1 """

     2 node.py - basic nodeid manipulation for mercurial

     3 

     4 Copyright 2005 Matt Mackall <mpm@selenic.com>

     5 

     6 This software may be used and distributed according to the terms

     7 of the GNU General Public License, incorporated herein by reference.

     8 """

     9 

    10 import sha, binascii

    11 

    12 nullid = "\0" * 20

    13 

    14 def hex(node):

    15     return binascii.hexlify(node)

    16 

    17 def bin(node):

    18     return binascii.unhexlify(node)

    19 

    20 def short(node):

    21     return hex(node[:6])

    22 

    23 def hash(text, p1, p2):

    24     """generate a hash from the given text and its parent hashes

    25 

    26     This hash combines both the current file contents and its history

    27     in a manner that makes it easy to distinguish nodes with the same

    28     content in the revision graph.

    29     """

    30     l = [p1, p2]

    31     l.sort()

    32     s = sha.new(l[0])

    33     s.update(l[1])

    34     s.update(text)

    35     return s.digest()

    36