Staging
v0.5.1
v0.5.1
https://github.com/python/cpython
Tip revision: 659fc426531517e09eb53cccc8ab4e861d8e0c22 authored by Barry Warsaw on 01 March 2008, 17:45:23 UTC
Copyright and version tweaks for 3.0a3.
Copyright and version tweaks for 3.0a3.
Tip revision: 659fc42
io.py
"""New I/O library conforming to PEP 3116.
This is a prototype; hopefully eventually some of this will be
reimplemented in C.
Conformance of alternative implementations: all arguments are intended
to be positional-only except the arguments of the open() function.
Argument names except those of the open() function are not part of the
specification. Instance variables and methods whose name starts with
a leading underscore are not part of the specification (except "magic"
names like __iter__). Only the top-level names listed in the __all__
variable are part of the specification.
XXX edge cases when switching between reading/writing
XXX need to support 1 meaning line-buffered
XXX whenever an argument is None, use the default value
XXX read/write ops should check readable/writable
XXX buffered readinto should work with arbitrary buffer objects
XXX use incremental encoder for text output, at least for UTF-16 and UTF-8-SIG
XXX check writable, readable and seekable in appropriate places
"""
__author__ = ("Guido van Rossum <guido@python.org>, "
"Mike Verdone <mike.verdone@gmail.com>, "
"Mark Russell <mark.russell@zen.co.uk>")
__all__ = ["BlockingIOError", "open", "IOBase", "RawIOBase", "FileIO",
"BytesIO", "StringIO", "BufferedIOBase",
"BufferedReader", "BufferedWriter", "BufferedRWPair",
"BufferedRandom", "TextIOBase", "TextIOWrapper"]
import os
import abc
import sys
import codecs
import _fileio
import warnings
# open() uses st_blksize whenever we can
DEFAULT_BUFFER_SIZE = 8 * 1024 # bytes
class BlockingIOError(IOError):
"""Exception raised when I/O would block on a non-blocking I/O stream."""
def __init__(self, errno, strerror, characters_written=0):
IOError.__init__(self, errno, strerror)
self.characters_written = characters_written
def open(file, mode="r", buffering=None, encoding=None, errors=None,
newline=None, closefd=True):
r"""Replacement for the built-in open function.
Args:
file: string giving the name of the file to be opened;
or integer file descriptor of the file to be wrapped (*).
mode: optional mode string; see below.
buffering: optional int >= 0 giving the buffer size; values
can be: 0 = unbuffered, 1 = line buffered,
larger = fully buffered.
encoding: optional string giving the text encoding.
errors: optional string giving the encoding error handling.
newline: optional newlines specifier; must be None, '', '\n', '\r'
or '\r\n'; all other values are illegal. It controls the
handling of line endings. It works as follows:
* On input, if `newline` is `None`, universal newlines
mode is enabled. Lines in the input can end in `'\n'`,
`'\r'`, or `'\r\n'`, and these are translated into
`'\n'` before being returned to the caller. If it is
`''`, universal newline mode is enabled, but line endings
are returned to the caller untranslated. If it has any of
the other legal values, input lines are only terminated by
the given string, and the line ending is returned to the
caller untranslated.
* On output, if `newline` is `None`, any `'\n'`
characters written are translated to the system default
line separator, `os.linesep`. If `newline` is `''`,
no translation takes place. If `newline` is any of the
other legal values, any `'\n'` characters written are
translated to the given string.
closefd: optional argument to keep the underlying file descriptor
open when the file is closed. It must not be false when
a filename is given.
(*) If a file descriptor is given, it is closed when the returned
I/O object is closed, unless closefd=False is given.
Mode strings characters:
'r': open for reading (default)
'w': open for writing, truncating the file first
'a': open for writing, appending to the end if the file exists
'b': binary mode
't': text mode (default)
'+': open a disk file for updating (implies reading and writing)
'U': universal newline mode (for backwards compatibility)
Constraints:
- encoding or errors must not be given when a binary mode is given
- buffering must not be zero when a text mode is given
Returns:
Depending on the mode and buffering arguments, either a raw
binary stream, a buffered binary stream, or a buffered text
stream, open for reading and/or writing.
