versioncmp.c

   1 #include "cache.h"
   2 #include "string-list.h"
   3
   4 /*
   5  * versioncmp(): copied from string/strverscmp.c in glibc commit
   6  * ee9247c38a8def24a59eb5cfb7196a98bef8cfdc, reformatted to Git coding
   7  * style. The implementation is under LGPL-2.1 and Git relicenses it
   8  * to GPLv2.
   9  */
  10
  11 /*
  12  * states: S_N: normal, S_I: comparing integral part, S_F: comparing
  13  * fractionnal parts, S_Z: idem but with leading Zeroes only
  14  */
  15 #define  S_N    0x0
  16 #define  S_I    0x3
  17 #define  S_F    0x6
  18 #define  S_Z    0x9
  19
  20 /* result_type: CMP: return diff; LEN: compare using len_diff/diff */
  21 #define  CMP    2
  22 #define  LEN    3
  23
  24 static const struct string_list *prereleases;
  25 static int initialized;
  26
  27 /*
  28  * off is the offset of the first different character in the two strings
  29  * s1 and s2. If either s1 or s2 contains a prerelease suffix starting
  30  * at that offset, it will be forced to be on top.
  31  *
  32  * If both s1 and s2 contain a (different) suffix at that position,
  33  * their order is determined by the order of those two suffixes in the
  34  * configuration.
  35  *
  36  * Return non-zero if *diff contains the return value for versioncmp()
  37  */
  38 static int swap_prereleases(const char *s1,
  39                             const char *s2,
  40                             int off,
  41                             int *diff)
  42 {
  43         int i, i1 = -1, i2 = -1;
  44
  45         for (i = 0; i < prereleases->nr; i++) {
  46                 const char *suffix = prereleases->items[i].string;
  47                 if (i1 == -1 && starts_with(s1 + off, suffix))
  48                         i1 = i;
  49                 if (i2 == -1 && starts_with(s2 + off, suffix))
  50                         i2 = i;
  51         }
  52         if (i1 == -1 && i2 == -1)
  53                 return 0;
  54         if (i1 >= 0 && i2 >= 0)
  55                 *diff = i1 - i2;
  56         else if (i1 >= 0)
  57                 *diff = -1;
  58         else /* if (i2 >= 0) */
  59                 *diff = 1;
  60         return 1;
  61 }
  62
  63 /*
  64  * Compare S1 and S2 as strings holding indices/version numbers,
  65  * returning less than, equal to or greater than zero if S1 is less
  66  * than, equal to or greater than S2 (for more info, see the texinfo
  67  * doc).
  68  */
  69
  70 int versioncmp(const char *s1, const char *s2)
  71 {
  72         const unsigned char *p1 = (const unsigned char *) s1;
  73         const unsigned char *p2 = (const unsigned char *) s2;
  74         unsigned char c1, c2;
  75         int state, diff;
  76
  77         /*
  78          * Symbol(s)    0       [1-9]   others
  79          * Transition   (10) 0  (01) d  (00) x
  80          */
  81         static const uint8_t next_state[] = {
  82                 /* state    x    d    0  */
  83                 /* S_N */  S_N, S_I, S_Z,
  84                 /* S_I */  S_N, S_I, S_I,
  85                 /* S_F */  S_N, S_F, S_F,
  86                 /* S_Z */  S_N, S_F, S_Z
  87         };
  88
  89         static const int8_t result_type[] = {
  90                 /* state   x/x  x/d  x/0  d/x  d/d  d/0  0/x  0/d  0/0  */
  91
  92                 /* S_N */  CMP, CMP, CMP, CMP, LEN, CMP, CMP, CMP, CMP,
  93                 /* S_I */  CMP, -1,  -1,  +1,  LEN, LEN, +1,  LEN, LEN,
  94                 /* S_F */  CMP, CMP, CMP, CMP, CMP, CMP, CMP, CMP, CMP,
  95                 /* S_Z */  CMP, +1,  +1,  -1,  CMP, CMP, -1,  CMP, CMP
  96         };
  97
  98         if (p1 == p2)
  99                 return 0;
 100
 101         c1 = *p1++;
 102         c2 = *p2++;
 103         /* Hint: '0' is a digit too.  */
 104         state = S_N + ((c1 == '0') + (isdigit (c1) != 0));
 105
 106         while ((diff = c1 - c2) == 0) {
 107                 if (c1 == '\0')
 108                         return diff;
 109
 110                 state = next_state[state];
 111                 c1 = *p1++;
 112                 c2 = *p2++;
 113                 state += (c1 == '0') + (isdigit (c1) != 0);
 114         }
 115
 116         if (!initialized) {
 117                 initialized = 1;
 118                 prereleases = git_config_get_value_multi("versionsort.prereleasesuffix");
 119         }
 120         if (prereleases && swap_prereleases(s1, s2, (const char *) p1 - s1 - 1,
 121                                             &diff))
 122                 return diff;
 123
 124         state = result_type[state * 3 + (((c2 == '0') + (isdigit (c2) != 0)))];
 125
 126         switch (state) {
 127         case CMP:
 128                 return diff;
 129
 130         case LEN:
 131                 while (isdigit (*p1++))
 132                         if (!isdigit (*p2++))
 133                                 return 1;
 134
 135                 return isdigit (*p2) ? -1 : diff;
 136
 137         default:
 138                 return state;
 139         }
 140 }