# HG changeset patch
# User Bryan O'Sullivan <bos@serpentine.com>
# Date 2016-01-08 03:45:03
# Node ID e70c97cc9243c6ea0acc0cbcc77e173c651e559a
# Parent  fb0cc863d172044a978ff01d104cddbdc15eca1d

config: add hasconfig method and supporting plumbing

We add the hasconfig method to make it possible to distinguish between a
config value that was never supplied and one that is empty.

diff --git a/mercurial/config.py b/mercurial/config.py
--- a/mercurial/config.py
+++ b/mercurial/config.py
@@ -30,6 +30,8 @@ class config(object):
         return config(self)
     def __contains__(self, section):
         return section in self._data
+    def hasitem(self, section, item):
+        return item in self._data.get(section, {})
     def __getitem__(self, section):
         return self._data.get(section, {})
     def __iter__(self):
diff --git a/mercurial/ui.py b/mercurial/ui.py
--- a/mercurial/ui.py
+++ b/mercurial/ui.py
@@ -507,6 +507,9 @@ class ui(object):
                 result = default or []
         return result
 
+    def hasconfig(self, section, name, untrusted=False):
+        return self._data(untrusted).hasitem(section, name)
+
     def has_section(self, section, untrusted=False):
         '''tell whether section exists in config.'''
         return section in self._data(untrusted)