"""
if not isinstance(file, (str, int)):
raise TypeError("invalid file: %r" % file)
if not isinstance(mode, str):
raise TypeError("invalid mode: %r" % mode)
if buffering is not None and not isinstance(buffering, int):
raise TypeError("invalid buffering: %r" % buffering)
if encoding is not None and not isinstance(encoding, str):
raise TypeError("invalid encoding: %r" % encoding)
if errors is not None and not isinstance(errors, str):
raise TypeError("invalid errors: %r" % errors)
modes = set(mode)
if modes - set("arwb+tU") or len(mode) > len(modes):
raise ValueError("invalid mode: %r" % mode)
reading = "r" in modes
writing = "w" in modes
appending = "a" in modes
updating = "+" in modes
text = "t" in modes
binary = "b" in modes
if "U" in modes:
if writing or appending:
raise ValueError("can't use U and writing mode at once")
reading = True
if text and binary:
raise ValueError("can't have text and binary mode at once")
if reading + writing + appending > 1:
raise ValueError("can't have read/write/append mode at once")
if not (reading or writing or appending):
raise ValueError("must have exactly one of read/write/append mode")
if binary and encoding is not None:
raise ValueError("binary mode doesn't take an encoding argument")
if binary and errors is not None:
raise ValueError("binary mode doesn't take an errors argument")
if binary and newline is not None:
raise ValueError("binary mode doesn't take a newline argument")
raw = FileIO(file,
(reading and "r" or "") +
(writing and "w" or "") +
(appending and "a" or "") +
(updating and "+" or ""),
closefd)
if buffering is None:
buffering = -1
line_buffering = False
if buffering == 1 or buffering < 0 and raw.isatty():
buffering = -1
line_buffering = True
if buffering < 0:
buffering = DEFAULT_BUFFER_SIZE
try:
bs = os.fstat(raw.fileno()).st_blksize
except (os.error, AttributeError):
pass
else:
if bs > 1:
buffering = bs
if buffering < 0:
raise ValueError("invalid buffering size")
if buffering == 0:
if binary:
raw._name = file
raw._mode = mode
return raw
raise ValueError("can't have unbuffered text I/O")
if updating:
buffer = BufferedRandom(raw, buffering)
elif writing or appending:
buffer = BufferedWriter(raw, buffering)
elif reading:
buffer = BufferedReader(raw, buffering)
else:
raise ValueError("unknown mode: %r" % mode)
if binary:
buffer.name = file
buffer.mode = mode
return buffer
text = TextIOWrapper(buffer, encoding, errors, newline, line_buffering)
text.name = file
text.mode = mode
return text
class _DocDescriptor:
"""Helper for builtins.open.__doc__
"""
def __get__(self, obj, typ):
return (
"open(file, mode='r', buffering=None, encoding=None, "
"errors=None, newline=None, closefd=True)\n\n" +
open.__doc__)
class OpenWrapper:
"""Wrapper for builtins.open
Trick so that open won't become a bound method when stored
as a class variable (as dumbdbm does).
See initstdio() in Python/pythonrun.c.
"""
__doc__ = _DocDescriptor()
def __new__(cls, *args, **kwargs):
return open(*args, **kwargs)
class UnsupportedOperation(ValueError, IOError):
pass
class IOBase(metaclass=abc.ABCMeta):
"""Base class for all I/O classes.
This class provides dummy implementations for many methods that
derived classes can override selectively; the default
implementations represent a file that cannot be read, written or
seeked.
This does not define read(), readinto() and write(), nor
readline() and friends, since their signatures vary per layer.
Not that calling any method (even inquiries) on a closed file is
undefined. Implementations may raise IOError in this case.
"""
### Internal ###
def _unsupported(self, name: str) -> IOError:
"""Internal: raise an exception for unsupported operations."""
raise UnsupportedOperation("%s.%s() not supported" %
(self.__class__.__name__, name))
### Positioning ###
def seek(self, pos: int, whence: int = 0) -> int:
"""seek(pos: int, whence: int = 0) -> int. Change stream position.
Seek to byte offset pos relative to position indicated by whence:
0 Start of stream (the default). pos should be >= 0;
1 Current position - whence may be negative;
2 End of stream - whence usually negative.
Returns the new absolute position.
"""
self._unsupported("seek")
def tell(self) -> int:
"""tell() -> int. Return current stream position."""
return self.seek(0, 1)
def truncate(self, pos: int = None) -> int:
"""truncate(size: int = None) -> int. Truncate file to size bytes.
Size defaults to the current IO position as reported by tell().
Returns the new size.
"""
self._unsupported("truncate")
### Flush and close ###
def flush(self) -> None:
"""flush() -> None. Flushes write buffers, if applicable.
This is a no-op for read-only and non-blocking streams.
"""
# XXX Should this return the number of bytes written???
__closed = False
def close(self) -> None:
"""close() -> None. Flushes and closes the IO object.
This must be idempotent. It should also set a flag for the
'closed' property (see below) to test.
"""
if not self.__closed:
try:
self.flush()
except IOError:
pass # If flush() fails, just give up
self.__closed = True
def __del__(self) -> None:
"""Destructor. Calls close()."""
# The try/except block is in case this is called at program
# exit time, when it's possible that globals have already been
# deleted, and then the close() call might fail. Since
# there's nothing we can do about such failures and they annoy
# the end users, we suppress the traceback.
try:
self.close()
except:
pass
### Inquiries ###
def seekable(self) -> bool:
"""seekable() -> bool. Return whether object supports random access.
