assumes that every platform uses Unicode codepoints directly
 * as the wchar_t representation of Unicode.  On some platforms
 * wchar_t is only 16 bits wide, so we have to punt for codepoints > 0xFFFF.
 *
 * 2b. In all other encodings, we use the <ctype.h> functions for pg_wchar
 * values up to 255, and punt for values above that.  This is 100% correct
 * only in single-byte encodings such as LATINn.  However, non-Unicode
 * multibyte encodings are mostly Far Eastern character sets for which the
 * properties being tested here aren't very relevant for higher code values
 * anyway.  The difficulty with using the <wctype.h> functions with
 * non-Unicode multibyte encodings is that we can have no certainty that
 * the platform's wchar_t representation matches what we do in pg_wchar
 * conversions.
 *
 * 3. Here, we use the locale_t-extended forms of the <wctype.h> and <ctype.h>
 * functions, under exactly the same cases as #2.
 *
 * There is one notable difference between cases 2 and 3: in the "default"
 * collation we force ASCII letters to follow ASCII upcase/downcase rules,
 * while in a non-default collation we just let the library functions do what
 * they will.  The case where this matters is treatment of I/i in Turkish,
 * and the behavior is meant to match the upper()/lower() SQL functions.
 *
 * We store the active collation setting in static variables.  In principle
 * it could be passed down to here via the regex library's "struct vars" data
 * structure; but that would require somewhat invasive changes in the regex
 * library, and right now there's no real benefit to be gained from that.
 *
 * NB: the coding here assumes pg_wchar is an unsigned type.
 */
 
typedef enum
{
    PG_REGEX_STRATEGY_C,        /* C locale (encoding independent) */
    PG_REGEX_STRATEGY_BUILTIN,  /* built-in Unicode semantics */
    PG_REGEX_STRATEGY_LIBC_WIDE,    /* Use locale_t <wctype.h> functions */
    PG_REGEX_STRATEGY_LIBC_1BYTE,   /* Use locale_t <ctype.h> functions */
    PG_REGEX_STRATEGY_ICU,      /* Use ICU uchar.h functions */
} PG_Locale_Strategy;
 
static PG_Locale_Strategy pg_regex_strategy;
static pg_locale_t pg_regex_locale;
static Oid  pg_regex_collation;
 
/*
 * Hard-wired character properties for C locale
 */
#define PG_ISDIGIT  0x01
#define PG_ISALPHA  0x02
#define PG_ISALNUM  (PG_ISDIGIT | PG_ISALPHA)
#define PG_ISUPPER  0x04
#define PG_ISLOWER  0x08
#define PG_ISGRAPH  0x10
#define PG_ISPRINT  0x20
#define PG_ISPUNCT  0x40
#define PG_ISSPACE  0x80
 
