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Python Compiled Bytecode | 2009-11-11 | 60.1 KB | 1,993 lines

# Source Generated with Decompyle++
# File: in.pyc (Python 2.6)

"""
The io module provides the Python interfaces to stream handling. The
builtin open function is defined in this module.

At the top of the I/O hierarchy is the abstract base class IOBase. It
defines the basic interface to a stream. Note, however, that there is no
separation between reading and writing to streams; implementations are
allowed to throw an IOError if they do not support a given operation.

Extending IOBase is RawIOBase which deals simply with the reading and
writing of raw bytes to a stream. FileIO subclasses RawIOBase to provide
an interface to OS files.

BufferedIOBase deals with buffering on a raw byte stream (RawIOBase). Its
subclasses, BufferedWriter, BufferedReader, and BufferedRWPair buffer
streams that are readable, writable, and both respectively.
BufferedRandom provides a buffered interface to random access
streams. BytesIO is a simple stream of in-memory bytes.

Another IOBase subclass, TextIOBase, deals with the encoding and decoding
of streams into text. TextIOWrapper, which extends it, is a buffered text
interface to a buffered raw stream (`BufferedIOBase`). Finally, StringIO
is a in-memory stream for text.

Argument names are not part of the specification, and only the arguments
of open() are intended to be used as keyword arguments.

data:

DEFAULT_BUFFER_SIZE

   An int containing the default buffer size used by the module's buffered
   I/O classes. open() uses the file's blksize (as obtained by os.stat) if
   possible.
"""
from __future__ import print_function
from __future__ import unicode_literals
__author__ = 'Guido van Rossum <[e-mail]>, Mike Verdone <[e-mail]>, Mark Russell <[e-mail]>'
__all__ = [
    'BlockingIOError',
    'open',
    'IOBase',
    'RawIOBase',
    'FileIO',
    'BytesIO',
    'StringIO',
    'BufferedIOBase',
    'BufferedReader',
    'BufferedWriter',
    'BufferedRWPair',
    'BufferedRandom',
    'TextIOBase',
    'TextIOWrapper']
import os
import abc
import codecs
import _fileio
import threading
DEFAULT_BUFFER_SIZE = 8 * 1024
__metaclass__ = type

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):
    """Open file and return a stream. If the file cannot be opened, an IOError is
    raised.

    file is either a 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), 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
    '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 (for backwards compatibility; unneeded
              for new code)
    ========= ===============================================================

    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.

    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.

    buffering is an optional integer used to set the buffering policy. By
    default full buffering is on. Pass 0 to switch buffering off (only
    allowed in binary mode), 1 to set line buffering, and an integer > 1
    for full buffering.

    encoding is the 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 controls 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.

    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.

    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.
    """
    if not isinstance(file, (basestring, int)):
        raise TypeError('invalid file: %r' % file)
    isinstance(file, (basestring, int))
    if not isinstance(mode, basestring):
        raise TypeError('invalid mode: %r' % mode)
    isinstance(mode, basestring)
    if buffering is not None and not isinstance(buffering, int):
        raise TypeError('invalid buffering: %r' % buffering)
    not isinstance(buffering, int)
    if encoding is not None and not isinstance(encoding, basestring):
        raise TypeError('invalid encoding: %r' % encoding)
    not isinstance(encoding, basestring)
    if errors is not None and not isinstance(errors, basestring):
        raise TypeError('invalid errors: %r' % errors)
    not isinstance(errors, basestring)
    modes = set(mode)
    if modes - set('arwb+tU') or len(mode) > len(modes):
        raise ValueError('invalid mode: %r' % mode)
    len(mode) > len(modes)
    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")
        appending
        reading = True

    if text and binary:
        raise ValueError("can't have text and binary mode at once")
    binary
    if reading + writing + appending > 1:
        raise ValueError("can't have read/write/append mode at once")
    reading + writing + appending > 1
    if not reading and writing or appending:
        raise ValueError('must have exactly one of read/write/append mode')
    appending
    if binary and encoding is not None:
        raise ValueError("binary mode doesn't take an encoding argument")
    encoding is not None
    if binary and errors is not None:
        raise ValueError("binary mode doesn't take an errors argument")
    errors is not None
    if binary and newline is not None:
        raise ValueError("binary mode doesn't take a newline argument")
    newline is not None
    if not reading or 'r':
        pass
    if not writing or 'w':
        pass
    if not appending or 'a':
        pass
    if not updating or '+':
        pass
    raw = FileIO(file, '' + '' + '' + '', 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

        if bs > 1:
            buffering = bs


    if buffering < 0:
        raise ValueError('invalid buffering size')
    buffering < 0
    if buffering == 0:
        if binary:
            return raw
        raise ValueError("can't have unbuffered text I/O")
    buffering == 0
    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 appending:
        return buffer
    text = TextIOWrapper(buffer, encoding, errors, newline, line_buffering)
    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(object):
    """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 a IOError when operations they do not support are called.

