Python库 | construct-2.8.3.tar.gz

# -*- coding: utf-8 -*- import struct as packer from struct import Struct as Packer from struct import error as PackerError from io import BytesIO, StringIO from binascii import hexlify import sys import collections import codecs from construct.lib.container import Container, FlagsContainer, ListContainer, LazyContainer, LazyRangeContainer, LazySequenceContainer from construct.lib.binary import integer2bits, integer2bytes, onebit2integer, bits2integer, bytes2integer, bytes2bits, bits2bytes, swapbytes from construct.lib.bitstream import RestreamedBytesIO, RebufferedBytesIO from construct.lib.hex import HexString, hexdump, hexundump from construct.lib.py3compat import PY2, PY3, PY26, PY32, PY33, PYPY, stringtypes, int2byte, byte2int, str2bytes, bytes2str, str2unicode, unicode2str, iteratebytes, iterateints #=============================================================================== # exceptions #=============================================================================== class ConstructError(Exception): pass class FieldError(ConstructError): pass class SizeofError(ConstructError): pass class AdaptationError(ConstructError): pass class ArrayError(ConstructError): pass class RangeError(ConstructError): pass class SwitchError(ConstructError): pass class SelectError(ConstructError): pass class UnionError(ConstructError): pass class TerminatorError(ConstructError): pass class OverwriteError(ConstructError): pass class PaddingError(ConstructError): pass class ConstError(ConstructError): pass class StringError(ConstructError): pass class ChecksumError(ConstructError): pass class ValidationError(ConstructError): pass class BitIntegerError(ConstructError): pass class MappingError(AdaptationError): pass #=============================================================================== # internal code #=============================================================================== def singleton(cls): return cls() def singletonfunction(func): return func() def _read_stream(stream, length): # if not isinstance(length, int): # raise TypeError("expected length to be int") if length < 0: raise ValueError("length must be >= 0", length) data = stream.read(length) if len(data) != length: raise FieldError("could not read enough bytes, expected %d, found %d" % (length, len(data))) return data def _write_stream(stream, length, data): # if not isinstance(data, bytes): # raise TypeError("expected data to be a bytes") if length < 0: raise ValueError("length must be >= 0", length) if len(data) != length: raise FieldError("could not write bytes, expected %d, found %d" % (length, len(data))) written = stream.write(data) if written != length: raise FieldError("could not write bytes, written %d, should %d" % (written, length)) def _subobj(sc, obj): if sc.flagembedded: return obj else: return obj[sc.name] def _updcon(con, sc, obj): if sc.flagembedded: con.update(obj) else: con[sc.name] = obj #=============================================================================== # abstract constructs #=============================================================================== class Construct(object): r""" The mother of all constructs. This object is generally not directly instantiated, and it does not directly implement parsing and building, so it is largely only of interest to subclass implementors. There are also other abstract classes. The external user API: * ``parse()`` * ``parse_stream()`` * ``build()`` * ``build_stream()`` * ``sizeof()`` Subclass authors should not override the external methods. Instead, another API is available: * ``_parse()`` * ``_build()`` * ``_sizeof()`` There is also a flag API: * ``_inherit_flags()`` And stateful copying: * ``__getstate__()`` * ``__setstate__()`` Attributes and Inheritance ========================== All constructs have a name and flags. The name is used for naming struct members and context dictionaries. Note that the name can either be a string, or None if the name is not needed. A single underscore ("_") is a reserved name, and so are names starting with a less-than character ("<"). The name should be descriptive, short, and valid as a Python identifier, although these rules are not enforced. The flags specify additional behavioral information about this construct. Flags are used by enclosing constructs to determine a proper course of action. Flags are inherited by default, from inner subconstructs to outer constructs. The enclosing construct may set new flags or clear existing ones, as necessary. """ __slots__ = ["name", "flagbuildnone", "flagembedded"] def __init__(self): self.name = None self.flagbuildnone = False self.flagembedded = False def __repr__(self): return "<%s: %s%s%s>" % (self.__class__.__name__, self.name, " +nonbuild" if self.flagbuildnone else "", " +embedded" if self.flagembedded else "") def _inherit_flags(self, *subcons): for sc in subcons: self.flagbuildnone |= sc.flagbuildnone self.flagembedded |= sc.flagembedded def __getstate__(self): # Obtain a dictionary representing this construct's state. attrs = {} if hasattr(self, "__dict__"): attrs.update(self.__dict__) slots = [] c = self.__class__ while c is not None: if hasattr(c, "__slots__"): slots.extend(c.__slots__) c = c.__base__ for name in slots: if hasattr(self, name): attrs[name] = getattr(self, name) return attrs def __setstate__(self, attrs): # Set this construct's state to a given state. for name, value in attrs.items(): setattr(self, name, value) def __copy__(self): # Returns a copy of this construct. self2 = object.__new__(self.__class__) self2.__setstate__(self, self.__getstate__()) return self2 def parse(self, data, context=None, **kw): """ Parse an in-memory buffer. Strings, buffers, memoryviews, and other complete buffers can be parsed with this method. """ return self.parse_stream(BytesIO(data), context, **kw) def parse_stream(self, stream, context=None, **kw): """ Parse a stream. Files, pipes, sockets, and other streaming sources of data are handled by this method. """ if context is None: context = Container() context.update(kw) return self._parse(stream, context) def _parse(self, stream, context): """ Override in your subclass. :returns: some value, usually based on bytes read from the stream but sometimes it is computed from nothing or context """ raise NotImplementedError() def build(self, obj, context=None, **kw): """ Build an object in memory. :returns: bytes """ stream = BytesIO() self.build_stream(obj, stream, context, **kw) return stream.getvalue() def build_stream(self, obj, stream, context=None, **kw): """ Build an object directly into a stream. :returns: None """ if context is None: context = Container() context.update(kw) self._build(obj, stream, context) def _build(self, obj, stream, context): """ Override in your subclass. :returns: None or a new value to put into context, few fields use this """ raise NotImplementedError() def sizeof(self, context=None, **kw): """ Calculate the size of this object, optionally using a context.