Group SCM-specific functions in classes to simplify generalization of the interface.

trychange.py

Index: trychange.py
diff --git a/trychange.py b/trychange.py
index cbe49f93f9b2444c4910d5f16fd3d7a8ade20901..a1c1de3585abd7add277122d54820d3e5734ac9e 100755
--- a/trychange.py
+++ b/trychange.py
@@ -21,11 +21,11 @@ import tempfile
 import urllib
 
 import gcl
-import gclient_scm
+import scm
 import presubmit_support
 import upload
 
-__version__ = '1.1.1'
+__version__ = '1.1.2'
 
 
 # Constants
@@ -150,50 +150,8 @@ class SVN(SCM):
     else:
       os.chdir(root)
 
-    diff = []
-    for filename in files:
-      # Use svn info output instead of os.path.isdir because the latter fails
-      # when the file is deleted.
-      if gclient_scm.CaptureSVNInfo(filename).get("Node Kind") in (
-          "dir", "directory"):
-        continue
-      # If the user specified a custom diff command in their svn config file,
-      # then it'll be used when we do svn diff, which we don't want to happen
-      # since we want the unified diff.  Using --diff-cmd=diff doesn't always
-      # work, since they can have another diff executable in their path that
-      # gives different line endings.  So we use a bogus temp directory as the
-      # config directory, which gets around these problems.
-      if sys.platform.startswith("win"):
-        parent_dir = tempfile.gettempdir()
-      else:
-        parent_dir = sys.path[0]  # tempdir is not secure.
-      bogus_dir = os.path.join(parent_dir, "temp_svn_config")
-      if not os.path.exists(bogus_dir):
-        os.mkdir(bogus_dir)
-      # Grabs the diff data.
-      data = gcl.RunShell(["svn", "diff", "--config-dir", bogus_dir, filename])
-
-      # We know the diff will be incorrectly formatted. Fix it.
-      if gcl.IsSVNMoved(filename):
-        # The file is "new" in the patch sense. Generate a homebrew diff.
-        # We can't use ReadFile() since it's not using binary mode.
-        file_handle = open(filename, 'rb')
-        file_content = file_handle.read()
-        file_handle.close()
-        # Prepend '+' to every lines.
-        file_content = ['+' + i for i in file_content.splitlines(True)]
-        nb_lines = len(file_content)
-        # We need to use / since patch on unix will fail otherwise.
-        filename = filename.replace('\\', '/')
-        data = "Index: %s\n" % filename
-        data += ("============================================================="
-                 "======\n")
-        # Note: Should we use /dev/null instead?
-        data += "--- %s\n" % filename
-        data += "+++ %s\n" % filename
-        data += "@@ -0,0 +1,%d @@\n" % nb_lines
-        data += ''.join(file_content)
-      diff.append(data)
+    # Directories will return None so filter them out.
+    diff = filter(None, [scm.SVN.Diff(f) for f in files])
     os.chdir(previous_cwd)
     return "".join(diff)
 
@@ -407,6 +365,7 @@ def GuessVCS(options):
   Returns:
     A SCM instance. Exits if the SCM can't be guessed.
   """
+  __pychecker__ = 'no-returnvalues'
   # Subversion has a .svn in all working directories.
   if os.path.isdir('.svn'):
     logging.info("Guessed VCS = Subversion")