static const unsigned char pg_char_properties[128] = {
     /* NUL */ 0,
     /* ^A */ 0,
     /* ^B */ 0,
     /* ^C */ 0,
     /* ^D */ 0,
     /* ^E */ 0,
     /* ^F */ 0,
     /* ^G */ 0,
     /* ^H */ 0,
     /* ^I */ PG_ISSPACE,
     /* ^J */ PG_ISSPACE,
     /* ^K */ PG_ISSPACE,
     /* ^L */ PG_ISSPACE,
     /* ^M */ PG_ISSPACE,
     /* ^N */ 0,
     /* ^O */ 0,
     /* ^P */ 0,
     /* ^Q */ 0,
     /* ^R */ 0,
     /* ^S */ 0,
     /* ^T */ 0,
     /* ^U */ 0,
     /* ^V */ 0,
     /* ^W */ 0,
     /* ^X */ 0,
     /* ^Y */ 0,
     /* ^Z */ 0,
     /* ^[ */ 0,
     /* ^\ */ 0,
     /* ^] */ 0,
     /* ^^ */ 0,
     /* ^_ */ 0,
     /* */ PG_ISPRINT | PG_ISSPACE,
     /* !  */ PG_ISGRAPH | PG_ISPRINT | PG_ISPUNCT,
     /* "  */ PG_ISGRAPH | PG_ISPRINT | PG_ISPUNCT,
     /* #  */ PG_ISGRAPH | PG_ISPRINT | PG_ISPUNCT,
     /* $  */ PG_ISGRAPH | PG_ISPRINT | PG_ISPUNCT,
     /* %  */ PG_ISGRAPH | PG_ISPRINT | PG_ISPUNCT,
     /* &  */ PG_ISGRAPH | PG_ISPRINT | PG_ISPUNCT,
     /* '  */ PG_ISGRAPH | PG_ISPRINT | PG_ISPUNCT,
     /* (  */ PG_ISGRAPH | PG_ISPRINT | PG_ISPUNCT,
     /* )  */ PG_ISGRAPH | PG_ISPRINT | PG_ISPUNCT,
     /* *  */ PG_ISGRAPH | PG_ISPRINT | PG_ISPUNCT,
     /* +  */ PG_ISGRAPH | PG_ISPRINT | PG_ISPUNCT,
     /* ,  */ PG_ISGRAPH | PG_ISPRINT | PG_ISPUNCT,
     /* -  */ PG_ISGRAPH | PG_ISPRINT | PG_ISPUNCT,
     /* .  */ PG_ISGRAPH | PG_ISPRINT | PG_ISPUNCT,
     /* /  */ PG_ISGRAPH | PG_ISPRINT | PG_ISPUNCT,
     /* 0  */ PG_ISDIGIT | PG_ISGRAPH | PG_ISPRINT,
     /* 1  */ PG_ISDIGIT | PG_ISGRAPH | PG_ISPRINT,
     /* 2  */ PG_ISDIGIT | PG_ISGRAPH | PG_ISPRINT,
     /* 3  */ PG_ISDIGIT | PG_ISGRAPH | PG_ISPRINT,
     /* 4  */ PG_ISDIGIT | PG_ISGRAPH | PG_ISPRINT,
     /* 5  */ PG_ISDIGIT | PG_ISGRAPH | PG_ISPRINT,
     /* 6  */ PG_ISDIGIT | PG_ISGRAPH | PG_ISPRINT,
     /* 7  */ PG_ISDIGIT | PG_ISGRAPH | PG_ISPRINT,
     /* 8  */ PG_ISDIGIT | PG_ISGRAPH | PG_ISPRINT,
     /* 9  */ PG_ISDIGIT | PG_ISGRAPH | PG_ISPRINT,
     /* :  */ PG_ISGRAPH | PG_ISPRINT | PG_ISPUNCT,
     /* ;  */ PG_ISGRAPH | PG_ISPRINT | PG_ISPUNCT,
     /* <  */ PG_ISGRAPH | PG_ISPRINT | PG_ISPUNCT,
     /* =  */ PG_ISGRAPH | PG_ISPRINT | PG_ISPUNCT,
     /* >  */ PG_ISGRAPH | PG_ISPRINT | PG_ISPUNCT,
     /* ?  */ PG_ISGRAPH | PG_ISPRINT | PG_ISPUNCT,
     /* @  */ PG_ISGRAPH | PG_ISPRINT | PG_ISPUNCT,
     /* A  */ PG_ISALPHA | PG_ISUPPER | PG_ISGRAPH | PG_ISPRINT,
     /* B  */ PG_ISALPHA | PG_ISUPPER | PG_ISGRAPH | PG_ISPRINT,
     /* C  */ PG_ISALPHA | PG_ISUPPER | PG_ISGRAPH | PG_ISPRINT,
     /* D  */ PG_ISALPHA | PG_ISUPPER | PG_ISGRAPH | PG_ISPRINT,
     /* E  */ PG_ISALPHA | PG_ISUPPER | PG_ISGRAPH | PG_ISPRINT,
     /* F  */ PG_ISALPHA | PG_ISUPPER | PG_ISGRAPH | PG_ISPRINT,
     /* G  */ PG_ISALPHA | PG_ISUPPER | PG_ISGRAPH | PG_ISPRINT,
     /* H  */ PG_ISALPHA | PG_ISUPPER | PG_ISGRAPH | PG_ISPRINT,
     /* I  */ PG_ISALPHA | PG_ISUPPER | PG_ISGRAPH | PG_ISPRINT,
     /* J  */ PG_ISALPHA | PG_ISUPPER | PG_ISGRAPH | PG_ISPRINT,
     /* K  */ PG_ISALPHA | PG_ISUPPER | PG_ISGRAPH | PG_ISPRINT,
     /* L  */ PG_ISALPHA | PG_ISUPPER | PG_ISGRAPH | PG_ISPRINT,
