[recipes.py] move refs arg parsing to its module

recipe_engine/refs.py

 # Copyright 2016 The LUCI Authors. All rights reserved.
 # Use of this source code is governed under the Apache License, Version 2.0
 # that can be found in the LICENSE file.
 
 from __future__ import print_function
 
 from . import loader
 
 
-def main(universe, own_package, modules, transitive):
+def add_subparser(parser):
+  refs_p = parser.add_parser(
+      'refs',
+      description='List places referencing given recipe module(s).')
+  refs_p.add_argument('modules', nargs='+', help='Module(s) to query for')
+  refs_p.add_argument('--transitive', action='store_true',
+                      help='Compute transitive closure of the references')
+
+  refs_p.set_defaults(command='refs', func=main)
+
+
+def main(package_deps, args):
+  universe = loader.RecipeUniverse(package_deps, args.package)
+  own_package = package_deps.root_package
+  modules = args.modules

[dnj, 2017/04/27 16:40:40]

nit: in other CLs, you would have used "args.modules" instead of creating a
local version. Maybe do this consistently?

+  transitive = args.transitive
+
   result_modules = set()
   result_recipes = set()
 
   module_dependencies = {}
 
   for package, module_name in universe.loop_over_recipe_modules():
     mod = universe.load(package, module_name)
     module_dependencies[mod.NAME] = mod.LOADED_DEPS
 
     for module in modules:
@@ skipping 22 matching lines @@
 
   if result_modules:
     print('Modules:')
     for module in sorted(result_modules):
       print('  %s' % module)
 
   if result_recipes:
     print('Recipes:')
     for recipe in sorted(result_recipes):
       print('  %s' % recipe)