Andrew's git - gitweb.git/blob

   1#include "cache.h"
   2
   3/*
   4 * versioncmp(): copied from string/strverscmp.c in glibc commit
   5 * ee9247c38a8def24a59eb5cfb7196a98bef8cfdc, reformatted to Git coding
   6 * style. The implementation is under LGPL-2.1 and Git relicenses it
   7 * to GPLv2.
   8 */
   9
  10/*
  11 * states: S_N: normal, S_I: comparing integral part, S_F: comparing
  12 * fractionnal parts, S_Z: idem but with leading Zeroes only
  13 */
  14#define  S_N    0x0
  15#define  S_I    0x3
  16#define  S_F    0x6
  17#define  S_Z    0x9
  18
  19/* result_type: CMP: return diff; LEN: compare using len_diff/diff */
  20#define  CMP    2
  21#define  LEN    3
  22
  23
  24/*
  25 * Compare S1 and S2 as strings holding indices/version numbers,
  26 * returning less than, equal to or greater than zero if S1 is less
  27 * than, equal to or greater than S2 (for more info, see the texinfo
  28 * doc).
  29 */
  30
  31int versioncmp(const char *s1, const char *s2)
  32{
  33        const unsigned char *p1 = (const unsigned char *) s1;
  34        const unsigned char *p2 = (const unsigned char *) s2;
  35        unsigned char c1, c2;
  36        int state, diff;
  37
  38        /*
  39         * Symbol(s)    0       [1-9]   others
  40         * Transition   (10) 0  (01) d  (00) x
  41         */
  42        static const uint8_t next_state[] = {
  43                /* state    x    d    0  */
  44                /* S_N */  S_N, S_I, S_Z,
  45                /* S_I */  S_N, S_I, S_I,
  46                /* S_F */  S_N, S_F, S_F,
  47                /* S_Z */  S_N, S_F, S_Z
  48        };
  49
  50        static const int8_t result_type[] = {
  51                /* state   x/x  x/d  x/0  d/x  d/d  d/0  0/x  0/d  0/0  */
  52
  53                /* S_N */  CMP, CMP, CMP, CMP, LEN, CMP, CMP, CMP, CMP,
  54                /* S_I */  CMP, -1,  -1,  +1,  LEN, LEN, +1,  LEN, LEN,
  55                /* S_F */  CMP, CMP, CMP, CMP, CMP, CMP, CMP, CMP, CMP,
  56                /* S_Z */  CMP, +1,  +1,  -1,  CMP, CMP, -1,  CMP, CMP
  57        };
  58
  59        if (p1 == p2)
  60                return 0;
  61
  62        c1 = *p1++;
  63        c2 = *p2++;
  64        /* Hint: '0' is a digit too.  */
  65        state = S_N + ((c1 == '0') + (isdigit (c1) != 0));
  66
  67        while ((diff = c1 - c2) == 0) {
  68                if (c1 == '\0')
  69                        return diff;
  70
  71                state = next_state[state];
  72                c1 = *p1++;
  73                c2 = *p2++;
  74                state += (c1 == '0') + (isdigit (c1) != 0);
  75        }
  76
  77        state = result_type[state * 3 + (((c2 == '0') + (isdigit (c2) != 0)))];
  78
  79        switch (state) {
  80        case CMP:
  81                return diff;
  82
  83        case LEN:
  84                while (isdigit (*p1++))
  85                        if (!isdigit (*p2++))
  86                                return 1;
  87
  88                return isdigit (*p2) ? -1 : diff;
  89
  90        default:
  91                return state;
  92        }
  93}