     /* M  */ PG_ISALPHA | PG_ISUPPER | PG_ISGRAPH | PG_ISPRINT,
     /* N  */ PG_ISALPHA | PG_ISUPPER | PG_ISGRAPH | PG_ISPRINT,
     /* O  */ PG_ISALPHA | PG_ISUPPER | PG_ISGRAPH | PG_ISPRINT,
     /* P  */ PG_ISALPHA | PG_ISUPPER | PG_ISGRAPH | PG_ISPRINT,
     /* Q  */ PG_ISALPHA | PG_ISUPPER | PG_ISGRAPH | PG_ISPRINT,
     /* R  */ PG_ISALPHA | PG_ISUPPER | PG_ISGRAPH | PG_ISPRINT,
     /* S  */ PG_ISALPHA | PG_ISUPPER | PG_ISGRAPH | PG_ISPRINT,
     /* T  */ PG_ISALPHA | PG_ISUPPER | PG_ISGRAPH | PG_ISPRINT,
     /* U  */ PG_ISALPHA | PG_ISUPPER | PG_ISGRAPH | PG_ISPRINT,
     /* V  */ PG_ISALPHA | PG_ISUPPER | PG_ISGRAPH | PG_ISPRINT,
     /* W  */ PG_ISALPHA | PG_ISUPPER | PG_ISGRAPH | PG_ISPRINT,
     /* X  */ PG_ISALPHA | PG_ISUPPER | PG_ISGRAPH | PG_ISPRINT,
     /* Y  */ PG_ISALPHA | PG_ISUPPER | PG_ISGRAPH | PG_ISPRINT,
     /* Z  */ PG_ISALPHA | PG_ISUPPER | PG_ISGRAPH | PG_ISPRINT,
     /* [  */ PG_ISGRAPH | PG_ISPRINT | PG_ISPUNCT,
     /* \  */ PG_ISGRAPH | PG_ISPRINT | PG_ISPUNCT,
     /* ]  */ PG_ISGRAPH | PG_ISPRINT | PG_ISPUNCT,
     /* ^  */ PG_ISGRAPH | PG_ISPRINT | PG_ISPUNCT,
     /* _  */ PG_ISGRAPH | PG_ISPRINT | PG_ISPUNCT,
     /* `  */ PG_ISGRAPH | PG_ISPRINT | PG_ISPUNCT,
     /* a  */ PG_ISALPHA | PG_ISLOWER | PG_ISGRAPH | PG_ISPRINT,
     /* b  */ PG_ISALPHA | PG_ISLOWER | PG_ISGRAPH | PG_ISPRINT,
     /* c  */ PG_ISALPHA | PG_ISLOWER | PG_ISGRAPH | PG_ISPRINT,
     /* d  */ PG_ISALPHA | PG_ISLOWER | PG_ISGRAPH | PG_ISPRINT,
     /* e  */ PG_ISALPHA | PG_ISLOWER | PG_ISGRAPH | PG_ISPRINT,
     /* f  */ PG_ISALPHA | PG_ISLOWER | PG_ISGRAPH | PG_ISPRINT,
     /* g  */ PG_ISALPHA | PG_ISLOWER | PG_ISGRAPH | PG_ISPRINT,
     /* h  */ PG_ISALPHA | PG_ISLOWER | PG_ISGRAPH | PG_ISPRINT,
     /* i  */ PG_ISALPHA | PG_ISLOWER | PG_ISGRAPH | PG_ISPRINT,
     /* j  */ PG_ISALPHA | PG_ISLOWER | PG_ISGRAPH | PG_ISPRINT,
     /* k  */ PG_ISALPHA | PG_ISLOWER | PG_ISGRAPH | PG_ISPRINT,
     /* l  */ PG_ISALPHA | PG_ISLOWER | PG_ISGRAPH | PG_ISPRINT,
     /* m  */ PG_ISALPHA | PG_ISLOWER | PG_ISGRAPH | PG_ISPRINT,
     /* n  */ PG_ISALPHA | PG_ISLOWER | PG_ISGRAPH | PG_ISPRINT,
     /* o  */ PG_ISALPHA | PG_ISLOWER | PG_ISGRAPH | PG_ISPRINT,
     /* p  */ PG_ISALPHA | PG_ISLOWER | PG_ISGRAPH | PG_ISPRINT,
     /* q  */ PG_ISALPHA | PG_ISLOWER | PG_ISGRAPH | PG_ISPRINT,
     /* r  */ PG_ISALPHA | PG_ISLOWER | PG_ISGRAPH | PG_ISPRINT,
     /* s  */ PG_ISALPHA | PG_ISLOWER | PG_ISGRAPH | PG_ISPRINT,
     /* t  */ PG_ISALPHA | PG_ISLOWER | PG_ISGRAPH | PG_ISPRINT,
     /* u  */ PG_ISALPHA | PG_ISLOWER | PG_ISGRAPH | PG_ISPRINT,
     /* v  */ PG_ISALPHA | PG_ISLOWER | PG_ISGRAPH | PG_ISPRINT,
     /* w  */ PG_ISALPHA | PG_ISLOWER | PG_ISGRAPH | PG_ISPRINT,
     /* x  */ PG_ISALPHA | PG_ISLOWER | PG_ISGRAPH | PG_ISPRINT,
     /* y  */ PG_ISALPHA | PG_ISLOWER | PG_ISGRAPH | PG_ISPRINT,
     /* z  */ PG_ISALPHA | PG_ISLOWER | PG_ISGRAPH | PG_ISPRINT,
     /* {  */ PG_ISGRAPH | PG_ISPRINT | PG_ISPUNCT,
     /* |  */ PG_ISGRAPH | PG_ISPRINT | PG_ISPUNCT,
     /* }  */ PG_ISGRAPH | PG_ISPRINT | PG_ISPUNCT,
     /* ~  */ PG_ISGRAPH | PG_ISPRINT | PG_ISPUNCT,
     /* DEL */ 0
};
 
