mercurial/node.py

treemanifest: make treemanifest.matches() faster

By converting treemanifest.matches() into a recursively additivie operation,
it becomes O(n).

The old matches function made a copy of the entire manifest and deleted
files that didn't match. With tree manifests, this was an O(n log n) operation
because del() was O(log n).

This change speeds up the command
  "hg status --rev .^ 'relglob:*.js'
on the Mozilla repo, now taking 2.53s, down from 3.51s.

# node.py - basic nodeid manipulation for mercurial
#
# Copyright 2005, 2006 Matt Mackall <[e-mail]>
#
# 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])