/**
* Open file and return a stream. Raise IOError upon failure. This is a port to Java of the
* CPython _io.open (Modules/_io/_iomodule.c) following the same logic, but expressed with the
* benefits of Java syntax.
*
* @param args array of arguments from Python call via Jython framework
* @param kwds array of keywords from Python call via Jython framework
* @return the stream object
*/
public static PyObject open(PyObject[] args, String[] kwds) {
// Get the arguments to variables
ArgParser ap = new ArgParser("open", args, kwds, openKwds, 1);
PyObject file = ap.getPyObject(0);
String m = ap.getString(1, "r");
int buffering = ap.getInt(2, -1);
final String encoding = ap.getString(3, null);
final String errors = ap.getString(4, null);
final String newline = ap.getString(5, null);
boolean closefd = Py.py2boolean(ap.getPyObject(6, Py.True));
// Decode the mode string
OpenMode mode =
new OpenMode(m) {
@Override
public void validate() {
super.validate();
validate(encoding, errors, newline);
}
};
mode.checkValid();
/*
* Create the Raw file stream. Let the constructor deal with the variants and argument
* checking.
*/
PyFileIO raw = new PyFileIO(file, mode, closefd);
/*
* From the Python documentation for io.open() buffering = 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 buffer.
*
* When no buffering argument is given, the default buffering policy works as follows:
* Binary files are buffered in fixed-size chunks; "Interactive" text files (files for which
* isatty() returns True) use line buffering. Other text files use the policy described
* above for binary files.
*
* In Java, it seems a stream never is *known* to be interactive, but we ask anyway, and
* maybe one day we shall know.
*/
boolean line_buffering = false;
if (buffering == 0) {
if (!mode.binary) {
throw Py.ValueError("can't have unbuffered text I/O");
}
return raw;
} else if (buffering == 1) {
// The stream is to be read line-by-line.
line_buffering = true;
// Force default size for actual buffer
buffering = -1;
} else if (buffering < 0 && raw.isatty()) {
// No buffering argument given but stream is inteeractive.
line_buffering = true;
}
if (buffering < 0) {
/*
* We are still being asked for the default buffer size. CPython establishes the default
* buffer size using fstat(fd), but Java appears to give no clue. A useful study of
* buffer sizes in NIO is http://www.evanjones.ca/software/java-bytebuffers.html . This
* leads us to the fixed choice of _DEFAULT_BUFFER_SIZE (=8KB).
*/
buffering = _DEFAULT_BUFFER_SIZE;
}
/*
* We now know just what particular class of file we are opening, and therefore what stack
* (buffering and text encoding) we should build.
*/
if (buffering == 0) {
// Not buffering, return the raw file object
return raw;
} else {
// We are buffering, so wrap raw into a buffered file
PyObject bufferType = null;
PyObject io = imp.load("io");
if (mode.updating) {
bufferType = io.__getattr__("BufferedRandom");
} else if (mode.writing || mode.appending) {
bufferType = io.__getattr__("BufferedWriter");
} else { // = reading
bufferType = io.__getattr__("BufferedReader");
}
PyInteger pyBuffering = new PyInteger(buffering);
PyObject buffer = bufferType.__call__(raw, pyBuffering);
if (mode.binary) {
// If binary, return the just the buffered file
return buffer;
} else {
// We are opening in text mode, so wrap buffered file in a TextIOWrapper.
PyObject textType = io.__getattr__("TextIOWrapper");
PyObject[] textArgs = {
buffer,
ap.getPyObject(3, Py.None),
ap.getPyObject(4, Py.None),
ap.getPyObject(5, Py.None),
Py.newBoolean(line_buffering)
};
PyObject wrapper = textType.__call__(textArgs);
wrapper.__setattr__("mode", new PyString(m));
return wrapper;
}
}
}