 
/*
 * pg_set_regex_collation: set collation for these functions to obey
 *
 * This is called when beginning compilation or execution of a regexp.
 * Since there's no need for reentrancy of regexp operations, it's okay
 * to store the results in static variables.
 */
void
pg_set_regex_collation(Oid collation)
{
    pg_locale_t locale = 0;
    PG_Locale_Strategy strategy;
 
    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 regular expression"),
                 errhint("Use the COLLATE clause to set the collation explicitly.")));
    }
 
    if (collation == C_COLLATION_OID)
    {
        /*
         * Some callers expect regexes to work for C_COLLATION_OID before
         * catalog access is available, so we can't call
         * pg_newlocale_from_collation().
         */
        strategy = PG_REGEX_STRATEGY_C;
        collation = C_COLLATION_OID;
    }
    else
    {
        locale = pg_newlocale_from_collation(collation);
 
        if (!locale->deterministic)
            ereport(ERROR,
                    (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                     errmsg("nondeterministic collations are not supported for regular expressions")));
 
        if (locale->ctype_is_c)
        {
            /*
             * C/POSIX collations use this path regardless of database
             * encoding
             */
            strategy = PG_REGEX_STRATEGY_C;
            locale = 0;
            collation = C_COLLATION_OID;
        }
        else if (locale->provider == COLLPROVIDER_BUILTIN)
        {
            Assert(GetDatabaseEncoding() == PG_UTF8);
            strategy = PG_REGEX_STRATEGY_BUILTIN;
        }
#ifdef USE_ICU
        else if (locale->provider == COLLPROVIDER_ICU)
        {
            strategy = PG_REGEX_STRATEGY_ICU;
        }
#endif
        else
        {
            Assert(locale->provider == COLLPROVIDER_LIBC);
            if (GetDatabaseEncoding() == PG_UTF8)
                strategy = PG_REGEX_STRATEGY_LIBC_WIDE;
            else
                strategy = PG_REGEX_STRATEGY_LIBC_1BYTE;
        }
    }
 
    pg_regex_strategy = strategy;
    pg_regex_locale = locale;
    pg_regex_collation = collation;
}
 
static int
pg_wc_isdigit(pg_wchar c)
{
    switch (pg_regex_strategy)
    {
        case PG_REGEX_STRATEGY_C:
            return (c <= (pg_wchar) 127 &&
                    (pg_char_properties[c] & PG_ISDIGIT));
        case PG_REGEX_STRATEGY_BUILTIN:
            return pg_u_isdigit(c, true);
        case PG_REGEX_STRATEGY_LIBC_WIDE:
            if (sizeof(wchar_t) >= 4 || c <= (pg_wchar) 0xFFFF)
                return iswdigit_l((wint_t) c, pg_regex_locale->info.lt);
            /* FALL THRU */
        case PG_REGEX_STRATEGY_LIBC_1BYTE:
            return (c <= (pg_wchar) UCHAR_MAX &&
                    isdigit_l((unsigned char) c, pg_regex_locale->info.lt));
            break;
        case PG_REGEX_STRATEGY_ICU:
#ifdef USE_ICU
            return u_isdigit(c);
#endif
            break;
    }
    return 0;                   /* can't get here, but keep compiler quiet */
}
 
static int
pg_wc_isalpha(pg_wchar c)
{
    switch (pg_regex_strategy)
    {
        case PG_REGEX_STRATEGY_C:
            return (c <= (pg_wchar) 127 &&
                    (pg_char_properties[c] & PG_ISALPHA));
        case PG_REGEX_STRATEGY_BUILTIN:
            return pg_u_isalpha(c);
        case PG_REGEX_STRATEGY_LIBC_WIDE:
            if (sizeof(wchar_t) >= 4 || c <= (pg_wchar) 0xFFFF)
                return iswalpha_l((wint_t) c, pg_regex_locale->info.lt);
            /* FALL THRU */
        case PG_REGEX_STRATEGY_LIBC_1BYTE:
            return (c <= (pg_wchar) UCHAR_MAX &&
                    isalpha_l((unsigned char) c, pg_regex_locale->info.lt));
            break;
        case PG_REGEX_STRATEGY_ICU:
#ifdef USE_ICU
            return u_isalpha(c);
#endif
            break;
    }
    return 0;                   /* can't get here, but keep compiler quiet */
}
 
