Modules/cjkcodecs/multibytecodec.c

/*
 * multibytecodec.c: Common Multibyte Codec Implementation
 *
 * Written by Hye-Shik Chang <perky@FreeBSD.org>
 */

#define PY_SSIZE_T_CLEAN
#include "Python.h"
#include "structmember.h"
#include "multibytecodec.h"

typedef struct {
    const Py_UNICODE    *inbuf, *inbuf_top, *inbuf_end;
    unsigned char       *outbuf, *outbuf_end;
    PyObject            *excobj, *outobj;
} MultibyteEncodeBuffer;

typedef struct {
    const unsigned char *inbuf, *inbuf_top, *inbuf_end;
    Py_UNICODE          *outbuf, *outbuf_end;
    PyObject            *excobj, *outobj;
} MultibyteDecodeBuffer;

PyDoc_STRVAR(MultibyteCodec_Encode__doc__,
"I.encode(unicode[, errors]) -> (string, length consumed)\n\
\n\
Return an encoded string version of `unicode'. errors may be given to\n\
set a different error handling scheme. Default is 'strict' meaning that\n\
encoding errors raise a UnicodeEncodeError. Other possible values are\n\
'ignore', 'replace' and 'xmlcharrefreplace' as well as any other name\n\
registered with codecs.register_error that can handle UnicodeEncodeErrors.");

PyDoc_STRVAR(MultibyteCodec_Decode__doc__,
"I.decode(string[, errors]) -> (unicodeobject, length consumed)\n\
\n\
Decodes `string' using I, an MultibyteCodec instance. errors may be given\n\
to set a different error handling scheme. Default is 'strict' meaning\n\
that encoding errors raise a UnicodeDecodeError. Other possible values\n\
are 'ignore' and 'replace' as well as any other name registerd with\n\
codecs.register_error that is able to handle UnicodeDecodeErrors.");

static char *codeckwarglist[] = {"input", "errors", NULL};
static char *incnewkwarglist[] = {"errors", NULL};
static char *incrementalkwarglist[] = {"input", "final", NULL};
static char *streamkwarglist[] = {"stream", "errors", NULL};

static PyObject *multibytecodec_encode(MultibyteCodec *,
		MultibyteCodec_State *, const Py_UNICODE **, Py_ssize_t,
		PyObject *, int);

#define MBENC_RESET	MBENC_MAX<<1 /* reset after an encoding session */

static PyObject *
make_tuple(PyObject *object, Py_ssize_t len)
{
	PyObject *v, *w;

	if (object == NULL)
		return NULL;

	v = PyTuple_New(2);
	if (v == NULL) {
		Py_DECREF(object);
		return NULL;
	}
	PyTuple_SET_ITEM(v, 0, object);

	w = PyInt_FromSsize_t(len);
	if (w == NULL) {
		Py_DECREF(v);
		return NULL;
	}
	PyTuple_SET_ITEM(v, 1, w);

	return v;
}

static PyObject *
internal_error_callback(const char *errors)
{
	if (errors == NULL || strcmp(errors, "strict") == 0)
		return ERROR_STRICT;
	else if (strcmp(errors, "ignore") == 0)
		return ERROR_IGNORE;
	else if (strcmp(errors, "replace") == 0)
		return ERROR_REPLACE;
	else
		return PyUnicode_FromString(errors);
}

static PyObject *
call_error_callback(PyObject *errors, PyObject *exc)
{
	PyObject *args, *cb, *r;
	const char *str;

	assert(PyUnicode_Check(errors));
	str = PyUnicode_AsString(errors);
	if (str == NULL)
		return NULL;
	cb = PyCodec_LookupError(str);
	if (cb == NULL)
		return NULL;

	args = PyTuple_New(1);
	if (args == NULL) {
		Py_DECREF(cb);
		return NULL;
	}

	PyTuple_SET_ITEM(args, 0, exc);
	Py_INCREF(exc);

	r = PyObject_CallObject(cb, args);
	Py_DECREF(args);
	Py_DECREF(cb);
	return r;
}

static PyObject *
codecctx_errors_get(MultibyteStatefulCodecContext *self)
{
	const char *errors;

	if (self->errors == ERROR_STRICT)
		errors = "strict";
	else if (self->errors == ERROR_IGNORE)
		errors = "ignore";
	else if (self->errors == ERROR_REPLACE)
		errors = "replace";
	else {
		Py_INCREF(self->errors);
		return self->errors;
	}

	return PyUnicode_FromString(errors);
}

static int
codecctx_errors_set(MultibyteStatefulCodecContext *self, PyObject *value,
		    void *closure)
{
	PyObject *cb;
	const char *str;

	if (!PyUnicode_Check(value)) {
		PyErr_SetString(PyExc_TypeError, "errors must be a string");
		return -1;
	}

	str = PyUnicode_AsString(value);
	if (str == NULL)
		return -1;

	cb = internal_error_callback(str);
	if (cb == NULL)
		return -1;

	ERROR_DECREF(self->errors);
	self->errors = cb;
	return 0;
}

/* This getset handlers list is used by all the stateful codec objects */
static PyGetSetDef codecctx_getsets[] = {
	{"errors",	(getter)codecctx_errors_get,
			(setter)codecctx_errors_set,
			PyDoc_STR("how to treat errors")},
	{NULL,}
};

static int
expand_encodebuffer(MultibyteEncodeBuffer *buf, Py_ssize_t esize)
{
	Py_ssize_t orgpos, orgsize;

	orgpos = (Py_ssize_t)((char *)buf->outbuf -
				PyBytes_AS_STRING(buf->outobj));
	orgsize = PyBytes_GET_SIZE(buf->outobj);
	if (PyBytes_Resize(buf->outobj, orgsize + (
	    esize < (orgsize >> 1) ? (orgsize >> 1) | 1 : esize)) == -1)
		return -1;

	buf->outbuf = (unsigned char *)PyBytes_AS_STRING(buf->outobj) +orgpos;
	buf->outbuf_end = (unsigned char *)PyBytes_AS_STRING(buf->outobj)
		+ PyBytes_GET_SIZE(buf->outobj);

	return 0;
}
#define REQUIRE_ENCODEBUFFER(buf, s) {					\
	if ((s) < 1 || (buf)->outbuf + (s) > (buf)->outbuf_end)		\
		if (expand_encodebuffer(buf, s) == -1)			\
			goto errorexit;					\
}

static int
expand_decodebuffer(MultibyteDecodeBuffer *buf, Py_ssize_t esize)
{
	Py_ssize_t orgpos, orgsize;

	orgpos = (Py_ssize_t)(buf->outbuf - PyUnicode_AS_UNICODE(buf->outobj));
	orgsize = PyUnicode_GET_SIZE(buf->outobj);
	if (PyUnicode_Resize(&buf->outobj, orgsize + (
	    esize < (orgsize >> 1) ? (orgsize >> 1) | 1 : esize)) == -1)
		return -1;

	buf->outbuf = PyUnicode_AS_UNICODE(buf->outobj) + orgpos;
	buf->outbuf_end = PyUnicode_AS_UNICODE(buf->outobj)
			  + PyUnicode_GET_SIZE(buf->outobj);

	return 0;
}
#define REQUIRE_DECODEBUFFER(buf, s) {					\
	if ((s) < 1 || (buf)->outbuf + (s) > (buf)->outbuf_end)		\
		if (expand_decodebuffer(buf, s) == -1)			\
			goto errorexit;					\
}


