forked from syndicate-lang/preserves
438 lines
13 KiB
Python
438 lines
13 KiB
Python
import sys
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import numbers
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import struct
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try:
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basestring
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except NameError:
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basestring = str
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if isinstance(chr(123), bytes):
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_ord = ord
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else:
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_ord = lambda x: x
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class Float(object):
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def __init__(self, value):
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self.value = value
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def __eq__(self, other):
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if other.__class__ is self.__class__:
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return self.value == other.value
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def __repr__(self):
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return 'Float(' + repr(self.value) + ')'
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def __preserve_on__(self, encoder):
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encoder.leadbyte(0, 0, 2)
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encoder.buffer.extend(struct.pack('>f', self.value))
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class Symbol(object):
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def __init__(self, name):
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self.name = name
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def __eq__(self, other):
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return isinstance(other, Symbol) and self.name == other.name
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def __hash__(self):
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return hash(self.name)
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def __repr__(self):
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return '#' + self.name
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def __preserve_on__(self, encoder):
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bs = self.name.encode('utf-8')
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encoder.header(1, 3, len(bs))
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encoder.buffer.extend(bs)
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class Record(object):
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def __init__(self, key, fields):
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self.key = key
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self.fields = tuple(fields)
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self.__hash = None
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def __eq__(self, other):
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return isinstance(other, Record) and (self.key, self.fields) == (other.key, other.fields)
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def __hash__(self):
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if self.__hash is None:
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self.__hash = hash((self.key, self.fields))
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return self.__hash
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def __repr__(self):
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return str(self.key) + '(' + ', '.join((repr(f) for f in self.fields)) + ')'
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def __preserve_on__(self, encoder):
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try:
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index = encoder.shortForms.index(self.key)
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except ValueError:
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index = None
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if index is None:
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encoder.header(2, 3, len(self.fields) + 1)
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encoder.append(self.key)
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else:
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encoder.header(2, index, len(self.fields))
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for f in self.fields:
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encoder.append(f)
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def __getitem__(self, index):
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return self.fields[index]
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@staticmethod
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def makeConstructor(labelSymbolText, fieldNames):
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return Record.makeBasicConstructor(Symbol(labelSymbolText), fieldNames)
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@staticmethod
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def makeBasicConstructor(label, fieldNames):
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if type(fieldNames) == str:
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fieldNames = fieldNames.split()
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arity = len(fieldNames)
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def ctor(*fields):
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if len(fields) != arity:
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raise Exception("Record: cannot instantiate %r expecting %d fields with %d fields"%(
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label,
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arity,
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len(fields)))
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return Record(label, fields)
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ctor.constructorInfo = RecordConstructorInfo(label, arity)
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ctor.isClassOf = lambda v: \
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isinstance(v, Record) and v.key == label and len(v.fields) == arity
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return ctor
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class RecordConstructorInfo(object):
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def __init__(self, key, arity):
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self.key = key
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self.arity = arity
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def __eq__(self, other):
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return isinstance(other, RecordConstructorInfo) and \
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(self.key, self.arity) == (other.key, other.arity)
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def __hash__(self):
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if self.__hash is None:
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self.__hash = hash((self.key, self.arity))
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return self.__hash
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def __repr__(self):
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return str(self.key) + '/' + str(self.arity)
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# Blub blub blub
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class ImmutableDict(dict):
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def __init__(self, *args, **kwargs):
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if hasattr(self, '__hash'): raise TypeError('Immutable')
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super(ImmutableDict, self).__init__(*args, **kwargs)
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self.__hash = None
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def __delitem__(self, key): raise TypeError('Immutable')
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def __setitem__(self, key, val): raise TypeError('Immutable')
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def clear(self): raise TypeError('Immutable')
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def pop(self, k, d=None): raise TypeError('Immutable')
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def popitem(self): raise TypeError('Immutable')
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def setdefault(self, k, d=None): raise TypeError('Immutable')
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def update(self, e, **f): raise TypeError('Immutable')
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def __hash__(self):
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if self.__hash is None:
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h = 0
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for k in self:
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h = ((h << 5) ^ (hash(k) << 2) ^ hash(self[k])) & sys.maxsize
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self.__hash = h
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return self.__hash
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@staticmethod
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def from_kvs(kvs):
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i = iter(kvs)
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result = ImmutableDict()
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result_proxy = super(ImmutableDict, result)
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try:
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while True:
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k = next(i)
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v = next(i)
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result_proxy.__setitem__(k, v)
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except StopIteration:
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pass
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return result
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def dict_kvs(d):
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for k in d:
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yield k
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yield d[k]
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class DecodeError(ValueError): pass
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class EncodeError(ValueError): pass
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class ShortPacket(DecodeError): pass
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class Codec(object):
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def __init__(self):
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self.shortForms = [Symbol(u'discard'), Symbol(u'capture'), Symbol(u'observe')]
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def set_shortform(self, index, v):
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if index >= 0 and index < 3:
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self.shortForms[index] = v
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else:
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raise ValueError('Invalid short form index %r' % (index,))
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class Stream(object):
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def __init__(self, iterator):
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self._iterator = iterator
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def __preserve_on__(self, encoder):
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arg = (self.major << 2) | self.minor
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encoder.leadbyte(0, 2, arg)
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self._emit(encoder)
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encoder.leadbyte(0, 3, arg)
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def _emit(self, encoder):
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raise NotImplementedError('Should be implemented in subclasses')
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class ValueStream(Stream):
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major = 3
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def _emit(self, encoder):
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for v in self._iterator:
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encoder.append(v)
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class SequenceStream(ValueStream):
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minor = 0
