formatter: move most of template option helper to formatter

We want to share this function between formatter and cmdutils. It
doesn't belong in templater because it imports knowledge of ui layers
that shouldn't be there. We'd prefer cmdutil to layer on the formatter
rather than vice-versa. Since the formatter is the handler for -T
options for all non-log commands, let's move the helper there. We
leave the bits specific to the old --style option behind.

mercurial/cmdutil.py

@@ -14,6 +14,7 b' import context, repair, graphmod, revset'
 import changelog
 import bookmarks
 import encoding
+import formatter
 import crecord as crecordmod
 import lock as lockmod
 
@@ -1493,40 +1494,7 b' def gettemplate(ui, tmpl, style):'
     if not tmpl:
         return None, None
 
-    # looks like a literal template?
-    if '{' in tmpl:
-        return tmpl, None
-
-    # perhaps a stock style?
-    if not os.path.split(tmpl)[0]:
-        mapname = (templater.templatepath('map-cmdline.' + tmpl)
-                   or templater.templatepath(tmpl))
-        if mapname and os.path.isfile(mapname):
-            return None, mapname
-
-    # perhaps it's a reference to [templates]
-    t = ui.config('templates', tmpl)
-    if t:
-        try:
-            tmpl = templater.unquotestring(t)
-        except SyntaxError:
-            tmpl = t
-        return tmpl, None
-
-    if tmpl == 'list':
-        ui.write(_("available styles: %s\n") % templater.stylelist())
-        raise util.Abort(_("specify a template"))
-
-    # perhaps it's a path to a map or a template
-    if ('/' in tmpl or '\\' in tmpl) and os.path.isfile(tmpl):
-        # is it a mapfile for a style?
-        if os.path.basename(tmpl).startswith("map-"):
-            return None, os.path.realpath(tmpl)
-        tmpl = open(tmpl).read()
-        return tmpl, None
-
-    # constant string?
-    return tmpl, None
+    return formatter.lookuptemplate(ui, 'changeset', tmpl)
 
 def show_changeset(ui, repo, opts, buffered=False):
     """show one changeset using template or regular display.

mercurial/formatter.py

@@ -9,6 +9,8 b' import cPickle'
 from node import hex, short
 from i18n import _
 import encoding, util
+import templater
+import os
 
 class baseformatter(object):
     def __init__(self, ui, topic, opts):
@@ -133,6 +135,42 b' class jsonformatter(baseformatter):'
         baseformatter.end(self)
         self._ui.write("\n]\n")
 
+def lookuptemplate(ui, topic, tmpl):
+    # looks like a literal template?
+    if '{' in tmpl:
+        return tmpl, None
+
+    # perhaps a stock style?
+    if not os.path.split(tmpl)[0]:
+        mapname = (templater.templatepath('map-cmdline.' + tmpl)
+                   or templater.templatepath(tmpl))
+        if mapname and os.path.isfile(mapname):
+            return None, mapname
+
+    # perhaps it's a reference to [templates]
+    t = ui.config('templates', tmpl)
+    if t:
+        try:
+            tmpl = templater.unquotestring(t)
+        except SyntaxError:
+            tmpl = t
+        return tmpl, None
+
+    if tmpl == 'list':
+        ui.write(_("available styles: %s\n") % templater.stylelist())
+        raise util.Abort(_("specify a template"))
+
+    # perhaps it's a path to a map or a template
+    if ('/' in tmpl or '\\' in tmpl) and os.path.isfile(tmpl):
+        # is it a mapfile for a style?
+        if os.path.basename(tmpl).startswith("map-"):
+            return None, os.path.realpath(tmpl)
+        tmpl = open(tmpl).read()
+        return tmpl, None
+
+    # constant string?
+    return tmpl, None
+
 def formatter(ui, topic, opts):
     template = opts.get("template", "")
     if template == "json":