Incremental changes towards more efficient refactoring of gclient.py

gclient_scm.py

 # Copyright (c) 2010 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.
 
 """Gclient-specific SCM-specific operations."""
 
 import logging
 import os
 import posixpath
 import re
@@ skipping 37 matching lines @@
           line.startswith(self.working_prefix)):
         self.ReplaceAndPrint(line)
       else:
         print line
 
 
 ### SCM abstraction layer
 
 # Factory Method for SCM wrapper creation
 
-def CreateSCM(url=None, root_dir=None, relpath=None, scm_name='svn'):
-  scm_map = {
+def GetScmName(url):
+  if url:
+    url, _ = gclient_utils.SplitUrlRevision(url)
+    if (url.startswith('git://') or url.startswith('ssh://') or
+        url.endswith('.git')):
+      return 'git'
+    elif (url.startswith('http://') or url.startswith('svn://') or
+          url.startswith('ssh+svn://')):
+      return 'svn'
+  return None
+
+
+def CreateSCM(url, root_dir=None, relpath=None):
+  SCM_MAP = {
     'svn' : SVNWrapper,
     'git' : GitWrapper,
   }
 
-  orig_url = url
-
-  if url:
-    url, _ = gclient_utils.SplitUrlRevision(url)
-    if url.startswith('git:') or url.startswith('ssh:') or url.endswith('.git'):
-      scm_name = 'git'
-
-  if not scm_name in scm_map:
-    raise gclient_utils.Error('Unsupported scm %s' % scm_name)
-  return scm_map[scm_name](orig_url, root_dir, relpath, scm_name)
+  scm_name = GetScmName(url)
+  if not scm_name in SCM_MAP:
+    raise gclient_utils.Error('No SCM found for url %s' % url)
+  return SCM_MAP[scm_name](url, root_dir, relpath)
 
 
 # SCMWrapper base class
 
 class SCMWrapper(object):
   """Add necessary glue between all the supported SCM.
 
   This is the abstraction layer to bind to different SCM.
   """
-  def __init__(self, url=None, root_dir=None, relpath=None,
-               scm_name='svn'):
-    self.scm_name = scm_name
+  def __init__(self, url=None, root_dir=None, relpath=None):
     self.url = url
     self._root_dir = root_dir
     if self._root_dir:
       self._root_dir = self._root_dir.replace('/', os.sep)
     self.relpath = relpath
     if self.relpath:
       self.relpath = self.relpath.replace('/', os.sep)
     if self.relpath and self._root_dir:
       self.checkout_path = os.path.join(self._root_dir, self.relpath)
 
   def RunCommand(self, command, options, args, file_list=None):
     # file_list will have all files that are modified appended to it.
     if file_list is None:
       file_list = []
 
     commands = ['cleanup', 'export', 'update', 'updatesingle', 'revert',
                 'revinfo', 'status', 'diff', 'pack', 'runhooks']
 
     if not command in commands:
       raise gclient_utils.Error('Unknown command %s' % command)
 
     if not command in dir(self):
       raise gclient_utils.Error('Command %s not implemented in %s wrapper' % (
-          command, self.scm_name))
+          command, self.__class__.__name__))
 
     return getattr(self, command)(options, args, file_list)
 
 
 class GitWrapper(SCMWrapper):
   """Wrapper for Git"""
 
   @staticmethod
   def cleanup(options, args, file_list):
     """'Cleanup' the repo.
@@ skipping 544 matching lines @@
   """ Wrapper for SVN """
 
   def cleanup(self, options, args, file_list):
     """Cleanup working copy."""
     command = ['cleanup']
     command.extend(args)
     scm.SVN.Run(command, os.path.join(self._root_dir, self.relpath))
 
   def diff(self, options, args, file_list):
     # NOTE: This function does not currently modify file_list.
+    path = os.path.join(self._root_dir, self.relpath)
+    if not os.path.isdir(path):
+      raise gclient_utils.Error('Directory %s is not present.' % path)
     command = ['diff']
     command.extend(args)
-    scm.SVN.Run(command, os.path.join(self._root_dir, self.relpath))
+    scm.SVN.Run(command, path)
 
   def export(self, options, args, file_list):
     """Export a clean directory tree into the given path."""
     assert len(args) == 1
     export_path = os.path.abspath(os.path.join(args[0], self.relpath))
     try:
       os.makedirs(export_path)
     except OSError:
       pass
     assert os.path.exists(export_path)
     command = ['export', '--force', '.']
     command.append(export_path)
     scm.SVN.Run(command, os.path.join(self._root_dir, self.relpath))
 
   def pack(self, options, args, file_list):
     """Generates a patch file which can be applied to the root of the
     repository."""
     path = os.path.join(self._root_dir, self.relpath)
+    if not os.path.isdir(path):
+      raise gclient_utils.Error('Directory %s is not present.' % path)
     command = ['diff']
     command.extend(args)
 
     filterer = DiffFilterer(self.relpath)
     scm.SVN.RunAndFilterOutput(command, path, False, False, filterer.Filter)
 
   def update(self, options, args, file_list):
     """Runs svn to update or transparently checkout the working copy.
 
     All updated files will be appended to file_list.
@@ skipping 214 matching lines @@
     command should be a list of strings that represents an svn command.
 
     This method returns a new list to be used as a command."""
     new_command = command[:]
     if revision:
       new_command.extend(['--revision', str(revision).strip()])
     # --force was added to 'svn update' in svn 1.5.
     if options.force and scm.SVN.AssertVersion("1.5")[0]:
       new_command.append('--force')
     return new_command