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Python implementation of the io module.
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r,t||}n t d!| |}|rF|S t|||||}|}||_|S |j Y nX dS )#a Open file and return a stream. Raise OSError upon failure.
file is either a text or byte string giving the name (and the path
if the file isn't in the current working directory) of the file to
be opened or an integer file descriptor of the file to be
wrapped. (If a file descriptor is given, it is closed when the
returned I/O object is closed, unless closefd is set to False.)
mode is an optional string that specifies the mode in which the file is
opened. It defaults to 'r' which means open for reading in text mode. Other
common values are 'w' for writing (truncating the file if it already
exists), 'x' for exclusive creation of a new file, and 'a' for appending
(which on some Unix systems, means that all writes append to the end of the
file regardless of the current seek position). In text mode, if encoding is
not specified the encoding used is platform dependent. (For reading and
writing raw bytes use binary mode and leave encoding unspecified.) The
available modes are:
========= ===============================================================
Character Meaning
--------- ---------------------------------------------------------------
'r' open for reading (default)
'w' open for writing, truncating the file first
'x' create a new file and open it for writing
'a' open for writing, appending to the end of the file if it exists
'b' binary mode
't' text mode (default)
'+' open a disk file for updating (reading and writing)
'U' universal newline mode (deprecated)
========= ===============================================================
The default mode is 'rt' (open for reading text). For binary random
access, the mode 'w+b' opens and truncates the file to 0 bytes, while
'r+b' opens the file without truncation. The 'x' mode implies 'w' and
raises an `FileExistsError` if the file already exists.
Python distinguishes between files opened in binary and text modes,
even when the underlying operating system doesn't. Files opened in
binary mode (appending 'b' to the mode argument) return contents as
bytes objects without any decoding. In text mode (the default, or when
't' is appended to the mode argument), the contents of the file are
returned as strings, the bytes having been first decoded using a
platform-dependent encoding or using the specified encoding if given.
'U' mode is deprecated and will raise an exception in future versions
of Python. It has no effect in Python 3. Use newline to control
universal newlines mode.
buffering is an optional integer used to set the buffering policy.
Pass 0 to switch buffering off (only allowed in binary mode), 1 to select
line buffering (only usable in text mode), and an integer > 1 to indicate
the size of a fixed-size chunk buffer. When no buffering argument is
given, the default buffering policy works as follows:
* Binary files are buffered in fixed-size chunks; the size of the buffer
is chosen using a heuristic trying to determine the underlying device's
"block size" and falling back on `io.DEFAULT_BUFFER_SIZE`.
On many systems, the buffer will typically be 4096 or 8192 bytes long.
* "Interactive" text files (files for which isatty() returns True)
use line buffering. Other text files use the policy described above
for binary files.
encoding is the str name of the encoding used to decode or encode the
file. This should only be used in text mode. The default encoding is
platform dependent, but any encoding supported by Python can be
passed. See the codecs module for the list of supported encodings.
errors is an optional string that specifies how encoding errors are to
be handled---this argument should not be used in binary mode. Pass
'strict' to raise a ValueError exception if there is an encoding error
(the default of None has the same effect), or pass 'ignore' to ignore
errors. (Note that ignoring encoding errors can lead to data loss.)
See the documentation for codecs.register for a list of the permitted
encoding error strings.
newline is a string controlling how universal newlines works (it only
applies to text mode). It can be None, '', '\n', '\r', and '\r\n'. 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.
closedfd is a bool. If closefd is False, the underlying file descriptor will
be kept open when the file is closed. This does not work when a file name is
given and must be True in that case.
The newly created file is non-inheritable.
A custom opener can be used by passing a callable as *opener*. The
underlying file descriptor for the file object is then obtained by calling
*opener* with (*file*, *flags*). *opener* must return an open file
descriptor (passing os.open as *opener* results in functionality similar to
passing None).
open() returns a file object whose type depends on the mode, and
through which the standard file operations such as reading and writing
are performed. When open() is used to open a file in a text mode ('w',
'r', 'wt', 'rt', etc.), it returns a TextIOWrapper. When used to open
a file in a binary mode, the returned class varies: in read binary
mode, it returns a BufferedReader; in write binary and append binary
modes, it returns a BufferedWriter, and in read/write mode, it returns
a BufferedRandom.