    The basic type used for binary data read from or written to a file is
    bytes. bytearrays are accepted too, and in some cases (such as
    readinto) needed. Text I/O classes work with str data.

    Note that calling any method (even inquiries) on a closed stream is
    undefined. Implementations may raise IOError 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 statment is complete:

    with open('spam.txt', 'r') as fp:
        fp.write('Spam and eggs!')
    """
    __metaclass__ = abc.ABCMeta

    def _unsupported(self, name):
        '''Internal: raise an exception for unsupported operations.'''
        raise UnsupportedOperation('%s.%s() not supported' % (self.__class__.__name__, name))


    def seek(self, pos, whence = 0):
        '''Change stream position.

        Change the stream position to byte offset offset. offset is
        interpreted relative to the position indicated by whence.  Values
        for whence are:

        * 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

        Return the new absolute position.
        '''
        self._unsupported('seek')


    def tell(self):
        '''Return current stream position.'''
        return self.seek(0, 1)


    def truncate(self, pos = None):
        '''Truncate file to size bytes.

        Size defaults to the current IO position as reported by tell().  Return
        the new size.
        '''
        self._unsupported('truncate')


    def flush(self):
        '''Flush write buffers, if applicable.

        This is not implemented for read-only and non-blocking streams.
        '''
        pass

    __closed = False

    def close(self):
        '''Flush and close the IO object.

        This method has no effect if the file is already closed.
        '''
        if not self._IOBase__closed:

            try:
                self.flush()
            except IOError:
                pass

            self._IOBase__closed = True



    def __del__(self):
        '''Destructor.  Calls close().'''

        try:
            self.close()
        except:
            pass



    def seekable(self):
        '''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 None(IOError if msg is None else msg)
        self.seekable()


    def readable(self):
        '''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 None(IOError if msg is None else msg)
        self.readable()


    def writable(self):
        '''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 None(IOError if msg is None else msg)
        self.writable()


    def closed(self):
        '''closed: bool.  True iff the file has been closed.

        For backwards compatibility, this is a property, not a predicate.
        '''
        return self._IOBase__closed

    closed = property(closed)

    def _checkClosed(self, msg = None):
        '''Internal: raise an ValueError if file is closed
        '''
        if self.closed:
            raise None(ValueError if msg is None else msg)
        self.closed


    def __enter__(self):
        '''Context management protocol.  Returns self.'''
        self._checkClosed()
        return self


    def __exit__(self, *args):
        '''Context management protocol.  Calls close()'''
        self.close()


    def fileno(self):
        '''Returns underlying file descriptor if one exists.

        An IOError is raised if the IO object does not use a file descriptor.
        '''
        self._unsupported('fileno')


    def isatty(self):
        """Return whether this is an 'interactive' stream.

        Return False if it can't be determined.
        """
        self._checkClosed()
        return False


    def readline(self, limit = -1):
        """Read and return a line from the stream.

        If limit is specified, at most limit bytes will be read.

        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.
        """
        self._checkClosed()
        if hasattr(self, 'peek'):

            def nreadahead():
                readahead = self.peek(1)
                if not readahead:
                    return 1
                if not readahead.find(b'\n') + 1:
                    pass
                n = len(readahead)
                if limit >= 0:
                    n = min(n, limit)

                return n

        else:

            def nreadahead():
                return 1

        if limit is None:
            limit = -1

        if not isinstance(limit, (int, long)):
            raise TypeError('limit must be an integer')
        isinstance(limit, (int, long))
        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
                continue
        return bytes(res)


    def __iter__(self):
        self._checkClosed()
        return self


    def next(self):
        line = self.readline()
        if not line:
            raise StopIteration
        line
        return line


    def readlines(self, hint = None):
        '''Return a list of lines from the stream.

