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320 lines
7.5 KiB
Python
320 lines
7.5 KiB
Python
"""Implements (a subset of) Sun XDR -- eXternal Data Representation.
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See: RFC 1014
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This module will conditionally use the _xdrmodule.so module to get
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support for those representations we can't do much with from Python.
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"""
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import struct
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from types import LongType
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# use C layer XDR libraries for some data types if available
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try:
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import _xdr
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except ImportError:
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_xdr = None
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# this test is done to see if machine representation is the same as
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# network representation. if so, we can use module struct for packing
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# some data types
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_USE_MACHINE_REP = (struct.pack('l', 1) == '\0\0\0\1')
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# exceptions
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class Error:
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"""Exception class for this module. Use:
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except xdrlib.Error, var:
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# var has the Error instance for the exception
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Public ivars:
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msg -- contains the message
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"""
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def __init__(self, msg):
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self.msg = msg
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def __repr__(self):
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return repr(self.msg)
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def __str__(self):
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return str(self.msg)
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class ConversionError(Error):
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pass
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class Packer:
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"""Pack various data representations into a buffer."""
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def __init__(self):
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self.reset()
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def reset(self):
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self.__buf = ''
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def get_buffer(self):
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return self.__buf
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# backwards compatibility
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get_buf = get_buffer
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def pack_uint(self, x):
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self.__buf = self.__buf + \
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(chr(int(x>>24 & 0xff)) + chr(int(x>>16 & 0xff)) + \
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chr(int(x>>8 & 0xff)) + chr(int(x & 0xff)))
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if _USE_MACHINE_REP:
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def pack_uint(self, x):
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if type(x) == LongType:
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x = int((x + 0x80000000L) % 0x100000000L - 0x80000000L)
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self.__buf = self.__buf + struct.pack('l', x)
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pack_int = pack_uint
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pack_enum = pack_int
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def pack_bool(self, x):
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if x: self.__buf = self.__buf + '\0\0\0\1'
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else: self.__buf = self.__buf + '\0\0\0\0'
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def pack_uhyper(self, x):
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self.pack_uint(int(x>>32 & 0xffffffff))
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self.pack_uint(int(x & 0xffffffff))
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pack_hyper = pack_uhyper
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def pack_float(self, x):
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raise ConversionError('Not supported')
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def pack_double(self, x):
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raise ConversionError('Not supported')
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# get these from the C layer if available
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if _xdr:
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def pack_float(self, x):
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try: self.__buf = self.__buf + _xdr.pack_float(x)
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except _xdr.error, msg:
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raise ConversionError(msg)
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def pack_double(self, x):
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try: self.__buf = self.__buf + _xdr.pack_double(x)
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except _xdr.error, msg:
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raise ConversionError(msg)
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def pack_fstring(self, n, s):
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if n < 0:
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raise ValueError, 'fstring size must be nonnegative'
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n = ((n+3)/4)*4
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data = s[:n]
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data = data + (n - len(data)) * '\0'
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self.__buf = self.__buf + data
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pack_fopaque = pack_fstring
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def pack_string(self, s):
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n = len(s)
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self.pack_uint(n)
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self.pack_fstring(n, s)
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pack_opaque = pack_string
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pack_bytes = pack_string
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def pack_list(self, list, pack_item):
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for item in list:
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self.pack_uint(1)
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pack_item(item)
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self.pack_uint(0)
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def pack_farray(self, n, list, pack_item):
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if len(list) <> n:
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raise ValueError, 'wrong array size'
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for item in list:
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pack_item(item)
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def pack_array(self, list, pack_item):
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n = len(list)
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self.pack_uint(n)
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self.pack_farray(n, list, pack_item)
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class Unpacker:
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"""Unpacks various data representations from the given buffer."""
