util: introduce datapath for getting the location of supporting data files

util: introduce datapath for getting the location of supporting data files

templates, help and locale data is normally stored as sub folders in the
directory containing the source of the mercurial module. In a frozen build they
live as sub folders next to 'hg.exe' and 'library.zip'.

These different kind of data were handled in different ways. Unify that by
introducing util.datapath. The value is computed from the environment and is
always used, so we just calculate the value on module load.

--- a/mercurial/help.py	Sun Sep 28 16:57:06 2014 +0200
+++ b/mercurial/help.py	Sun Sep 28 16:57:06 2014 +0200
@@ -6,7 +6,7 @@
 # GNU General Public License version 2 or any later version.
 
 from i18n import gettext, _
-import itertools, sys, os
+import itertools, os
 import error
 import extensions, revset, fileset, templatekw, templatefilters, filemerge
 import encoding, util, minirst
@@ -129,14 +129,8 @@
     """Return a delayed loader for help/topic.txt."""
 
     def loader():
-        if util.mainfrozen():
-            module = sys.executable
-        else:
-            module = __file__
-        base = os.path.dirname(module)
-
         for dir in ('.', '..'):
-            docdir = os.path.join(base, dir, 'help')
+            docdir = os.path.join(util.datapath, dir, 'help')
             if os.path.isdir(docdir):
                 break
 

--- a/mercurial/templater.py	Sun Sep 28 16:57:06 2014 +0200
+++ b/mercurial/templater.py	Sun Sep 28 16:57:06 2014 +0200
@@ -6,7 +6,7 @@
 # GNU General Public License version 2 or any later version.
 
 from i18n import _
-import sys, os, re
+import os, re
 import util, config, templatefilters, templatekw, parser, error
 import revset as revsetmod
 import types
@@ -715,17 +715,12 @@
     returns None if not found.'''
     normpaths = []
 
-    # executable version (py2exe) doesn't support __file__
-    if util.mainfrozen():
-        module = sys.executable
-    else:
-        module = __file__
     for f in path:
         if f.startswith('/'):
             p = f
         else:
             fl = f.split('/')
-            p = os.path.join(os.path.dirname(module), *fl)
+            p = os.path.join(util.datapath, *fl)
         if name:
             p = os.path.join(p, name)
         if name and os.path.exists(p):

--- a/mercurial/util.py	Sun Sep 28 16:57:06 2014 +0200
+++ b/mercurial/util.py	Sun Sep 28 16:57:06 2014 +0200
@@ -460,6 +460,13 @@
             safehasattr(sys, "importers") or # old py2exe
             imp.is_frozen("__main__")) # tools/freeze
 
+# the location of data files matching the source code
+if mainfrozen():
+    # executable version (py2exe) doesn't support __file__
+    datapath = os.path.dirname(sys.executable)
+else:
+    datapath = os.path.dirname(__file__)
+
 _hgexecutable = None
 
 def hgexecutable():