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