[Predator] Add ``Project`` class and ``ClassifySuspect`` method to project and component classifier

appengine/findit/libs/gitiles/change_log.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.
 
 from collections import namedtuple
 
 from libs.gitiles.diff import ChangeType
 
 
 # TODO(wrengr): it'd be better to have a class hierarchy here, so we can
@@ skipping 32 matching lines @@
   def FromDict(cls, info):
     return cls(info['change_type'].lower(), info['old_path'], info['new_path'])
 
   def ToDict(self):
     return {
         'change_type': self.change_type,
         'old_path': self.old_path,
         'new_path': self.new_path
     }
 
+  @property
+  def changed_path(self):
+    """Returns the changed path to check when analyzing component or project.
+
+    Except for delete change type, the changed path means the new path after
+    change, for delete type, it is the old path.
+    """
+    # TODO(crbug.com/685884): use component of new path as default. RENAME might
+    # need to return two (old path new path may have different components)
+    if self.change_type == ChangeType.DELETE:
+      return self.old_path
+
+    return self.new_path
+
 
 class Contributor(namedtuple('Contributor', ['name', 'email', 'time'])):
   """A generalization of the "author" and "committer" in Git's terminology."""
   __slots__ = ()
 
 
 class ChangeLog(namedtuple('ChangeLog',
     ['author', 'committer', 'revision', 'commit_position', 'message',
      'touched_files', 'commit_url', 'code_review_url', 'reverted_revision'])):
   """Represents the change log of a revision."""
@@ skipping 45 matching lines @@
 
     return ChangeLog(
         Contributor(info['author']['name'], info['author']['email'],
                     info['author']['time']),
         Contributor(info['committer']['name'], info['committer']['email'],
                     info['committer']['time']),
         info['revision'], info['commit_position'], info['message'],
         touched_files, info['commit_url'], info['code_review_url'],
         info['reverted_revision']
     )