Line data    Source code

       1             : /*-------------------------------------------------------------------------
       2             :  *
       3             :  * pgstrcasecmp.c
       4             :  *     Portable SQL-like case-independent comparisons and conversions.
       5             :  *
       6             :  * SQL99 specifies Unicode-aware case normalization, which we don't yet
       7             :  * have the infrastructure for.  Instead we use tolower() to provide a
       8             :  * locale-aware translation.  However, there are some locales where this
       9             :  * is not right either (eg, Turkish may do strange things with 'i' and
      10             :  * 'I').  Our current compromise is to use tolower() for characters with
      11             :  * the high bit set, and use an ASCII-only downcasing for 7-bit
      12             :  * characters.
      13             :  *
      14             :  * NB: this code should match downcase_truncate_identifier() in scansup.c.
      15             :  *
      16             :  *
      17             :  * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
      18             :  *
      19             :  * src/port/pgstrcasecmp.c
      20             :  *
      21             :  *-------------------------------------------------------------------------
      22             :  */
      23             : #include "c.h"
      24             : 
      25             : #include <ctype.h>
      26             : 
      27             : 
      28             : /*
      29             :  * Case-independent comparison of two null-terminated strings.
      30             :  */
      31             : int
      32    20745714 : pg_strcasecmp(const char *s1, const char *s2)
      33             : {
      34             :     for (;;)
      35     8587752 :     {
      36    29333466 :         unsigned char ch1 = (unsigned char) *s1++;
      37    29333466 :         unsigned char ch2 = (unsigned char) *s2++;
      38             : 
      39    29333466 :         if (ch1 != ch2)
      40             :         {
      41    20457426 :             if (ch1 >= 'A' && ch1 <= 'Z')
      42     7454628 :                 ch1 += 'a' - 'A';
      43    13002798 :             else if (IS_HIGHBIT_SET(ch1) && isupper(ch1))
      44           0 :                 ch1 = tolower(ch1);
      45             : 
      46    20457426 :             if (ch2 >= 'A' && ch2 <= 'Z')
      47     4940690 :                 ch2 += 'a' - 'A';
      48    15516736 :             else if (IS_HIGHBIT_SET(ch2) && isupper(ch2))
      49           0 :                 ch2 = tolower(ch2);
      50             : 
      51    20457426 :             if (ch1 != ch2)
      52    18722232 :                 return (int) ch1 - (int) ch2;
      53             :         }
      54    10611234 :         if (ch1 == 0)
      55     2023482 :             break;
      56             :     }
      57     2023482 :     return 0;
      58             : }
      59             : 
      60             : /*
      61             :  * Case-independent comparison of two not-necessarily-null-terminated strings.
      62             :  * At most n bytes will be examined from each string.
      63             :  */
      64             : int
      65    11504572 : pg_strncasecmp(const char *s1, const char *s2, size_t n)
      66             : {
      67    16575416 :     while (n-- > 0)
      68             :     {
      69    12900804 :         unsigned char ch1 = (unsigned char) *s1++;
      70    12900804 :         unsigned char ch2 = (unsigned char) *s2++;
      71             : 
      72    12900804 :         if (ch1 != ch2)
      73             :         {
      74     8016300 :             if (ch1 >= 'A' && ch1 <= 'Z')
      75     5652996 :                 ch1 += 'a' - 'A';
      76     2363304 :             else if (IS_HIGHBIT_SET(ch1) && isupper(ch1))
      77           0 :                 ch1 = tolower(ch1);
      78             : 
      79     8016300 :             if (ch2 >= 'A' && ch2 <= 'Z')
      80      385654 :                 ch2 += 'a' - 'A';
      81     7630646 :             else if (IS_HIGHBIT_SET(ch2) && isupper(ch2))
      82           0 :                 ch2 = tolower(ch2);
      83             : 
      84     8016300 :             if (ch1 != ch2)
      85     7829960 :                 return (int) ch1 - (int) ch2;
      86             :         }
      87     5070844 :         if (ch1 == 0)
      88           0 :             break;
      89             :     }
      90     3674612 :     return 0;
      91             : }
      92             : 
      93             : /*
      94             :  * Fold a character to upper case.
      95             :  *
      96             :  * Unlike some versions of toupper(), this is safe to apply to characters
      97             :  * that aren't lower case letters.  Note however that the whole thing is
      98             :  * a bit bogus for multibyte character sets.
      99             :  */
     100             : unsigned char
     101      344862 : pg_toupper(unsigned char ch)
     102             : {
     103      344862 :     if (ch >= 'a' && ch <= 'z')
     104      205236 :         ch += 'A' - 'a';
     105      139626 :     else if (IS_HIGHBIT_SET(ch) && islower(ch))
     106           0 :         ch = toupper(ch);
     107      344862 :     return ch;
     108             : }
     109             : 
     110             : /*
     111             :  * Fold a character to lower case.
     112             :  *
     113             :  * Unlike some versions of tolower(), this is safe to apply to characters
     114             :  * that aren't upper case letters.  Note however that the whole thing is
     115             :  * a bit bogus for multibyte character sets.
     116             :  */
     117             : unsigned char
     118    14725078 : pg_tolower(unsigned char ch)
     119             : {
     120    14725078 :     if (ch >= 'A' && ch <= 'Z')
     121     9865604 :         ch += 'a' - 'A';
     122     4859474 :     else if (IS_HIGHBIT_SET(ch) && isupper(ch))
     123           0 :         ch = tolower(ch);
     124    14725078 :     return ch;
     125             : }