Make expr[:ender] equivalent to expr[...:ender]

3 files changed, 54 insertions, 13 deletions

diff --git a/CHANGES b/CHANGES
index ac542a3..3074d6f 100644
--- a/CHANGES
+++ b/CHANGES
@@ -4,13 +4,14 @@ Change Log
 
 Version 3.0.10 - (in development)
 ---------------------------------
-- Extended `expr[]` notation to accept a slice, indicating a `stop_on`
+- Extended `expr[]` notation for repetition of expr to accept a
+  slice, where the slice's stop value indicates a `stop_on`
   expression:
 
       test = "BEGIN aaa bbb ccc END"
       BEGIN, END = map(Keyword, "BEGIN END".split())
       body_word = Word(alphas)
-      expr = BEGIN + Group(body_word[...: END]) + END
+      expr = BEGIN + Group(body_word[:END]) + END
       print(expr.parse_string(test).as_list())
 
   Prints:
diff --git a/pyparsing/core.py b/pyparsing/core.py
index 4638d19..a806f5b 100644
--- a/pyparsing/core.py
+++ b/pyparsing/core.py
@@ -1651,15 +1651,17 @@ class ParserElement(ABC):
         stop_on = NoMatch()
         if isinstance(key, slice):
             key, stop_on = key.start, key.stop
+            if key is None:
+                key = ...
             stop_on_defined = True
         elif isinstance(key, tuple) and isinstance(key[-1], slice):
             key, stop_on = (key[0], key[1].start), key[1].stop
             stop_on_defined = True
 
         # convert single arg keys to tuples
+        if isinstance(key, str_type):
+            key = (key,)
         try:
-            if isinstance(key, str_type):
-                key = (key,)
             iter(key)
         except TypeError:
             key = (key, key)
diff --git a/tests/test_unit.py b/tests/test_unit.py
index c070c52..b9c8111 100644
--- a/tests/test_unit.py
+++ b/tests/test_unit.py
@@ -5729,13 +5729,28 @@ class Test02_WithoutPackrat(ppt.TestParseResultsAsserts, TestCase):
             )
 
             expr = BEGIN + body_word[1, ...].stopOn(ender) + END
-            self.assertParseAndCheckList(expr, test, test.split(), "Did not successfully stop on ending expression %r" % ender)
+            self.assertParseAndCheckList(
+                expr,
+                test,
+                test.split(),
+                "Did not successfully stop on ending expression %r" % ender,
+            )
 
-            expr = BEGIN + body_word[1, ...: ender] + END
-            self.assertParseAndCheckList(expr, test, test.split(), "Did not successfully stop on ending expression %r" % ender)
+            expr = BEGIN + body_word[1, ...:ender] + END
+            self.assertParseAndCheckList(
+                expr,
+                test,
+                test.split(),
+                "Did not successfully stop on ending expression %r" % ender,
+            )
 
-            expr = BEGIN + body_word[(1, ...): ender] + END
-            self.assertParseAndCheckList(expr, test, test.split(), "Did not successfully stop on ending expression %r" % ender)
+            expr = BEGIN + body_word[(1, ...):ender] + END
+            self.assertParseAndCheckList(
+                expr,
+                test,
+                test.split(),
+                "Did not successfully stop on ending expression %r" % ender,
+            )
 
         number = pp.Word(pp.nums + ",.()").setName("number with optional commas")
         parser = pp.OneOrMore(pp.Word(pp.alphanums + "-/."), stopOn=number)(
@@ -5755,13 +5770,36 @@ class Test02_WithoutPackrat(ppt.TestParseResultsAsserts, TestCase):
         body_word = pp.Word(pp.alphas).setName("word")
         for ender in (END, "END", pp.CaselessKeyword("END")):
             expr = BEGIN + pp.ZeroOrMore(body_word, stopOn=ender) + END
-            self.assertParseAndCheckList(expr, test, test.split(), "Did not successfully stop on ending expression %r" % ender)
+            self.assertParseAndCheckList(
+                expr,
+                test,
+                test.split(),
+                "Did not successfully stop on ending expression %r" % ender,
+            )
 
             expr = BEGIN + body_word[...].stopOn(ender) + END
-            self.assertParseAndCheckList(expr, test, test.split(), "Did not successfully stop on ending expression %r" % ender)
+            self.assertParseAndCheckList(
+                expr,
+                test,
+                test.split(),
+                "Did not successfully stop on ending expression %r" % ender,
+            )
+
+            expr = BEGIN + body_word[...:ender] + END
+            self.assertParseAndCheckList(
+                expr,
+                test,
+                test.split(),
+                "Did not successfully stop on ending expression %r" % ender,
+            )
 
-            expr = BEGIN + body_word[...: ender] + END
-            self.assertParseAndCheckList(expr, test, test.split(), "Did not successfully stop on ending expression %r" % ender)
+            expr = BEGIN + body_word[:ender] + END
+            self.assertParseAndCheckList(
+                expr,
+                test,
+                test.split(),
+                "Did not successfully stop on ending expression %r" % ender,
+            )
 
     def testNestedAsDict(self):