sys/src/libregexp/rregexec.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 rregexec(Reprog *prog, Rune *str, Resub *sem, int msize)
  15 {
  16         RethreadQ lists[2], *clist, *nlist, *tmp;
  17         Rethread *t, *next, *pooltop, *avail;
  18         Reinst *curinst;
  19         Rune *rsp, *rep, endr, last;
  20         int match, first, gen, pri, matchpri;
  21
  22         if(msize > NSUBEXPM)
  23                 msize = NSUBEXPM;
  24
  25         if(prog->startinst->gen != 0) {
  26                 for(curinst = prog->startinst; curinst < prog->startinst + prog->len; curinst++)
  27                         curinst->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         pooltop = prog->threads + prog->nthr;
  38         avail = nil;
  39
  40         pri = matchpri = gen = match = 0;
  41         rsp = str;
  42         rep = nil;
  43         endr = L'\0';
  44         if(sem != nil && msize > 0) {
  45                 if(sem->rsp != nil)
  46                         rsp = sem->rsp;
  47                 if(sem->rep != nil && *sem->rep != L'\0') {
  48                         rep = sem->rep;
  49                         endr = *sem->rep;
  50                         *sem->rep = '\0';
  51                 }
  52         }
  53         last = 1;
  54         for(; last != L'\0'; rsp++) {
  55                 gen++;
  56                 last = *rsp;
  57                 first = 1;
  58                 t = clist->head;
  59                 if(t == nil)
  60                         goto Start;
  61                 curinst = t->pc;
  62 Again:
  63                 if(curinst->gen == gen)
  64                         goto Done;
  65                 curinst->gen = gen;
  66                 switch(curinst->op) {
  67                 case ORUNE:
  68                         if(*rsp != curinst->r)
  69                                 goto Done;
  70                 case OANY: /* fallthrough */
  71                 Any:
  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(*rsp < curinst->r)
  85                                 goto Done;
  86                         if(*rsp > 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(*rsp != L'\n') {
 102                                 curinst++;
 103                                 goto Again;
 104                         }
 105                         goto Done;
 106                 case OBOL:
 107                         if(rsp == str || rsp[-1] == L'\n') {
 108                                 curinst++;
 109                                 goto Again;
 110                         }
 111                         goto Done;
 112                 case OEOL:
 113                         if(*rsp == L'\0' && rep == nil) {
 114                                 curinst++;
 115                                 goto Again;
 116                         }
 117                         if(*rsp == '\n')
 118                                 goto Any;
 119                         goto Done;
 120                 case OJMP:
 121                         curinst = curinst->a;
 122                         goto Again;
 123                 case OSPLIT:
 124                         if(avail == nil)
 125                                 next = --pooltop;
 126                         else {
 127                                 next = avail;
 128                                 avail = avail->next;
 129                         }
 130                         next->pc = curinst->b;
 131                         if(msize > 0)
 132                                 memcpy(next->sem, t->sem, sizeof(Resub)*msize);
 133                         next->pri = t->pri;
 134                         next->next = t->next;
 135                         t->next = next;
 136                         curinst = curinst->a;
 137                         goto Again;
 138                 case OSAVE:
 139                         if(curinst->sub < msize)
 140                                 t->sem[curinst->sub].rsp = rsp;
 141                         curinst++;
 142                         goto Again;
 143                 case OUNSAVE:
 144                         if(curinst->sub == 0) {
 145                                 /* "Highest" priority is the left-most longest. */
 146                                 if (t->pri > matchpri)
 147                                         goto Done;
 148                                 match = 1;
 149                                 matchpri = t->pri;
 150                                 if(sem != nil && msize > 0) {
 151                                         memcpy(sem, t->sem, sizeof(Resub)*msize);
 152                                         sem->rep = rsp;
 153                                 }
 154                                 goto Done;
 155                         }
 156                         if(curinst->sub < msize)
 157                                 t->sem[curinst->sub].rep = rsp;
 158                         curinst++;
 159                         goto Again;
 160                 Done:
 161                         next = t->next;
 162                         t->next = avail;
 163                         avail = t;
 164                         if(next == nil)
 165                                 break;
 166                         t = next;
 167                         curinst = t->pc;
 168                         goto Again;
 169                 }
 170 Start:
 171                 /* Start again once if we haven't found anything. */
 172                 if(first == 1 && match == 0) {
 173                         first = 0;
 174                         if(avail == nil)
 175                                 t = --pooltop;
 176                         else {
 177                                 t = avail;
 178                                 avail = avail->next;
 179                         }
 180                         if(msize > 0)
 181                                 memset(t->sem, 0, sizeof(Resub)*msize);
 182                         /* "Lower" priority thread */
 183                         t->pri = matchpri = pri++;
 184                         t->next = nil;
 185                         curinst = prog->startinst;
 186                         goto Again;
 187                 }
 188                 /* If we have a match and no extant threads, we are done. */
 189                 if(match == 1 && nlist->head == nil)
 190                         break;
 191                 tmp = clist;
 192                 clist = nlist;
 193                 nlist = tmp;
 194                 nlist->head = nil;
 195                 nlist->tail = &nlist->head;
 196         }
 197         if(rep != nil)
 198                 *rep = endr;
 199         return match;
 200 }