From 6a6c1535ea98e2f84a479cd6873dee553fee92c3 Mon Sep 17 00:00:00 2001
From: Paul McGuire <ptmcg@austin.rr.com>
Date: Sat, 29 Sep 2018 13:55:54 -0500
Subject: tighten up error checking in Regex.sub()

---
 pyparsing.py | 18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

(limited to 'pyparsing.py')

diff --git a/pyparsing.py b/pyparsing.py
index cdbf398..3ea7660 100644
--- a/pyparsing.py
+++ b/pyparsing.py
@@ -2846,7 +2846,23 @@ class Regex(Token):
         Return Regex with an attached parse action to transform the parsed
         result as if called using C{re.sub(expr, repl, string)}.
         """
-        return self.addParseAction(lambda s, l, t: self.re.sub(repl, t[0]))
+        if self.asGroupList:
+            warnings.warn("cannot use sub() with Regex(asGroupList=True)", 
+                           SyntaxWarning, stacklevel=2)
+            raise SyntaxError()
+
+        if self.asMatch and callable(repl):
+            warnings.warn("cannot use sub() with a callable with Regex(asMatch=True)", 
+                           SyntaxWarning, stacklevel=2)
+            raise SyntaxError()        
+
+        if self.asMatch:
+            def pa(tokens):
+                return tokens[0].expand(repl)
+        else:
+            def pa(tokens):
+                return self.re.sub(repl, tokens[0])
+        return self.addParseAction(pa)
 
 class QuotedString(Token):
     r"""
-- 
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