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, *nextthr, **availthr;
  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         for(i = 0; i < prog->nthr; i++)
  39                 prog->thrpool[i] = prog->threads + i;
  40         availthr = prog->thrpool + prog->nthr;
  41
  42         pri = matchpri = gen = match = 0;
  43         sp = str;
  44         ep = nil;
  45         endc = '\0';
  46         if(sem != nil && msize > 0) {
  47                 if(sem->sp != nil)
  48                         sp = sem->sp;
  49                 if(sem->ep != nil && *sem->ep != '\0') {
  50                         ep = sem->ep;
  51                         endc = *sem->ep;
  52                         *sem->ep = '\0';
  53                 }
  54         }
  55         r = Runemax + 1;
  56         for(; r != L'\0'; sp += i) {
  57                 gen++;
  58                 i = chartorune(&r, sp);
  59                 first = 1;
  60                 t = clist->head;
  61                 if(t == nil)
  62                         goto Start;
  63                 curinst = t->pc;
  64 Again:
  65                 if(curinst->gen == gen)
  66                         goto Done;
  67                 curinst->gen = gen;
  68                 switch(curinst->op) {
  69                 case ORUNE:
  70                         if(r != curinst->r)
  71                                 goto Done;
  72                 case OANY: /* fallthrough */
  73                 Any:
  74                         nextthr = t->next;
  75                         t->pc = curinst + 1;
  76                         t->next = nil;
  77                         *nlist->tail = t;
  78                         nlist->tail = &t->next;
  79                         if(nextthr == nil)
  80                                 break;
  81                         t = nextthr;
  82                         curinst = t->pc;
  83                         goto Again;
  84                 case OCLASS:
  85                 Class:
  86                         if(r < curinst->r)
  87                                 goto Done;
  88                         if(r > curinst->r1) {
  89                                 curinst++;
  90                                 goto Class;
  91                         }
  92                         nextthr = t->next;
  93                         t->pc = curinst->a;
  94                         t->next = nil;
  95                         *nlist->tail = t;
  96                         nlist->tail = &t->next;
  97                         if(nextthr == nil)
  98                                 break;
  99                         t = nextthr;
 100                         curinst = t->pc;
 101                         goto Again;
 102                 case ONOTNL:
 103                         if(r != L'\n') {
 104                                 curinst++;
 105                                 goto Again;
 106                         }
 107                         goto Done;
 108                 case OBOL:
 109                         if(sp == str || sp[-1] == '\n') {
 110                                 curinst++;
 111                                 goto Again;
 112                         }
 113                         goto Done;
 114                 case OEOL:
 115                         if(r == L'\0' && ep == nil) {
 116                                 curinst++;
 117                                 goto Again;
 118                         }
 119                         if(r == L'\n')
 120                                 goto Any;
 121                         goto Done;
 122                 case OJMP:
 123                         curinst = curinst->a;
 124                         goto Again;
 125                 case OSPLIT:
 126                         nextthr = *--availthr;
 127                         nextthr->pc = curinst->b;
 128                         if(msize > 0)
 129                                 memcpy(nextthr->sem, t->sem, sizeof(Resub)*msize);
 130                         nextthr->pri = t->pri;
 131                         nextthr->next = t->next;
 132                         t->next = nextthr;
 133                         curinst = curinst->a;
 134                         goto Again;
 135                 case OSAVE:
 136                         if(curinst->sub < msize)
 137                                 t->sem[curinst->sub].sp = sp;
 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->ep = sp;
 150                                 }
 151                                 goto Done;
 152                         }
 153                         if(curinst->sub < msize)
 154                                 t->sem[curinst->sub].ep = sp;
 155                         curinst++;
 156                         goto Again;
 157                 Done:
 158                         *availthr++ = t;
 159                         t = t->next;
 160                         if(t == nil)
 161                                 break;
 162                         curinst = t->pc;
 163                         goto Again;
 164                 }
 165 Start:
 166                 /* Start again once if we haven't found anything. */
 167                 if(first == 1 && match == 0) {
 168                         first = 0;
 169                         t = *--availthr;
 170                         if(msize > 0)
 171                                 memset(t->sem, 0, sizeof(Resub)*msize);
 172                         /* "Lower" priority thread */
 173                         t->pri = matchpri = pri++;
 174                         t->next = nil;
 175                         curinst = prog->startinst;
 176                         goto Again;
 177                 }
 178                 /* If we have a match and no extant threads, we are done. */
 179                 if(match == 1 && nlist->head == nil)
 180                         break;
 181                 tmp = clist;
 182                 clist = nlist;
 183                 nlist = tmp;
 184                 nlist->head = nil;
 185                 nlist->tail = &nlist->head;
 186         }
 187         if(ep != nil)
 188                 *ep = endc;
 189         return match;
 190 }