If False, seek(), tell() and truncate() will raise IOError.
This method may need to do a test seek().
"""
return False
def _checkSeekable(self, msg=None):
"""Internal: raise an IOError if file is not seekable
"""
if not self.seekable():
raise IOError("File or stream is not seekable."
if msg is None else msg)
def readable(self) -> bool:
"""readable() -> bool. Return whether object was opened for reading.
If False, read() will raise IOError.
"""
return False
def _checkReadable(self, msg=None):
"""Internal: raise an IOError if file is not readable
"""
if not self.readable():
raise IOError("File or stream is not readable."
if msg is None else msg)
def writable(self) -> bool:
"""writable() -> bool. Return whether object was opened for writing.
If False, write() and truncate() will raise IOError.
"""
return False
def _checkWritable(self, msg=None):
"""Internal: raise an IOError if file is not writable
"""
if not self.writable():
raise IOError("File or stream is not writable."
if msg is None else msg)
@property
def closed(self):
"""closed: bool. True iff the file has been closed.
For backwards compatibility, this is a property, not a predicate.
"""
return self.__closed
def _checkClosed(self, msg=None):
"""Internal: raise an ValueError if file is closed
"""
if self.closed:
raise ValueError("I/O operation on closed file."
if msg is None else msg)
### Context manager ###
def __enter__(self) -> "IOBase": # That's a forward reference
"""Context management protocol. Returns self."""
self._checkClosed()
return self
def __exit__(self, *args) -> None:
"""Context management protocol. Calls close()"""
self.close()
### Lower-level APIs ###
# XXX Should these be present even if unimplemented?
def fileno(self) -> int:
"""fileno() -> int. Returns underlying file descriptor if one exists.
Raises IOError if the IO object does not use a file descriptor.
"""
self._unsupported("fileno")
def isatty(self) -> bool:
"""isatty() -> int. Returns whether this is an 'interactive' stream.
Returns False if we don't know.
"""
self._checkClosed()
return False
### Readline[s] and writelines ###
def readline(self, limit: int = -1) -> bytes:
"""For backwards compatibility, a (slowish) readline()."""
if hasattr(self, "peek"):
def nreadahead():
readahead = self.peek(1, unsafe=True)
if not readahead:
return 1
n = (readahead.find(b"\n") + 1) or len(readahead)
if limit >= 0:
n = min(n, limit)
return n
else:
def nreadahead():
return 1
if limit is None:
limit = -1
res = bytearray()
while limit < 0 or len(res) < limit:
b = self.read(nreadahead())
if not b:
break
res += b
if res.endswith(b"\n"):
break
return bytes(res)
def __iter__(self):
self._checkClosed()
return self
def __next__(self):
line = self.readline()
if not line:
raise StopIteration
return line
def readlines(self, hint=None):
if hint is None:
return list(self)
n = 0
lines = []
for line in self:
lines.append(line)
n += len(line)
if n >= hint:
break
return lines
def writelines(self, lines):
self._checkClosed()
for line in lines:
self.write(line)
class RawIOBase(IOBase):
"""Base class for raw binary I/O.
The read() method is implemented by calling readinto(); derived
classes that want to support read() only need to implement
readinto() as a primitive operation. In general, readinto()
can be more efficient than read().
(It would be tempting to also provide an implementation of
readinto() in terms of read(), in case the latter is a more
suitable primitive operation, but that would lead to nasty
recursion in case a subclass doesn't implement either.)
"""
def read(self, n: int = -1) -> bytes:
"""read(n: int) -> bytes. Read and return up to n bytes.
Returns an empty bytes array on EOF, or None if the object is
set not to block and has no data to read.
"""
if n is None:
n = -1
if n < 0:
return self.readall()
b = bytearray(n.__index__())
n = self.readinto(b)
del b[n:]
return bytes(b)
def readall(self):
"""readall() -> bytes. Read until EOF, using multiple read() call."""
res = bytearray()
while True:
data = self.read(DEFAULT_BUFFER_SIZE)
if not data:
break
res += data
return bytes(res)
def readinto(self, b: bytes) -> int:
"""readinto(b: bytes) -> int. Read up to len(b) bytes into b.
Returns number of bytes read (0 for EOF), or None if the object
is set not to block as has no data to read.
"""
self._unsupported("readinto")
def write(self, b: bytes) -> int:
"""write(b: bytes) -> int. Write the given buffer to the IO stream.
Returns the number of bytes written, which may be less than len(b).
"""
self._unsupported("write")
class FileIO(_fileio._FileIO, RawIOBase):
"""Raw I/O implementation for OS files.
This multiply inherits from _FileIO and RawIOBase to make
isinstance(io.FileIO(), io.RawIOBase) return True without
requiring that _fileio._FileIO inherits from io.RawIOBase (which
would be hard to do since _fileio.c is written in C).