static int
pg_wc_isalnum(pg_wchar c)
{
    switch (pg_regex_strategy)
    {
        case PG_REGEX_STRATEGY_C:
            return (c <= (pg_wchar) 127 &&
                    (pg_char_properties[c] & PG_ISALNUM));
        case PG_REGEX_STRATEGY_BUILTIN:
            return pg_u_isalnum(c, true);
        case PG_REGEX_STRATEGY_LIBC_WIDE:
            if (sizeof(wchar_t) >= 4 || c <= (pg_wchar) 0xFFFF)
                return iswalnum_l((wint_t) c, pg_regex_locale->info.lt);
            /* FALL THRU */
        case PG_REGEX_STRATEGY_LIBC_1BYTE:
            return (c <= (pg_wchar) UCHAR_MAX &&
                    isalnum_l((unsigned char) c, pg_regex_locale->info.lt));
            break;
        case PG_REGEX_STRATEGY_ICU:
#ifdef USE_ICU
            return u_isalnum(c);
#endif
            break;
    }
    return 0;                   /* can't get here, but keep compiler quiet */
}
 
static int
pg_wc_isword(pg_wchar c)
{
    /* We define word characters as alnum class plus underscore */
    if (c == CHR('_'))
        return 1;
    return pg_wc_isalnum(c);
}
 
static int
pg_wc_isupper(pg_wchar c)
{
    switch (pg_regex_strategy)
    {
        case PG_REGEX_STRATEGY_C:
            return (c <= (pg_wchar) 127 &&
                    (pg_char_properties[c] & PG_ISUPPER));
        case PG_REGEX_STRATEGY_BUILTIN:
            return pg_u_isupper(c);
        case PG_REGEX_STRATEGY_LIBC_WIDE:
            if (sizeof(wchar_t) >= 4 || c <= (pg_wchar) 0xFFFF)
                return iswupper_l((wint_t) c, pg_regex_locale->info.lt);
            /* FALL THRU */
        case PG_REGEX_STRATEGY_LIBC_1BYTE:
            return (c <= (pg_wchar) UCHAR_MAX &&
                    isupper_l((unsigned char) c, pg_regex_locale->info.lt));
            break;
        case PG_REGEX_STRATEGY_ICU:
#ifdef USE_ICU
            return u_isupper(c);
#endif
            break;
    }
    return 0;                   /* can't get here, but keep compiler quiet */
}
 
static int
pg_wc_islower(pg_wchar c)
{
    switch (pg_regex_strategy)
    {
        case PG_REGEX_STRATEGY_C:
            return (c <= (pg_wchar) 127 &&
                    (pg_char_properties[c] & PG_ISLOWER));
        case PG_REGEX_STRATEGY_BUILTIN:
            return pg_u_islower(c);
        case PG_REGEX_STRATEGY_LIBC_WIDE:
            if (sizeof(wchar_t) >= 4 || c <= (pg_wchar) 0xFFFF)
                return iswlower_l((wint_t) c, pg_regex_locale->info.lt);
            /* FALL THRU */
        case PG_REGEX_STRATEGY_LIBC_1BYTE:
            return (c <= (pg_wchar) UCHAR_MAX &&
                    islower_l((unsigned char) c, pg_regex_locale->info.lt));
            break;
        case PG_REGEX_STRATEGY_ICU:
#ifdef USE_ICU
            return u_islower(c);
#endif
            break;
    }
    return 0;                   /* can't get here, but keep compiler quiet */
}
 
static int
pg_wc_isgraph(pg_wchar c)
{
    switch (pg_regex_strategy)
    {
        case PG_REGEX_STRATEGY_C:
            return (c <= (pg_wchar) 127 &&
                    (pg_char_properties[c] & PG_ISGRAPH));
        case PG_REGEX_STRATEGY_BUILTIN:
            return pg_u_isgraph(c);
        case PG_REGEX_STRATEGY_LIBC_WIDE:
            if (sizeof(wchar_t) >= 4 || c <= (pg_wchar) 0xFFFF)
                return iswgraph_l((wint_t) c, pg_regex_locale->info.lt);
            /* FALL THRU */
        case PG_REGEX_STRATEGY_LIBC_1BYTE:
            return (c <= (pg_wchar) UCHAR_MAX &&
                    isgraph_l((unsigned char) c, pg_regex_locale->info.lt));
            break;
        case PG_REGEX_STRATEGY_ICU:
#ifdef USE_ICU
            return u_isgraph(c);
#endif
            break;
    }
    return 0;                   /* can't get here, but keep compiler quiet */
}
 