/**
 * MultibyteCodec object
 */

static int
multibytecodec_encerror(MultibyteCodec *codec,
			MultibyteCodec_State *state,
			MultibyteEncodeBuffer *buf,
			PyObject *errors, Py_ssize_t e)
{
	PyObject *retobj = NULL, *retstr = NULL, *tobj;
	Py_ssize_t retstrsize, newpos;
	Py_ssize_t esize, start, end;
	const char *reason;

	if (e > 0) {
		reason = "illegal multibyte sequence";
		esize = e;
	}
	else {
		switch (e) {
		case MBERR_TOOSMALL:
			REQUIRE_ENCODEBUFFER(buf, -1);
			return 0; /* retry it */
		case MBERR_TOOFEW:
			reason = "incomplete multibyte sequence";
			esize = (Py_ssize_t)(buf->inbuf_end - buf->inbuf);
			break;
		case MBERR_INTERNAL:
			PyErr_SetString(PyExc_RuntimeError,
					"internal codec error");
			return -1;
		default:
			PyErr_SetString(PyExc_RuntimeError,
					"unknown runtime error");
			return -1;
		}
	}

	if (errors == ERROR_REPLACE) {
		const Py_UNICODE replchar = '?', *inbuf = &replchar;
		Py_ssize_t r;

		for (;;) {
			Py_ssize_t outleft;

			outleft = (Py_ssize_t)(buf->outbuf_end - buf->outbuf);
			r = codec->encode(state, codec->config, &inbuf, 1,
					  &buf->outbuf, outleft, 0);
			if (r == MBERR_TOOSMALL) {
				REQUIRE_ENCODEBUFFER(buf, -1);
				continue;
			}
			else
				break;
		}

		if (r != 0) {
			REQUIRE_ENCODEBUFFER(buf, 1);
			*buf->outbuf++ = '?';
		}
	}
	if (errors == ERROR_IGNORE || errors == ERROR_REPLACE) {
		buf->inbuf += esize;
		return 0;
	}

	start = (Py_ssize_t)(buf->inbuf - buf->inbuf_top);
	end = start + esize;

	/* use cached exception object if available */
	if (buf->excobj == NULL) {
		buf->excobj = PyUnicodeEncodeError_Create(codec->encoding,
				buf->inbuf_top,
				buf->inbuf_end - buf->inbuf_top,
				start, end, reason);
		if (buf->excobj == NULL)
			goto errorexit;
	}
	else
		if (PyUnicodeEncodeError_SetStart(buf->excobj, start) != 0 ||
		    PyUnicodeEncodeError_SetEnd(buf->excobj, end) != 0 ||
		    PyUnicodeEncodeError_SetReason(buf->excobj, reason) != 0)
			goto errorexit;

	if (errors == ERROR_STRICT) {
		PyCodec_StrictErrors(buf->excobj);
		goto errorexit;
	}

	retobj = call_error_callback(errors, buf->excobj);
	if (retobj == NULL)
		goto errorexit;

	if (!PyTuple_Check(retobj) || PyTuple_GET_SIZE(retobj) != 2 ||
	    !PyUnicode_Check((tobj = PyTuple_GET_ITEM(retobj, 0))) ||
	    !(PyInt_Check(PyTuple_GET_ITEM(retobj, 1)) ||
	      PyLong_Check(PyTuple_GET_ITEM(retobj, 1)))) {
		PyErr_SetString(PyExc_TypeError,
				"encoding error handler must return "
				"(unicode, int) tuple");
		goto errorexit;
	}

	{
		const Py_UNICODE *uraw = PyUnicode_AS_UNICODE(tobj);

		retstr = multibytecodec_encode(codec, state, &uraw,
				PyUnicode_GET_SIZE(tobj), ERROR_STRICT,
				MBENC_FLUSH);
		if (retstr == NULL)
			goto errorexit;
	}

        assert(PyBytes_Check(retstr));
	retstrsize = PyBytes_GET_SIZE(retstr);
	REQUIRE_ENCODEBUFFER(buf, retstrsize);

	memcpy(buf->outbuf, PyBytes_AS_STRING(retstr), retstrsize);
	buf->outbuf += retstrsize;

	newpos = PyInt_AsSsize_t(PyTuple_GET_ITEM(retobj, 1));
	if (newpos < 0 && !PyErr_Occurred())
		newpos += (Py_ssize_t)(buf->inbuf_end - buf->inbuf_top);
	if (newpos < 0 || buf->inbuf_top + newpos > buf->inbuf_end) {
		PyErr_Clear();
		PyErr_Format(PyExc_IndexError,
			     "position %zd from error handler out of bounds",
			     newpos);
		goto errorexit;
	}
	buf->inbuf = buf->inbuf_top + newpos;

	Py_DECREF(retobj);
	Py_DECREF(retstr);
	return 0;

errorexit:
	Py_XDECREF(retobj);
	Py_XDECREF(retstr);
	return -1;
}

static int
multibytecodec_decerror(MultibyteCodec *codec,
			MultibyteCodec_State *state,
			MultibyteDecodeBuffer *buf,
			PyObject *errors, Py_ssize_t e)
{
	PyObject *retobj = NULL, *retuni = NULL;
	Py_ssize_t retunisize, newpos;
	const char *reason;
	Py_ssize_t esize, start, end;

	if (e > 0) {
		reason = "illegal multibyte sequence";
		esize = e;
	}
	else {
		switch (e) {
		case MBERR_TOOSMALL:
			REQUIRE_DECODEBUFFER(buf, -1);
			return 0; /* retry it */
		case MBERR_TOOFEW:
			reason = "incomplete multibyte sequence";
			esize = (Py_ssize_t)(buf->inbuf_end - buf->inbuf);
			break;
		case MBERR_INTERNAL:
			PyErr_SetString(PyExc_RuntimeError,
					"internal codec error");
			return -1;
		default:
			PyErr_SetString(PyExc_RuntimeError,
					"unknown runtime error");
			return -1;
		}
	}

	if (errors == ERROR_REPLACE) {
		REQUIRE_DECODEBUFFER(buf, 1);
		*buf->outbuf++ = Py_UNICODE_REPLACEMENT_CHARACTER;
	}
	if (errors == ERROR_IGNORE || errors == ERROR_REPLACE) {
		buf->inbuf += esize;
		return 0;
	}

	start = (Py_ssize_t)(buf->inbuf - buf->inbuf_top);
	end = start + esize;