"""
def close(self):
_fileio._FileIO.close(self)
RawIOBase.close(self)
@property
def name(self):
return self._name
@property
def mode(self):
return self._mode
class BufferedIOBase(IOBase):
"""Base class for buffered IO objects.
The main difference with RawIOBase is that the read() method
supports omitting the size argument, and does not have a default
implementation that defers to readinto().
In addition, read(), readinto() and write() may raise
BlockingIOError if the underlying raw stream is in non-blocking
mode and not ready; unlike their raw counterparts, they will never
return None.
A typical implementation should not inherit from a RawIOBase
implementation, but wrap one.
"""
def read(self, n: int = None) -> bytes:
"""read(n: int = None) -> bytes. Read and return up to n bytes.
If the argument is omitted, None, or negative, reads and
returns all data until EOF.
If the argument is positive, and the underlying raw stream is
not 'interactive', multiple raw reads may be issued to satisfy
the byte count (unless EOF is reached first). But for
interactive raw streams (XXX and for pipes?), at most one raw
read will be issued, and a short result does not imply that
EOF is imminent.
Returns an empty bytes array on EOF.
Raises BlockingIOError if the underlying raw stream has no
data at the moment.
"""
self._unsupported("read")
def readinto(self, b: bytes) -> int:
"""readinto(b: bytes) -> int. Read up to len(b) bytes into b.
Like read(), this may issue multiple reads to the underlying
raw stream, unless the latter is 'interactive' (XXX or a
pipe?).
Returns the number of bytes read (0 for EOF).
Raises BlockingIOError if the underlying raw stream has no
data at the moment.
"""
# XXX This ought to work with anything that supports the buffer API
data = self.read(len(b))
n = len(data)
try:
b[:n] = data
except TypeError as err:
import array
if not isinstance(b, array.array):
raise err
b[:n] = array.array('b', data)
return n
def write(self, b: bytes) -> int:
"""write(b: bytes) -> int. Write the given buffer to the IO stream.
Returns the number of bytes written, which is never less than
len(b).
Raises BlockingIOError if the buffer is full and the
underlying raw stream cannot accept more data at the moment.
"""
self._unsupported("write")
class _BufferedIOMixin(BufferedIOBase):
"""A mixin implementation of BufferedIOBase with an underlying raw stream.
This passes most requests on to the underlying raw stream. It
does *not* provide implementations of read(), readinto() or
write().
"""
def __init__(self, raw):
self.raw = raw
### Positioning ###
def seek(self, pos, whence=0):
return self.raw.seek(pos, whence)
def tell(self):
return self.raw.tell()
def truncate(self, pos=None):
# Flush the stream. We're mixing buffered I/O with lower-level I/O,
# and a flush may be necessary to synch both views of the current
# file state.
self.flush()
if pos is None:
pos = self.tell()
return self.raw.truncate(pos)
### Flush and close ###
def flush(self):
self.raw.flush()
def close(self):
if not self.closed:
try:
self.flush()
except IOError:
pass # If flush() fails, just give up
self.raw.close()
### Inquiries ###
def seekable(self):
return self.raw.seekable()
def readable(self):
return self.raw.readable()
def writable(self):
return self.raw.writable()
@property
def closed(self):
return self.raw.closed
### Lower-level APIs ###
def fileno(self):
return self.raw.fileno()
def isatty(self):
return self.raw.isatty()
class BytesIO(BufferedIOBase):
"""Buffered I/O implementation using an in-memory bytes buffer."""
# XXX More docs
def __init__(self, initial_bytes=None):
buf = bytearray()
if initial_bytes is not None:
buf += initial_bytes
self._buffer = buf
self._pos = 0
def getvalue(self):
return bytes(self._buffer)
def read(self, n=None):
if n is None:
n = -1
if n < 0:
n = len(self._buffer)
newpos = min(len(self._buffer), self._pos + n)
b = self._buffer[self._pos : newpos]
self._pos = newpos
return bytes(b)
def read1(self, n):
return self.read(n)
def write(self, b):
if self.closed:
raise ValueError("write to closed file")
if isinstance(b, str):
raise TypeError("can't write str to binary stream")
n = len(b)
newpos = self._pos + n
if newpos > len(self._buffer):
# Inserts null bytes between the current end of the file
# and the new write position.
padding = b'\x00' * (newpos - len(self._buffer) - n)
self._buffer[self._pos:newpos - n] = padding
self._buffer[self._pos:newpos] = b
self._pos = newpos
return n
def seek(self, pos, whence=0):
try:
pos = pos.__index__()
except AttributeError as err:
raise TypeError("an integer is required") from err
if whence == 0:
self._pos = max(0, pos)
elif whence == 1:
self._pos = max(0, self._pos + pos)
elif whence == 2:
self._pos = max(0, len(self._buffer) + pos)
else:
raise IOError("invalid whence value")
return self._pos
def tell(self):
return self._pos
def truncate(self, pos=None):
if pos is None:
pos = self._pos
del self._buffer[pos:]
return pos
def readable(self):
return True
def writable(self):
return True
def seekable(self):
return True
class BufferedReader(_BufferedIOMixin):
"""Buffer for a readable sequential RawIO object."""
def __init__(self, raw, buffer_size=DEFAULT_BUFFER_SIZE):
"""Create a new buffered reader using the given readable raw IO object.