        hint can be specified to control the number of lines read: no more
        lines will be read if the total size (in bytes/characters) of all
        lines so far exceeds hint.
        '''
        if hint is None:
            hint = -1

        if not isinstance(hint, (int, long)):
            raise TypeError('hint must be an integer')
        isinstance(hint, (int, long))
        if hint <= 0:
            return list(self)
        n = 0
        lines = []
        for line in self:
            lines.append(line)
            n += len(line)
            if n >= hint:
                break
                continue
            hint <= 0

        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.'''

    def read(self, n = -1):
        '''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):
        '''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):
        '''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):
        '''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.'''

    def __init__(self, name, mode = 'r', closefd = True):
        _fileio._FileIO.__init__(self, name, mode, closefd)
        self._name = name


    def close(self):
        _fileio._FileIO.close(self)
        RawIOBase.close(self)


    def name(self):
        return self._name

    name = property(name)


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 = None):
        """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):
        """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'.

        Returns the number of bytes read (0 for EOF).

        Raises BlockingIOError if the underlying raw stream has no
        data at the moment.
        """
        data = self.read(len(b))
        n = len(data)

        try:
            b[:n] = data
        except TypeError:
            err = None
            import array
            if not isinstance(b, array.array):
                raise err
            isinstance(b, array.array)
            b[:n] = array.array(b'b', data)

        return n


    def write(self, b):
        '''Write the given buffer to the IO stream.

        Return 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


    def seek(self, pos, whence = 0):
        return self.raw.seek(pos, whence)


    def tell(self):
        return self.raw.tell()


    def truncate(self, pos = None):
        self.flush()
        if pos is None:
            pos = self.tell()

        return self.raw.truncate(pos)


    def flush(self):
        self.raw.flush()


    def close(self):
        if not self.closed:

            try:
                self.flush()
            except IOError:
                pass

            self.raw.close()



    def seekable(self):
        return self.raw.seekable()


    def readable(self):
        return self.raw.readable()


    def writable(self):
        return self.raw.writable()


    def closed(self):
        return self.raw.closed

    closed = property(closed)

    def name(self):
        return self.raw.name

    name = property(name)

    def mode(self):
        return self.raw.mode

    mode = property(mode)

    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.'''

    def __init__(self, initial_bytes = None):
        buf = bytearray()
        if initial_bytes is not None:
            buf += bytearray(initial_bytes)

        self._buffer = buf
        self._pos = 0


    def getvalue(self):
        '''Return the bytes value (contents) of the buffer
        '''
        if self.closed:
            raise ValueError('getvalue on closed file')
        self.closed
        return bytes(self._buffer)


    def read(self, n = None):
        if self.closed:
            raise ValueError('read from closed file')
        self.closed
        if n is None:
            n = -1

        if not isinstance(n, (int, long)):
            raise TypeError('argument must be an integer')
        isinstance(n, (int, long))
        if n < 0:
            n = len(self._buffer)

        if len(self._buffer) <= self._pos:
            return b''
        newpos = min(len(self._buffer), self._pos + n)
        b = self._buffer[self._pos:newpos]
        self._pos = newpos
        return bytes(b)


    def read1(self, n):
        '''this is the same as read.
        '''
        return self.read(n)


    def write(self, b):
        if self.closed:
            raise ValueError('write to closed file')
        self.closed
        if isinstance(b, unicode):
            raise TypeError("can't write unicode to binary stream")
        isinstance(b, unicode)
        n = len(b)
        if n == 0:
            return 0
        pos = self._pos
        self._buffer[pos:pos + n] = b
        self._pos += n
        return n


    def seek(self, pos, whence = 0):
        if self.closed:
            raise ValueError('seek on closed file')
        self.closed

        try:
            pos = pos.__index__()
        except AttributeError:
            err = None
            raise TypeError('an integer is required')

        if whence == 0:
            if pos < 0:
                raise ValueError('negative seek position %r' % (pos,))
            pos < 0
            self._pos = pos
        elif whence == 1:
            self._pos = max(0, self._pos + pos)
        elif whence == 2:
            self._pos = max(0, len(self._buffer) + pos)
        else:
            raise ValueError('invalid whence value')
        return (whence == 0)._pos


    def tell(self):
        if self.closed:
            raise ValueError('tell on closed file')
        self.closed
        return self._pos


