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# 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.
#
# Modifications copyright (C) 2008 Canonical Ltd
from __future__ import absolute_import
import sys
class BDecoder(object):
def __init__(self, yield_tuples=False):
"""Constructor.
:param yield_tuples: if true, decode "l" elements as tuples rather than
lists.
"""
self.yield_tuples = yield_tuples
decode_func = {}
decode_func[b'l'] = self.decode_list
decode_func[b'd'] = self.decode_dict
decode_func[b'i'] = self.decode_int
decode_func[b'0'] = self.decode_string
decode_func[b'1'] = self.decode_string
decode_func[b'2'] = self.decode_string
decode_func[b'3'] = self.decode_string
decode_func[b'4'] = self.decode_string
decode_func[b'5'] = self.decode_string
decode_func[b'6'] = self.decode_string
decode_func[b'7'] = self.decode_string
decode_func[b'8'] = self.decode_string
decode_func[b'9'] = self.decode_string
self.decode_func = decode_func
def decode_int(self, x, f):
f += 1
newf = x.index(b'e', f)
n = int(x[f:newf])
if x[f:f+2] == b'-0':
raise ValueError
elif x[f:f+1] == b'0' and newf != f+1:
raise ValueError
return (n, newf+1)
def decode_string(self, x, f):
colon = x.index(b':', f)
n = int(x[f:colon])
if x[f:f+1] == b'0' and colon != f+1:
raise ValueError
colon += 1
return (x[colon:colon+n], colon+n)
def decode_list(self, x, f):
r, f = [], f+1
while x[f:f+1] != b'e':
v, f = self.decode_func[x[f:f+1]](x, f)
r.append(v)
if self.yield_tuples:
r = tuple(r)
return (r, f + 1)
def decode_dict(self, x, f):
r, f = {}, f+1
lastkey = None
while x[f:f+1] != b'e':
k, f = self.decode_string(x, f)
if lastkey is not None and lastkey >= k:
raise ValueError
lastkey = k
r[k], f = self.decode_func[x[f:f+1]](x, f)
return (r, f + 1)
def bdecode(self, x):
if not isinstance(x, bytes):
raise TypeError
try:
r, l = self.decode_func[x[:1]](x, 0)
except (IndexError, KeyError, OverflowError) as e:
raise ValueError(str(e))
if l != len(x):
raise ValueError
return r
_decoder = BDecoder()
bdecode = _decoder.bdecode
_tuple_decoder = BDecoder(True)
bdecode_as_tuple = _tuple_decoder.bdecode
class Bencached(object):
__slots__ = ['bencoded']
def __init__(self, s):
self.bencoded = s
def encode_bencached(x,r):
r.append(x.bencoded)
def encode_bool(x,r):
encode_int(int(x), r)
def encode_int(x, r):
r.extend((b'i', int_to_bytes(x), b'e'))
def encode_string(x, r):
r.extend((int_to_bytes(len(x)), b':', x))
def encode_list(x, r):
r.append(b'l')
for i in x:
encode_func[type(i)](i, r)
r.append(b'e')
def encode_dict(x,r):
r.append(b'd')
ilist = sorted(x.items())
for k, v in ilist:
r.extend((int_to_bytes(len(k)), b':', k))
encode_func[type(v)](v, r)
r.append(b'e')
encode_func = {}
encode_func[type(Bencached(0))] = encode_bencached
encode_func[int] = encode_int
if sys.version_info < (3,):
encode_func[long] = encode_int
int_to_bytes = str
else:
def int_to_bytes(n):
return b'%d' % n
encode_func[bytes] = encode_string
encode_func[list] = encode_list
encode_func[tuple] = encode_list
encode_func[dict] = encode_dict
encode_func[bool] = encode_bool
from breezy._static_tuple_py import StaticTuple
encode_func[StaticTuple] = encode_list
try:
from breezy._static_tuple_c import StaticTuple
except ImportError:
pass
else:
encode_func[StaticTuple] = encode_list
def bencode(x):
r = []
encode_func[type(x)](x, r)
return b''.join(r)
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