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https://github.com/iKarith/cppo-ng.git
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2c44e50316
If you read one index from a bytes or bytearray, you get an int, not a single character bytes object. Originally I didn't want to mimic that feature because it's actually somewhat annoying at times. Realizing it was done that way for a reason, and not doing it in ByteBuffer is gonna be even more annoying.
141 lines
3.9 KiB
Python
141 lines
3.9 KiB
Python
# vim: set tabstop=4 shiftwidth=4 noexpandtab filetype=python:
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# Copyright (C) 2017 T. Joseph Carter
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#
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# This program is free software; you can redistribute it and/or modify it
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# under the terms of the GNU General Public License as published by the
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# Free Software Foundation; either version 2 of the License, or (at your
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# option) any later version.
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#
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# This program is distributed in the hope that it will be useful, but
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# WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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# or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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# for more details.
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#
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# You should have received a copy of the GNU General Public License along
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# with this program; if not, write to the Free Software Foundation, Inc.,
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# 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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from typing import Dict, List, Optional, Union
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from .buffertype import BufferType
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from .. import util
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class ByteBuffer(BufferType):
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"""ByteBuffer(bytes_or_int[, changed[, locked]]) -> ByteBuffer
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Create a BufferType object in memory. If an int is provided, the buffer
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will be zero-filled. If it is a bytes-type object, the object will be
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copied into the buffer.
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"""
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def __init__(
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self,
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bytes_or_int: Union[bytes,int],
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changed: bool = False,
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locked: bool = False
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) -> None:
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self._buf = bytearray(bytes_or_int)
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self._changed = changed
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self._locked = locked
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def __len__(self) -> int:
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"""Return len(self)"""
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return len(self._buf)
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def read(
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self,
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start: int = 0,
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count: int = 1,
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limit: bool = True
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) -> bytearray:
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"""Return bytearray of count bytes from buffer beginning at start
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By default, an IndexError will be raised if you read past the end of
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the buffer. Pass limit=False if reads outside the buffer should just
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return trncated or empty results as with python slicing
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"""
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if count is None:
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count = len(self)
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try:
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assert(start >= 0)
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assert(count >= 0)
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if limit == True:
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assert(start + count <= len(self._buf))
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except AssertionError:
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raise IndexError('buffer read with index out of range')
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ret = self._buf[start:start + count]
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return bytes(ret) if count != 1 else int(ret[0])
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def write(
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self,
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buf: bytes,
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start: int,
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count: Optional[int] = None,
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limit: bool = True
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) -> None:
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"""Writes bytes to buffer beginning at start
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If count is not supplied, the entire bytes-like object will be written
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to the buffer. An IndexError will be raised if the write would extend
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past the end of the buffer. Pass limit=False
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"""
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if self.locked:
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raise BufferError('cannot write to locked buffer')
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if not count:
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count = len(buf)
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try:
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assert(start >= 0)
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assert(count >= 0)
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if limit == True:
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assert(start + count <= len(self._buf))
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except AssertionError:
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raise IndexError('buffer write with index out of range')
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self._buf[start:start+count] = buf
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self._changed = True
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def resize(self, size):
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"""Resize buffer to size
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If size is larger than len(self), the buffer is appended with zero
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bytes. If it is smaller, the buffer will be truncated.
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"""
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if self.locked:
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raise BufferError('cannot write to locked buffer')
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if size <= len(self._buf):
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del self._buf[size:]
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else:
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self._buf.append(bytes(size - len(self._buf)))
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self._changed = True
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@property
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def locked(self):
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"""Returns True for read-only buffers."""
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return self._locked
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@locked.setter
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def locked(self, value: bool) -> None:
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self._locked = value
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def __repr__(self):
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"""Return repr(self)
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This will be a very long string for any buffer of non-trivial length
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"""
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return 'ByteBuffer({_buf}, {_changed}, {_locked})'.format_map(
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vars(self))
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def __str__(self) -> str:
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"""Implement str(self)"""
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return '<ByteBuffer of {} bytes>'.format(len(self._buf))
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def hexdump(self, *args: List, **kwargs: Dict) -> None:
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"""Performas a canonical hexdump of self.
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Args:
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Any for blocksfree.util.hexdump, see that function for details.
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"""
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util.hexdump(self._buf, *args, **kwargs)
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