    def truncate(self, pos = None):
        if self.closed:
            raise ValueError('truncate on closed file')
        self.closed
        if pos is None:
            pos = self._pos
        elif pos < 0:
            raise ValueError('negative truncate position %r' % (pos,))

        del self._buffer[pos:]
        return self.seek(pos)


    def readable(self):
        return True


    def writable(self):
        return True


    def seekable(self):
        return True



try:
    import _bytesio

    class BytesIO(_bytesio._BytesIO, BufferedIOBase):
        __doc__ = _bytesio._BytesIO.__doc__

except ImportError:
    BytesIO = _BytesIO


class BufferedReader(_BufferedIOMixin):
    '''BufferedReader(raw[, buffer_size])

    A buffer for a readable, sequential BaseRawIO object.

    The constructor creates a BufferedReader for the given readable raw
    stream and buffer_size. If buffer_size is omitted, DEFAULT_BUFFER_SIZE
    is used.
    '''

    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.buffer_size = buffer_size
        self._reset_read_buf()
        self._read_lock = threading.Lock()


    def _reset_read_buf(self):
        self._read_buf = b''
        self._read_pos = 0


    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.
        '''
        self._read_lock.__enter__()

        try:
            return self._read_unlocked(n)
        finally:
            pass



    def _read_unlocked(self, n = None):
        nodata_val = b''
        empty_values = (b'', None)
        buf = self._read_buf
        pos = self._read_pos
        if n is None or n == -1:
            self._reset_read_buf()
            chunks = [
                buf[pos:]]
            current_size = 0
            while True:
                chunk = self.raw.read()
                if chunk in empty_values:
                    nodata_val = chunk
                    break

                current_size += len(chunk)
                chunks.append(chunk)
            if not b''.join(chunks):
                pass
            return nodata_val
        avail = len(buf) - pos
        if n <= avail:
            self._read_pos += n
            return buf[pos:pos + n]
        chunks = [
            buf[pos:]]
        wanted = max(self.buffer_size, n)
        while avail < n:
            chunk = self.raw.read(wanted)
            avail += len(chunk)
            chunks.append(chunk)
            continue
            None if chunk in empty_values else n == -1
        n = min(n, avail)
        out = b''.join(chunks)
        self._read_buf = out[n:]
        self._read_pos = 0
        if out:
            return out[:n]
        return nodata_val


    def peek(self, n = 0):
        '''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.
        '''
        self._read_lock.__enter__()

        try:
            return self._peek_unlocked(n)
        finally:
            pass



    def _peek_unlocked(self, n = 0):
        want = min(n, self.buffer_size)
        have = len(self._read_buf) - self._read_pos
        if have < want:
            to_read = self.buffer_size - have
            current = self.raw.read(to_read)
            if current:
                self._read_buf = self._read_buf[self._read_pos:] + current
                self._read_pos = 0


        return self._read_buf[self._read_pos:]


    def read1(self, n):
        '''Reads up to n bytes, with at most one read() system call.'''
        if n <= 0:
            return b''
        self._read_lock.__enter__()

        try:
            self._peek_unlocked(1)
            return self._read_unlocked(min(n, len(self._read_buf) - self._read_pos))
        finally:
            pass



    def tell(self):
        return (self.raw.tell() - len(self._read_buf)) + self._read_pos


    def seek(self, pos, whence = 0):
        self._read_lock.__enter__()

        try:
            pos = self.raw.seek(pos, whence)
            self._reset_read_buf()
            return pos
        finally:
            pass




class BufferedWriter(_BufferedIOMixin):
    '''A buffer for a writeable sequential RawIO object.

    The constructor creates a BufferedWriter for the given writeable raw
    stream. If the buffer_size is not given, it defaults to
    DEAFULT_BUFFER_SIZE. If max_buffer_size is omitted, it defaults to
    twice the buffer size.
    '''