It is also possible to use a string or bytearray as a file for both
reading and writing. For strings StringIO can be used like a file
opened in a text mode, and for bytes a BytesIO can be used like a file
opened in a binary mode.
zinvalid file: %rzinvalid mode: %rzinvalid buffering: %rNzinvalid encoding: %rzinvalid errors: %rzaxrwb+tUxr wa+tbUz4mode U cannot be combined with 'x', 'w', 'a', or '+'r z'U' mode is deprecatedr Tz'can't have text and binary mode at oncer
z)can't have read/write/append mode at oncez/must have exactly one of read/write/append modez-binary mode doesn't take an encoding argumentz+binary mode doesn't take an errors argumentz+binary mode doesn't take a newline argument )openerFzinvalid buffering sizez can't have unbuffered text I/Ozunknown mode: %r)
isinstanceintosfspathstrbytes TypeErrorsetlen
ValueErrorwarningswarnDeprecationWarningFileIOisattyDEFAULT_BUFFER_SIZEfstatfileno
st_blksizeOSErrorAttributeErrorBufferedRandomBufferedWriterBufferedReader
TextIOWrappermodeclose)filer2 bufferingencodingerrorsnewlineclosefdr ZmodesZcreatingZreadingZwritingZ appendingZupdatingtextZbinaryr# rawresultline_bufferingZbsbuffer r? /usr/lib64/python3.6/_pyio.pyopen( s {
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rA c @ s e Zd ZdZdd ZdS )
DocDescriptorz%Helper for builtins.open.__doc__
c C s
dt j S )Nz\open(file, mode='r', buffering=-1, encoding=None, errors=None, newline=None, closefd=True)
)rA __doc__)selfobjtypr? r? r@ __get__ s zDocDescriptor.__get__N)__name__
__module__ __qualname__rC rG r? r? r? r@ rB s rB c @ s e Zd ZdZe Zdd ZdS ) OpenWrapperzWrapper for builtins.open
Trick so that open won't become a bound method when stored
as a class variable (as dbm.dumb does).
See initstdio() in Python/pylifecycle.c.
c O s
t ||S )N)rA )clsargskwargsr? r? r@ __new__ s zOpenWrapper.__new__N)rH rI rJ rC rB rO r? r? r? r@ rK s rK c @ s e Zd ZdS )UnsupportedOperationN)rH rI rJ r? r? r? r@ rP s rP c @ s e Zd ZdZdd Zd6ddZdd Zd7d
d Zd d
ZdZ dd Z
dd Z dd Z d8ddZ
dd Zd9ddZdd Zd:d d Zed d Zd;d!d"Zd#d$ Zd%d& Zd'd( Zd)d* Zd=d,d-Zd.d/ Zd0d1 Zd>d2d3Z d4d5 Z d S )?IOBaseag The abstract base class for all I/O classes, acting on streams of
bytes. There is no public constructor.
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.
Even though IOBase does not declare read, readinto, or write because
their signatures will vary, implementations and clients should
consider those methods part of the interface. Also, implementations
may raise UnsupportedOperation when operations they do not support are
called.
The basic type used for binary data read from or written to a file is
bytes. Other bytes-like objects are accepted as method arguments too. In
some cases (such as readinto), a writable object is required. Text I/O
classes work with str data.
Note that calling any method (even inquiries) on a closed stream is
undefined. Implementations may raise OSError in this case.
IOBase (and its subclasses) support the iterator protocol, meaning
that an IOBase object can be iterated over yielding the lines in a
stream.
IOBase also supports the :keyword:`with` statement. In this example,
fp is closed after the suite of the with statement is complete:
with open('spam.txt', 'r') as fp:
fp.write('Spam and eggs!')
c C s t d| jj|f dS )z@Internal: raise an OSError exception for unsupported operations.z%s.%s() not supportedN)rP __class__rH )rD namer? r? r@ _unsupported@ s zIOBase._unsupportedr c C s | j d dS )a$ Change stream position.