	/* use cached exception object if available */
	if (buf->excobj == NULL) {
		buf->excobj = PyUnicodeDecodeError_Create(codec->encoding,
				(const char *)buf->inbuf_top,
				(Py_ssize_t)(buf->inbuf_end - buf->inbuf_top),
				start, end, reason);
		if (buf->excobj == NULL)
			goto errorexit;
	}
	else
		if (PyUnicodeDecodeError_SetStart(buf->excobj, start) ||
		    PyUnicodeDecodeError_SetEnd(buf->excobj, end) ||
		    PyUnicodeDecodeError_SetReason(buf->excobj, reason))
			goto errorexit;

	if (errors == ERROR_STRICT) {
		PyCodec_StrictErrors(buf->excobj);
		goto errorexit;
	}

	retobj = call_error_callback(errors, buf->excobj);
	if (retobj == NULL)
		goto errorexit;

	if (!PyTuple_Check(retobj) || PyTuple_GET_SIZE(retobj) != 2 ||
	    !PyUnicode_Check((retuni = PyTuple_GET_ITEM(retobj, 0))) ||
	    !(PyInt_Check(PyTuple_GET_ITEM(retobj, 1)) ||
	      PyLong_Check(PyTuple_GET_ITEM(retobj, 1)))) {
		PyErr_SetString(PyExc_TypeError,
				"decoding error handler must return "
				"(unicode, int) tuple");
		goto errorexit;
	}

	retunisize = PyUnicode_GET_SIZE(retuni);
	if (retunisize > 0) {
		REQUIRE_DECODEBUFFER(buf, retunisize);
		memcpy((char *)buf->outbuf, PyUnicode_AS_DATA(retuni),
				retunisize * Py_UNICODE_SIZE);
		buf->outbuf += retunisize;
	}

	newpos = PyInt_AsSsize_t(PyTuple_GET_ITEM(retobj, 1));
	if (newpos < 0 && !PyErr_Occurred())
		newpos += (Py_ssize_t)(buf->inbuf_end - buf->inbuf_top);
	if (newpos < 0 || buf->inbuf_top + newpos > buf->inbuf_end) {
		PyErr_Clear();
		PyErr_Format(PyExc_IndexError,
			     "position %zd from error handler out of bounds",
			     newpos);
		goto errorexit;
	}
	buf->inbuf = buf->inbuf_top + newpos;
	Py_DECREF(retobj);
	return 0;

errorexit:
	Py_XDECREF(retobj);
	return -1;
}

static PyObject *
multibytecodec_encode(MultibyteCodec *codec,
		      MultibyteCodec_State *state,
		      const Py_UNICODE **data, Py_ssize_t datalen,
		      PyObject *errors, int flags)
{
	MultibyteEncodeBuffer buf;
	Py_ssize_t finalsize, r = 0;

	if (datalen == 0)
		return PyBytes_FromStringAndSize(NULL, 0);

	buf.excobj = NULL;
	buf.inbuf = buf.inbuf_top = *data;
	buf.inbuf_end = buf.inbuf_top + datalen;
	buf.outobj = PyBytes_FromStringAndSize(NULL, datalen * 2 + 16);
	if (buf.outobj == NULL)
		goto errorexit;
	buf.outbuf = (unsigned char *)PyBytes_AS_STRING(buf.outobj);
	buf.outbuf_end = buf.outbuf + PyBytes_GET_SIZE(buf.outobj);

	while (buf.inbuf < buf.inbuf_end) {
		Py_ssize_t inleft, outleft;

		/* we don't reuse inleft and outleft here.
		 * error callbacks can relocate the cursor anywhere on buffer*/
		inleft = (Py_ssize_t)(buf.inbuf_end - buf.inbuf);
		outleft = (Py_ssize_t)(buf.outbuf_end - buf.outbuf);
		r = codec->encode(state, codec->config, &buf.inbuf, inleft,
				  &buf.outbuf, outleft, flags);
		*data = buf.inbuf;
		if ((r == 0) || (r == MBERR_TOOFEW && !(flags & MBENC_FLUSH)))
			break;
		else if (multibytecodec_encerror(codec, state, &buf, errors,r))
			goto errorexit;
		else if (r == MBERR_TOOFEW)
			break;
	}

	if (codec->encreset != NULL)
		for (;;) {
			Py_ssize_t outleft;

			outleft = (Py_ssize_t)(buf.outbuf_end - buf.outbuf);
			r = codec->encreset(state, codec->config, &buf.outbuf,
					    outleft);
			if (r == 0)
				break;
			else if (multibytecodec_encerror(codec, state,
							 &buf, errors, r))
				goto errorexit;
		}

	finalsize = (Py_ssize_t)((char *)buf.outbuf -
				 PyBytes_AS_STRING(buf.outobj));

	if (finalsize != PyBytes_GET_SIZE(buf.outobj))
		if (PyBytes_Resize(buf.outobj, finalsize) == -1)
			goto errorexit;

	Py_XDECREF(buf.excobj);
	return buf.outobj;

errorexit:
	Py_XDECREF(buf.excobj);
	Py_XDECREF(buf.outobj);
	return NULL;
}

static PyObject *
MultibyteCodec_Encode(MultibyteCodecObject *self,
		      PyObject *args, PyObject *kwargs)
{
	MultibyteCodec_State state;
	Py_UNICODE *data;
	PyObject *errorcb, *r, *arg, *ucvt;
	const char *errors = NULL;
	Py_ssize_t datalen;

	if (!PyArg_ParseTupleAndKeywords(args, kwargs, "O|z:encode",
				codeckwarglist, &arg, &errors))
		return NULL;

	if (PyUnicode_Check(arg))
		ucvt = NULL;
	else {
		arg = ucvt = PyObject_Unicode(arg);
		if (arg == NULL)
			return NULL;
		else if (!PyUnicode_Check(arg)) {
			PyErr_SetString(PyExc_TypeError,
				"couldn't convert the object to unicode.");
			Py_DECREF(ucvt);
			return NULL;
		}
	}

	data = PyUnicode_AS_UNICODE(arg);
	datalen = PyUnicode_GET_SIZE(arg);

	errorcb = internal_error_callback(errors);
	if (errorcb == NULL) {
		Py_XDECREF(ucvt);
		return NULL;
	}

	if (self->codec->encinit != NULL &&
	    self->codec->encinit(&state, self->codec->config) != 0)
		goto errorexit;
	r = multibytecodec_encode(self->codec, &state,
			(const Py_UNICODE **)&data, datalen, errorcb,
			MBENC_FLUSH | MBENC_RESET);
	if (r == NULL)
		goto errorexit;

