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, *nextthr, **availthr;
  18         Reinst *curinst;
  19         Rune *rsp, *rep, endr, last;
  20         int i, 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         for(i = 0; i < prog->nthr; i++)
  38                 prog->thrpool[i] = prog->threads + i;
  39         availthr = prog->thrpool + prog->nthr;
  40
  41         pri = matchpri = gen = match = 0;
  42         rsp = str;
  43         rep = nil;
  44         endr = L'\0';
  45         if(sem != nil && msize > 0) {
  46                 if(sem->rsp != nil)
  47                         rsp = sem->rsp;
  48                 if(sem->rep != nil && *sem->rep != L'\0') {
  49                         rep = sem->rep;
  50                         endr = *sem->rep;
  51                         *sem->rep = '\0';
  52                 }
  53         }
  54         last = 1;
  55         for(; last != L'\0'; rsp++) {
  56                 gen++;
  57                 last = *rsp;
  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(*rsp != curinst->r)
  70                                 goto Done;
  71                 case OANY: /* fallthrough */
  72                 Any:
  73                         nextthr = t->next;
  74                         t->pc = curinst + 1;
  75                         t->next = nil;
  76                         *nlist->tail = t;
  77                         nlist->tail = &t->next;
  78                         if(nextthr == nil)
  79                                 break;
  80                         t = nextthr;
  81                         curinst = t->pc;
  82                         goto Again;
  83                 case OCLASS:
  84                 Class:
  85                         if(*rsp < curinst->r)
  86                                 goto Done;
  87                         if(*rsp > curinst->r1) {
  88                                 curinst++;
  89                                 goto Class;
  90                         }
  91                         nextthr = t->next;
  92                         t->pc = curinst->a;
  93                         t->next = nil;
  94                         *nlist->tail = t;
  95                         nlist->tail = &t->next;
  96                         if(nextthr == nil)
  97                                 break;
  98                         t = nextthr;
  99                         curinst = t->pc;
 100                         goto Again;
 101                 case ONOTNL:
 102                         if(*rsp != L'\n') {
 103                                 curinst++;
 104                                 goto Again;
 105                         }
 106                         goto Done;
 107                 case OBOL:
 108                         if(rsp == str || rsp[-1] == L'\n') {
 109                                 curinst++;
 110                                 goto Again;
 111                         }
 112                         goto Done;
 113                 case OEOL:
 114                         if(*rsp == L'\0' && rep == nil) {
 115                                 curinst++;
 116                                 goto Again;
 117                         }
 118                         if(*rsp == '\n')
 119                                 goto Any;
 120                         goto Done;
 121                 case OJMP:
 122                         curinst = curinst->a;
 123                         goto Again;
 124                 case OSPLIT:
 125                         nextthr = *--availthr;
 126                         nextthr->pc = curinst->b;
 127                         if(msize > 0)
 128                                 memcpy(nextthr->sem, t->sem, sizeof(Resub)*msize);
 129                         nextthr->pri = t->pri;
 130                         nextthr->next = t->next;
 131                         t->next = nextthr;
 132                         curinst = curinst->a;
 133                         goto Again;
 134                 case OSAVE:
 135                         if(curinst->sub < msize)
 136                                 t->sem[curinst->sub].rsp = rsp;
 137                         curinst++;
 138                         goto Again;
 139                 case OUNSAVE:
 140                         if(curinst->sub == 0) {
 141                                 /* "Highest" priority is the left-most longest. */
 142                                 if (t->pri > matchpri)
 143                                         goto Done;
 144                                 match = 1;
 145                                 matchpri = t->pri;
 146                                 if(sem != nil && msize > 0) {
 147                                         memcpy(sem, t->sem, sizeof(Resub)*msize);
 148                                         sem->rep = rsp;
 149                                 }
 150                                 goto Done;
 151                         }
 152                         if(curinst->sub < msize)
 153                                 t->sem[curinst->sub].rep = rsp;
 154                         curinst++;
 155                         goto Again;
 156                 Done:
 157                         *availthr++ = t;
 158                         t = t->next;
 159                         if(t == nil)
 160                                 break;
 161                         curinst = t->pc;
 162                         goto Again;
 163                 }
 164 Start:
 165                 /* Start again once if we haven't found anything. */
 166                 if(first == 1 && match == 0) {
 167                         first = 0;
 168                         t = *--availthr;
 169                         if(msize > 0)
 170                                 memset(t->sem, 0, sizeof(Resub)*msize);
 171                         /* "Lower" priority thread */
 172                         t->pri = matchpri = pri++;
 173                         t->next = nil;
 174                         curinst = prog->startinst;
 175                         goto Again;
 176                 }
 177                 /* If we have a match and no extant threads, we are done. */
 178                 if(match == 1 && nlist->head == nil)
 179                         break;
 180                 tmp = clist;
 181                 clist = nlist;
 182                 nlist = tmp;
 183                 nlist->head = nil;
 184                 nlist->tail = &nlist->head;
 185         }
 186         if(rep != nil)
 187                 *rep = endr;
 188         return match;
 189 }