Micro-optimize parse_val_and_cond()

Saves a source line as well as some bytecode.

Tuple evaluation is guaranteed to be from left to right:
https://docs.python.org/2/reference/expressions.html#evaluation-order

1 files changed, 4 insertions, 5 deletions

diff --git a/kconfiglib.py b/kconfiglib.py
index b279f57..23afdf5 100644
--- a/kconfiglib.py
+++ b/kconfiglib.py
@@ -804,11 +804,10 @@ class Config(object):
             """Parses '<expr1> if <expr2>' constructs, where the 'if' part is
             optional. Returns a tuple containing the parsed expressions, with
             None as the second element if the 'if' part is missing."""
-            val = self._parse_expr(tokens, stmt, line, filename, linenr, False)
-            if tokens.check(T_IF):
-                return (val, self._parse_expr(tokens, stmt, line, filename,
-                                              linenr))
-            return (val, None)
+            return (self._parse_expr(tokens, stmt, line, filename, linenr,
+                                     False),
+                    self._parse_expr(tokens, stmt, line, filename, linenr)
+                    if tokens.check(T_IF) else None)
 
         # In case the symbol is defined in multiple locations, we need to
         # remember what prompts, defaults, and selects are new for this