--- a/regexParser/subsetConstraction.cc	Sat Dec 26 14:05:14 2015 +0900
+++ b/regexParser/subsetConstraction.cc	Sat Dec 26 18:09:27 2015 +0900
@@ -117,11 +117,13 @@
     while (next->left) {
         CharClassStackPtr ccs = NEW(CharClassStack);
         ccs->next = walk->stack;
-        ccs->turn = LEFT;
+        ccs->turn = walk->turn;
+        walk->turn = LEFT;
         ccs->cc = next;
         walk->stack = ccs;
         next = next->left;
     }
+    walk->turn = SELF;
     walk->next = next;
 }
 
@@ -130,10 +132,6 @@
     walk->next = NULL;
     walk->stack = NULL;
     if (!next) return walk;
-    if (!next->left) {
-        walk->next = next;
-        return walk;
-    }
     findLeftMost(next,walk);
     return walk;
 }
@@ -143,36 +141,32 @@
 }
 
 CharClassStackPtr charClassStackPop(CharClassWalkerPtr walk) {
-    if (!walk->stack) {
-        return NULL;
-    }
     CharClassStackPtr prev = walk->stack->next;
     free(walk->stack);
     walk->stack = prev;
+    walk->turn = prev->turn;
     return prev;
 }
 
 CharClassPtr getNext(CharClassWalkerPtr walk) {
     CharClassPtr current = walk->next;
     walk->next = NULL;
-    while (walk->stack) {
-        while (walk->stack->turn == RIGHT) {
-            if (charClassStackPop(walk) == NULL) {
-                return current;
-            }
-        }
-        if (walk->stack->turn == LEFT) {
-            walk->next = walk->stack->cc;
-            walk->stack->turn = SELF;
-            return current;
-        }
+    if (walk->turn == SELF) {
         if (current->right) {
-            walk->stack->turn = RIGHT;
+            walk->turn = RIGHT;
             findLeftMost(current->right,walk);
             return current;
         }
+    }
+    while (walk->stack) {
+        walk->next = walk->stack->cc;
         charClassStackPop(walk);
-    }
+        if (walk->turn == LEFT) {
+            walk->turn = SELF;
+            return current;
+        }
+    } 
+    walk->next = NULL;
     return current;
 }