[PATCH 5 of 6] config: give it a mapfile option, for parsing them specially

[Jordi Gutiérrez Hermoso]

# HG changeset patch
# User Jordi Gutiérrez Hermoso <jordigh at octave.org>
# Date 1430344009 14400
#      Wed Apr 29 17:46:49 2015 -0400
# Node ID c06e371d76b759b900b34120d8d3e90a63790660
# Parent  5adc92b85bfe045bfd527d836eccad53a5568e92
config: give it a mapfile option, for parsing them specially

It is desirable to "derive" templates from the provided templates. A
simple way to do this is e.g.

    %include map-cmdline.default

in your own mapfile. Then you only have to redefine a few templates
instead of copying over the whole thing. This %include mechanism
already works for the built-in templates because by default it *only*
looks for files that are in the same directory as the including
mapfile.

With this changeset, config grows an option to optionally add the
templates directory to the %include path.

diff --git a/mercurial/config.py b/mercurial/config.py
--- a/mercurial/config.py
+++ b/mercurial/config.py
@@ -8,12 +8,14 @@
 from i18n import _
 import error, util
 import os, errno
+import templater
 
 class config(object):
-    def __init__(self, data=None):
+    def __init__(self, data=None, mapfile=False):
         self._data = {}
         self._source = {}
         self._unset = []
+        self._mapfile = mapfile
         if data:
             for k in data._data:
                 self._data[k] = data[k].copy()
@@ -110,18 +112,29 @@ class config(object):
                 item = None
                 cont = False
             m = includere.match(l)
-            if m:
-                inc = util.expandpath(m.group(1))
-                base = os.path.dirname(src)
-                inc = os.path.normpath(os.path.join(base, inc))
+            def includefile(inc):
                 if include:
                     try:
                         include(inc, remap=remap, sections=sections)
+                        return True
                     except IOError, inst:
                         if inst.errno != errno.ENOENT:
                             raise error.ParseError(_("cannot include %s (%s)")
                                                    % (inc, inst.strerror),
                                                    "%s:%s" % (src, line))
+                        else:
+                            return False
+            if m:
+                expanded = util.expandpath(m.group(1))
+                base = os.path.dirname(src)
+                inc = os.path.normpath(os.path.join(base, expanded))
+
+                if not includefile(inc) and self._mapfile:
+                    # For template mapfiles, try to include from the
+                    # template directory, after looking in the current
+                    # directory already failed.
+                    includefile(templater.templatepath(expanded))
+
                 continue
             if emptyre.match(l):
                 continue