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/*-------------------------------------------------------------------------
*
* pgstrcasecmp.c
* Portable SQL-like case-independent comparisons and conversions.
*
* SQL99 specifies Unicode-aware case normalization, which we don't yet
* have the infrastructure for. Instead we use tolower() to provide a
* locale-aware translation. However, there are some locales where this
* is not right either (eg, Turkish may do strange things with 'i' and
* 'I'). Our current compromise is to use tolower() for characters with
* the high bit set, and use an ASCII-only downcasing for 7-bit
* characters.
*
* NB: this code should match downcase_truncate_identifier() in scansup.c.
*
* We also provide strict ASCII-only case conversion functions, which can
* be used to implement C/POSIX case folding semantics no matter what the
* C library thinks the locale is.
*
*
* Portions Copyright (c) 1996-2023, PostgreSQL Global Development Group
*
* src/port/pgstrcasecmp.c
*
*-------------------------------------------------------------------------
*/
#include "c.h"
#include <ctype.h>
/*
* Case-independent comparison of two null-terminated strings.
*/
int
pg_strcasecmp(const char *s1, const char *s2)
{
for (;;)
{
unsigned char ch1 = (unsigned char) *s1++;
unsigned char ch2 = (unsigned char) *s2++;
if (ch1 != ch2)
{
if (ch1 >= 'A' && ch1 <= 'Z')
ch1 += 'a' - 'A';
else if (IS_HIGHBIT_SET(ch1) && isupper(ch1))
ch1 = tolower(ch1);
if (ch2 >= 'A' && ch2 <= 'Z')
ch2 += 'a' - 'A';
else if (IS_HIGHBIT_SET(ch2) && isupper(ch2))
ch2 = tolower(ch2);
if (ch1 != ch2)
return (int) ch1 - (int) ch2;
}
if (ch1 == 0)
break;
}
return 0;
}
/*
* Case-independent comparison of two not-necessarily-null-terminated strings.
* At most n bytes will be examined from each string.
*/
int
pg_strncasecmp(const char *s1, const char *s2, size_t n)
{
while (n-- > 0)
{
unsigned char ch1 = (unsigned char) *s1++;
unsigned char ch2 = (unsigned char) *s2++;
if (ch1 != ch2)
{
if (ch1 >= 'A' && ch1 <= 'Z')
ch1 += 'a' - 'A';
else if (IS_HIGHBIT_SET(ch1) && isupper(ch1))
ch1 = tolower(ch1);
if (ch2 >= 'A' && ch2 <= 'Z')
ch2 += 'a' - 'A';
else if (IS_HIGHBIT_SET(ch2) && isupper(ch2))
ch2 = tolower(ch2);
if (ch1 != ch2)
return (int) ch1 - (int) ch2;
}
if (ch1 == 0)
break;
}
return 0;
}
/*
* Fold a character to upper case.
*
* Unlike some versions of toupper(), this is safe to apply to characters
* that aren't lower case letters. Note however that the whole thing is
* a bit bogus for multibyte character sets.
*/
unsigned char
pg_toupper(unsigned char ch)
{
if (ch >= 'a' && ch <= 'z')
ch += 'A' - 'a';
else if (IS_HIGHBIT_SET(ch) && islower(ch))
ch = toupper(ch);
return ch;
}
/*
* Fold a character to lower case.
*
* Unlike some versions of tolower(), this is safe to apply to characters
* that aren't upper case letters. Note however that the whole thing is
* a bit bogus for multibyte character sets.
*/
unsigned char
pg_tolower(unsigned char ch)
{
if (ch >= 'A' && ch <= 'Z')
ch += 'a' - 'A';
else if (IS_HIGHBIT_SET(ch) && isupper(ch))
ch = tolower(ch);
return ch;
}
/*
* Fold a character to upper case, following C/POSIX locale rules.
*/
unsigned char
pg_ascii_toupper(unsigned char ch)
{
if (ch >= 'a' && ch <= 'z')
ch += 'A' - 'a';
return ch;
}
/*
* Fold a character to lower case, following C/POSIX locale rules.
*/
unsigned char
pg_ascii_tolower(unsigned char ch)
{
if (ch >= 'A' && ch <= 'Z')
ch += 'a' - 'A';
return ch;
}
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