"""
raw._checkReadable()
_BufferedIOMixin.__init__(self, raw)
self._read_buf = b""
self.buffer_size = buffer_size
def read(self, n=None):
"""Read n bytes.
Returns exactly n bytes of data unless the underlying raw IO
stream reaches EOF or if the call would block in non-blocking
mode. If n is negative, read until EOF or until read() would
block.
"""
if n is None:
n = -1
nodata_val = b""
while n < 0 or len(self._read_buf) < n:
to_read = max(self.buffer_size,
n if n is not None else 2*len(self._read_buf))
current = self.raw.read(to_read)
if current in (b"", None):
nodata_val = current
break
self._read_buf += current
if self._read_buf:
if n < 0:
n = len(self._read_buf)
out = self._read_buf[:n]
self._read_buf = self._read_buf[n:]
else:
out = nodata_val
return out
def peek(self, n=0, *, unsafe=False):
"""Returns buffered bytes without advancing the position.
The argument indicates a desired minimal number of bytes; we
do at most one raw read to satisfy it. We never return more
than self.buffer_size.
Unless unsafe=True is passed, we return a copy.
"""
want = min(n, self.buffer_size)
have = len(self._read_buf)
if have < want:
to_read = self.buffer_size - have
current = self.raw.read(to_read)
if current:
self._read_buf += current
result = self._read_buf
if unsafe:
result = result[:]
return result
def read1(self, n):
"""Reads up to n bytes.
Returns up to n bytes. If at least one byte is buffered,
we only return buffered bytes. Otherwise, we do one
raw read.
"""
if n <= 0:
return b""
self.peek(1, unsafe=True)
return self.read(min(n, len(self._read_buf)))
def tell(self):
return self.raw.tell() - len(self._read_buf)
def seek(self, pos, whence=0):
if whence == 1:
pos -= len(self._read_buf)
pos = self.raw.seek(pos, whence)
self._read_buf = b""
return pos
class BufferedWriter(_BufferedIOMixin):
# XXX docstring
def __init__(self, raw,
buffer_size=DEFAULT_BUFFER_SIZE, max_buffer_size=None):
raw._checkWritable()
_BufferedIOMixin.__init__(self, raw)
self.buffer_size = buffer_size
self.max_buffer_size = (2*buffer_size
if max_buffer_size is None
else max_buffer_size)
self._write_buf = bytearray()
def write(self, b):
if self.closed:
raise ValueError("write to closed file")
if isinstance(b, str):
raise TypeError("can't write str to binary stream")
# XXX we can implement some more tricks to try and avoid partial writes
if len(self._write_buf) > self.buffer_size:
# We're full, so let's pre-flush the buffer
try:
self.flush()
except BlockingIOError as e:
# We can't accept anything else.
# XXX Why not just let the exception pass through?
raise BlockingIOError(e.errno, e.strerror, 0)
before = len(self._write_buf)
self._write_buf.extend(b)
written = len(self._write_buf) - before
if len(self._write_buf) > self.buffer_size:
try:
self.flush()
except BlockingIOError as e:
if (len(self._write_buf) > self.max_buffer_size):
# We've hit max_buffer_size. We have to accept a partial
# write and cut back our buffer.
overage = len(self._write_buf) - self.max_buffer_size
self._write_buf = self._write_buf[:self.max_buffer_size]
raise BlockingIOError(e.errno, e.strerror, overage)
return written
def flush(self):
if self.closed:
raise ValueError("flush of closed file")
written = 0
try:
while self._write_buf:
n = self.raw.write(self._write_buf)
del self._write_buf[:n]
written += n
except BlockingIOError as e:
n = e.characters_written
del self._write_buf[:n]
written += n
raise BlockingIOError(e.errno, e.strerror, written)
def tell(self):
return self.raw.tell() + len(self._write_buf)
def seek(self, pos, whence=0):
self.flush()
return self.raw.seek(pos, whence)
class BufferedRWPair(BufferedIOBase):
"""A buffered reader and writer object together.
A buffered reader object and buffered writer object put together
to form a sequential IO object that can read and write.
This is typically used with a socket or two-way pipe.
XXX The usefulness of this (compared to having two separate IO
objects) is questionable.
"""
def __init__(self, reader, writer,
buffer_size=DEFAULT_BUFFER_SIZE, max_buffer_size=None):
"""Constructor.
