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      1 """The io module provides the Python interfaces to stream handling. The
      2 builtin open function is defined in this module.
      3 
      4 At the top of the I/O hierarchy is the abstract base class IOBase. It
      5 defines the basic interface to a stream. Note, however, that there is no
      6 separation between reading and writing to streams; implementations are
      7 allowed to raise an IOError if they do not support a given operation.
      8 
      9 Extending IOBase is RawIOBase which deals simply with the reading and
     10 writing of raw bytes to a stream. FileIO subclasses RawIOBase to provide
     11 an interface to OS files.
     12 
     13 BufferedIOBase deals with buffering on a raw byte stream (RawIOBase). Its
     14 subclasses, BufferedWriter, BufferedReader, and BufferedRWPair buffer
     15 streams that are readable, writable, and both respectively.
     16 BufferedRandom provides a buffered interface to random access
     17 streams. BytesIO is a simple stream of in-memory bytes.
     18 
     19 Another IOBase subclass, TextIOBase, deals with the encoding and decoding
     20 of streams into text. TextIOWrapper, which extends it, is a buffered text
     21 interface to a buffered raw stream (`BufferedIOBase`). Finally, StringIO
     22 is a in-memory stream for text.
     23 
     24 Argument names are not part of the specification, and only the arguments
     25 of open() are intended to be used as keyword arguments.
     26 
     27 data:
     28 
     29 DEFAULT_BUFFER_SIZE
     30 
     31    An int containing the default buffer size used by the module's buffered
     32    I/O classes. open() uses the file's blksize (as obtained by os.stat) if
     33    possible.
     34 """
     35 # New I/O library conforming to PEP 3116.
     36 
     37 __author__ = ("Guido van Rossum <guido (at] python.org>, "
     38               "Mike Verdone <mike.verdone (at] gmail.com>, "
     39               "Mark Russell <mark.russell (at] zen.co.uk>, "
     40               "Antoine Pitrou <solipsis (at] pitrou.net>, "
     41               "Amaury Forgeot d'Arc <amauryfa (at] gmail.com>, "
     42               "Benjamin Peterson <benjamin (at] python.org>")
     43 
     44 __all__ = ["BlockingIOError", "open", "IOBase", "RawIOBase", "FileIO",
     45            "BytesIO", "StringIO", "BufferedIOBase",
     46            "BufferedReader", "BufferedWriter", "BufferedRWPair",
     47            "BufferedRandom", "TextIOBase", "TextIOWrapper",
     48            "UnsupportedOperation", "SEEK_SET", "SEEK_CUR", "SEEK_END"]
     49 
     50 
     51 import _io
     52 import abc
     53 
     54 from _io import (DEFAULT_BUFFER_SIZE, BlockingIOError, UnsupportedOperation,
     55                  open, FileIO, BytesIO, StringIO, BufferedReader,
     56                  BufferedWriter, BufferedRWPair, BufferedRandom,
     57                  IncrementalNewlineDecoder, TextIOWrapper)
     58 
     59 OpenWrapper = _io.open # for compatibility with _pyio
     60 
     61 # for seek()
     62 SEEK_SET = 0
     63 SEEK_CUR = 1
     64 SEEK_END = 2
     65 
     66 # Declaring ABCs in C is tricky so we do it here.
     67 # Method descriptions and default implementations are inherited from the C
     68 # version however.
     69 class IOBase(_io._IOBase):
     70     __metaclass__ = abc.ABCMeta
     71 
     72 class RawIOBase(_io._RawIOBase, IOBase):
     73     pass
     74 
     75 class BufferedIOBase(_io._BufferedIOBase, IOBase):
     76     pass
     77 
     78 class TextIOBase(_io._TextIOBase, IOBase):
     79     pass
     80 
     81 RawIOBase.register(FileIO)
     82 
     83 for klass in (BytesIO, BufferedReader, BufferedWriter, BufferedRandom,
     84               BufferedRWPair):
     85     BufferedIOBase.register(klass)
     86 
     87 for klass in (StringIO, TextIOWrapper):
     88     TextIOBase.register(klass)
     89 del klass
     90