static int
pg_wc_isprint(pg_wchar c)
{
    switch (pg_regex_strategy)
    {
        case PG_REGEX_STRATEGY_C:
            return (c <= (pg_wchar) 127 &&
                    (pg_char_properties[c] & PG_ISPRINT));
        case PG_REGEX_STRATEGY_BUILTIN:
            return pg_u_isprint(c);
        case PG_REGEX_STRATEGY_LIBC_WIDE:
            if (sizeof(wchar_t) >= 4 || c <= (pg_wchar) 0xFFFF)
                return iswprint_l((wint_t) c, pg_regex_locale->info.lt);
            /* FALL THRU */
        case PG_REGEX_STRATEGY_LIBC_1BYTE:
            return (c <= (pg_wchar) UCHAR_MAX &&
                    isprint_l((unsigned char) c, pg_regex_locale->info.lt));
            break;
        case PG_REGEX_STRATEGY_ICU:
#ifdef USE_ICU
            return u_isprint(c);
#endif
            break;
    }
    return 0;                   /* can't get here, but keep compiler quiet */
}
 
static int
pg_wc_ispunct(pg_wchar c)
{
    switch (pg_regex_strategy)
    {
        case PG_REGEX_STRATEGY_C:
            return (c <= (pg_wchar) 127 &&
                    (pg_char_properties[c] & PG_ISPUNCT));
        case PG_REGEX_STRATEGY_BUILTIN:
            return pg_u_ispunct(c, true);
        case PG_REGEX_STRATEGY_LIBC_WIDE:
            if (sizeof(wchar_t) >= 4 || c <= (pg_wchar) 0xFFFF)
                return iswpunct_l((wint_t) c, pg_regex_locale->info.lt);
            /* FALL THRU */
        case PG_REGEX_STRATEGY_LIBC_1BYTE:
            return (c <= (pg_wchar) UCHAR_MAX &&
                    ispunct_l((unsigned char) c, pg_regex_locale->info.lt));
            break;
        case PG_REGEX_STRATEGY_ICU:
#ifdef USE_ICU
            return u_ispunct(c);
#endif
            break;
    }
    return 0;                   /* can't get here, but keep compiler quiet */
}
 
static int
pg_wc_isspace(pg_wchar c)
{
    switch (pg_regex_strategy)
    {
        case PG_REGEX_STRATEGY_C:
            return (c <= (pg_wchar) 127 &&
                    (pg_char_properties[c] & PG_ISSPACE));
        case PG_REGEX_STRATEGY_BUILTIN:
            return pg_u_isspace(c);
        case PG_REGEX_STRATEGY_LIBC_WIDE:
            if (sizeof(wchar_t) >= 4 || c <= (pg_wchar) 0xFFFF)
                return iswspace_l((wint_t) c, pg_regex_locale->info.lt);
            /* FALL THRU */
        case PG_REGEX_STRATEGY_LIBC_1BYTE:
            return (c <= (pg_wchar) UCHAR_MAX &&
                    isspace_l((unsigned char) c, pg_regex_locale->info.lt));
            break;
        case PG_REGEX_STRATEGY_ICU:
#ifdef USE_ICU
            return u_isspace(c);
#endif
            break;
    }
    return 0;                   /* can't get here, but keep compiler quiet */
}
 
static pg_wchar
pg_wc_toupper(pg_wchar c)
{
    switch (pg_regex_strategy)
    {
        case PG_REGEX_STRATEGY_C:
            if (c <= (pg_wchar) 127)
                return pg_ascii_toupper((unsigned char) c);
            return c;
        case PG_REGEX_STRATEGY_BUILTIN:
            return unicode_uppercase_simple(c);
        case PG_REGEX_STRATEGY_LIBC_WIDE:
            if (sizeof(wchar_t) >= 4 || c <= (pg_wchar) 0xFFFF)
                return towupper_l((wint_t) c, pg_regex_locale->info.lt);
            /* FALL THRU */
        case PG_REGEX_STRATEGY_LIBC_1BYTE:
            if (c <= (pg_wchar) UCHAR_MAX)
                return toupper_l((unsigned char) c, pg_regex_locale->info.lt);
            return c;
        case PG_REGEX_STRATEGY_ICU:
#ifdef USE_ICU
            return u_toupper(c);
#endif
            break;
    }
    return 0;                   /* can't get here, but keep compiler quiet */
}
 
