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/*-------------------------------------------------------------------------
* unicode_case.c
* Unicode case mapping and case conversion.
*
* Portions Copyright (c) 2017-2023, PostgreSQL Global Development Group
*
* IDENTIFICATION
* src/common/unicode_case.c
*
*-------------------------------------------------------------------------
*/
#ifndef FRONTEND
#include "postgres.h"
#else
#include "postgres_fe.h"
#endif
#include "common/unicode_case.h"
#include "common/unicode_case_table.h"
#include "common/unicode_category.h"
#include "mb/pg_wchar.h"
static const pg_case_map *find_case_map(pg_wchar ucs);
static size_t convert_case(char *dst, size_t dstsize, const char *src,
ssize_t srclen, CaseKind casekind);
pg_wchar
unicode_lowercase_simple(pg_wchar code)
{
const pg_case_map *map = find_case_map(code);
return map ? map->simplemap[CaseLower] : code;
}
pg_wchar
unicode_titlecase_simple(pg_wchar code)
{
const pg_case_map *map = find_case_map(code);
return map ? map->simplemap[CaseTitle] : code;
}
pg_wchar
unicode_uppercase_simple(pg_wchar code)
{
const pg_case_map *map = find_case_map(code);
return map ? map->simplemap[CaseUpper] : code;
}
/*
* unicode_strlower()
*
* Convert src to lowercase, and return the result length (not including
* terminating NUL).
*
* String src must be encoded in UTF-8. If srclen < 0, src must be
* NUL-terminated.
*
* Result string is stored in dst, truncating if larger than dstsize. If
* dstsize is greater than the result length, dst will be NUL-terminated;
* otherwise not.
*
* If dstsize is zero, dst may be NULL. This is useful for calculating the
* required buffer size before allocating.
*/
size_t
unicode_strlower(char *dst, size_t dstsize, const char *src, ssize_t srclen)
{
return convert_case(dst, dstsize, src, srclen, CaseLower);
}
/*
* unicode_strupper()
*
* Convert src to uppercase, and return the result length (not including
* terminating NUL).
*
* String src must be encoded in UTF-8. If srclen < 0, src must be
* NUL-terminated.
*
* Result string is stored in dst, truncating if larger than dstsize. If
* dstsize is greater than the result length, dst will be NUL-terminated;
* otherwise not.
*
* If dstsize is zero, dst may be NULL. This is useful for calculating the
* required buffer size before allocating.
*/
size_t
unicode_strupper(char *dst, size_t dstsize, const char *src, ssize_t srclen)
{
return convert_case(dst, dstsize, src, srclen, CaseUpper);
}
/*
* Implement Unicode Default Case Conversion algorithm.
*
* Map each character in the string for which a mapping is available.
*/
static size_t
convert_case(char *dst, size_t dstsize, const char *src, ssize_t srclen,
CaseKind casekind)
{
size_t srcoff = 0;
size_t result_len = 0;
while (src[srcoff] != '\0' && (srclen < 0 || srcoff < srclen))
{
pg_wchar u1 = utf8_to_unicode((unsigned char *) src + srcoff);
int u1len = unicode_utf8len(u1);
const pg_case_map *casemap = find_case_map(u1);
if (casemap)
{
pg_wchar u2 = casemap->simplemap[casekind];
pg_wchar u2len = unicode_utf8len(u2);
if (result_len + u2len < dstsize)
unicode_to_utf8(u2, (unsigned char *) dst + result_len);
result_len += u2len;
}
else
{
/* no mapping; copy bytes from src */
if (result_len + u1len < dstsize)
memcpy(dst + result_len, src + srcoff, u1len);
result_len += u1len;
}
srcoff += u1len;
}
if (result_len < dstsize)
dst[result_len] = '\0';
return result_len;
}
/* find entry in simple case map, if any */
static const pg_case_map *
find_case_map(pg_wchar ucs)
{
int min;
int mid;
int max;
/* all chars <= 0x80 are stored in array for fast lookup */
Assert(lengthof(case_map) >= 0x80);
if (ucs < 0x80)
{
const pg_case_map *map = &case_map[ucs];
Assert(map->codepoint == ucs);
return map;
}
/* otherwise, binary search */
min = 0x80;
max = lengthof(case_map) - 1;
while (max >= min)
{
mid = (min + max) / 2;
if (ucs > case_map[mid].codepoint)
min = mid + 1;
else if (ucs < case_map[mid].codepoint)
max = mid - 1;
else
return &case_map[mid];
}
return NULL;
}
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