+ global __head
+
+ if not __head or __head != val:
+ if __run('git-update-ref HEAD', [val]) != 0:
+ raise GitException, 'Could not update HEAD to "%s".' % val
+ __head = val
+
+def __clear_head_cache():
+ """Sets the __head to None so that a re-read is forced
+ """
+ global __head
+
+ __head = None
+
+def refresh_index():
+ """Refresh index with stat() information from the working directory.
+ """
+ __run('git-update-index -q --unmerged --refresh')
+
+def rev_parse(git_id):
+ """Parse the string and return a verified SHA1 id
+ """
+ try:
+ return _output_one_line(['git-rev-parse', '--verify', git_id])
+ except GitException:
+ raise GitException, 'Unknown revision: %s' % git_id
+
+def branch_exists(branch):
+ """Existance check for the named branch
+ """
+ for line in _output_lines(['git-rev-parse', '--symbolic', '--all']):
+ if line.strip() == branch:
+ return True
+ return False
+
+def create_branch(new_branch, tree_id = None):
+ """Create a new branch in the git repository
+ """
+ new_head = os.path.join('refs', 'heads', new_branch)
+ if branch_exists(new_head):
+ raise GitException, 'Branch "%s" already exists' % new_branch
+
+ current_head = get_head()
+ set_head_file(new_head)
+ __set_head(current_head)
+
+ # a checkout isn't needed if new branch points to the current head
+ if tree_id:
+ switch(tree_id)
+
+ if os.path.isfile(os.path.join(base_dir, 'MERGE_HEAD')):
+ os.remove(os.path.join(base_dir, 'MERGE_HEAD'))
+
+def switch_branch(name):
+ """Switch to a git branch
+ """
+ global __head
+
+ new_head = os.path.join('refs', 'heads', name)
+ if not branch_exists(new_head):
+ raise GitException, 'Branch "%s" does not exist' % name
+
+ tree_id = rev_parse(new_head + '^0')
+ if tree_id != get_head():
+ refresh_index()
+ if __run('git-read-tree -u -m', [get_head(), tree_id]) != 0:
+ raise GitException, 'git-read-tree failed (local changes maybe?)'
+ __head = tree_id
+ set_head_file(new_head)
+
+ if os.path.isfile(os.path.join(base_dir, 'MERGE_HEAD')):
+ os.remove(os.path.join(base_dir, 'MERGE_HEAD'))
+
+def delete_branch(name):
+ """Delete a git branch
+ """
+ branch_head = os.path.join('refs', 'heads', name)
+ if not branch_exists(branch_head):
+ raise GitException, 'Branch "%s" does not exist' % name
+ os.remove(os.path.join(base_dir, branch_head))
+
+def rename_branch(from_name, to_name):
+ """Rename a git branch
+ """
+ from_head = os.path.join('refs', 'heads', from_name)
+ if not branch_exists(from_head):
+ raise GitException, 'Branch "%s" does not exist' % from_name
+ to_head = os.path.join('refs', 'heads', to_name)
+ if branch_exists(to_head):
+ raise GitException, 'Branch "%s" already exists' % to_name
+
+ if get_head_file() == from_name:
+ set_head_file(to_head)
+ os.rename(os.path.join(base_dir, from_head), os.path.join(base_dir, to_head))