root/memstream-cython/memstream.pyx

# Copyright (c) 2009, samurai-x.org
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cdef extern from "Python.h":

    object PyString_FromStringAndSize(char *s, Py_ssize_t len)

cdef class MemoryInputStream:
    cdef unsigned int _root, _ptr
    cdef bool _opened

    def __init__(self, address):
        self._root = address
        self._ptr = address
        self._opened = True

    def close(self):
        self._opened = False

    property closed:
        def __get__(self):
            return not self._opened

    def fileno(self):
        raise IOError()

    def isatty(self):
        return False

    def readable(self):
        return True

    def readline(self, limit=0):
        raise NotImplementedError()

    def readlines(self, hint=0):
        raise NotImplementedError()

    def seek(self, offset, whence=0):
        if whence == 0:
            # from the start position of the stream
            self._ptr = self._root + offset
            return offset
        elif whence == 1:
            # from the current position of the stream
            self._ptr += offset
            return self._ptr - self._root
        elif whence == 2:
            # from the end of the stream ... impossible, sorry.
            raise NotImplementedError('The memory stream has no end!')
        else:
            raise NotImplementedError('Unknown whence: %d' % whence)

    property address:
        def __get__(self):
            return self._root

    def seekable(self):
        return True

    def tell(self):
        return self._ptr - self._root

    def truncate(self):
        raise NotImplementedError()

    def writable(self):
        return False

    def write(self, b):
        raise NotImplementedError()

    def read(self, b=None):
        if b is None:
            raise NotImplementedError('The memory stream has no end!')
        chunk = PyString_FromStringAndSize(<char*>(self._ptr), b)
        self._ptr += b
        return chunk

    def readall(self):
        raise NotImplementedError('The memory stream has no end!')

    def readinto(self, b):
        length = len(b)
        b.extend(self.read(length))
        return length