    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 = None if max_buffer_size is None else max_buffer_size
        self._write_buf = bytearray()
        self._write_lock = threading.Lock()


    def write(self, b):
        if self.closed:
            raise ValueError('write to closed file')
        self.closed
        if isinstance(b, unicode):
            raise TypeError("can't write unicode to binary stream")
        isinstance(b, unicode)
        self._write_lock.__enter__()

        try:
            if len(self._write_buf) > self.buffer_size:

                try:
                    self._flush_unlocked()
                except BlockingIOError:
                    self._write_lock.__exit__
                    e = self._write_lock.__exit__
                    self._write_lock
                    raise BlockingIOError(e.errno, e.strerror, 0)
                except:
                    self._write_lock.__exit__<EXCEPTION MATCH>BlockingIOError


            self._write_lock.__exit__
            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_unlocked()
                except BlockingIOError:
                    self._write_lock.__exit__
                    e = self._write_lock.__exit__
                    self._write_lock
                    if len(self._write_buf) > self.max_buffer_size:
                        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)
                    len(self._write_buf) > self.max_buffer_size
                except:
                    self._write_lock.__exit__<EXCEPTION MATCH>BlockingIOError


            self._write_lock.__exit__
            return written
        finally:
            pass



    def truncate(self, pos = None):
        self._write_lock.__enter__()

        try:
            self._flush_unlocked()
            return self.raw.truncate(pos)
        finally:
            pass



    def flush(self):
        self._write_lock.__enter__()

        try:
            self._flush_unlocked()
        finally:
            pass



    def _flush_unlocked(self):
        if self.closed:
            raise ValueError('flush of closed file')
        self.closed
        written = 0

        try:
            while self._write_buf:
                n = self.raw.write(self._write_buf)
                del self._write_buf[:n]
                written += n
        except BlockingIOError:
            e = None
            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._write_lock.__enter__()

        try:
            self._flush_unlocked()
            return self.raw.seek(pos, whence)
        finally:
            pass




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.

    reader and writer are RawIOBase objects that are readable and
    writeable respectively. If the buffer_size is omitted it defaults to
    DEFAULT_BUFFER_SIZE. The max_buffer_size (for the buffered writer)
    defaults to twice the buffer size.
    '''

    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):
        return self.reader.peek(n)


    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):
        if not self.reader.isatty():
            pass
        return self.writer.isatty()


    def closed(self):
        return self.writer.closed

    closed = property(closed)


class BufferedRandom(BufferedWriter, BufferedReader):
    '''A buffered interface to random access streams.

    The constructor creates a reader and writer for a seekable stream,
    raw, given in the first argument. If the buffer_size is omitted it
    defaults to DEFAULT_BUFFER_SIZE. The max_buffer_size (for the buffered
    writer) defaults to twice the buffer size.
    '''

    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()
        pos = self.raw.seek(pos, whence)
        self._read_lock.__enter__()

        try:
            self._reset_read_buf()
        finally:
            pass

        return pos


    def tell(self):
        if self._write_buf:
            return self.raw.tell() + len(self._write_buf)
        return BufferedReader.tell(self)


    def truncate(self, pos = None):
        if pos is None:
            pos = self.tell()

        self.seek(pos)
        return BufferedWriter.truncate(self)


    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):
        self.flush()
        return BufferedReader.peek(self, n)


    def read1(self, n):
        self.flush()
        return BufferedReader.read1(self, n)


    def write(self, 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 because Python's character strings
    are immutable. There is no public constructor.
    """

    def read(self, n = -1):
        '''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):
        '''Write string s to stream.'''
        self._unsupported('write')


    def truncate(self, pos = None):
        '''Truncate size to pos.'''
        self._unsupported('truncate')


    def readline(self):
        '''Read until newline or EOF.

        Returns an empty string if EOF is hit immediately.
        '''
        self._unsupported('readline')


    def encoding(self):
        '''Subclasses should override.'''
        pass

    encoding = property(encoding)

    def newlines(self):
        '''Line endings translated so far.

        Only line endings translated during reading are considered.

        Subclasses should override.
        '''
        pass

    newlines = property(newlines)


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.translate = translate
        self.decoder = decoder
        self.seennl = 0
        self.pendingcr = False


    def decode(self, input, final = False):
        output = self.decoder.decode(input, final = final)
        if self.pendingcr:
            if output or final:
                output = '\r' + output
                self.pendingcr = False

        if output.endswith('\r') and not final:
            output = output[:-1]
            self.pendingcr = True

        crlf = output.count('\r\n')
        cr = output.count('\r') - crlf
        lf = output.count('\n') - crlf
        if lf:
            pass
        if cr:
            pass
        if crlf:
            pass
        self.seennl |= self._LF | self._CR | 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()
        flag <<= 1
        if self.pendingcr:
            flag |= 1

        return (buf, flag)


    def setstate(self, state):
        (buf, flag) = state
        self.pendingcr = bool(flag & 1)
        self.decoder.setstate((buf, flag >> 1))


    def reset(self):
        self.seennl = 0
        self.pendingcr = False
        self.decoder.reset()

