#
# Copyright (c) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009 The SCons Foundation
#
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# a copy of this software and associated documentation files (the
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# permit persons to whom the Software is furnished to do so, subject to
# the following conditions:
#
# The above copyright notice and this permission notice shall be included
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__doc__ = """
hashlib backwards-compatibility module for older (pre-2.5) Python versions

This does not not NOT (repeat, *NOT*) provide complete hashlib
functionality.  It only wraps the portions of MD5 functionality used
by SCons, in an interface that looks like hashlib (or enough for our
purposes, anyway).  In fact, this module will raise an ImportError if
the underlying md5 module isn't available.
"""

__revision__ = "src/engine/SCons/compat/_scons_hashlib.py 4043 2009/02/23 09:06:45 scons"

import md5
import string

class md5obj:

    md5_module = md5

    def __init__(self, name, string=''):
        if not name in ('MD5', 'md5'):
            raise ValueError, "unsupported hash type"
        self.name = 'md5'
        self.m = self.md5_module.md5()

    def __repr__(self):
        return '<%s HASH object @ %#x>' % (self.name, id(self))

    def copy(self):
        import copy
        result = copy.copy(self)
        result.m = self.m.copy()
        return result

    def digest(self):
        return self.m.digest()

    def update(self, arg):
        return self.m.update(arg)

    if hasattr(md5.md5(), 'hexdigest'):

        def hexdigest(self):
            return self.m.hexdigest()

    else:

        # Objects created by the underlying md5 module have no native
        # hexdigest() method (*cough* 1.5.2 *cough*), so provide an
        # equivalent lifted from elsewhere.
        def hexdigest(self):
            h = string.hexdigits
            r = ''
            for c in self.digest():
                i = ord(c)
                r = r + h[(i >> 4) & 0xF] + h[i & 0xF]
            return r

new = md5obj

def md5(string=''):
    return md5obj('md5', string)

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