	ERROR_DECREF(errorcb);
	Py_XDECREF(ucvt);
	return make_tuple(r, datalen);

errorexit:
	ERROR_DECREF(errorcb);
	Py_XDECREF(ucvt);
	return NULL;
}

static PyObject *
MultibyteCodec_Decode(MultibyteCodecObject *self,
		      PyObject *args, PyObject *kwargs)
{
	MultibyteCodec_State state;
	MultibyteDecodeBuffer buf;
	PyObject *errorcb;
	const char *data, *errors = NULL;
	Py_ssize_t datalen, finalsize;

	if (!PyArg_ParseTupleAndKeywords(args, kwargs, "s#|z:decode",
				codeckwarglist, &data, &datalen, &errors))
		return NULL;

	errorcb = internal_error_callback(errors);
	if (errorcb == NULL)
		return NULL;

	if (datalen == 0) {
		ERROR_DECREF(errorcb);
		return make_tuple(PyUnicode_FromUnicode(NULL, 0), 0);
	}

	buf.excobj = NULL;
	buf.inbuf = buf.inbuf_top = (unsigned char *)data;
	buf.inbuf_end = buf.inbuf_top + datalen;
	buf.outobj = PyUnicode_FromUnicode(NULL, datalen);
	if (buf.outobj == NULL)
		goto errorexit;
	buf.outbuf = PyUnicode_AS_UNICODE(buf.outobj);
	buf.outbuf_end = buf.outbuf + PyUnicode_GET_SIZE(buf.outobj);

	if (self->codec->decinit != NULL &&
	    self->codec->decinit(&state, self->codec->config) != 0)
		goto errorexit;

	while (buf.inbuf < buf.inbuf_end) {
		Py_ssize_t inleft, outleft, r;

		inleft = (Py_ssize_t)(buf.inbuf_end - buf.inbuf);
		outleft = (Py_ssize_t)(buf.outbuf_end - buf.outbuf);

		r = self->codec->decode(&state, self->codec->config,
				&buf.inbuf, inleft, &buf.outbuf, outleft);
		if (r == 0)
			break;
		else if (multibytecodec_decerror(self->codec, &state,
						 &buf, errorcb, r))
			goto errorexit;
	}

	finalsize = (Py_ssize_t)(buf.outbuf -
				 PyUnicode_AS_UNICODE(buf.outobj));

	if (finalsize != PyUnicode_GET_SIZE(buf.outobj))
		if (PyUnicode_Resize(&buf.outobj, finalsize) == -1)
			goto errorexit;

	Py_XDECREF(buf.excobj);
	ERROR_DECREF(errorcb);
	return make_tuple(buf.outobj, datalen);

errorexit:
	ERROR_DECREF(errorcb);
	Py_XDECREF(buf.excobj);
	Py_XDECREF(buf.outobj);

	return NULL;
}

static struct PyMethodDef multibytecodec_methods[] = {
	{"encode",	(PyCFunction)MultibyteCodec_Encode,
			METH_VARARGS | METH_KEYWORDS,
			MultibyteCodec_Encode__doc__},
	{"decode",	(PyCFunction)MultibyteCodec_Decode,
			METH_VARARGS | METH_KEYWORDS,
			MultibyteCodec_Decode__doc__},
	{NULL,		NULL},
};

static void
multibytecodec_dealloc(MultibyteCodecObject *self)
{
	PyObject_Del(self);
}

static PyTypeObject MultibyteCodec_Type = {
	PyVarObject_HEAD_INIT(NULL, 0)
	"MultibyteCodec",		/* tp_name */
	sizeof(MultibyteCodecObject),	/* tp_basicsize */
	0,				/* tp_itemsize */
	/* methods */
	(destructor)multibytecodec_dealloc, /* tp_dealloc */
	0,				/* tp_print */
	0,				/* tp_getattr */
	0,				/* tp_setattr */
	0,				/* tp_compare */
	0,				/* tp_repr */
	0,				/* tp_as_number */
	0,				/* tp_as_sequence */
	0,				/* tp_as_mapping */
	0,				/* tp_hash */
	0,				/* tp_call */
	0,				/* tp_str */
	PyObject_GenericGetAttr,	/* tp_getattro */
	0,				/* tp_setattro */
	0,				/* tp_as_buffer */
	Py_TPFLAGS_DEFAULT,		/* tp_flags */
	0,				/* tp_doc */
	0,				/* tp_traverse */
	0,				/* tp_clear */
	0,				/* tp_richcompare */
	0,				/* tp_weaklistoffset */
	0,				/* tp_iter */
	0,				/* tp_iterext */
	multibytecodec_methods,		/* tp_methods */
};


/**
 * Utility functions for stateful codec mechanism
 */

#define STATEFUL_DCTX(o)	((MultibyteStatefulDecoderContext *)(o))
#define STATEFUL_ECTX(o)	((MultibyteStatefulEncoderContext *)(o))

static PyObject *
encoder_encode_stateful(MultibyteStatefulEncoderContext *ctx,
			PyObject *unistr, int final)
{
	PyObject *ucvt, *r = NULL;
	Py_UNICODE *inbuf, *inbuf_end, *inbuf_tmp = NULL;
	Py_ssize_t datalen, origpending;

	if (PyUnicode_Check(unistr))
		ucvt = NULL;
	else {
		unistr = ucvt = PyObject_Unicode(unistr);
		if (unistr == NULL)
			return NULL;
		else if (!PyUnicode_Check(unistr)) {
			PyErr_SetString(PyExc_TypeError,
				"couldn't convert the object to unicode.");
			Py_DECREF(ucvt);
			return NULL;
		}
	}

	datalen = PyUnicode_GET_SIZE(unistr);
	origpending = ctx->pendingsize;

	if (origpending > 0) {
		inbuf_tmp = PyMem_New(Py_UNICODE, datalen + ctx->pendingsize);
		if (inbuf_tmp == NULL)
			goto errorexit;
		memcpy(inbuf_tmp, ctx->pending,
			Py_UNICODE_SIZE * ctx->pendingsize);
		memcpy(inbuf_tmp + ctx->pendingsize,
			PyUnicode_AS_UNICODE(unistr),
			Py_UNICODE_SIZE * datalen);
		datalen += ctx->pendingsize;
		ctx->pendingsize = 0;
		inbuf = inbuf_tmp;
	}
	else
		inbuf = (Py_UNICODE *)PyUnicode_AS_UNICODE(unistr);

	inbuf_end = inbuf + datalen;

