2 files changed, 120 insertions, 0 deletions

diff --git a/project.py b/project.py
index 2b4a4f95..e88afcca 100644
--- a/project.py
+++ b/project.py
@@ -45,6 +45,31 @@ def _info(fmt, *args):
 def not_rev(r):
   return '^' + r
 
+class DownloadedChange(object):
+  _commit_cache = None
+
+  def __init__(self, project, base, change_id, ps_id, commit):
+    self.project = project
+    self.base = base
+    self.change_id = change_id
+    self.ps_id = ps_id
+    self.commit = commit
+
+  @property
+  def commits(self):
+    if self._commit_cache is None:
+      self._commit_cache = self.project.bare_git.rev_list(
+        '--abbrev=8',
+        '--abbrev-commit',
+        '--pretty=oneline',
+        '--reverse',
+        '--date-order',
+        not_rev(self.base),
+        self.commit,
+        '--')
+    return self._commit_cache
+
+
 class ReviewableBranch(object):
   _commit_cache = None
 
@@ -612,6 +637,23 @@ class Project(object):
     src = os.path.join(self.worktree, src)
     self.copyfiles.append(_CopyFile(src, dest))
 
+  def DownloadPatchSet(self, change_id, patch_id):
+    """Download a single patch set of a single change to FETCH_HEAD.
+    """
+    remote = self.GetRemote(self.remote.name)
+
+    cmd = ['fetch', remote.name]
+    cmd.append('refs/changes/%2.2d/%d/%d' \
+               % (change_id % 100, change_id, patch_id))
+    cmd.extend(map(lambda x: str(x), remote.fetch))
+    if GitCommand(self, cmd, bare=True).Wait() != 0:
+      return None
+    return DownloadedChange(self,
+                            remote.ToLocal(self.revision),
+                            change_id,
+                            patch_id,
+                            self.bare_git.rev_parse('FETCH_HEAD'))
+
 
 ## Branch Management ##
 
diff --git a/subcmds/download.py b/subcmds/download.py
new file mode 100644
index 00000000..a6f3aa45
--- /dev/null
+++ b/subcmds/download.py
@@ -0,0 +1,78 @@
+#
+# Copyright (C) 2008 The Android Open Source Project
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import os
+import re
+import sys
+
+from command import Command
+
+CHANGE_RE = re.compile(r'^([1-9][0-9]*)(?:[/\.-]([1-9][0-9]*))?$')
+
+class Download(Command):
+  common = True
+  helpSummary = "Download and checkout a change"
+  helpUsage = """
+%prog {project change[/patchset]}...
+"""
+  helpDescription = """
+The '%prog' command downloads a change from the review system and
+makes it available in your project's local working directory.
+"""
+
+  def _Options(self, p):
+    pass
+
+  def _ParseChangeIds(self, args):
+    to_get = []
+    project = None
+
+    for a in args:
+      m = CHANGE_RE.match(a)
+      if m:
+        if not project:
+          self.Usage()
+        chg_id = int(m.group(1))
+        if m.group(2):
+          ps_id = int(m.group(2))
+        else:
+          ps_id = 1
+        to_get.append((project, chg_id, ps_id))
+      else:
+        project = self.GetProjects([a])[0]
+    return to_get
+
+  def Execute(self, opt, args):
+    for project, change_id, ps_id in self._ParseChangeIds(args):
+      dl = project.DownloadPatchSet(change_id, ps_id)
+      if not dl:
+        print >>sys.stderr, \
+          '[%s] change %d/%d not found' \
+          % (project.name, change_id, ps_id)
+        sys.exit(1)
+
+      if not dl.commits:
+        print >>sys.stderr, \
+          '[%s] change %d/%d has already been merged' \
+          % (project.name, change_id, ps_id)
+        continue
+
+      if len(dl.commits) > 1:
+        print >>sys.stderr, \
+          '[%s] %d/%d depends on %d unmerged changes:' \
+          % (project.name, change_id, ps_id, len(dl.commits))
+        for c in dl.commits:
+          print >>sys.stderr, '  %s' % (c)
+      project._Checkout(dl.commit)