    _LF = 1
    _CR = 2
    _CRLF = 4

    def newlines(self):
        return (None, '\n', '\r', ('\r', '\n'), '\r\n', ('\n', '\r\n'), ('\r', '\r\n'), ('\r', '\n', '\r\n'))[self.seennl]

    newlines = property(newlines)


class TextIOWrapper(TextIOBase):
    '''Character and line based layer over a BufferedIOBase object, buffer.

    encoding gives the name of the encoding that the stream will be
    decoded or encoded with. It defaults to locale.getpreferredencoding.

    errors determines the strictness of encoding and decoding (see the
    codecs.register) and defaults to "strict".

    newline can be None, \'\', \'\\n\', \'\\r\', or \'\\r\\n\'.  It controls the
    handling of line endings. If it is None, universal newlines is
    enabled.  With this enabled, on input, the lines endings \'\\n\', \'\\r\',
    or \'\\r\\n\' are translated to \'\\n\' before being returned to the
    caller. Conversely, on output, \'\\n\' is translated to the system
    default line separator, os.linesep. If newline is any other of its
    legal values, that newline becomes the newline when the file is read
    and it is returned untranslated. On output, \'\\n\' is converted to the
    newline.

    If line_buffering is True, a call to flush is implied when a call to
    write contains a newline character.
    '''
    _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,))
        newline not in (None, '', '\n', '\r', '\r\n')
        if encoding is None:

            try:
                encoding = os.device_encoding(buffer.fileno())
            except (AttributeError, UnsupportedOperation):
                pass

            if encoding is None:

                try:
                    import locale
                except ImportError:
                    encoding = 'ascii'

                encoding = locale.getpreferredencoding()


        if not isinstance(encoding, basestring):
            raise ValueError('invalid encoding: %r' % encoding)
        isinstance(encoding, basestring)
        if errors is None:
            errors = 'strict'
        elif not isinstance(errors, basestring):
            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 != ''
        if not newline:
            pass
        self._writenl = os.linesep
        self._encoder = None
        self._decoder = None
        self._decoded_chars = ''
        self._decoded_chars_used = 0
        self._snapshot = None
        self._seekable = self._telling = self.buffer.seekable()


    def encoding(self):
        return self._encoding

    encoding = property(encoding)

    def errors(self):
        return self._errors

    errors = property(errors)

    def line_buffering(self):
        return self._line_buffering

    line_buffering = property(line_buffering)

    def seekable(self):
        return self._seekable


    def readable(self):
        return self.buffer.readable()


    def writable(self):
        return self.buffer.writable()


    def flush(self):
        self.buffer.flush()
        self._telling = self._seekable


    def close(self):

        try:
            self.flush()
        except:
            pass

        self.buffer.close()


    def closed(self):
        return self.buffer.closed

    closed = property(closed)

    def name(self):
        return self.buffer.name

    name = property(name)

    def fileno(self):
        return self.buffer.fileno()


    def isatty(self):
        return self.buffer.isatty()


    def write(self, s):
        if self.closed:
            raise ValueError('write to closed file')
        self.closed
        if not isinstance(s, unicode):
            raise TypeError("can't write %s to text stream" % s.__class__.__name__)
        isinstance(s, unicode)
        length = len(s)
        if self._writetranslate or self._line_buffering:
            pass
        haslf = '\n' in s
        if haslf and self._writetranslate and self._writenl != '\n':
            s = s.replace('\n', self._writenl)

        if not self._encoder:
            pass
        encoder = self._get_encoder()
        b = encoder.encode(s)
        self.buffer.write(b)
        if self._line_buffering:
            if 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 _set_decoded_chars(self, chars):
        '''Set the _decoded_chars buffer.'''
        self._decoded_chars = chars
        self._decoded_chars_used = 0


    def _get_decoded_chars(self, n = None):
        '''Advance into the _decoded_chars buffer.'''
        offset = self._decoded_chars_used
        if n is None:
            chars = self._decoded_chars[offset:]
        else:
            chars = self._decoded_chars[offset:offset + n]
        self._decoded_chars_used += len(chars)
        return chars


    def _rewind_decoded_chars(self, n):
        '''Rewind the _decoded_chars buffer.'''
        if self._decoded_chars_used < n:
            raise AssertionError('rewind decoded_chars out of bounds')
        self._decoded_chars_used < n
        self._decoded_chars_used -= n


    def _read_chunk(self):
        '''
        Read and decode the next chunk of data from the BufferedReader.