	r = multibytecodec_encode(ctx->codec, &ctx->state,
			(const Py_UNICODE **)&inbuf,
			datalen, ctx->errors, final ? MBENC_FLUSH : 0);
	if (r == NULL) {
		/* recover the original pending buffer */
		if (origpending > 0)
			memcpy(ctx->pending, inbuf_tmp,
				Py_UNICODE_SIZE * origpending);
		ctx->pendingsize = origpending;
		goto errorexit;
	}

	if (inbuf < inbuf_end) {
		ctx->pendingsize = (Py_ssize_t)(inbuf_end - inbuf);
		if (ctx->pendingsize > MAXENCPENDING) {
			/* normal codecs can't reach here */
			ctx->pendingsize = 0;
			PyErr_SetString(PyExc_UnicodeError,
					"pending buffer overflow");
			goto errorexit;
		}
		memcpy(ctx->pending, inbuf,
			ctx->pendingsize * Py_UNICODE_SIZE);
	}

	if (inbuf_tmp != NULL)
		PyMem_Del(inbuf_tmp);
	Py_XDECREF(ucvt);
	return r;

errorexit:
	if (inbuf_tmp != NULL)
		PyMem_Del(inbuf_tmp);
	Py_XDECREF(r);
	Py_XDECREF(ucvt);
	return NULL;
}

static int
decoder_append_pending(MultibyteStatefulDecoderContext *ctx,
		       MultibyteDecodeBuffer *buf)
{
	Py_ssize_t npendings;

	npendings = (Py_ssize_t)(buf->inbuf_end - buf->inbuf);
	if (npendings + ctx->pendingsize > MAXDECPENDING) {
		PyErr_SetString(PyExc_UnicodeError, "pending buffer overflow");
		return -1;
	}
	memcpy(ctx->pending + ctx->pendingsize, buf->inbuf, npendings);
	ctx->pendingsize += npendings;
	return 0;
}

static int
decoder_prepare_buffer(MultibyteDecodeBuffer *buf, const char *data,
		       Py_ssize_t size)
{
	buf->inbuf = buf->inbuf_top = (const unsigned char *)data;
	buf->inbuf_end = buf->inbuf_top + size;
	if (buf->outobj == NULL) { /* only if outobj is not allocated yet */
		buf->outobj = PyUnicode_FromUnicode(NULL, size);
		if (buf->outobj == NULL)
			return -1;
		buf->outbuf = PyUnicode_AS_UNICODE(buf->outobj);
		buf->outbuf_end = buf->outbuf +
				  PyUnicode_GET_SIZE(buf->outobj);
	}

	return 0;
}

static int
decoder_feed_buffer(MultibyteStatefulDecoderContext *ctx,
		    MultibyteDecodeBuffer *buf)
{
	while (buf->inbuf < buf->inbuf_end) {
		Py_ssize_t inleft, outleft;
		Py_ssize_t r;

		inleft = (Py_ssize_t)(buf->inbuf_end - buf->inbuf);
		outleft = (Py_ssize_t)(buf->outbuf_end - buf->outbuf);

		r = ctx->codec->decode(&ctx->state, ctx->codec->config,
			&buf->inbuf, inleft, &buf->outbuf, outleft);
		if (r == 0 || r == MBERR_TOOFEW)
			break;
		else if (multibytecodec_decerror(ctx->codec, &ctx->state,
						 buf, ctx->errors, r))
			return -1;
	}
	return 0;
}


/**
 * MultibyteIncrementalEncoder object
 */

static PyObject *
mbiencoder_encode(MultibyteIncrementalEncoderObject *self,
		  PyObject *args, PyObject *kwargs)
{
	PyObject *data;
	int final = 0;

	if (!PyArg_ParseTupleAndKeywords(args, kwargs, "O|i:encode",
			incrementalkwarglist, &data, &final))
		return NULL;

	return encoder_encode_stateful(STATEFUL_ECTX(self), data, final);
}

static PyObject *
mbiencoder_reset(MultibyteIncrementalEncoderObject *self)
{
	if (self->codec->decreset != NULL &&
	    self->codec->decreset(&self->state, self->codec->config) != 0)
		return NULL;
	self->pendingsize = 0;

	Py_RETURN_NONE;
}

static struct PyMethodDef mbiencoder_methods[] = {
	{"encode",	(PyCFunction)mbiencoder_encode,
			METH_VARARGS | METH_KEYWORDS, NULL},
	{"reset",	(PyCFunction)mbiencoder_reset,
			METH_NOARGS, NULL},
	{NULL,		NULL},
};

static PyObject *
mbiencoder_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
{
	MultibyteIncrementalEncoderObject *self;
	PyObject *codec = NULL;
	char *errors = NULL;

	if (!PyArg_ParseTupleAndKeywords(args, kwds, "|s:IncrementalEncoder",
					 incnewkwarglist, &errors))
		return NULL;

	self = (MultibyteIncrementalEncoderObject *)type->tp_alloc(type, 0);
	if (self == NULL)
		return NULL;

	codec = PyObject_GetAttrString((PyObject *)type, "codec");
	if (codec == NULL)
		goto errorexit;
	if (!MultibyteCodec_Check(codec)) {
		PyErr_SetString(PyExc_TypeError, "codec is unexpected type");
		goto errorexit;
	}

	self->codec = ((MultibyteCodecObject *)codec)->codec;
	self->pendingsize = 0;
	self->errors = internal_error_callback(errors);
	if (self->errors == NULL)
		goto errorexit;
	if (self->codec->encinit != NULL &&
	    self->codec->encinit(&self->state, self->codec->config) != 0)
		goto errorexit;

	Py_DECREF(codec);
	return (PyObject *)self;

errorexit:
	Py_XDECREF(self);
	Py_XDECREF(codec);
	return NULL;
}

static int
mbiencoder_init(PyObject *self, PyObject *args, PyObject *kwds)
{
	return 0;
}

static int
mbiencoder_traverse(MultibyteIncrementalEncoderObject *self,
		    visitproc visit, void *arg)
{
	if (ERROR_ISCUSTOM(self->errors))
		Py_VISIT(self->errors);
	return 0;
}

static void
mbiencoder_dealloc(MultibyteIncrementalEncoderObject *self)
{
	PyObject_GC_UnTrack(self);
	ERROR_DECREF(self->errors);
	Py_Type(self)->tp_free(self);
}

