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                         next = t->next;
  72                         t->pc = curinst + 1;
  73                         t->next = nil;
  74                         *nlist->tail = t;
  75                         nlist->tail = &t->next;
  76                         if(next == nil)
  77                                 break;
  78                         t = next;
  79                         curinst = t->pc;
  80                         goto Again;
  81                 case OCLASS:
  82                 Class:
  83                         if(*rsp < curinst->r)
  84                                 goto Done;
  85                         if(*rsp > curinst->r1) {
  86                                 curinst++;
  87                                 goto Class;
  88                         }
  89                         next = t->next;
  90                         t->pc = curinst->a;
  91                         t->next = nil;
  92                         *nlist->tail = t;
  93                         nlist->tail = &t->next;
  94                         if(next == nil)
  95                                 break;
  96                         t = next;
  97                         curinst = t->pc;
  98                         goto Again;
  99                 case ONOTNL:
 100                         if(*rsp != L'\n') {
 101                                 curinst++;
 102                                 goto Again;
 103                         }
 104                         goto Done;
 105                 case OBOL:
 106                         if(rsp == str || rsp[-1] == L'\n') {
 107                                 curinst++;
 108                                 goto Again;
 109                         }
 110                         goto Done;
 111                 case OEOL:
 112                         if(*rsp == '\n' || *rsp == L'\0' && rep == nil) {
 113                                 curinst++;
 114                                 goto Again;
 115                         }
 116                         goto Done;
 117                 case OJMP:
 118                         curinst = curinst->a;
 119                         goto Again;
 120                 case OSPLIT:
 121                         if(avail == nil)
 122                                 next = --pooltop;
 123                         else {
 124                                 next = avail;
 125                                 avail = avail->next;
 126                         }
 127                         next->pc = curinst->b;
 128                         if(msize > 0)
 129                                 memcpy(next->sem, t->sem, sizeof(Resub)*msize);
 130                         next->pri = t->pri;
 131                         next->next = t->next;
 132                         t->next = next;
 133                         curinst = curinst->a;
 134                         goto Again;
 135                 case OSAVE:
 136                         if(curinst->sub < msize)
 137                                 t->sem[curinst->sub].rsp = rsp;
 138                         curinst++;
 139                         goto Again;
 140                 case OUNSAVE:
 141                         if(curinst->sub == 0) {
 142                                 /* "Highest" priority is the left-most longest. */
 143                                 if (t->pri > matchpri)
 144                                         goto Done;
 145                                 match = 1;
 146                                 matchpri = t->pri;
 147                                 if(sem != nil && msize > 0) {
 148                                         memcpy(sem, t->sem, sizeof(Resub)*msize);
 149                                         sem->rep = rsp;
 150                                 }
 151                                 goto Done;
 152                         }
 153                         if(curinst->sub < msize)
 154                                 t->sem[curinst->sub].rep = rsp;
 155                         curinst++;
 156                         goto Again;
 157                 Done:
 158                         next = t->next;
 159                         t->next = avail;
 160                         avail = t;
 161                         if(next == nil)
 162                                 break;
 163                         t = next;
 164                         curinst = t->pc;
 165                         goto Again;
 166                 }
 167 Start:
 168                 /* Start again once if we haven't found anything. */
 169                 if(first == 1 && match == 0) {
 170                         first = 0;
 171                         if(avail == nil)
 172                                 t = --pooltop;
 173                         else {
 174                                 t = avail;
 175                                 avail = avail->next;
 176                         }
 177                         if(msize > 0)
 178                                 memset(t->sem, 0, sizeof(Resub)*msize);
 179                         /* "Lower" priority thread */
 180                         t->pri = matchpri = pri++;
 181                         t->next = nil;
 182                         curinst = prog->startinst;
 183                         goto Again;
 184                 }
 185                 /* If we have a match and no extant threads, we are done. */
 186                 if(match == 1 && nlist->head == nil)
 187                         break;
 188                 tmp = clist;
 189                 clist = nlist;
 190                 nlist = tmp;
 191                 nlist->head = nil;
 192                 nlist->tail = &nlist->head;
 193         }
 194         if(rep != nil)
 195                 *rep = endr;
 196         return match;
 197 }