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class SetStream(ValueStream):
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minor = 1
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class DictStream(ValueStream):
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minor = 2
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def _emit(self, encoder):
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for (k, v) in self._iterator:
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encoder.append(k)
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encoder.append(v)
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class BinaryStream(Stream):
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major = 1
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minor = 2
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def _emit(self, encoder):
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for chunk in self._iterator:
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if not isinstance(chunk, bytes):
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raise EncodeError('Illegal chunk in BinaryStream %r' % (chunk,))
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encoder.append(chunk)
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class StringStream(BinaryStream):
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minor = 1
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class SymbolStream(BinaryStream):
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minor = 3
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class Decoder(Codec):
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def __init__(self, packet=b''):
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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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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 wirelength(self, arg):
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if arg < 15:
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return arg
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return self.varint()
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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 nextvalues(self, n):
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result = []
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for i in range(n):
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result.append(self.next())
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return result
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def nextop(self):
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b = self.nextbyte()
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major = b >> 6
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minor = (b >> 4) & 3
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arg = b & 15
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return (major, minor, arg)
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def peekend(self, arg):
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matched = (self.nextop() == (0, 3, arg))
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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 binarystream(self, arg, minor):
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result = []
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while not self.peekend(arg):
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chunk = self.next()
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if isinstance(chunk, bytes):
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result.append(chunk)
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else:
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raise DecodeError('Unexpected non-binary chunk')
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return self.decodebinary(minor, b''.join(result))
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def valuestream(self, arg, minor, decoder):
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result = []
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while not self.peekend(arg):
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result.append(self.next())
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return decoder(minor, result)
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def decodeint(self, bs):
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if len(bs) == 0: return 0
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acc = _ord(bs[0])
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if acc & 0x80: acc = acc - 256
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for b in bs[1:]:
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acc = (acc << 8) | _ord(b)
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return acc
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def decodebinary(self, minor, bs):
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if minor == 0: return self.decodeint(bs)
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if minor == 1: return bs.decode('utf-8')
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if minor == 2: return bs
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if minor == 3: return Symbol(bs.decode('utf-8'))
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def decoderecord(self, minor, vs):
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if minor == 3:
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if not vs: raise DecodeError('Too few elements in encoded record')
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return Record(vs[0], vs[1:])
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else:
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return Record(self.shortForms[minor], vs)
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def decodecollection(self, minor, vs):
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if minor == 0: return tuple(vs)
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if minor == 1: return frozenset(vs)
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if minor == 2: return ImmutableDict.from_kvs(vs)
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if minor == 3: raise DecodeError('Invalid collection type')
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def next(self):
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(major, minor, arg) = self.nextop()
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if major == 0:
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if minor == 0:
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if arg == 0: return False
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if arg == 1: return True
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if arg == 2: return Float(struct.unpack('>f', self.nextbytes(4))[0])
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if arg == 3: return struct.unpack('>d', self.nextbytes(8))[0]
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raise DecodeError('Invalid format A encoding')
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elif minor == 1:
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return arg - 16 if arg > 12 else arg
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elif minor == 2:
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t = arg >> 2
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n = arg & 3
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if t == 0: raise DecodeError('Invalid format C start byte')
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if t == 1: return self.binarystream(arg, n)
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if t == 2: return self.valuestream(arg, n, self.decoderecord)
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if t == 3: return self.valuestream(arg, n, self.decodecollection)
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else: # minor == 3
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raise DecodeError('Unexpected format C end byte')
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elif major == 1:
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return self.decodebinary(minor, self.nextbytes(self.wirelength(arg)))
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elif major == 2:
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return self.decoderecord(minor, self.nextvalues(self.wirelength(arg)))
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else: # major == 3
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return self.decodecollection(minor, self.nextvalues(self.wirelength(arg)))
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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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class Encoder(Codec):
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def __init__(self):
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super(Encoder, self).__init__()
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self.buffer = bytearray()
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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 leadbyte(self, major, minor, arg):
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self.buffer.append(((major & 3) << 6) | ((minor & 3) << 4) | (arg & 15))
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def header(self, major, minor, wirelength):
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if wirelength < 15:
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self.leadbyte(major, minor, wirelength)
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else:
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self.leadbyte(major, minor, 15)
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self.varint(wirelength)
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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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self.header(1, 0, 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 encodecollection(self, minor, items):
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self.header(3, minor, len(items))
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for i in items: self.append(i)
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def encodestream(self, t, n, items):
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tn = ((t & 3) << 2) | (n & 3)
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self.header(0, 2, tn)
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for i in items: self.append(i)
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self.header(0, 3, tn)
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def append(self, v):
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if hasattr(v, '__preserve_on__'):
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v.__preserve_on__(self)
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elif v is False:
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self.leadbyte(0, 0, 0)
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elif v is True:
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self.leadbyte(0, 0, 1)
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elif isinstance(v, float):
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self.leadbyte(0, 0, 3)
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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.leadbyte(0, 1, 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.header(1, 2, len(v))
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self.buffer.extend(v)
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elif isinstance(v, basestring):
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bs = v.encode('utf-8')
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self.header(1, 1, len(bs))
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self.buffer.extend(bs)
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elif isinstance(v, list):
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self.encodecollection(0, v)
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elif isinstance(v, tuple):
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self.encodecollection(0, v)
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elif isinstance(v, set):
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self.encodecollection(1, v)
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elif isinstance(v, frozenset):
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self.encodecollection(1, v)
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elif isinstance(v, dict):
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self.encodecollection(2, list(dict_kvs(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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raise EncodeError('Cannot encode %r' % (v,))
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self.encodestream(3, 0, i)
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