static pg_wchar
pg_wc_tolower(pg_wchar c)
{
    switch (pg_regex_strategy)
    {
        case PG_REGEX_STRATEGY_C:
            if (c <= (pg_wchar) 127)
                return pg_ascii_tolower((unsigned char) c);
            return c;
        case PG_REGEX_STRATEGY_BUILTIN:
            return unicode_lowercase_simple(c);
        case PG_REGEX_STRATEGY_LIBC_WIDE:
            if (sizeof(wchar_t) >= 4 || c <= (pg_wchar) 0xFFFF)
                return towlower_l((wint_t) c, pg_regex_locale->info.lt);
            /* FALL THRU */
        case PG_REGEX_STRATEGY_LIBC_1BYTE:
            if (c <= (pg_wchar) UCHAR_MAX)
                return tolower_l((unsigned char) c, pg_regex_locale->info.lt);
            return c;
        case PG_REGEX_STRATEGY_ICU:
#ifdef USE_ICU
            return u_tolower(c);
#endif
            break;
    }
    return 0;                   /* can't get here, but keep compiler quiet */
}
 
 
/*
 * These functions cache the results of probing libc's ctype behavior for
 * all character codes of interest in a given encoding/collation.  The
 * result is provided as a "struct cvec", but notice that the representation
 * is a touch different from a cvec created by regc_cvec.c: we allocate the
 * chrs[] and ranges[] arrays separately from the struct so that we can
 * realloc them larger at need.  This is okay since the cvecs made here
 * should never be freed by freecvec().
 *
 * We use malloc not palloc since we mustn't lose control on out-of-memory;
 * the main regex code expects us to return a failure indication instead.
 */
 
typedef int (*pg_wc_probefunc) (pg_wchar c);
 
typedef struct pg_ctype_cache
{
    pg_wc_probefunc probefunc;  /* pg_wc_isalpha or a sibling */
    Oid         collation;      /* collation this entry is for */
    struct cvec cv;             /* cache entry contents */
    struct pg_ctype_cache *next;    /* chain link */
} pg_ctype_cache;
 
static pg_ctype_cache *pg_ctype_cache_list = NULL;
 
/*
 * Add a chr or range to pcc->cv; return false if run out of memory
 */
static bool
store_match(pg_ctype_cache *pcc, pg_wchar chr1, int nchrs)
{
    chr        *newchrs;
 
    if (nchrs > 1)
    {
        if (pcc->cv.nranges >= pcc->cv.rangespace)
        {
            pcc->cv.rangespace *= 2;
            newchrs = (chr *) realloc(pcc->cv.ranges,
                                      pcc->cv.rangespace * sizeof(chr) * 2);
            if (newchrs == NULL)
                return false;
            pcc->cv.ranges = newchrs;
        }
        pcc->cv.ranges[pcc->cv.nranges * 2] = chr1;
        pcc->cv.ranges[pcc->cv.nranges * 2 + 1] = chr1 + nchrs - 1;
        pcc->cv.nranges++;
    }
    else
    {
        assert(nchrs == 1);
        if (pcc->cv.nchrs >= pcc->cv.chrspace)
        {
            pcc->cv.chrspace *= 2;
            newchrs = (chr *) realloc(pcc->cv.chrs,
                                      pcc->cv.chrspace * sizeof(chr));
            if (newchrs == NULL)
                return false;
            pcc->cv.chrs = newchrs;
        }
        pcc->cv.chrs[pcc->cv.nchrs++] = chr1;
    }
    return true;
}
 
/*
 * Given a probe function (e.g., pg_wc_isalpha) get a struct cvec for all
 * chrs satisfying the probe function.  The active collation is the one
 * previously set by pg_set_regex_collation.  Return NULL if out of memory.
 *
 * Note that the result must not be freed or modified by caller.
 */
static struct cvec *
pg_ctype_get_cache(pg_wc_probefunc probefunc, int cclasscode)
{
    pg_ctype_cache *pcc;
    pg_wchar    max_chr;
    pg_wchar    cur_chr;
    int         nmatches;
    chr        *newchrs;
 
    /*
     * Do we already have the answer cached?
     */
    for (pcc = pg_ctype_cache_list; pcc != NULL; pcc = pcc->next)
    {
        if (pcc->probefunc == probefunc &&
            pcc->collation == pg_regex_collation)
            return &pcc->cv;
    }
 