static PyTypeObject MultibyteIncrementalEncoder_Type = {
	PyVarObject_HEAD_INIT(NULL, 0)
	"MultibyteIncrementalEncoder",	/* tp_name */
	sizeof(MultibyteIncrementalEncoderObject), /* tp_basicsize */
	0,				/* tp_itemsize */
	/*  methods  */
	(destructor)mbiencoder_dealloc, /* tp_dealloc */
	0,				/* tp_print */
	0,				/* tp_getattr */
	0,				/* tp_setattr */
	0,				/* tp_compare */
	0,				/* tp_repr */
	0,				/* tp_as_number */
	0,				/* tp_as_sequence */
	0,				/* tp_as_mapping */
	0,				/* tp_hash */
	0,				/* tp_call */
	0,				/* tp_str */
	PyObject_GenericGetAttr,	/* tp_getattro */
	0,				/* tp_setattro */
	0,				/* tp_as_buffer */
	Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC
		| Py_TPFLAGS_BASETYPE,	/* tp_flags */
	0,				/* tp_doc */
	(traverseproc)mbiencoder_traverse,	/* tp_traverse */
	0,				/* tp_clear */
	0,				/* tp_richcompare */
	0,				/* tp_weaklistoffset */
	0,				/* tp_iter */
	0,				/* tp_iterext */
	mbiencoder_methods,		/* tp_methods */
	0,				/* tp_members */
	codecctx_getsets,		/* tp_getset */
	0,				/* tp_base */
	0,				/* tp_dict */
	0,				/* tp_descr_get */
	0,				/* tp_descr_set */
	0,				/* tp_dictoffset */
	mbiencoder_init,		/* tp_init */
	0,				/* tp_alloc */
	mbiencoder_new,			/* tp_new */
};


/**
 * MultibyteIncrementalDecoder object
 */

static PyObject *
mbidecoder_decode(MultibyteIncrementalDecoderObject *self,
		  PyObject *args, PyObject *kwargs)
{
	MultibyteDecodeBuffer buf;
	char *data, *wdata;
	Py_ssize_t wsize, finalsize = 0, size, origpending;
	int final = 0;

	if (!PyArg_ParseTupleAndKeywords(args, kwargs, "t#|i:decode",
			incrementalkwarglist, &data, &size, &final))
		return NULL;

	buf.outobj = buf.excobj = NULL;
	origpending = self->pendingsize;

	if (self->pendingsize == 0) {
		wsize = size;
		wdata = data;
	}
	else {
		wsize = size + self->pendingsize;
		wdata = PyMem_Malloc(wsize);
		if (wdata == NULL)
			goto errorexit;
		memcpy(wdata, self->pending, self->pendingsize);
		memcpy(wdata + self->pendingsize, data, size);
		self->pendingsize = 0;
	}

	if (decoder_prepare_buffer(&buf, wdata, wsize) != 0)
		goto errorexit;

	if (decoder_feed_buffer(STATEFUL_DCTX(self), &buf))
		goto errorexit;

	if (final && buf.inbuf < buf.inbuf_end) {
		if (multibytecodec_decerror(self->codec, &self->state,
				&buf, self->errors, MBERR_TOOFEW)) {
			/* recover the original pending buffer */
			memcpy(self->pending, wdata, origpending);
			self->pendingsize = origpending;
			goto errorexit;
		}
	}

	if (buf.inbuf < buf.inbuf_end) { /* pending sequence still exists */
		if (decoder_append_pending(STATEFUL_DCTX(self), &buf) != 0)
			goto errorexit;
	}

	finalsize = (Py_ssize_t)(buf.outbuf - PyUnicode_AS_UNICODE(buf.outobj));
	if (finalsize != PyUnicode_GET_SIZE(buf.outobj))
		if (PyUnicode_Resize(&buf.outobj, finalsize) == -1)
			goto errorexit;

	if (wdata != data)
		PyMem_Del(wdata);
	Py_XDECREF(buf.excobj);
	return buf.outobj;

errorexit:
	if (wdata != NULL && wdata != data)
		PyMem_Del(wdata);
	Py_XDECREF(buf.excobj);
	Py_XDECREF(buf.outobj);
	return NULL;
}

static PyObject *
mbidecoder_reset(MultibyteIncrementalDecoderObject *self)
{
	if (self->codec->decreset != NULL &&
	    self->codec->decreset(&self->state, self->codec->config) != 0)
		return NULL;
	self->pendingsize = 0;

	Py_RETURN_NONE;
}

static struct PyMethodDef mbidecoder_methods[] = {
	{"decode",	(PyCFunction)mbidecoder_decode,
			METH_VARARGS | METH_KEYWORDS, NULL},
	{"reset",	(PyCFunction)mbidecoder_reset,
			METH_NOARGS, NULL},
	{NULL,		NULL},
};

static PyObject *
mbidecoder_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
{
	MultibyteIncrementalDecoderObject *self;
	PyObject *codec = NULL;
	char *errors = NULL;

	if (!PyArg_ParseTupleAndKeywords(args, kwds, "|s:IncrementalDecoder",
					 incnewkwarglist, &errors))
		return NULL;

	self = (MultibyteIncrementalDecoderObject *)type->tp_alloc(type, 0);
	if (self == NULL)
		return NULL;

	codec = PyObject_GetAttrString((PyObject *)type, "codec");
	if (codec == NULL)
		goto errorexit;
	if (!MultibyteCodec_Check(codec)) {
		PyErr_SetString(PyExc_TypeError, "codec is unexpected type");
		goto errorexit;
	}

	self->codec = ((MultibyteCodecObject *)codec)->codec;
	self->pendingsize = 0;
	self->errors = internal_error_callback(errors);
	if (self->errors == NULL)
		goto errorexit;
	if (self->codec->decinit != NULL &&
	    self->codec->decinit(&self->state, self->codec->config) != 0)
		goto errorexit;

	Py_DECREF(codec);
	return (PyObject *)self;

errorexit:
	Py_XDECREF(self);
	Py_XDECREF(codec);
	return NULL;
}

static int
mbidecoder_init(PyObject *self, PyObject *args, PyObject *kwds)
{
	return 0;
}

static int
mbidecoder_traverse(MultibyteIncrementalDecoderObject *self,
		    visitproc visit, void *arg)
{
	if (ERROR_ISCUSTOM(self->errors))
		Py_VISIT(self->errors);
	return 0;
}

static void
mbidecoder_dealloc(MultibyteIncrementalDecoderObject *self)
{
	PyObject_GC_UnTrack(self);
	ERROR_DECREF(self->errors);
	Py_Type(self)->tp_free(self);
}

