regex: closure operations don't output epsilon states.

* regex.c (nfa_closure, nfa_move_closure): Do not add epsilon
states to the output array. We only need to add them to the
stack for the spanning traversal. Epsilon states are not real
states; they are just a representation of the concept of
transitioning to multiple states at the same time.
When we add them to the output, they just end up being ignored
when nfa_move_closure is called again on that set, since it
only cares about states that have real transitions for a
character.

1 files changed, 12 insertions, 6 deletions

diff --git a/regex.c b/regex.c
index 670f9243..7a73d5a6 100644
--- a/regex.c
+++ b/regex.c
@@ -1292,7 +1292,8 @@ static int nfa_closure(nfa_state_t **stack, nfa_state_t **set, int nin,
 
     s->a.visited = visited;
     stack[stackp++] = s;
-    set[nout++] = s;
+    if (!nfa_empty_state_p(s))
+      set[nout++] = s;
     if (nfa_accept_state_p(s))
       *accept = 1;
     if (!moreset && nfa_has_transitions(s))
@@ -1311,7 +1312,8 @@ static int nfa_closure(nfa_state_t **stack, nfa_state_t **set, int nin,
 
       if (nfa_test_set_visited(e0, visited)) {
         stack[stackp++] = e0;
-        set[nout++] = e0;
+        if (!nfa_empty_state_p(e0))
+          set[nout++] = e0;
         if (nfa_accept_state_p(e0))
           *accept = 1;
         if (!moreset && nfa_has_transitions(e0))
@@ -1320,7 +1322,8 @@ static int nfa_closure(nfa_state_t **stack, nfa_state_t **set, int nin,
 
       if (nfa_test_set_visited(e1, visited)) {
         stack[stackp++] = e1;
-        set[nout++] = e1;
+        if (!nfa_empty_state_p(e1))
+          set[nout++] = e1;
         if (nfa_accept_state_p(e1))
           *accept = 1;
         if (!moreset && nfa_has_transitions(e1))
@@ -1382,7 +1385,8 @@ static int nfa_move_closure(nfa_state_t **stack, nfa_state_t **set, int nin,
 
       if (nfa_test_set_visited(mov, visited)) {
         stack[stackp++] = mov;
-        set[nout++] = mov;
+        if (!nfa_empty_state_p(mov))
+          set[nout++] = mov;
         if (nfa_accept_state_p(mov))
           *accept = 1;
         if (!moreset && nfa_has_transitions(mov))
@@ -1403,7 +1407,8 @@ static int nfa_move_closure(nfa_state_t **stack, nfa_state_t **set, int nin,
 
       if (nfa_test_set_visited(e0, visited)) {
         stack[stackp++] = e0;
-        set[nout++] = e0;
+        if (!nfa_empty_state_p(e0))
+          set[nout++] = e0;
         if (nfa_accept_state_p(e0))
           *accept = 1;
         if (!moreset && nfa_has_transitions(e0))
@@ -1412,7 +1417,8 @@ static int nfa_move_closure(nfa_state_t **stack, nfa_state_t **set, int nin,
 
       if (nfa_test_set_visited(e1, visited)) {
         stack[stackp++] = e1;
-        set[nout++] = e1;
+        if (!nfa_empty_state_p(e1))
+          set[nout++] = e1;
         if (nfa_accept_state_p(e1))
           *accept = 1;
         if (!moreset && nfa_has_transitions(e0))