fix #1955 for Python

runtime/Python2/src/antlr4/atn/ParserATNSimulator.py

@@ -1145,11 +1145,6 @@ def closure_(self, config, configs, closureBusy, collectPredicates, fullCtx, dep
             continueCollecting = collectPredicates and not isinstance(t, ActionTransition)
             c = self.getEpsilonTarget(config, t, continueCollecting, depth == 0, fullCtx, treatEofAsEpsilon)
             if c is not None:
-                if not t.isEpsilon:
-                    if c in closureBusy:
-                        # avoid infinite recursion for EOF* and EOF+
-                        continue
-                    closureBusy.add(c)
                 newDepth = depth
                 if isinstance( config.state, RuleStopState):
                     # target fell off end of rule; mark resulting c as having dipped into outer context
@@ -1158,23 +1153,28 @@ def closure_(self, config, configs, closureBusy, collectPredicates, fullCtx, dep
                     # come in handy and we avoid evaluating context dependent
                     # preds if this is > 0.
 
-                    if c in closureBusy:
-                        # avoid infinite recursion for right-recursive rules
-                        continue
-                    closureBusy.add(c)
-
                     if self._dfa is not None and self._dfa.precedenceDfa:
                         if t.outermostPrecedenceReturn == self._dfa.atnStartState.ruleIndex:
                             c.precedenceFilterSuppressed = True
                     c.reachesIntoOuterContext += 1
+                    if c in closureBusy:
+                        # avoid infinite recursion for right-recursive rules
+                        continue
+                    closureBusy.add(c)
                     configs.dipsIntoOuterContext = True # TODO: can remove? only care when we add to set per middle of this method
                     newDepth -= 1
                     if ParserATNSimulator.debug:
                         print("dips into outer ctx: " + str(c))
-                elif isinstance(t, RuleTransition):
-                    # latch when newDepth goes negative - once we step out of the entry context we can't return
-                    if newDepth >= 0:
-                        newDepth += 1
+                else:
+                    if not t.isEpsilon:
+                        if c in closureBusy:
+                            # avoid infinite recursion for EOF* and EOF+
+                            continue
+                        closureBusy.add(c)
+                    if isinstance(t, RuleTransition):
+                        # latch when newDepth goes negative - once we step out of the entry context we can't return
+                        if newDepth >= 0:
+                            newDepth += 1
 
                 self.closureCheckingStopState(c, configs, closureBusy, continueCollecting, fullCtx, newDepth, treatEofAsEpsilon)
 

runtime/Python3/src/antlr4/atn/ParserATNSimulator.py

@@ -1150,36 +1150,35 @@ def closure_(self, config:ATNConfig, configs:ATNConfigSet, closureBusy:set, coll
             continueCollecting = collectPredicates and not isinstance(t, ActionTransition)
             c = self.getEpsilonTarget(config, t, continueCollecting, depth == 0, fullCtx, treatEofAsEpsilon)
             if c is not None:
-                if not t.isEpsilon:
-                    if c in closureBusy:
-                        # avoid infinite recursion for EOF* and EOF+
-                        continue
-                    closureBusy.add(c)
                 newDepth = depth
                 if isinstance( config.state, RuleStopState):
                     # target fell off end of rule; mark resulting c as having dipped into outer context
                     # We can't get here if incoming config was rule stop and we had context
                     # track how far we dip into outer context.  Might
                     # come in handy and we avoid evaluating context dependent
                     # preds if this is > 0.
-
-                    if c in closureBusy:
-                        # avoid infinite recursion for right-recursive rules
-                        continue
-                    closureBusy.add(c)
-
                     if self._dfa is not None and self._dfa.precedenceDfa:
                         if t.outermostPrecedenceReturn == self._dfa.atnStartState.ruleIndex:
                             c.precedenceFilterSuppressed = True
                     c.reachesIntoOuterContext += 1
+                    if c in closureBusy:
+                        # avoid infinite recursion for right-recursive rules
+                        continue
+                    closureBusy.add(c)
                     configs.dipsIntoOuterContext = True # TODO: can remove? only care when we add to set per middle of this method
                     newDepth -= 1
                     if ParserATNSimulator.debug:
                         print("dips into outer ctx: " + str(c))
-                elif isinstance(t, RuleTransition):
-                    # latch when newDepth goes negative - once we step out of the entry context we can't return
-                    if newDepth >= 0:
-                        newDepth += 1
+                else:
+                    if not t.isEpsilon:
+                        if c in closureBusy:
+                            # avoid infinite recursion for EOF* and EOF+
+                            continue
+                        closureBusy.add(c)
+                    if isinstance(t, RuleTransition):
+                        # latch when newDepth goes negative - once we step out of the entry context we can't return
+                        if newDepth >= 0:
+                            newDepth += 1
 
                 self.closureCheckingStopState(c, configs, closureBusy, continueCollecting, fullCtx, newDepth, treatEofAsEpsilon)