        The return value is True unless EOF was reached.  The decoded string
        is placed in self._decoded_chars (replacing its previous value).
        The entire input chunk is sent to the decoder, though some of it
        may remain buffered in the decoder, yet to be converted.
        '''
        if self._decoder is None:
            raise ValueError('no decoder')
        self._decoder is None
        if self._telling:
            (dec_buffer, dec_flags) = self._decoder.getstate()

        input_chunk = self.buffer.read1(self._CHUNK_SIZE)
        eof = not input_chunk
        self._set_decoded_chars(self._decoder.decode(input_chunk, eof))
        if self._telling:
            self._snapshot = (dec_flags, dec_buffer + input_chunk)

        return not eof


    def _pack_cookie(self, position, dec_flags = 0, bytes_to_feed = 0, need_eof = 0, chars_to_skip = 0):
        return position | dec_flags << 64 | bytes_to_feed << 128 | chars_to_skip << 192 | bool(need_eof) << 256


    def _unpack_cookie(self, bigint):
        (rest, position) = divmod(bigint, 0x10000000000000000L)
        (rest, dec_flags) = divmod(rest, 0x10000000000000000L)
        (rest, bytes_to_feed) = divmod(rest, 0x10000000000000000L)
        (need_eof, chars_to_skip) = divmod(rest, 0x10000000000000000L)
        return (position, dec_flags, bytes_to_feed, need_eof, chars_to_skip)


    def tell(self):
        if not self._seekable:
            raise IOError('underlying stream is not seekable')
        self._seekable
        if not self._telling:
            raise IOError('telling position disabled by next() call')
        self._telling
        self.flush()
        position = self.buffer.tell()
        decoder = self._decoder
        if decoder is None or self._snapshot is None:
            if self._decoded_chars:
                raise AssertionError('pending decoded text')
            self._decoded_chars
            return position
        (dec_flags, next_input) = self._snapshot
        position -= len(next_input)
        chars_to_skip = self._decoded_chars_used
        if chars_to_skip == 0:
            return self._pack_cookie(position, dec_flags)
        saved_state = decoder.getstate()

        try:
            decoder.setstate((b'', dec_flags))
            start_pos = position
            start_flags = dec_flags
            bytes_fed = 0
            chars_decoded = 0
            need_eof = 0
            for next_byte in next_input:
                bytes_fed += 1
                chars_decoded += len(decoder.decode(next_byte))
                (dec_buffer, dec_flags) = decoder.getstate()
                if chars_decoded >= chars_to_skip:
                    break
                    continue
                None if not dec_buffer and chars_decoded <= chars_to_skip else self._snapshot is None
            else:
                chars_decoded += len(decoder.decode(b'', final = True))
                need_eof = 1
                if chars_decoded < chars_to_skip:
                    raise IOError("can't reconstruct logical file position")
            return self._pack_cookie(start_pos, start_flags, bytes_fed, need_eof, chars_to_skip)
        finally:
            decoder.setstate(saved_state)



    def truncate(self, pos = None):
        self.flush()
        if pos is None:
            pos = self.tell()

        self.seek(pos)
        return self.buffer.truncate()


    def seek(self, cookie, whence = 0):
        if self.closed:
            raise ValueError('tell on closed file')
        self.closed
        if not self._seekable:
            raise IOError('underlying stream is not seekable')
        self._seekable
        if whence == 1:
            if cookie != 0:
                raise IOError("can't do nonzero cur-relative seeks")
            cookie != 0
            whence = 0
            cookie = self.tell()

        if whence == 2:
            if cookie != 0:
                raise IOError("can't do nonzero end-relative seeks")
            cookie != 0
            self.flush()
            position = self.buffer.seek(0, 2)
            self._set_decoded_chars('')
            self._snapshot = None
            if self._decoder:
                self._decoder.reset()

