Small perf optimization for expr | "" mapping to Optional(expr)

pyparsing · Mar 29, 2023 · 05d894d · 05d894d
1 parent 14067a9
commit 05d894d
Showing 1 changed file with 3 additions and 0 deletions.
diff --git a/pyparsing/core.py b/pyparsing/core.py
@@ -1552,6 +1552,9 @@ def __or__(self, other) -> "ParserElement":
             return _PendingSkip(self, must_skip=True)
 
         if isinstance(other, str_type):
+            # `expr | ""` is equivalent to `Opt(expr)`
+            if other == "":
+                return Opt(self)
             other = self._literalStringClass(other)
         if not isinstance(other, ParserElement):
             return NotImplemented