sys/src/libregexp/regexec.c

   1 #include <u.h>
   2 #include <libc.h>
   3 #include <regexp.h>
   4 #include "regimpl.h"
   5
   6 typedef struct RethreadQ RethreadQ;
   7 struct RethreadQ
   8 {
   9         Rethread *head;
  10         Rethread **tail;
  11 };
  12
  13 int
  14 regexec(Reprog *prog, char *str, Resub *sem, int msize)
  15 {
  16         RethreadQ lists[2], *clist, *nlist, *tmp;
  17         Rethread *t, *next, *pooltop, *avail;
  18         Reinst *curinst;
  19         Rune r;
  20         char *sp, *ep, endc;
  21         int i, match, first, gen, matchpri, pri;
  22
  23         if(msize > NSUBEXPM)
  24                 msize = NSUBEXPM;
  25
  26         if(prog->startinst->gen != 0) {
  27                 for(curinst = prog->startinst; curinst < prog->startinst + prog->len; curinst++)
  28                         curinst->gen = 0;
  29         }
  30
  31         clist = lists;
  32         clist->head = nil;
  33         clist->tail = &clist->head;
  34         nlist = lists + 1;
  35         nlist->head = nil;
  36         nlist->tail = &nlist->head;
  37
  38         pooltop = prog->threads + prog->nthr;
  39         avail = nil;
  40
  41         pri = matchpri = gen = match = 0;
  42         sp = str;
  43         ep = nil;
  44         endc = '\0';
  45         if(sem != nil && msize > 0) {
  46                 if(sem->sp != nil)
  47                         sp = sem->sp;
  48                 if(sem->ep != nil && *sem->ep != '\0') {
  49                         ep = sem->ep;
  50                         endc = *sem->ep;
  51                         *sem->ep = '\0';
  52                 }
  53         }
  54         r = Runemax + 1;
  55         for(; r != L'\0'; sp += i) {
  56                 gen++;
  57                 i = chartorune(&r, sp);
  58                 first = 1;
  59                 t = clist->head;
  60                 if(t == nil)
  61                         goto Start;
  62                 curinst = t->pc;
  63 Again:
  64                 if(curinst->gen == gen)
  65                         goto Done;
  66                 curinst->gen = gen;
  67                 switch(curinst->op) {
  68                 case ORUNE:
  69                         if(r != curinst->r)
  70                                 goto Done;
  71                 case OANY: /* fallthrough */
  72                         next = t->next;
  73                         t->pc = curinst + 1;
  74                         t->next = nil;
  75                         *nlist->tail = t;
  76                         nlist->tail = &t->next;
  77                         if(next == nil)
  78                                 break;
  79                         t = next;
  80                         curinst = t->pc;
  81                         goto Again;
  82                 case OCLASS:
  83                 Class:
  84                         if(r < curinst->r)
  85                                 goto Done;
  86                         if(r > curinst->r1) {
  87                                 curinst++;
  88                                 goto Class;
  89                         }
  90                         next = t->next;
  91                         t->pc = curinst->a;
  92                         t->next = nil;
  93                         *nlist->tail = t;
  94                         nlist->tail = &t->next;
  95                         if(next == nil)
  96                                 break;
  97                         t = next;
  98                         curinst = t->pc;
  99                         goto Again;
 100                 case ONOTNL:
 101                         if(r != L'\n') {
 102                                 curinst++;
 103                                 goto Again;
 104                         }
 105                         goto Done;
 106                 case OBOL:
 107                         if(sp == str || sp[-1] == '\n') {
 108                                 curinst++;
 109                                 goto Again;
 110                         }
 111                         goto Done;
 112                 case OEOL:
 113                         if(r == L'\n' || r == L'\0' && ep == nil) {
 114                                 curinst++;
 115                                 goto Again;
 116                         }
 117                         goto Done;
 118                 case OJMP:
 119                         curinst = curinst->a;
 120                         goto Again;
 121                 case OSPLIT:
 122                         if(avail == nil)
 123                                 next = --pooltop;
 124                         else {
 125                                 next = avail;
 126                                 avail = avail->next;
 127                         }
 128                         next->pc = curinst->b;
 129                         if(msize > 0)
 130                                 memcpy(next->sem, t->sem, sizeof(Resub)*msize);
 131                         next->pri = t->pri;
 132                         next->next = t->next;
 133                         t->next = next;
 134                         curinst = curinst->a;
 135                         goto Again;
 136                 case OSAVE:
 137                         if(curinst->sub < msize)
 138                                 t->sem[curinst->sub].sp = sp;
 139                         curinst++;
 140                         goto Again;
 141                 case OUNSAVE:
 142                         if(curinst->sub == 0) {
 143                                 /* "Highest" priority is the left-most longest. */
 144                                 if (t->pri > matchpri)
 145                                         goto Done;
 146                                 match = 1;
 147                                 matchpri = t->pri;
 148                                 if(sem != nil && msize > 0) {
 149                                         memcpy(sem, t->sem, sizeof(Resub)*msize);
 150                                         sem->ep = sp;
 151                                 }
 152                                 goto Done;
 153                         }
 154                         if(curinst->sub < msize)
 155                                 t->sem[curinst->sub].ep = sp;
 156                         curinst++;
 157                         goto Again;
 158                 Done:
 159                         next = t->next;
 160                         t->next = avail;
 161                         avail = t;
 162                         if(next == nil)
 163                                 break;
 164                         t = next;
 165                         curinst = t->pc;
 166                         goto Again;
 167                 }
 168 Start:
 169                 /* Start again once if we haven't found anything. */
 170                 if(first == 1 && match == 0) {
 171                         first = 0;
 172                         if(avail == nil)
 173                                 t = --pooltop;
 174                         else {
 175                                 t = avail;
 176                                 avail = avail->next;
 177                         }
 178                         if(msize > 0)
 179                                 memset(t->sem, 0, sizeof(Resub)*msize);
 180                         /* "Lower" priority thread */
 181                         t->pri = matchpri = pri++;
 182                         t->next = nil;
 183                         curinst = prog->startinst;
 184                         goto Again;
 185                 }
 186                 /* If we have a match and no extant threads, we are done. */
 187                 if(match == 1 && nlist->head == nil)
 188                         break;
 189                 tmp = clist;
 190                 clist = nlist;
 191                 nlist = tmp;
 192                 nlist->head = nil;
 193                 nlist->tail = &nlist->head;
 194         }
 195         if(ep != nil)
 196                 *ep = endc;
 197         return match;
 198 }