            return position
        if whence != 0:
            raise ValueError('invalid whence (%r, should be 0, 1 or 2)' % (whence,))
        whence != 0
        if cookie < 0:
            raise ValueError('negative seek position %r' % (cookie,))
        cookie < 0
        self.flush()
        (start_pos, dec_flags, bytes_to_feed, need_eof, chars_to_skip) = self._unpack_cookie(cookie)
        self.buffer.seek(start_pos)
        self._set_decoded_chars('')
        self._snapshot = None
        if self._decoder and dec_flags or chars_to_skip:
            if not self._decoder:
                pass
            self._decoder = self._get_decoder()
            self._decoder.setstate((b'', dec_flags))
            self._snapshot = (dec_flags, b'')

        if chars_to_skip:
            input_chunk = self.buffer.read(bytes_to_feed)
            self._set_decoded_chars(self._decoder.decode(input_chunk, need_eof))
            self._snapshot = (dec_flags, input_chunk)
            if len(self._decoded_chars) < chars_to_skip:
                raise IOError("can't restore logical file position")
            len(self._decoded_chars) < chars_to_skip
            self._decoded_chars_used = chars_to_skip

        return cookie


    def read(self, n = None):
        if n is None:
            n = -1

        if not self._decoder:
            pass
        decoder = self._get_decoder()
        if n < 0:
            result = self._get_decoded_chars() + decoder.decode(self.buffer.read(), final = True)
            self._set_decoded_chars('')
            self._snapshot = None
            return result
        eof = False
        result = self._get_decoded_chars(n)
        while len(result) < n and not eof:
            eof = not self._read_chunk()
            result += self._get_decoded_chars(n - len(result))
            continue
            n < 0
        return result


    def next(self):
        self._telling = False
        line = self.readline()
        if not line:
            self._snapshot = None
            self._telling = self._seekable
            raise StopIteration
        line
        return line


    def readline(self, limit = None):
        if self.closed:
            raise ValueError('read from closed file')
        self.closed
        if limit is None:
            limit = -1

        if not isinstance(limit, (int, long)):
            raise TypeError('limit must be an integer')
        isinstance(limit, (int, long))
        line = self._get_decoded_chars()
        start = 0
        if not self._decoder:
            pass
        decoder = self._get_decoder()
        pos = None
        endpos = None
        while True:
            if self._readtranslate:
                pos = line.find('\n', start)
                if pos >= 0:
                    endpos = pos + 1
                    break
                else:
                    start = len(line)
            elif self._readuniversal:
                nlpos = line.find('\n', start)
                crpos = line.find('\r', start)
                if crpos == -1:
                    if nlpos == -1:
                        start = len(line)
                    else:
                        endpos = nlpos + 1
                        break
                elif nlpos == -1:
                    endpos = crpos + 1
                    break
                elif nlpos < crpos:
                    endpos = nlpos + 1
                    break
                elif nlpos == crpos + 1:
                    endpos = crpos + 2
                    break
                else:
                    endpos = crpos + 1
                    break
            else:
                pos = line.find(self._readnl)
                if pos >= 0:
                    endpos = pos + len(self._readnl)
                    break

            if limit >= 0 and len(line) >= limit:
                endpos = limit
                break

            more_line = ''
            while self._read_chunk():
                if self._decoded_chars:
                    break
                    continue
            if self._decoded_chars:
                line += self._get_decoded_chars()
                continue
            self._set_decoded_chars('')
            self._snapshot = None
            return line
        if limit >= 0 and endpos > limit:
            endpos = limit

        self._rewind_decoded_chars(len(line) - endpos)
        return line[:endpos]


    def newlines(self):
        if self._decoder:
            return self._decoder.newlines

    newlines = property(newlines)


class StringIO(TextIOWrapper):
    """An in-memory stream for text. The initial_value argument sets the
    value of object. The other arguments are like those of TextIOWrapper's
    constructor.
    """

    def __init__(self, initial_value = '', encoding = 'utf-8', errors = 'strict', newline = '\n'):
        super(StringIO, self).__init__(BytesIO(), encoding = encoding, errors = errors, newline = newline)
        if newline is None:
            self._writetranslate = False

        if initial_value:
            if not isinstance(initial_value, unicode):
                initial_value = unicode(initial_value)

            self.write(initial_value)
            self.seek(0)



    def getvalue(self):
        self.flush()
        return self.buffer.getvalue().decode(self._encoding, self._errors)