255 lines
8.1 KiB
Python
255 lines
8.1 KiB
Python
import numbers
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import struct
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from .values import *
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from .error import *
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from .compat import basestring_, ord_
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class BinaryCodec(object): pass
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class Decoder(BinaryCodec):
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def __init__(self, packet=b'', include_annotations=False, decode_embedded=lambda x: x):
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super(Decoder, self).__init__()
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self.packet = packet
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self.index = 0
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self.include_annotations = include_annotations
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self.decode_embedded = decode_embedded
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def extend(self, data):
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self.packet = self.packet[self.index:] + data
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self.index = 0
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def nextbyte(self):
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if self.index >= len(self.packet):
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raise ShortPacket('Short packet')
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self.index = self.index + 1
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return ord_(self.packet[self.index - 1])
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def nextbytes(self, n):
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start = self.index
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end = start + n
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if end > len(self.packet):
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raise ShortPacket('Short packet')
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self.index = end
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return self.packet[start : end]
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def varint(self):
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v = self.nextbyte()
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if v < 128:
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return v
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else:
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return self.varint() * 128 + (v - 128)
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def peekend(self):
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matched = (self.nextbyte() == 0x84)
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if not matched:
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self.index = self.index - 1
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return matched
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def nextvalues(self):
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result = []
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while not self.peekend():
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result.append(self.next())
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return result
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def nextint(self, n):
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if n == 0: return 0
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acc = self.nextbyte()
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if acc & 0x80: acc = acc - 256
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for _i in range(n - 1):
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acc = (acc << 8) | self.nextbyte()
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return acc
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def wrap(self, v):
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return Annotated(v) if self.include_annotations else v
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def unshift_annotation(self, a, v):
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if self.include_annotations:
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v.annotations.insert(0, a)
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return v
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def next(self):
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tag = self.nextbyte()
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if tag == 0x80: return self.wrap(False)
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if tag == 0x81: return self.wrap(True)
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if tag == 0x82: return self.wrap(Float.from_bytes(self.nextbytes(4)))
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if tag == 0x83: return self.wrap(struct.unpack('>d', self.nextbytes(8))[0])
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if tag == 0x84: raise DecodeError('Unexpected end-of-stream marker')
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if tag == 0x85:
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a = self.next()
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v = self.next()
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return self.unshift_annotation(a, v)
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if tag == 0x86:
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if self.decode_embedded is None:
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raise DecodeError('No decode_embedded function supplied')
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return self.wrap(Embedded(self.decode_embedded(self.next())))
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if tag >= 0x90 and tag <= 0x9f: return self.wrap(tag - (0xa0 if tag > 0x9c else 0x90))
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if tag >= 0xa0 and tag <= 0xaf: return self.wrap(self.nextint(tag - 0xa0 + 1))
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if tag == 0xb0: return self.wrap(self.nextint(self.varint()))
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if tag == 0xb1: return self.wrap(self.nextbytes(self.varint()).decode('utf-8'))
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if tag == 0xb2: return self.wrap(self.nextbytes(self.varint()))
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if tag == 0xb3: return self.wrap(Symbol(self.nextbytes(self.varint()).decode('utf-8')))
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if tag == 0xb4:
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vs = self.nextvalues()
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if not vs: raise DecodeError('Too few elements in encoded record')
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return self.wrap(Record(vs[0], vs[1:]))
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if tag == 0xb5: return self.wrap(tuple(self.nextvalues()))
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if tag == 0xb6: return self.wrap(frozenset(self.nextvalues()))
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if tag == 0xb7: return self.wrap(ImmutableDict.from_kvs(self.nextvalues()))
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raise DecodeError('Invalid tag: ' + hex(tag))
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def try_next(self):
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start = self.index
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try:
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return self.next()
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except ShortPacket:
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self.index = start
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return None
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def __iter__(self):
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return self
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def __next__(self):
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v = self.try_next()
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if v is None:
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raise StopIteration
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return v
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def decode(bs, **kwargs):
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return Decoder(packet=bs, **kwargs).next()
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def decode_with_annotations(bs, **kwargs):
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return Decoder(packet=bs, include_annotations=True, **kwargs).next()
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class Encoder(BinaryCodec):
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def __init__(self, encode_embedded=lambda x: x, canonicalize=False):