The arguments are two RawIO instances.
"""
reader._checkReadable()
writer._checkWritable()
self.reader = BufferedReader(reader, buffer_size)
self.writer = BufferedWriter(writer, buffer_size, max_buffer_size)
def read(self, n=None):
if n is None:
n = -1
return self.reader.read(n)
def readinto(self, b):
return self.reader.readinto(b)
def write(self, b):
return self.writer.write(b)
def peek(self, n=0, *, unsafe=False):
return self.reader.peek(n, unsafe=unsafe)
def read1(self, n):
return self.reader.read1(n)
def readable(self):
return self.reader.readable()
def writable(self):
return self.writer.writable()
def flush(self):
return self.writer.flush()
def close(self):
self.writer.close()
self.reader.close()
def isatty(self):
return self.reader.isatty() or self.writer.isatty()
@property
def closed(self):
return self.writer.closed()
class BufferedRandom(BufferedWriter, BufferedReader):
# XXX docstring
def __init__(self, raw,
buffer_size=DEFAULT_BUFFER_SIZE, max_buffer_size=None):
raw._checkSeekable()
BufferedReader.__init__(self, raw, buffer_size)
BufferedWriter.__init__(self, raw, buffer_size, max_buffer_size)
def seek(self, pos, whence=0):
self.flush()
# First do the raw seek, then empty the read buffer, so that
# if the raw seek fails, we don't lose buffered data forever.
pos = self.raw.seek(pos, whence)
self._read_buf = b""
return pos
def tell(self):
if (self._write_buf):
return self.raw.tell() + len(self._write_buf)
else:
return self.raw.tell() - len(self._read_buf)
def read(self, n=None):
if n is None:
n = -1
self.flush()
return BufferedReader.read(self, n)
def readinto(self, b):
self.flush()
return BufferedReader.readinto(self, b)
def peek(self, n=0, *, unsafe=False):
self.flush()
return BufferedReader.peek(self, n, unsafe=unsafe)
def read1(self, n):
self.flush()
return BufferedReader.read1(self, n)
def write(self, b):
if self._read_buf:
self.raw.seek(-len(self._read_buf), 1) # Undo readahead
self._read_buf = b""
return BufferedWriter.write(self, b)
class TextIOBase(IOBase):
"""Base class for text I/O.
This class provides a character and line based interface to stream I/O.
There is no readinto() method, as character strings are immutable.
"""
def read(self, n: int = -1) -> str:
"""read(n: int = -1) -> str. Read at most n characters from stream.
Read from underlying buffer until we have n characters or we hit EOF.
If n is negative or omitted, read until EOF.
"""
self._unsupported("read")
def write(self, s: str) -> int:
"""write(s: str) -> int. Write string s to stream."""
self._unsupported("write")
def truncate(self, pos: int = None) -> int:
"""truncate(pos: int = None) -> int. Truncate size to pos."""
self.flush()
if pos is None:
pos = self.tell()
self.seek(pos)
return self.buffer.truncate()
def readline(self) -> str:
"""readline() -> str. Read until newline or EOF.
Returns an empty string if EOF is hit immediately.
"""
self._unsupported("readline")
@property
def encoding(self):
"""Subclasses should override."""
return None
@property
def newlines(self):
"""newlines -> None | str | tuple of str. Line endings translated
so far.
Only line endings translated during reading are considered.
Subclasses should override.
"""
return None
class IncrementalNewlineDecoder(codecs.IncrementalDecoder):
"""Codec used when reading a file in universal newlines mode.
It wraps another incremental decoder, translating \\r\\n and \\r into \\n.
It also records the types of newlines encountered.
When used with translate=False, it ensures that the newline sequence is
returned in one piece.
"""
def __init__(self, decoder, translate, errors='strict'):
codecs.IncrementalDecoder.__init__(self, errors=errors)
self.buffer = b''
self.translate = translate
self.decoder = decoder
self.seennl = 0
def decode(self, input, final=False):
# decode input (with the eventual \r from a previous pass)
if self.buffer:
input = self.buffer + input
output = self.decoder.decode(input, final=final)
# retain last \r even when not translating data:
# then readline() is sure to get \r\n in one pass
if output.endswith("\r") and not final:
output = output[:-1]
self.buffer = b'\r'
else:
self.buffer = b''
# Record which newlines are read
crlf = output.count('\r\n')
cr = output.count('\r') - crlf
lf = output.count('\n') - crlf
self.seennl |= (lf and self._LF) | (cr and self._CR) \
| (crlf and self._CRLF)
if self.translate:
if crlf:
output = output.replace("\r\n", "\n")
if cr:
output = output.replace("\r", "\n")
return output
def getstate(self):
buf, flag = self.decoder.getstate()
return buf + self.buffer, flag
def setstate(self, state):
buf, flag = state
if buf.endswith(b'\r'):
self.buffer = b'\r'
buf = buf[:-1]
else:
self.buffer = b''
self.decoder.setstate((buf, flag))
def reset(self):
self.seennl = 0
self.buffer = b''
self.decoder.reset()
_LF = 1
_CR = 2
_CRLF = 4
@property
def newlines(self):
return (None,
"\n",
"\r",
("\r", "\n"),
"\r\n",
("\n", "\r\n"),
("\r", "\r\n"),
("\r", "\n", "\r\n")
)[self.seennl]
class TextIOWrapper(TextIOBase):
"""Buffered text stream.
