Minor optimization

CHANGES.rst

@@ -3,6 +3,9 @@ Changes
 
 In next release ...
 
+- Minor optimization when rendering translations with a static
+  message id (don't need to test if it's non-empty).
+
 - Fix a bug where a macro could not be used correctly to render a
   translation name.
   (`#419 <https://github.com/malthe/chameleon/issues/419>`_)

src/chameleon/compiler.py

@@ -1492,13 +1492,20 @@ def visit_Translate(self, node):
             msgid = ast.Str(s=node.msgid)
 
         # emit the translation expression
-        body += template(
-            "if msgid: __append(translate("
+        translation = template(
+            "__append(translate("
             "msgid, mapping=mapping, default=default, domain=__i18n_domain, context=__i18n_context, target_language=target_language))",  # noqa:  E501 line too long
             msgid=msgid,
             default=default,
             mapping=mapping)
 
+        if not node.msgid:
+            translation = [ast.If(
+                test=load(msgid), body=translation, orelse=[]
+            )]
+
+        body += translation
+
         # pop away translation block reference
         self._translations.pop()