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def __init__(self, data):
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self.reset(data)
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def reset(self, data):
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self.__buf = data
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self.__pos = 0
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def get_position(self):
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return self.__pos
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def set_position(self, position):
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self.__pos = position
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def done(self):
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if self.__pos < len(self.__buf):
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raise Error('unextracted data remains')
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def unpack_uint(self):
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i = self.__pos
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self.__pos = j = i+4
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data = self.__buf[i:j]
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if len(data) < 4:
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raise EOFError
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x = long(ord(data[0]))<<24 | ord(data[1])<<16 | \
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ord(data[2])<<8 | ord(data[3])
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# Return a Python long only if the value is not representable
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# as a nonnegative Python int
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if x < 0x80000000L:
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x = int(x)
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return x
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if _USE_MACHINE_REP:
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def unpack_uint(self):
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i = self.__pos
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self.__pos = j = i+4
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data = self.__buf[i:j]
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if len(data) < 4:
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raise EOFError
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return struct.unpack('l', data)[0]
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def unpack_int(self):
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x = self.unpack_uint()
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if x >= 0x80000000L:
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x = x - 0x100000000L
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return int(x)
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unpack_enum = unpack_int
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unpack_bool = unpack_int
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def unpack_uhyper(self):
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hi = self.unpack_uint()
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lo = self.unpack_uint()
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return long(hi)<<32 | lo
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def unpack_hyper(self):
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x = self.unpack_uhyper()
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if x >= 0x8000000000000000L:
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x = x - 0x10000000000000000L
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return x
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def unpack_float(self):
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raise ConversionError('Not supported')
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def unpack_double(self):
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raise ConversionError('Not supported')
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# get these from the C layer if available
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if _xdr:
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def unpack_float(self):
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i = self.__pos
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self.__pos = j = i+4
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data = self.__buf[i:j]
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if len(data) < 4:
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raise EOFError
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try: return _xdr.unpack_float(data)
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except _xdr.error, msg:
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raise ConversionError(msg)
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def unpack_double(self):
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i = self.__pos
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self.__pos = j = i+8
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data = self.__buf[i:j]
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if len(data) < 8:
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raise EOFError
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try: return _xdr.unpack_double(data)
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except _xdr.error, msg:
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raise ConversionError(msg)
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def unpack_fstring(self, n):
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if n < 0:
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raise ValueError, 'fstring size must be nonnegative'
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i = self.__pos
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j = i + (n+3)/4*4
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if j > len(self.__buf):
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raise EOFError
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self.__pos = j
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return self.__buf[i:i+n]
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unpack_fopaque = unpack_fstring
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def unpack_string(self):
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n = self.unpack_uint()
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return self.unpack_fstring(n)
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unpack_opaque = unpack_string
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unpack_bytes = unpack_string
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def unpack_list(self, unpack_item):
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list = []
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while 1:
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x = self.unpack_uint()
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if x == 0: break
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if x <> 1:
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raise ConversionError('0 or 1 expected, got ' + `x`)
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item = unpack_item()
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list.append(item)
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return list
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def unpack_farray(self, n, unpack_item):
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list = []
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for i in range(n):
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list.append(unpack_item())
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return list
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def unpack_array(self, unpack_item):
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n = self.unpack_uint()
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return self.unpack_farray(n, unpack_item)
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# test suite
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def _test():
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p = Packer()
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packtest = [
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(p.pack_uint, (9,)),
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(p.pack_bool, (None,)),
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(p.pack_bool, ('hello',)),
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(p.pack_uhyper, (45L,)),
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(p.pack_float, (1.9,)),
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(p.pack_double, (1.9,)),
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(p.pack_string, ('hello world',)),
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(p.pack_list, (range(5), p.pack_uint)),
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(p.pack_array, (['what', 'is', 'hapnin', 'doctor'], p.pack_string)),
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]
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succeedlist = [1] * len(packtest)
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count = 0
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for method, args in packtest:
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print 'pack test', count,
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try:
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apply(method, args)
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print 'succeeded'
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except ConversionError, var:
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print 'ConversionError:', var.msg
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succeedlist[count] = 0
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count = count + 1
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data = p.get_buffer()
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# now verify
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up = Unpacker(data)
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unpacktest = [
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(up.unpack_uint, (), lambda x: x == 9),
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(up.unpack_bool, (), lambda x: not x),
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(up.unpack_bool, (), lambda x: x),
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(up.unpack_uhyper, (), lambda x: x == 45L),
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(up.unpack_float, (), lambda x: 1.89 < x < 1.91),
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(up.unpack_double, (), lambda x: 1.89 < x < 1.91),
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(up.unpack_string, (), lambda x: x == 'hello world'),
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(up.unpack_list, (up.unpack_uint,), lambda x: x == range(5)),
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(up.unpack_array, (up.unpack_string,),
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lambda x: x == ['what', 'is', 'hapnin', 'doctor']),
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]
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count = 0
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for method, args, pred in unpacktest:
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print 'unpack test', count,
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try:
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if succeedlist[count]:
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x = apply(method, args)
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print pred(x) and 'succeeded' or 'failed', ':', x
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else:
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print 'skipping'
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except ConversionError, var:
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print 'ConversionError:', var.msg
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count = count + 1
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if __name__ == '__main__':
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_test()
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