Character and line based layer over a BufferedIOBase object.
"""
_CHUNK_SIZE = 128
def __init__(self, buffer, encoding=None, errors=None, newline=None,
line_buffering=False):
if newline not in (None, "", "\n", "\r", "\r\n"):
raise ValueError("illegal newline value: %r" % (newline,))
if encoding is None:
try:
encoding = os.device_encoding(buffer.fileno())
except (AttributeError, UnsupportedOperation):
pass
if encoding is None:
try:
import locale
except ImportError:
# Importing locale may fail if Python is being built
encoding = "ascii"
else:
encoding = locale.getpreferredencoding()
if not isinstance(encoding, str):
raise ValueError("invalid encoding: %r" % encoding)
if errors is None:
errors = "strict"
else:
if not isinstance(errors, str):
raise ValueError("invalid errors: %r" % errors)
self.buffer = buffer
self._line_buffering = line_buffering
self._encoding = encoding
self._errors = errors
self._readuniversal = not newline
self._readtranslate = newline is None
self._readnl = newline
self._writetranslate = newline != ''
self._writenl = newline or os.linesep
self._encoder = None
self._decoder = None
self._pending = ""
self._snapshot = None
self._seekable = self._telling = self.buffer.seekable()
@property
def encoding(self):
return self._encoding
@property
def errors(self):
return self._errors
@property
def line_buffering(self):
return self._line_buffering
# A word about _snapshot. This attribute is either None, or a
# tuple (decoder_state, readahead, pending) where decoder_state is
# the second (integer) item of the decoder state, readahead is the
# chunk of bytes that was read, and pending is the characters that
# were rendered by the decoder after feeding it those bytes. We
# use this to reconstruct intermediate decoder states in tell().
def _seekable(self):
return self._seekable
def flush(self):
self.buffer.flush()
self._telling = self._seekable
def close(self):
try:
self.flush()
except:
pass # If flush() fails, just give up
self.buffer.close()
@property
def closed(self):
return self.buffer.closed
def fileno(self):
return self.buffer.fileno()
def isatty(self):
return self.buffer.isatty()
def write(self, s: str):
if self.closed:
raise ValueError("write to closed file")
if not isinstance(s, str):
raise TypeError("can't write %s to text stream" %
s.__class__.__name__)
length = len(s)
haslf = (self._writetranslate or self._line_buffering) and "\n" in s
if haslf and self._writetranslate and self._writenl != "\n":
s = s.replace("\n", self._writenl)
encoder = self._encoder or self._get_encoder()
# XXX What if we were just reading?
b = encoder.encode(s)
self.buffer.write(b)
if self._line_buffering and (haslf or "\r" in s):
self.flush()
self._snapshot = None
if self._decoder:
self._decoder.reset()
return length
def _get_encoder(self):
make_encoder = codecs.getincrementalencoder(self._encoding)
self._encoder = make_encoder(self._errors)
return self._encoder
def _get_decoder(self):
make_decoder = codecs.getincrementaldecoder(self._encoding)
decoder = make_decoder(self._errors)
if self._readuniversal:
decoder = IncrementalNewlineDecoder(decoder, self._readtranslate)
self._decoder = decoder
return decoder
def _read_chunk(self):
if self._decoder is None:
raise ValueError("no decoder")
if not self._telling:
readahead = self.buffer.read1(self._CHUNK_SIZE)
pending = self._decoder.decode(readahead, not readahead)
return readahead, pending
decoder_buffer, decoder_state = self._decoder.getstate()
readahead = self.buffer.read1(self._CHUNK_SIZE)
pending = self._decoder.decode(readahead, not readahead)
self._snapshot = (decoder_state, decoder_buffer + readahead, pending)
return readahead, pending
def _encode_decoder_state(self, ds, pos):
x = 0
for i in bytes(ds):
x = x<<8 | i
return (x<<64) | pos
def _decode_decoder_state(self, pos):
x, pos = divmod(pos, 1<<64)
if not x:
return None, pos
b = b""
while x:
b.append(x&0xff)
x >>= 8
return str(b[::-1]), pos
def tell(self):
if not self._seekable:
raise IOError("Underlying stream is not seekable")
if not self._telling:
raise IOError("Telling position disabled by next() call")
self.flush()
position = self.buffer.tell()
decoder = self._decoder
if decoder is None or self._snapshot is None:
if self._pending:
raise ValueError("pending data")
return position