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super(Encoder, self).__init__()
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self.buffer = bytearray()
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self._encode_embedded = encode_embedded
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self._canonicalize = canonicalize
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def reset(self):
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self.buffer = bytearray()
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def encode_embedded(self, v):
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if self._encode_embedded is None:
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raise EncodeError('No encode_embedded function supplied')
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return self._encode_embedded(v)
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def contents(self):
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return bytes(self.buffer)
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def varint(self, v):
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if v < 128:
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self.buffer.append(v)
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else:
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self.buffer.append((v % 128) + 128)
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self.varint(v // 128)
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def encodeint(self, v):
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bitcount = (~v if v < 0 else v).bit_length() + 1
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bytecount = (bitcount + 7) // 8
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if bytecount <= 16:
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self.buffer.append(0xa0 + bytecount - 1)
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else:
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self.buffer.append(0xb0)
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self.varint(bytecount)
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def enc(n,x):
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if n > 0:
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enc(n-1, x >> 8)
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self.buffer.append(x & 255)
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enc(bytecount, v)
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def encodevalues(self, tag, items):
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self.buffer.append(0xb0 + tag)
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for i in items: self.append(i)
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self.buffer.append(0x84)
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def encodebytes(self, tag, bs):
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self.buffer.append(0xb0 + tag)
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self.varint(len(bs))
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self.buffer.extend(bs)
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def encodeset(self, v):
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if not self._canonicalize:
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self.encodevalues(6, v)
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else:
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c = Canonicalizer(self._encode_embedded)
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for i in v: c.entry([i])
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c.emit_entries(self, 6)
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def encodedict(self, v):
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if not self._canonicalize:
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self.encodevalues(7, list(dict_kvs(v)))
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else:
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c = Canonicalizer(self._encode_embedded)
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for (kk, vv) in v.items(): c.entry([kk, vv])
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c.emit_entries(self, 7)
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def append(self, v):
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v = preserve(v)
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if hasattr(v, '__preserve_write_binary__'):
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v.__preserve_write_binary__(self)
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elif v is False:
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self.buffer.append(0x80)
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elif v is True:
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self.buffer.append(0x81)
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elif isinstance(v, float):
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self.buffer.append(0x83)
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self.buffer.extend(struct.pack('>d', v))
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elif isinstance(v, numbers.Number):
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if v >= -3 and v <= 12:
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self.buffer.append(0x90 + (v if v >= 0 else v + 16))
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else:
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self.encodeint(v)
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elif isinstance(v, bytes):
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self.encodebytes(2, v)
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elif isinstance(v, basestring_):
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self.encodebytes(1, v.encode('utf-8'))
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elif isinstance(v, list):
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self.encodevalues(5, v)
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elif isinstance(v, tuple):
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self.encodevalues(5, v)
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elif isinstance(v, set):
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self.encodeset(v)
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elif isinstance(v, frozenset):
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self.encodeset(v)
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elif isinstance(v, dict):
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self.encodedict(v)
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else:
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try:
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i = iter(v)
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except TypeError:
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i = None
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if i is None:
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self.cannot_encode(v)
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else:
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self.encodevalues(5, i)
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def cannot_encode(self, v):
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raise TypeError('Cannot preserves-encode: ' + repr(v))
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class Canonicalizer:
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def __init__(self, encode_embedded):
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self.encoder = Encoder(encode_embedded, canonicalize=True)
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self.entries = []
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def entry(self, pieces):
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for piece in pieces: self.encoder.append(piece)
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entry = self.encoder.contents()
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self.encoder.reset()
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self.entries.append(entry)
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def emit_entries(self, outer_encoder, tag):
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outer_encoder.buffer.append(0xb0 + tag)
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for e in sorted(self.entries): outer_encoder.buffer.extend(e)
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outer_encoder.buffer.append(0x84)
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def encode(v, **kwargs):
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e = Encoder(**kwargs)
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e.append(v)
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return e.contents()
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def canonicalize(v, **kwargs):
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return encode(v, canonicalize=True, **kwargs)
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