    /*
     * Nope, so initialize some workspace ...
     */
    pcc = (pg_ctype_cache *) malloc(sizeof(pg_ctype_cache));
    if (pcc == NULL)
        return NULL;
    pcc->probefunc = probefunc;
    pcc->collation = pg_regex_collation;
    pcc->cv.nchrs = 0;
    pcc->cv.chrspace = 128;
    pcc->cv.chrs = (chr *) malloc(pcc->cv.chrspace * sizeof(chr));
    pcc->cv.nranges = 0;
    pcc->cv.rangespace = 64;
    pcc->cv.ranges = (chr *) malloc(pcc->cv.rangespace * sizeof(chr) * 2);
    if (pcc->cv.chrs == NULL || pcc->cv.ranges == NULL)
        goto out_of_memory;
    pcc->cv.cclasscode = cclasscode;
 
    /*
     * Decide how many character codes we ought to look through.  In general
     * we don't go past MAX_SIMPLE_CHR; chr codes above that are handled at
     * runtime using the "high colormap" mechanism.  However, in C locale
     * there's no need to go further than 127, and if we only have a 1-byte
     * <ctype.h> API there's no need to go further than that can handle.
     *
     * If it's not MAX_SIMPLE_CHR that's constraining the search, mark the
     * output cvec as not having any locale-dependent behavior, since there
     * will be no need to do any run-time locale checks.  (The #if's here
     * would always be true for production values of MAX_SIMPLE_CHR, but it's
     * useful to allow it to be small for testing purposes.)
     */
    switch (pg_regex_strategy)
    {
        case PG_REGEX_STRATEGY_C:
#if MAX_SIMPLE_CHR >= 127
            max_chr = (pg_wchar) 127;
            pcc->cv.cclasscode = -1;
#else
            max_chr = (pg_wchar) MAX_SIMPLE_CHR;
#endif
            break;
        case PG_REGEX_STRATEGY_BUILTIN:
            max_chr = (pg_wchar) MAX_SIMPLE_CHR;
            break;
        case PG_REGEX_STRATEGY_LIBC_WIDE:
            max_chr = (pg_wchar) MAX_SIMPLE_CHR;
            break;
        case PG_REGEX_STRATEGY_LIBC_1BYTE:
#if MAX_SIMPLE_CHR >= UCHAR_MAX
            max_chr = (pg_wchar) UCHAR_MAX;
            pcc->cv.cclasscode = -1;
#else
            max_chr = (pg_wchar) MAX_SIMPLE_CHR;
#endif
            break;
        case PG_REGEX_STRATEGY_ICU:
            max_chr = (pg_wchar) MAX_SIMPLE_CHR;
            break;
        default:
            Assert(false);
            max_chr = 0;        /* can't get here, but keep compiler quiet */
            break;
    }
 
    /*
     * And scan 'em ...
     */
    nmatches = 0;               /* number of consecutive matches */
 
    for (cur_chr = 0; cur_chr <= max_chr; cur_chr++)
    {
        if ((*probefunc) (cur_chr))
            nmatches++;
        else if (nmatches > 0)
        {
            if (!store_match(pcc, cur_chr - nmatches, nmatches))
                goto out_of_memory;
            nmatches = 0;
        }
    }
 
    if (nmatches > 0)
        if (!store_match(pcc, cur_chr - nmatches, nmatches))
            goto out_of_memory;
 
    /*
     * We might have allocated more memory than needed, if so free it
     */
    if (pcc->cv.nchrs == 0)
    {
        free(pcc->cv.chrs);
        pcc->cv.chrs = NULL;
        pcc->cv.chrspace = 0;
    }
    else if (pcc->cv.nchrs < pcc->cv.chrspace)
    {
        newchrs = (chr *) realloc(pcc->cv.chrs,
                                  pcc->cv.nchrs * sizeof(chr));
        if (newchrs == NULL)
            goto out_of_memory;
        pcc->cv.chrs = newchrs;
        pcc->cv.chrspace = pcc->cv.nchrs;
    }
    if (pcc->cv.nranges == 0)
    {
        free(pcc->cv.ranges);
        pcc->cv.ranges = NULL;
        pcc->cv.rangespace = 0;
    }
    else if (pcc->cv.nranges < pcc->cv.rangespace)
    {
        newchrs = (chr *) realloc(pcc->cv.ranges,
                                  pcc->cv.nranges * sizeof(chr) * 2);
        if (newchrs == NULL)
            goto out_of_memory;
        pcc->cv.ranges = newchrs;
        pcc->cv.rangespace = pcc->cv.nranges;
    }
 
    /*
     * Success, link it into cache chain
     */
    pcc->next = pg_ctype_cache_list;
    pg_ctype_cache_list = pcc;
 
    return &pcc->cv;
 
    /*
     * Failure, clean up
     */
out_of_memory:
    free(pcc->cv.chrs);
    free(pcc->cv.ranges);
    free(pcc);
 
    return NULL;
}