diff options
| -rw-r--r-- | CHANGES | 4 | ||||
| -rw-r--r-- | pyparsing.py | 10 | ||||
| -rw-r--r-- | unitTests.py | 15 |
3 files changed, 23 insertions, 6 deletions
@@ -8,7 +8,9 @@ Version 2.4.3 - September, 2019 create a recursion error at parser definition time. Thanks to Michael Clerx for the assist. (Addresses issue #123) -- Backport from pyparsing 3.0.0 of __diag__.enable_all_warnings(). +- Backports from pyparsing 3.0.0: + . __diag__.enable_all_warnings(). + . Fixed bug in PrecededBy which caused infinite recursion, issue #127 Version 2.4.2 - July, 2019 diff --git a/pyparsing.py b/pyparsing.py index ffbe78b..17e0bdf 100644 --- a/pyparsing.py +++ b/pyparsing.py @@ -4570,6 +4570,7 @@ class PrecededBy(ParseElementEnhance): self.retreat = retreat self.errmsg = "not preceded by " + str(expr) self.skipWhitespace = False + self.parseAction.append(lambda s, l, t: t.__delitem__(slice(None, None))) def parseImpl(self, instring, loc=0, doActions=True): if self.exact: @@ -4580,19 +4581,18 @@ class PrecededBy(ParseElementEnhance): else: # retreat specified a maximum lookbehind window, iterate test_expr = self.expr + StringEnd() - instring_slice = instring[:loc] + instring_slice = instring[max(0, loc - self.retreat):loc] last_expr = ParseException(instring, loc, self.errmsg) - for offset in range(1, min(loc, self.retreat + 1)): + for offset in range(1, min(loc, self.retreat + 1)+1): try: - _, ret = test_expr._parse(instring_slice, loc - offset) + # print('trying', offset, instring_slice, repr(instring_slice[loc - offset:])) + _, ret = test_expr._parse(instring_slice, len(instring_slice) - offset) except ParseBaseException as pbe: last_expr = pbe else: break else: raise last_expr - # return empty list of tokens, but preserve any defined results names - del ret[:] return loc, ret diff --git a/unitTests.py b/unitTests.py index 40dd58b..cfc4e90 100644 --- a/unitTests.py +++ b/unitTests.py @@ -2046,6 +2046,21 @@ class PrecededByTest(ParseTestCase): "Erroneous named results for {0}: expected {1}, got {2}".format(expr, expected_dict, result.asDict())) + # infinite loop test - from Issue #127 + string_test = 'notworking' + # negs = pp.Or(['not', 'un'])('negs') + negs_pb = pp.PrecededBy('not', retreat=100)('negs_lb') + # negs_pb = pp.PrecededBy(negs, retreat=100)('negs_lb') + pattern = pp.Group(negs_pb + pp.Literal('working'))('main') + + results = pattern.searchString(string_test) + try: + print_(results.dump()) + except RecursionError: + self.assertTrue(False, "got maximum excursion limit exception") + else: + self.assertTrue(True, "got maximum excursion limit exception") + class CountedArrayTest(ParseTestCase): def runTest(self): |