[Findit] Factoring the gitiles (etc) stuff out into its own directory

appengine/findit/common/deps_parser.py

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 """ This is an incomplete implementation of a DEPS file parser.
 
 Now only keys 'vars', 'deps', and 'deps_os' are taken care of.
 
 TODO: support strict mode, 'target_os', 'target_os_only', 'use_relative_paths',
       both forms of recursion, both forms of hooks, 'allowed_hosts', etc.
@@ skipping 147 matching lines @@
   def _NormalizeTargetOSName(target_os):
     os_name = target_os.lower()
     assert os_name in DEPS_OS_CHOICES, 'Target OS "%s" is invalid' % os_name
     return os_name
 
   if 'all' in target_os_list:
     target_os_list = DEPS_OS_CHOICES
   else:
     target_os_list = [_NormalizeTargetOSName(name) for name in target_os_list]
 
+  # TODO(wrengr): why not just pass the deps_loader to a method on
+  # root_dep which returns the deps_content? What's the point in threading
+  # things through like this?
   deps_content = deps_loader.Load(
       root_dep.deps_repo_url, root_dep.deps_repo_revision, root_dep.deps_file)
   deps, deps_os = ParseDEPSContent(deps_content, keys=('deps', 'deps_os'))
 
   all_deps = MergeWithOsDeps(deps, deps_os, target_os_list)
 
+  # TODO(wrengr): why close over root_dep to get at deps_file, but then
+  # force callsers to patch things up after the fact with SetParent? Why
+  # not just call SetParent ourselves?
   def _CreateDependency(path, repo_info):
     if not path.endswith('/'):
       path = path + '/'
 
     repo_url = repo_info
     revision = None
     if '@' in repo_info:
       # The dependency is pinned to some revision.
       repo_url, revision = repo_info.split('@')
 
     return dependency.Dependency(
         path, repo_url, revision, root_dep.deps_file)
 
   for path, repo_info in all_deps.iteritems():
     if repo_info is None:
       # The dependency is not needed for all the target os.
       continue
 
+    # TODO(wrengr): why are we doing this? i.e., it looks like we're
+    # allocating a dependency.Dependency object and then just dropping it
+    # on the floor. To what end?
     sub_dep = _CreateDependency(path, repo_info)
     sub_dep.SetParent(root_dep)
 
     # TODO: go into the next level of dependency if needed.