treemanifest: add treemanifest._isempty()
During operations that involve building up a new manifest tree, it will be
useful to be able to quickly check if a submanifest is empty, and if so, to
avoid including it in the final tree. Doing this check lets us avoid creating
treemanifest structures that contain any empty submanifests.
# node.py - basic nodeid manipulation for mercurial
#
# Copyright 2005, 2006 Matt Mackall <mpm@selenic.com>
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.
import binascii
nullrev = -1
nullid = "\0" * 20
# This ugly style has a noticeable effect in manifest parsing
hex = binascii.hexlify
bin = binascii.unhexlify
def short(node):
return hex(node[:6])