Fixed PEP-8 compatibility logic in WordStart and WordEnd (Issue #346)

CHANGES

@@ -7,6 +7,10 @@ Version 3.0.7 -
 - Fixed bug #345, in which delimitedList changed expressions in place
   using expr.streamline(). Reported by Kim Gräsman, thanks!
 
+- Fixed bug #346, when a string of word characters was passed to WordStart
+  or WordEnd instead of just taking the default value. Originally posted
+  as a question by Parag on StackOverflow, good catch!
+
 - Added optional "min" and "max" arguments to `delimited_list`. PR
   submitted by Marius, thanks!
 

pyparsing/__init__.py

@@ -126,7 +126,7 @@ def __repr__(self):
 
 
 __version_info__ = version_info(3, 0, 7, "final", 0)
-__version_time__ = "15 Dec 2021 05:56 UTC"
+__version_time__ = "18 Dec 2021 23:16 UTC"
 __version__ = __version_info__.__version__
 __versionTime__ = __version_time__
 __author__ = "Paul McGuire <ptmcg.gm+pyparsing@gmail.com>"

pyparsing/core.py

@@ -3521,7 +3521,7 @@ class WordStart(PositionToken):
     """
 
     def __init__(self, word_chars: str = printables, *, wordChars: str = printables):
-        wordChars = word_chars if wordChars != printables else wordChars
+        wordChars = word_chars if wordChars == printables else wordChars
         super().__init__()
         self.wordChars = set(wordChars)
         self.errmsg = "Not at the start of a word"
@@ -3546,7 +3546,7 @@ class WordEnd(PositionToken):
     """
 
     def __init__(self, word_chars: str = printables, *, wordChars: str = printables):
-        wordChars = word_chars if wordChars != printables else wordChars
+        wordChars = word_chars if wordChars == printables else wordChars
         super().__init__()
         self.wordChars = set(wordChars)
         self.skipWhitespace = False

tests/test_unit.py

@@ -4913,6 +4913,24 @@ def testWordBoundaryExpressions(self):
                 ),
             )
 
+    def testWordBoundaryExpressions2(self):
+        from itertools import product
+        ws1 = pp.WordStart(pp.alphas)
+        ws2 = pp.WordStart(wordChars=pp.alphas)
+        ws3 = pp.WordStart(word_chars=pp.alphas)
+        we1 = pp.WordEnd(pp.alphas)
+        we2 = pp.WordEnd(wordChars=pp.alphas)
+        we3 = pp.WordEnd(word_chars=pp.alphas)
+
+        for i, (ws, we) in enumerate(product((ws1, ws2, ws3), (we1, we2, we3))):
+            try:
+                expr = ("(" + ws + pp.Word(pp.alphas) + we + ")")
+                expr.parseString("(abc)")
+            except pp.ParseException as pe:
+                self.fail(f"Test {i} failed: {pe}")
+            else:
+                pass
+
     def testRequiredEach(self):
 
         parser = pp.Keyword("bam") & pp.Keyword("boo")