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

recipe_engine/depgraph.py

Index: recipe_engine/depgraph.py
diff --git a/recipe_engine/depgraph.py b/recipe_engine/depgraph.py
index efd2022e991620d7a271e3734e874033eff4a720..91a1f2ffb0d06d18036d55a54d80fa67d8b02622 100644
--- a/recipe_engine/depgraph.py
+++ b/recipe_engine/depgraph.py
@@ -4,6 +4,9 @@
 
 from __future__ import print_function
 
+import argparse
+import sys
+
 from . import loader
 
 
@@ -17,25 +20,53 @@ _GRAPH_FOOTER = """}
 """
 
 
-def main(universe, own_package, ignore_packages, stdout, recipe_filter):
+def add_subparser(parser):
+  depgraph_p = parser.add_parser(
+      'depgraph',
+      description=(
+          'Produce graph of recipe and recipe module dependencies. Example: '
+          './recipes.py --package infra/config/recipes.cfg depgraph | tred | '
+          'dot -Tpdf > graph.pdf'))
+  depgraph_p.add_argument(
+      '--output', type=argparse.FileType('w'), default=sys.stdout,
+      help='The file to write output to')
+  depgraph_p.add_argument(
+      '--ignore-package', action='append', default=[],
+      dest='ignore_packages',
+      help='Ignore a recipe package (e.g. recipe_engine). Can be passed '
+           'multiple times')
+  depgraph_p.add_argument(
+      '--recipe-filter', default='',
+      help='A recipe substring to examine. If present, the depgraph will '
+           'include a recipe section containing recipes whose names contain '
+           'this substring. It will also filter all nodes of the graph to only '
+           'include modules touched by the filtered recipes.')
+
+  depgraph_p.set_defaults(command='depgraph', func=main)
+
+
+def main(package_deps, args):
+  universe = loader.RecipeUniverse(package_deps, args.package)
+  own_package = package_deps.root_package
+
   module_to_package = {}
 
   # All deps maps a tuple of (is_recipe, id) to deps (list of ids). is_recipe is
   # a boolean, all ids are strings.
   all_deps = {}
   for package, module_name in universe.loop_over_recipe_modules():
-    if package in ignore_packages:
+    if package in args.ignore_packages:
       continue
     mod = universe.load(package, module_name)
 
     all_deps[(False, mod.NAME)] = mod.LOADED_DEPS
     module_to_package[mod.NAME] = package.name
 
-  if recipe_filter:
+  if args.recipe_filter:
     recipe_to_package = {}
     universe_view = loader.UniverseView(universe, own_package)
     for _, recipe_name in universe_view.loop_over_recipes():
-      if recipe_filter not in recipe_name:
+      if args.recipe_filter not in recipe_name:
         continue
 
       recipe = universe_view.load_recipe(recipe_name)
@@ -72,7 +103,7 @@ def main(universe, own_package, ignore_packages, stdout, recipe_filter):
           if r_name in recipe_names}
 
 
-  print(_GRAPH_HEADER, file=stdout)
+  print(_GRAPH_HEADER, file=args.output)
   edges = []
   for (is_recipe, name), deps in all_deps.items():
     for dep in deps:
@@ -82,33 +113,33 @@ def main(universe, own_package, ignore_packages, stdout, recipe_filter):
     (is_recipe, first_name), second_name = edge
 
     if not is_recipe:
-      if module_to_package[first_name] in ignore_packages:
+      if module_to_package[first_name] in args.ignore_packages:
         continue
     else:
-      if recipe_to_package[first_name] in ignore_packages:
+      if recipe_to_package[first_name] in args.ignore_packages:
         continue
       first_name = 'recipe ' + first_name
 
-    if module_to_package[second_name] in ignore_packages:
+    if module_to_package[second_name] in args.ignore_packages:
       continue
 
-    print('  "%s" -> "%s"' % (first_name, second_name), file=stdout)
+    print('  "%s" -> "%s"' % (first_name, second_name), file=args.output)
 
   packages = {}
   for module, package in module_to_package.iteritems():
     packages.setdefault(package, []).append(module)
   for package, modules in packages.iteritems():
-    if package in ignore_packages:
+    if package in args.ignore_packages:
       continue
     # The "cluster_" prefix has magic meaning for graphviz and makes it
     # draw a box around the subgraph.
     print('  subgraph "cluster_%s" { label="%s"; %s; }' % (
-        package, package, '; '.join(modules)), file=stdout)
+        package, package, '; '.join(modules)), file=args.output)
 
-  if recipe_filter and recipe_to_package:
+  if args.recipe_filter and recipe_to_package:
     recipe_names = [
         '"recipe %s"' % name for name in recipe_to_package.keys()]
     print('  subgraph "cluster_recipes" { label="recipes"; %s; }' % (
-        '; '.join(recipe_names)), file=stdout)
+        '; '.join(recipe_names)), file=args.output)
 
-  print(_GRAPH_FOOTER, file=stdout)
+  print(_GRAPH_FOOTER, file=args.output)