static PyTypeObject MultibyteIncrementalDecoder_Type = {
	PyVarObject_HEAD_INIT(NULL, 0)
	"MultibyteIncrementalDecoder",	/* tp_name */
	sizeof(MultibyteIncrementalDecoderObject), /* tp_basicsize */
	0,				/* tp_itemsize */
	/*  methods  */
	(destructor)mbidecoder_dealloc, /* tp_dealloc */
	0,				/* tp_print */
	0,				/* tp_getattr */
	0,				/* tp_setattr */
	0,				/* tp_compare */
	0,				/* tp_repr */
	0,				/* tp_as_number */
	0,				/* tp_as_sequence */
	0,				/* tp_as_mapping */
	0,				/* tp_hash */
	0,				/* tp_call */
	0,				/* tp_str */
	PyObject_GenericGetAttr,	/* tp_getattro */
	0,				/* tp_setattro */
	0,				/* tp_as_buffer */
	Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC
		| Py_TPFLAGS_BASETYPE,	/* tp_flags */
	0,				/* tp_doc */
	(traverseproc)mbidecoder_traverse,	/* tp_traverse */
	0,				/* tp_clear */
	0,				/* tp_richcompare */
	0,				/* tp_weaklistoffset */
	0,				/* tp_iter */
	0,				/* tp_iterext */
	mbidecoder_methods,		/* tp_methods */
	0,				/* tp_members */
	codecctx_getsets,		/* tp_getset */
	0,				/* tp_base */
	0,				/* tp_dict */
	0,				/* tp_descr_get */
	0,				/* tp_descr_set */
	0,				/* tp_dictoffset */
	mbidecoder_init,		/* tp_init */
	0,				/* tp_alloc */
	mbidecoder_new,			/* tp_new */
};


/**
 * MultibyteStreamReader object
 */

static PyObject *
mbstreamreader_iread(MultibyteStreamReaderObject *self,
		     const char *method, Py_ssize_t sizehint)
{
	MultibyteDecodeBuffer buf;
	PyObject *cres;
	Py_ssize_t rsize, finalsize = 0;

	if (sizehint == 0)
		return PyUnicode_FromUnicode(NULL, 0);

	buf.outobj = buf.excobj = NULL;
	cres = NULL;

	for (;;) {
		int endoffile;

		if (sizehint < 0)
			cres = PyObject_CallMethod(self->stream,
					(char *)method, NULL);
		else
			cres = PyObject_CallMethod(self->stream,
					(char *)method, "i", sizehint);
		if (cres == NULL)
			goto errorexit;

		if (PyString_Check(cres)) {
			PyObject *cres2 = PyBytes_FromObject(cres);
			if (cres2 == NULL)
				return NULL;
			Py_DECREF(cres);
			cres = cres2;
		}

		if (!PyBytes_Check(cres)) {
			PyErr_Format(PyExc_TypeError,
                                     "stream function returned a "
                                     "non-bytes object (%.100s)",
                                     cres->ob_type->tp_name);
			goto errorexit;
		}

 		endoffile = (PyBytes_GET_SIZE(cres) == 0);

		if (self->pendingsize > 0) {
			PyObject *ctr;
			char *ctrdata;

			rsize = PyBytes_GET_SIZE(cres) + self->pendingsize;
			ctr = PyBytes_FromStringAndSize(NULL, rsize);
			if (ctr == NULL)
				goto errorexit;
			ctrdata = PyBytes_AS_STRING(ctr);
			memcpy(ctrdata, self->pending, self->pendingsize);
			memcpy(ctrdata + self->pendingsize,
				PyBytes_AS_STRING(cres),
				PyBytes_GET_SIZE(cres));
			Py_DECREF(cres);
			cres = ctr;
			self->pendingsize = 0;
		}

		rsize = PyBytes_GET_SIZE(cres);
		if (decoder_prepare_buffer(&buf, PyBytes_AS_STRING(cres),
					   rsize) != 0)
			goto errorexit;

		if (rsize > 0 && decoder_feed_buffer(
				(MultibyteStatefulDecoderContext *)self, &buf))
			goto errorexit;

		if (endoffile || sizehint < 0) {
			if (buf.inbuf < buf.inbuf_end &&
			    multibytecodec_decerror(self->codec, &self->state,
					&buf, self->errors, MBERR_TOOFEW))
				goto errorexit;
		}

		if (buf.inbuf < buf.inbuf_end) { /* pending sequence exists */
			if (decoder_append_pending(STATEFUL_DCTX(self),
						   &buf) != 0)
				goto errorexit;
		}

		finalsize = (Py_ssize_t)(buf.outbuf -
				PyUnicode_AS_UNICODE(buf.outobj));
		Py_DECREF(cres);
		cres = NULL;

		if (sizehint < 0 || finalsize != 0 || rsize == 0)
			break;

		sizehint = 1; /* read 1 more byte and retry */
	}

	if (finalsize != PyUnicode_GET_SIZE(buf.outobj))
		if (PyUnicode_Resize(&buf.outobj, finalsize) == -1)
			goto errorexit;

	Py_XDECREF(cres);
	Py_XDECREF(buf.excobj);
	return buf.outobj;

errorexit:
	Py_XDECREF(cres);
	Py_XDECREF(buf.excobj);
	Py_XDECREF(buf.outobj);
	return NULL;
}

static PyObject *
mbstreamreader_read(MultibyteStreamReaderObject *self, PyObject *args)
{
	PyObject *sizeobj = NULL;
	Py_ssize_t size;

	if (!PyArg_UnpackTuple(args, "read", 0, 1, &sizeobj))
		return NULL;

	if (sizeobj == Py_None || sizeobj == NULL)
		size = -1;
	else if (PyInt_Check(sizeobj))
		size = PyInt_AsSsize_t(sizeobj);
	else {
		PyErr_SetString(PyExc_TypeError, "arg 1 must be an integer");
		return NULL;
	}

	if (size == -1 && PyErr_Occurred())
		return NULL;

	return mbstreamreader_iread(self, "read", size);
}

static PyObject *
mbstreamreader_readline(MultibyteStreamReaderObject *self, PyObject *args)
{
	PyObject *sizeobj = NULL;
	Py_ssize_t size;

	if (!PyArg_UnpackTuple(args, "readline", 0, 1, &sizeobj))
		return NULL;

	if (sizeobj == Py_None || sizeobj == NULL)
		size = -1;
	else if (PyInt_Check(sizeobj))
		size = PyInt_AsSsize_t(sizeobj);
	else {
		PyErr_SetString(PyExc_TypeError, "arg 1 must be an integer");
		return NULL;
	}

	if (size == -1 && PyErr_Occurred())
		return NULL;

	return mbstreamreader_iread(self, "readline", size);
}

static PyObject *
mbstreamreader_readlines(MultibyteStreamReaderObject *self, PyObject *args)
{
	PyObject *sizehintobj = NULL, *r, *sr;
	Py_ssize_t sizehint;

	if (!PyArg_UnpackTuple(args, "readlines", 0, 1, &sizehintobj))
		return NULL;

	if (sizehintobj == Py_None || sizehintobj == NULL)
		sizehint = -1;
	else if (PyInt_Check(sizehintobj))
		sizehint = PyInt_AsSsize_t(sizehintobj);
	else {
		PyErr_SetString(PyExc_TypeError, "arg 1 must be an integer");
		return NULL;
	}

	if (sizehint == -1 && PyErr_Occurred())
		return NULL;

	r = mbstreamreader_iread(self, "read", sizehint);
	if (r == NULL)
		return NULL;

	sr = PyUnicode_Splitlines(r, 1);
	Py_DECREF(r);
	return sr;
}

static PyObject *
mbstreamreader_reset(MultibyteStreamReaderObject *self)
{
	if (self->codec->decreset != NULL &&
	    self->codec->decreset(&self->state, self->codec->config) != 0)
		return NULL;
	self->pendingsize = 0;

