1 files changed, 43 insertions, 13 deletions

diff --git a/lpvm.c b/lpvm.c
index 277acf7..db996e5 100644
--- a/lpvm.c
+++ b/lpvm.c
@@ -48,6 +48,12 @@ typedef struct Stack {
 } Stack;
 
 
+typedef struct RecStack {
+  const Labelset *ls; /* labeled failure */
+  const Instruction *prec;  /* recovery instruction */
+} RecStack;
+
+
 #define getstackbase(L, ptop)   ((Stack *)lua_touserdata(L, stackidx(ptop)))
 
 
@@ -156,15 +162,20 @@ static int removedyncap (lua_State *L, Capture *capture,
 const char *match (lua_State *L, const char *o, const char *s, const char *e,
                    Instruction *op, Capture *capture, int ptop, byte *labelf, const char **sfail) { /* labeled failure */
   Stack stackbase[INITBACK];
+  RecStack recbase[MAXRECOVERY];
   Stack *stacklimit = stackbase + INITBACK;
   Stack *stack = stackbase;  /* point to first empty slot in stack */
-  int capsize = INITCAPSIZE;
+  RecStack *reclimit = recbase + MAXRECOVERY;
+        RecStack *recstack = recbase;
+        int capsize = INITCAPSIZE;
   int captop = 0;  /* point to first empty slot in captures */
   int ndyncap = 0;  /* number of dynamic captures (in Lua stack) */
   const Instruction *p = op;  /* current instruction */
+  const Instruction *pk = NULL;  /* resume instruction */
         Labelset lsfail;
         setlabelfail(&lsfail);
   stack->p = &giveup; stack->s = s; stack->ls = &lsfail; stack->caplevel = 0; stack++;  /* labeled failure */
+  recstack->prec = &giveup; recstack->ls = &lsfail; recstack++;  /* labeled failure */
   lua_pushlightuserdata(L, stackbase);
   for (;;) {
 #if defined(DEBUG)
@@ -194,6 +205,7 @@ const char *match (lua_State *L, const char *o, const char *s, const char *e,
         if (s < e) { p++; s++; }
         else {
           *labelf = LFAIL; /* labeled failure */
+          pk = p + 1; 
                                         *sfail = s;
           goto fail;
         }
@@ -208,6 +220,7 @@ const char *match (lua_State *L, const char *o, const char *s, const char *e,
         if ((byte)*s == p->i.aux && s < e) { p++; s++; }
         else {
           *labelf = LFAIL; /* labeled failure */
+          pk = p + 1; 
                                         *sfail = s;
           goto fail;
         }
@@ -224,6 +237,7 @@ const char *match (lua_State *L, const char *o, const char *s, const char *e,
           { p += CHARSETINSTSIZE; s++; }
         else {
           *labelf = LFAIL; /* labeled failure */
+          pk = p + CHARSETINSTSIZE; 
                                         *sfail = s;
           goto fail;
         }
@@ -240,6 +254,7 @@ const char *match (lua_State *L, const char *o, const char *s, const char *e,
         int n = p->i.aux;
         if (n > s - o) {
           *labelf = LFAIL; /* labeled failure */
+          pk = p + 1; 
                                         *sfail = s;
           goto fail;
         }
@@ -281,17 +296,14 @@ const char *match (lua_State *L, const char *o, const char *s, const char *e,
         continue;
       }
                         case IRecov: { /* labeled failure */
-        if (stack == stacklimit)
-          stack = doublestack(L, &stacklimit, ptop);
-        stack->p = p + getoffset(p);
-        stack->s = NULL;
-        stack->ls = (const Labelset *) ((p + 2)->buff);
-        stack->caplevel = captop;
-        stack++;
+        if (recstack == reclimit)
+                        luaL_error(L, "recovery stack overflow (current limit is %d)", MAXRECOVERY);
+        recstack->prec = p + getoffset(p);
+        recstack->ls = (const Labelset *) ((p + 2)->buff);
+        recstack++;
         p += (CHARSETINSTSIZE - 1) + 2;
         continue;
       }
-
       case ICall: {
         if (stack == stacklimit)
           stack = doublestack(L, &stacklimit, ptop);
@@ -303,8 +315,8 @@ const char *match (lua_State *L, const char *o, const char *s, const char *e,
         continue;
       }
       case ICommit: {
-        assert(stack > getstackbase(L, ptop) && (stack - 1)->ls != NULL); /* labeled failure */
-        /* assert((stack - 1)->s != NULL); labeled failure: IRecov does not push s onto the stack */
+        /*assert(stack > getstackbase(L, ptop) && (stack - 1)->ls != NULL); */ /* labeled failure */
+        assert((stack - 1)->s != NULL); /* labeled failure: IRecov does not push s onto the stack */
         stack--;
         p += getoffset(p);
         continue;
@@ -325,8 +337,24 @@ const char *match (lua_State *L, const char *o, const char *s, const char *e,
       }
       case IThrow: { /* labeled failure */
         *labelf = p->i.aux;
+                                while ((--recstack)->prec != &giveup) {
+                                        if (testlabel(recstack->ls->cs, *labelf)) {
+                                                /* Push resume/call frame */
+                        stack->s = NULL;
+                        stack->p = p + 1;  /* resume to instruction after IThrow */
+                        stack->ls = NULL;
+                        stack++;
+                                                p = recstack->prec;
+                                                break;
+                                        }
+                                }
+                                if (recstack->prec != &giveup)
+                                        continue;
+                                p = recstack->prec; /* p = IGiveup */
+                                stack = getstackbase(L, ptop);
                                 *sfail = s;
-        goto fail;
+        /*goto fail;*/
+                                continue;
       }
       case IFailTwice:
         assert(stack > getstackbase(L, ptop));
@@ -334,6 +362,7 @@ const char *match (lua_State *L, const char *o, const char *s, const char *e,
         /* go through */
       case IFail:
       *labelf = LFAIL; /* labeled failure */
+      pk = NULL;
                         *sfail = s;
       fail: { /* pattern failed: try to backtrack */
         const Labelset *auxlab = NULL;
@@ -343,7 +372,7 @@ const char *match (lua_State *L, const char *o, const char *s, const char *e,
         } while (auxlab == NULL || (stack->p != &giveup && !testlabel(stack->ls->cs, *labelf)));
         if (stack->p == &giveup || stack->s != NULL) { /* labeled failure */
                                         s = stack->s;
-                                }
+                                } 
         if (ndyncap > 0)  /* is there matchtime captures? */
           ndyncap -= removedyncap(L, capture, stack->caplevel, captop);
         captop = stack->caplevel;
@@ -362,6 +391,7 @@ const char *match (lua_State *L, const char *o, const char *s, const char *e,
         if (res == -1) { /* fail? */
                 *labelf = LFAIL;  /* labeled failure */
                                         *sfail = (const char *) s; /* TODO: ??? */
+          pk = NULL;
           goto fail;
         }
         s = o + res;  /* else update current position */