decoder_state, readahead, pending = self._snapshot
position -= len(readahead)
needed = len(pending) - len(self._pending)
if not needed:
return self._encode_decoder_state(decoder_state, position)
saved_state = decoder.getstate()
try:
decoder.setstate((b"", decoder_state))
n = 0
bb = bytearray(1)
for i, bb[0] in enumerate(readahead):
n += len(decoder.decode(bb))
if n >= needed:
decoder_buffer, decoder_state = decoder.getstate()
return self._encode_decoder_state(
decoder_state,
position + (i+1) - len(decoder_buffer) - (n - needed))
raise IOError("Can't reconstruct logical file position")
finally:
decoder.setstate(saved_state)
def seek(self, pos, whence=0):
if not self._seekable:
raise IOError("Underlying stream is not seekable")
if whence == 1:
if pos != 0:
raise IOError("Can't do nonzero cur-relative seeks")
pos = self.tell()
whence = 0
if whence == 2:
if pos != 0:
raise IOError("Can't do nonzero end-relative seeks")
self.flush()
pos = self.buffer.seek(0, 2)
self._snapshot = None
self._pending = ""
if self._decoder:
self._decoder.reset()
return pos
if whence != 0:
raise ValueError("Invalid whence (%r, should be 0, 1 or 2)" %
(whence,))
if pos < 0:
raise ValueError("Negative seek position %r" % (pos,))
self.flush()
orig_pos = pos
ds, pos = self._decode_decoder_state(pos)
if not ds:
self.buffer.seek(pos)
self._snapshot = None
self._pending = ""
if self._decoder:
self._decoder.reset()
return pos
decoder = self._decoder or self._get_decoder()
decoder.set_state(("", ds))
self.buffer.seek(pos)
self._snapshot = (ds, b"", "")
self._pending = ""
self._decoder = decoder
return orig_pos
def read(self, n=None):
if n is None:
n = -1
decoder = self._decoder or self._get_decoder()
res = self._pending
if n < 0:
res += decoder.decode(self.buffer.read(), True)
self._pending = ""
self._snapshot = None
return res
else:
while len(res) < n:
readahead, pending = self._read_chunk()
res += pending
if not readahead:
break
self._pending = res[n:]
return res[:n]
def __next__(self):
self._telling = False
line = self.readline()
if not line:
self._snapshot = None
self._telling = self._seekable
raise StopIteration
return line
def readline(self, limit=None):
if limit is None:
limit = -1
if limit >= 0:
# XXX Hack to support limit argument, for backwards compatibility
line = self.readline()
if len(line) <= limit:
return line
line, self._pending = line[:limit], line[limit:] + self._pending
return line
line = self._pending
start = 0
decoder = self._decoder or self._get_decoder()
pos = endpos = None
while True:
if self._readtranslate:
# Newlines are already translated, only search for \n
pos = line.find('\n', start)
if pos >= 0:
endpos = pos + 1
break
else:
start = len(line)
elif self._readuniversal:
# Universal newline search. Find any of \r, \r\n, \n
# The decoder ensures that \r\n are not split in two pieces
# In C we'd look for these in parallel of course.
nlpos = line.find("\n", start)
crpos = line.find("\r", start)
if crpos == -1:
if nlpos == -1:
# Nothing found
start = len(line)
else:
# Found \n
endpos = nlpos + 1
break
elif nlpos == -1:
# Found lone \r
endpos = crpos + 1
break
elif nlpos < crpos:
# Found \n
endpos = nlpos + 1
break
elif nlpos == crpos + 1:
# Found \r\n
endpos = crpos + 2
break
else:
# Found \r
endpos = crpos + 1
break
else:
# non-universal
pos = line.find(self._readnl)
if pos >= 0:
endpos = pos + len(self._readnl)
break
# No line ending seen yet - get more data
more_line = ''
while True:
readahead, pending = self._read_chunk()
more_line = pending
if more_line or not readahead:
break
if more_line:
line += more_line
else:
# end of file
self._pending = ''
self._snapshot = None
return line
self._pending = line[endpos:]
return line[:endpos]
@property
def newlines(self):
return self._decoder.newlines if self._decoder else None
class StringIO(TextIOWrapper):
# XXX This is really slow, but fully functional
def __init__(self, initial_value="", encoding="utf-8",
errors="strict", newline="\n"):
super(StringIO, self).__init__(BytesIO(),
encoding=encoding,
errors=errors,
newline=newline)
if initial_value:
if not isinstance(initial_value, str):
initial_value = str(initial_value)
self.write(initial_value)
self.seek(0)
def getvalue(self):
self.flush()
return self.buffer.getvalue().decode(self._encoding, self._errors)