Change the stream position to byte offset pos. Argument pos is
interpreted relative to the position indicated by whence. Values
for whence are ints:
* 0 -- start of stream (the default); offset should be zero or positive
* 1 -- current stream position; offset may be negative
* 2 -- end of stream; offset is usually negative
Some operating systems / file systems could provide additional values.
Return an int indicating the new absolute position.
seekN)rT )rD poswhencer? r? r@ rU G s z IOBase.seekc C s | j ddS )z5Return an int indicating the current stream position.r r
)rU )rD r? r? r@ tellW s z IOBase.tellNc C s | j d dS )zTruncate file to size bytes.
Size defaults to the current IO position as reported by tell(). Return
the new size.
truncateN)rT )rD rV r? r? r@ rY [ s zIOBase.truncatec C s | j dS )zuFlush write buffers, if applicable.
This is not implemented for read-only and non-blocking streams.
N) _checkClosed)rD r? r? r@ flushe s z IOBase.flushFc C s | j s z | j W dd| _ X dS )ziFlush and close the IO object.
This method has no effect if the file is already closed.
NT)_IOBase__closedr[ )rD r? r? r@ r3 o s z IOBase.closec C s y | j W n Y nX dS )zDestructor. Calls close().N)r3 )rD r? r? r@ __del__z s zIOBase.__del__c C s dS )zReturn a bool indicating whether object supports random access.
If False, seek(), tell() and truncate() will raise OSError.
This method may need to do a test seek().
Fr? )rD r? r? r@ seekable s zIOBase.seekablec C s | j s t|dkrdn|dS )zEInternal: raise UnsupportedOperation if file is not seekable
Nz File or stream is not seekable.)r^ rP )rD msgr? r? r@ _checkSeekable s zIOBase._checkSeekablec C s dS )zvReturn a bool indicating whether object was opened for reading.
If False, read() will raise OSError.
Fr? )rD r? r? r@ readable s zIOBase.readablec C s | j s t|dkrdn|dS )zEInternal: raise UnsupportedOperation if file is not readable
Nz File or stream is not readable.)ra rP )rD r_ r? r? r@ _checkReadable s zIOBase._checkReadablec C s dS )zReturn a bool indicating whether object was opened for writing.
If False, write() and truncate() will raise OSError.
Fr? )rD r? r? r@ writable s zIOBase.writablec C s | j s t|dkrdn|dS )zEInternal: raise UnsupportedOperation if file is not writable
Nz File or stream is not writable.)rc rP )rD r_ r? r? r@ _checkWritable s zIOBase._checkWritablec C s | j S )zclosed: bool. True iff the file has been closed.
For backwards compatibility, this is a property, not a predicate.
)r\ )rD r? r? r@ closed s z
IOBase.closedc C s | j rt|dkrdn|dS )z7Internal: raise a ValueError if file is closed
Nz I/O operation on closed file.)re r" )rD r_ r? r? r@ rZ s zIOBase._checkClosedc C s | j | S )zCContext management protocol. Returns self (an instance of IOBase).)rZ )rD r? r? r@ __enter__ s zIOBase.__enter__c G s | j dS )z+Context management protocol. Calls close()N)r3 )rD rM r? r? r@ __exit__ s zIOBase.__exit__c C s | j d dS )zReturns underlying file descriptor (an int) if one exists.
An OSError is raised if the IO object does not use a file descriptor.
r* N)rT )rD r? r? r@ r* s z
IOBase.filenoc C s | j dS )z{Return a bool indicating whether this is an 'interactive' stream.
Return False if it can't be determined.
F)rZ )rD r? r? r@ r' s z
IOBase.isattyr
c s t dr fdd}ndd }dkr0d
nttsBtdt }x>dk s^t|k r j| }|spP ||7 }|jd rJP qJW t|S ) aN Read and return a line of bytes from the stream.
If size is specified, at most size bytes will be read.
Size should be an int.
The line terminator is always b'\n' for binary files; for text
files, the newlines argument to open can be used to select the line
terminator(s) recognized.
peekc s> j d} | sdS | jdd p&t| }dkr:t|}|S )Nr
r )rh findr! min)Z readaheadn)rD sizer? r@
nreadahead s
z#IOBase.readline.