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from dataclasses import dataclass, field
from typing import Any, Callable, Mapping
from .. import ClosedResourceError, DelimiterNotFound, EndOfStream, IncompleteRead
from ..abc import AnyByteReceiveStream, ByteReceiveStream
@dataclass(eq=False)
class BufferedByteReceiveStream(ByteReceiveStream):
"""
Wraps any bytes-based receive stream and uses a buffer to provide sophisticated receiving
capabilities in the form of a byte stream.
"""
receive_stream: AnyByteReceiveStream
_buffer: bytearray = field(init=False, default_factory=bytearray)
_closed: bool = field(init=False, default=False)
async def aclose(self) -> None:
await self.receive_stream.aclose()
self._closed = True
@property
def buffer(self) -> bytes:
"""The bytes currently in the buffer."""
return bytes(self._buffer)
@property
def extra_attributes(self) -> Mapping[Any, Callable[[], Any]]:
return self.receive_stream.extra_attributes
async def receive(self, max_bytes: int = 65536) -> bytes:
if self._closed:
raise ClosedResourceError
if self._buffer:
chunk = bytes(self._buffer[:max_bytes])
del self._buffer[:max_bytes]
return chunk
elif isinstance(self.receive_stream, ByteReceiveStream):
return await self.receive_stream.receive(max_bytes)
else:
# With a bytes-oriented object stream, we need to handle any surplus bytes we get from
# the receive() call
chunk = await self.receive_stream.receive()
if len(chunk) > max_bytes:
# Save the surplus bytes in the buffer
self._buffer.extend(chunk[max_bytes:])
return chunk[:max_bytes]
else:
return chunk
async def receive_exactly(self, nbytes: int) -> bytes:
"""
Read exactly the given amount of bytes from the stream.
:param nbytes: the number of bytes to read
:return: the bytes read
:raises ~anyio.IncompleteRead: if the stream was closed before the requested
amount of bytes could be read from the stream
"""
while True:
remaining = nbytes - len(self._buffer)
if remaining <= 0:
retval = self._buffer[:nbytes]
del self._buffer[:nbytes]
return bytes(retval)
try:
if isinstance(self.receive_stream, ByteReceiveStream):
chunk = await self.receive_stream.receive(remaining)
else:
chunk = await self.receive_stream.receive()
except EndOfStream as exc:
raise IncompleteRead from exc
self._buffer.extend(chunk)
async def receive_until(self, delimiter: bytes, max_bytes: int) -> bytes:
"""
Read from the stream until the delimiter is found or max_bytes have been read.
:param delimiter: the marker to look for in the stream
:param max_bytes: maximum number of bytes that will be read before raising
:exc:`~anyio.DelimiterNotFound`
:return: the bytes read (not including the delimiter)
:raises ~anyio.IncompleteRead: if the stream was closed before the delimiter
was found
:raises ~anyio.DelimiterNotFound: if the delimiter is not found within the
bytes read up to the maximum allowed
"""
delimiter_size = len(delimiter)
offset = 0
while True:
# Check if the delimiter can be found in the current buffer
index = self._buffer.find(delimiter, offset)
if index >= 0:
found = self._buffer[:index]
del self._buffer[: index + len(delimiter) :]
return bytes(found)
# Check if the buffer is already at or over the limit
if len(self._buffer) >= max_bytes:
raise DelimiterNotFound(max_bytes)
# Read more data into the buffer from the socket
try:
data = await self.receive_stream.receive()
except EndOfStream as exc:
raise IncompleteRead from exc
# Move the offset forward and add the new data to the buffer
offset = max(len(self._buffer) - delimiter_size + 1, 0)
self._buffer.extend(data)
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