152 lines
3.5 KiB
C
152 lines
3.5 KiB
C
/*-------------------------------------------------------------------------
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*
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* pgstrcasecmp.c
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* Portable SQL-like case-independent comparisons and conversions.
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*
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* SQL99 specifies Unicode-aware case normalization, which we don't yet
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* have the infrastructure for. Instead we use tolower() to provide a
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* locale-aware translation. However, there are some locales where this
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* is not right either (eg, Turkish may do strange things with 'i' and
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* 'I'). Our current compromise is to use tolower() for characters with
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* the high bit set, and use an ASCII-only downcasing for 7-bit
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* characters.
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*
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* NB: this code should match downcase_truncate_identifier() in scansup.c.
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*
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* We also provide strict ASCII-only case conversion functions, which can
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* be used to implement C/POSIX case folding semantics no matter what the
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* C library thinks the locale is.
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*
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*
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* Portions Copyright (c) 1996-2024, PostgreSQL Global Development Group
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*
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* src/port/pgstrcasecmp.c
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*
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*-------------------------------------------------------------------------
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*/
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#include "c.h"
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#include <ctype.h>
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/*
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* Case-independent comparison of two null-terminated strings.
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*/
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int
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pg_strcasecmp(const char *s1, const char *s2)
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{
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for (;;)
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{
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unsigned char ch1 = (unsigned char) *s1++;
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unsigned char ch2 = (unsigned char) *s2++;
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if (ch1 != ch2)
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{
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if (ch1 >= 'A' && ch1 <= 'Z')
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ch1 += 'a' - 'A';
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else if (IS_HIGHBIT_SET(ch1) && isupper(ch1))
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ch1 = tolower(ch1);
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if (ch2 >= 'A' && ch2 <= 'Z')
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ch2 += 'a' - 'A';
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else if (IS_HIGHBIT_SET(ch2) && isupper(ch2))
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ch2 = tolower(ch2);
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if (ch1 != ch2)
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return (int) ch1 - (int) ch2;
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}
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if (ch1 == 0)
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break;
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}
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return 0;
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}
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/*
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* Case-independent comparison of two not-necessarily-null-terminated strings.
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* At most n bytes will be examined from each string.
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*/
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int
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pg_strncasecmp(const char *s1, const char *s2, size_t n)
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{
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while (n-- > 0)
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{
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unsigned char ch1 = (unsigned char) *s1++;
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unsigned char ch2 = (unsigned char) *s2++;
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if (ch1 != ch2)
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{
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if (ch1 >= 'A' && ch1 <= 'Z')
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ch1 += 'a' - 'A';
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else if (IS_HIGHBIT_SET(ch1) && isupper(ch1))
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ch1 = tolower(ch1);
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if (ch2 >= 'A' && ch2 <= 'Z')
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ch2 += 'a' - 'A';
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else if (IS_HIGHBIT_SET(ch2) && isupper(ch2))
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ch2 = tolower(ch2);
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if (ch1 != ch2)
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return (int) ch1 - (int) ch2;
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}
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if (ch1 == 0)
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break;
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}
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return 0;
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}
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/*
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* Fold a character to upper case.
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*
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* Unlike some versions of toupper(), this is safe to apply to characters
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* that aren't lower case letters. Note however that the whole thing is
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* a bit bogus for multibyte character sets.
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*/
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unsigned char
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pg_toupper(unsigned char ch)
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{
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if (ch >= 'a' && ch <= 'z')
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ch += 'A' - 'a';
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else if (IS_HIGHBIT_SET(ch) && islower(ch))
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ch = toupper(ch);
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return ch;
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}
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/*
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* Fold a character to lower case.
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*
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* Unlike some versions of tolower(), this is safe to apply to characters
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* that aren't upper case letters. Note however that the whole thing is
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* a bit bogus for multibyte character sets.
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*/
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unsigned char
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pg_tolower(unsigned char ch)
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{
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if (ch >= 'A' && ch <= 'Z')
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ch += 'a' - 'A';
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else if (IS_HIGHBIT_SET(ch) && isupper(ch))
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ch = tolower(ch);
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return ch;
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}
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/*
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* Fold a character to upper case, following C/POSIX locale rules.
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*/
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unsigned char
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pg_ascii_toupper(unsigned char ch)
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{
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if (ch >= 'a' && ch <= 'z')
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ch += 'A' - 'a';
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return ch;
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}
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/*
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* Fold a character to lower case, following C/POSIX locale rules.
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*/
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unsigned char
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pg_ascii_tolower(unsigned char ch)
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{
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if (ch >= 'A' && ch <= 'Z')
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ch += 'a' - 'A';
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return ch;
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}
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