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         Rethread *head;
   9         Rethread **tail;
  10 };
  11
  12 int
  13 regexec(Reprog *p, char *str, Resub *sem, int msize)
  14 {
  15         RethreadQ lists[2], *clist, *nlist, *tmp;
  16         Rethread *t, *next, *pool, *avail;
  17         Reinst *ci;
  18         Rune r;
  19         char *sp, *ep, endc;
  20         int i, matchgen, gen;
  21
  22         memset(p->threads, 0, sizeof(Rethread)*p->nthr);
  23         if(msize > NSUBEXPM)
  24                 msize = NSUBEXPM;
  25         if(p->startinst->gen != 0) {
  26                 for(ci = p->startinst; ci < p->startinst + p->len; ci++)
  27                         ci->gen = 0;
  28         }
  29
  30         clist = lists;
  31         clist->head = nil;
  32         clist->tail = &clist->head;
  33         nlist = lists + 1;
  34         nlist->head = nil;
  35         nlist->tail = &nlist->head;
  36
  37         pool = p->threads;
  38         avail = nil;
  39         gen = matchgen = 0;
  40
  41         sp = str;
  42         ep = nil;
  43         endc = '\0';
  44         if(sem != nil && msize > 0) {
  45                 if(sem->sp != nil)
  46                         sp = sem->sp;
  47                 if(sem->ep != nil && *sem->ep != '\0') {
  48                         ep = sem->ep;
  49                         endc = *sem->ep;
  50                         *sem->ep = '\0';
  51                 }
  52         }
  53
  54         for(r = L'☺'; r != L'\0'; sp += i) {
  55                 i = chartorune(&r, sp);
  56                 gen++;
  57                 if(matchgen == 0) {
  58                         if(avail == nil) {
  59                                 assert(pool < p->threads + p->nthr);
  60                                 t = pool++;
  61                         } else {
  62                                 t = avail;
  63                                 avail = avail->next;
  64                         }
  65                         t->i = p->startinst;
  66                         if(msize > 0)
  67                                 memset(t->sem, 0, sizeof(Resub)*msize);
  68                         t->next = nil;
  69                         t->gen = gen;
  70                         *clist->tail = t;
  71                         clist->tail = &t->next;
  72                 }
  73                 t = clist->head;
  74                 if(t == nil)
  75                         break;
  76                 ci = t->i;
  77 Again:
  78                 if(ci->gen == gen)
  79                         goto Done;
  80                 ci->gen = gen;
  81                 switch(ci->op) {
  82                 case ORUNE:
  83                         if(r != ci->r)
  84                                 goto Done;
  85                 case OANY: /* fallthrough */
  86                         next = t->next;
  87                         t->i = ci + 1;
  88                         t->next = nil;
  89                         *nlist->tail = t;
  90                         nlist->tail = &t->next;
  91                         goto Next;
  92                 case OCLASS:
  93                 Class:
  94                         if(r < ci->r)
  95                                 goto Done;
  96                         if(r > ci->r1) {
  97                                 ci++;
  98                                 goto Class;
  99                         }
 100                         next = t->next;
 101                         t->i = ci->a;
 102                         t->next = nil;
 103                         *nlist->tail = t;
 104                         nlist->tail = &t->next;
 105                         goto Next;
 106                 case ONOTNL:
 107                         if(r != L'\n') {
 108                                 ci++;
 109                                 goto Again;
 110                         }
 111                         goto Done;
 112                 case OBOL:
 113                         if(sp == str || sp[-1] == '\n') {
 114                                 ci++;
 115                                 goto Again;
 116                         }
 117                         goto Done;
 118                 case OEOL:
 119                         if(r == L'\n' || r == L'\0' && ep == nil) {
 120                                 ci++;
 121                                 goto Again;
 122                         }
 123                         goto Done;
 124                 case OJMP:
 125                         ci = ci->a;
 126                         goto Again;
 127                 case OSPLIT:
 128                         if(avail == nil) {
 129                                 assert(pool < p->threads + p->nthr);
 130                                 next = pool++;
 131                         } else {
 132                                 next = avail;
 133                                 avail = avail->next;
 134                         }
 135                         next->i = ci->b;
 136                         if(msize > 0)
 137                                 memcpy(next->sem, t->sem, sizeof(Resub)*msize);
 138                         next->next = t->next;
 139                         next->gen = t->gen;
 140                         t->next = next;
 141                         ci = ci->a;
 142                         goto Again;
 143                 case OSAVE:
 144                         if(ci->sub < msize)
 145                                 t->sem[ci->sub].sp = sp;
 146                         ci++;
 147                         goto Again;
 148                 case OUNSAVE:
 149                         if(ci->sub == 0) {
 150                                 matchgen = t->gen;
 151                                 if(sem != nil && msize > 0) {
 152                                         memcpy(sem, t->sem, sizeof(Resub)*msize);
 153                                         sem->ep = sp;
 154                                 }
 155                                 goto Done;
 156                         }
 157                         if(ci->sub < msize)
 158                                 t->sem[ci->sub].ep = sp;
 159                         ci++;
 160                         goto Again;
 161                 Done:
 162                         next = t->next;
 163                         t->next = avail;
 164                         avail = t;
 165                 Next:
 166                         if(next == nil)
 167                                 break;
 168                         if(matchgen && next->gen > matchgen) {
 169                                 *clist->tail = avail;
 170                                 avail = next;
 171                                 break;
 172                         }
 173                         t = next;
 174                         ci = t->i;
 175                         goto Again;
 176                 }
 177                 tmp = clist;
 178                 clist = nlist;
 179                 nlist = tmp;
 180                 nlist->head = nil;
 181                 nlist->tail = &nlist->head;
 182         }
 183         if(ep != nil)
 184                 *ep = endc;
 185         return matchgen > 0 ? 1 : 0;
 186 }