~bzr-pqm/bzr/bzr.dev

# bencode structured encoding

#

# Written by Petru Paler

#

# Permission is hereby granted, free of charge, to any person

# obtaining a copy of this software and associated documentation files

# (the "Software"), to deal in the Software without restriction,

# including without limitation the rights to use, copy, modify, merge,

# publish, distribute, sublicense, and/or sell copies of the Software,

# and to 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 in all copies or substantial portions of the Software.

# 

# The Software is provided "AS IS", without warranty of any kind,

# express or implied, including but not limited to the warranties of

# merchantability,  fitness for a particular purpose and

# noninfringement. In no event shall the  authors or copyright holders

# be liable for any claim, damages or other liability, whether in an

# action of contract, tort or otherwise, arising from, out of or in

# connection with the Software or the use or other dealings in the

# Software.

def decode_int(x, f):

    f += 1

    newf = x.index('e', f)

    try:

        n = int(x[f:newf])

    except (OverflowError, ValueError):

        n = long(x[f:newf])

    if x[f] == '-':

        if x[f + 1] == '0':

            raise ValueError

    elif x[f] == '0' and newf != f+1:

        raise ValueError

    return (n, newf+1)

def decode_string(x, f):

    colon = x.index(':', f)

    try:

        n = int(x[f:colon])

    except (OverflowError, ValueError):

        n = long(x[f:colon])

    if x[f] == '0' and colon != f+1:

        raise ValueError

    colon += 1

    return (x[colon:colon+n], colon+n)

def decode_list(x, f):

    r, f = [], f+1

    while x[f] != 'e':

        v, f = decode_func[x[f]](x, f)

        r.append(v)

    return (r, f + 1)

def decode_dict(x, f):

    r, f = {}, f+1

    lastkey = None

    while x[f] != 'e':

        k, f = decode_string(x, f)

        if lastkey >= k:

            raise ValueError

        lastkey = k

        r[k], f = decode_func[x[f]](x, f)

    return (r, f + 1)

decode_func = {}

decode_func['l'] = decode_list

decode_func['d'] = decode_dict

decode_func['i'] = decode_int

decode_func['0'] = decode_string

decode_func['1'] = decode_string

decode_func['2'] = decode_string

decode_func['3'] = decode_string

decode_func['4'] = decode_string

decode_func['5'] = decode_string

decode_func['6'] = decode_string

decode_func['7'] = decode_string

decode_func['8'] = decode_string

decode_func['9'] = decode_string

def bdecode(x):

    try:

        r, l = decode_func[x[0]](x, 0)

    except (IndexError, KeyError):

        raise ValueError

    if l != len(x):

        raise ValueError

    return r

from types import StringType, IntType, LongType, DictType, ListType, TupleType

class Bencached(object):

    __slots__ = ['bencoded']

    def __init__(self, s):

        self.bencoded = s

def encode_bencached(x,r):

    r.append(x.bencoded)

def encode_int(x, r):

    r.extend(('i', str(x), 'e'))

def encode_string(x, r):

    r.extend((str(len(x)), ':', x))

def encode_list(x, r):

    r.append('l')

    for i in x:

        encode_func[type(i)](i, r)

    r.append('e')

def encode_dict(x,r):

    r.append('d')

    ilist = x.items()

    ilist.sort()

    for k, v in ilist:

        r.extend((str(len(k)), ':', k))

        encode_func[type(v)](v, r)

    r.append('e')

encode_func = {}

encode_func[type(Bencached(0))] = encode_bencached

encode_func[IntType] = encode_int

encode_func[LongType] = encode_int

encode_func[StringType] = encode_string

encode_func[ListType] = encode_list

encode_func[TupleType] = encode_list

encode_func[DictType] = encode_dict

try:

    from types import BooleanType

    encode_func[BooleanType] = encode_int

except ImportError:

    pass

def bencode(x):

    r = []

    encode_func[type(x)](x, r)

    return ''.join(r)