Allow multiplying an expr by 0 or (0,0)

3 files changed, 25 insertions, 16 deletions

diff --git a/pyparsing/core.py b/pyparsing/core.py
index a8d1f32..17428bf 100644
--- a/pyparsing/core.py
+++ b/pyparsing/core.py
@@ -1386,7 +1386,7 @@ class ParserElement(ABC):
                 "second tuple value must be greater or equal to first tuple value"
             )
         if minElements == optElements == 0:
-            raise ValueError("cannot multiply ParserElement by 0 or (0, 0)")
+            return And([])
 
         if optElements:
 
@@ -3629,10 +3629,12 @@ class And(ParseExpression):
             exprs[:] = tmp
         super().__init__(exprs, savelist)
         self.mayReturnEmpty = all(e.mayReturnEmpty for e in self.exprs)
-        self.set_whitespace_chars(
-            self.exprs[0].whiteChars, copy_defaults=self.exprs[0].copyDefaultWhiteChars
-        )
-        self.skipWhitespace = self.exprs[0].skipWhitespace
+        if self.exprs:
+            self.set_whitespace_chars(
+                self.exprs[0].whiteChars,
+                copy_defaults=self.exprs[0].copyDefaultWhiteChars,
+            )
+            self.skipWhitespace = self.exprs[0].skipWhitespace
         self.callPreparse = True
 
     def streamline(self):
diff --git a/pyparsing/helpers.py b/pyparsing/helpers.py
index 42510b8..251092a 100644
--- a/pyparsing/helpers.py
+++ b/pyparsing/helpers.py
@@ -92,11 +92,12 @@ def counted_array(
         # - type: 'bool'
     """
     intExpr = intExpr or int_expr
-    arrayExpr = Forward()
+    array_expr = Forward()
 
-    def countFieldParseAction(s, l, t):
+    def count_field_parse_action(s, l, t):
+        nonlocal array_expr
         n = t[0]
-        arrayExpr << (And([expr] * n) if n else empty)
+        array_expr <<= (expr * n) if n else Empty()
         # clear list contents, but keep any named results
         del t[:]
 
@@ -105,8 +106,8 @@ def counted_array(
     else:
         intExpr = intExpr.copy()
     intExpr.set_name("arrayLen")
-    intExpr.add_parse_action(countFieldParseAction, callDuringTry=True)
-    return (intExpr + arrayExpr).set_name("(len) " + str(expr) + "...")
+    intExpr.add_parse_action(count_field_parse_action, call_during_try=True)
+    return (intExpr + array_expr).set_name("(len) " + str(expr) + "...")
 
 
 def match_previous_literal(expr: ParserElement) -> ParserElement:
diff --git a/tests/test_unit.py b/tests/test_unit.py
index 6df6002..1ad8f82 100644
--- a/tests/test_unit.py
+++ b/tests/test_unit.py
@@ -2477,12 +2477,6 @@ class Test02_WithoutPackrat(ppt.TestParseResultsAsserts, TestCase):
     def testParserElementMulOperatorWithTuples(self):
         """test ParserElement "*" with various tuples"""
 
-        # ParserElement * (0, 0)
-        with self.assertRaises(
-            ValueError, msg="ParserElement * (0,0) should raise error"
-        ):
-            expr = pp.Word(pp.alphas)("first") + pp.Word(pp.nums)("second*") * (0, 0)
-
         # ParserElement * (None, n)
         expr = pp.Word(pp.alphas)("first") + pp.Word(pp.nums)("second*") * (None, 3)
 
@@ -2556,6 +2550,18 @@ class Test02_WithoutPackrat(ppt.TestParseResultsAsserts, TestCase):
         ):
             expr = pp.Word(pp.alphas)("first") + pp.Word(pp.nums)("second") * ("2", "3")
 
+    def testParserElementMulByZero(self):
+        alpwd = pp.Word(pp.alphas)
+        numwd = pp.Word(pp.nums)
+
+        test_string = "abd def ghi jkl"
+
+        parser = alpwd * 2 + numwd * 0 + alpwd * 2
+        self.assertParseAndCheckList(parser, test_string, expected_list=test_string.split())
+
+        parser = alpwd * 2 + numwd * (0, 0) + alpwd * 2
+        self.assertParseAndCheckList(parser, test_string, expected_list=test_string.split())
+
     def testParserElementMulOperatorWithOtherTypes(self):
         """test the overridden "*" operator with other data types"""