	Py_RETURN_NONE;
}

static struct PyMethodDef mbstreamreader_methods[] = {
	{"read",	(PyCFunction)mbstreamreader_read,
			METH_VARARGS, NULL},
	{"readline",	(PyCFunction)mbstreamreader_readline,
			METH_VARARGS, NULL},
	{"readlines",	(PyCFunction)mbstreamreader_readlines,
			METH_VARARGS, NULL},
	{"reset",	(PyCFunction)mbstreamreader_reset,
			METH_NOARGS, NULL},
	{NULL,		NULL},
};

static PyMemberDef mbstreamreader_members[] = {
	{"stream",	T_OBJECT,
			offsetof(MultibyteStreamReaderObject, stream),
			READONLY, NULL},
	{NULL,}
};

static PyObject *
mbstreamreader_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
{
	MultibyteStreamReaderObject *self;
	PyObject *stream, *codec = NULL;
	char *errors = NULL;

	if (!PyArg_ParseTupleAndKeywords(args, kwds, "O|s:StreamReader",
				streamkwarglist, &stream, &errors))
		return NULL;

	self = (MultibyteStreamReaderObject *)type->tp_alloc(type, 0);
	if (self == NULL)
		return NULL;

	codec = PyObject_GetAttrString((PyObject *)type, "codec");
	if (codec == NULL)
		goto errorexit;
	if (!MultibyteCodec_Check(codec)) {
		PyErr_SetString(PyExc_TypeError, "codec is unexpected type");
		goto errorexit;
	}

	self->codec = ((MultibyteCodecObject *)codec)->codec;
	self->stream = stream;
	Py_INCREF(stream);
	self->pendingsize = 0;
	self->errors = internal_error_callback(errors);
	if (self->errors == NULL)
		goto errorexit;
	if (self->codec->decinit != NULL &&
	    self->codec->decinit(&self->state, self->codec->config) != 0)
		goto errorexit;

	Py_DECREF(codec);
	return (PyObject *)self;

errorexit:
	Py_XDECREF(self);
	Py_XDECREF(codec);
	return NULL;
}

static int
mbstreamreader_init(PyObject *self, PyObject *args, PyObject *kwds)
{
	return 0;
}

static int
mbstreamreader_traverse(MultibyteStreamReaderObject *self,
			visitproc visit, void *arg)
{
	if (ERROR_ISCUSTOM(self->errors))
		Py_VISIT(self->errors);
	Py_VISIT(self->stream);
	return 0;
}

static void
mbstreamreader_dealloc(MultibyteStreamReaderObject *self)
{
	PyObject_GC_UnTrack(self);
	ERROR_DECREF(self->errors);
	Py_DECREF(self->stream);
	Py_Type(self)->tp_free(self);
}

static PyTypeObject MultibyteStreamReader_Type = {
	PyVarObject_HEAD_INIT(NULL, 0)
	"MultibyteStreamReader",	/* tp_name */
	sizeof(MultibyteStreamReaderObject), /* tp_basicsize */
	0,				/* tp_itemsize */
	/*  methods  */
	(destructor)mbstreamreader_dealloc, /* tp_dealloc */
	0,				/* tp_print */
	0,				/* tp_getattr */
	0,				/* tp_setattr */
	0,				/* tp_compare */
	0,				/* tp_repr */
	0,				/* tp_as_number */
	0,				/* tp_as_sequence */
	0,				/* tp_as_mapping */
	0,				/* tp_hash */
	0,				/* tp_call */
	0,				/* tp_str */
	PyObject_GenericGetAttr,	/* tp_getattro */
	0,				/* tp_setattro */
	0,				/* tp_as_buffer */
	Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC
		| Py_TPFLAGS_BASETYPE,	/* tp_flags */
	0,				/* tp_doc */
	(traverseproc)mbstreamreader_traverse,	/* tp_traverse */
	0,				/* tp_clear */
	0,				/* tp_richcompare */
	0,				/* tp_weaklistoffset */
	0,				/* tp_iter */
	0,				/* tp_iterext */
	mbstreamreader_methods,		/* tp_methods */
	mbstreamreader_members,		/* tp_members */
	codecctx_getsets,		/* tp_getset */
	0,				/* tp_base */
	0,				/* tp_dict */
	0,				/* tp_descr_get */
	0,				/* tp_descr_set */
	0,				/* tp_dictoffset */
	mbstreamreader_init,		/* tp_init */
	0,				/* tp_alloc */
	mbstreamreader_new,		/* tp_new */
};


/**
 * MultibyteStreamWriter object
 */

static int
mbstreamwriter_iwrite(MultibyteStreamWriterObject *self,
		      PyObject *unistr)
{
	PyObject *str, *wr;

	str = encoder_encode_stateful(STATEFUL_ECTX(self), unistr, 0);
	if (str == NULL)
		return -1;

	wr = PyObject_CallMethod(self->stream, "write", "O", str);
	Py_DECREF(str);
	if (wr == NULL)
		return -1;

	Py_DECREF(wr);
	return 0;
}

static PyObject *
mbstreamwriter_write(MultibyteStreamWriterObject *self, PyObject *strobj)
{
	if (mbstreamwriter_iwrite(self, strobj))
		return NULL;
	else
		Py_RETURN_NONE;
}

static PyObject *
mbstreamwriter_writelines(MultibyteStreamWriterObject *self, PyObject *lines)
{
	PyObject *strobj;
	int i, r;

	if (!PySequence_Check(lines)) {
		PyErr_SetString(PyExc_TypeError,
				"arg must be a sequence object");
		return NULL;
	}

	for (i = 0; i < PySequence_Length(lines); i++) {
		/* length can be changed even within this loop */
		strobj = PySequence_GetItem(lines, i);
		if (strobj == NULL)
			return NULL;

		r = mbstreamwriter_iwrite(self, strobj);
		Py_DECREF(strobj);
		if (r == -1)
			return NULL;
	}

	Py_RETURN_NONE;
}

static PyObject *
mbstreamwriter_reset(MultibyteStreamWriterObject *self)
{
	const Py_UNICODE *pending;
	PyObject *pwrt;

	pending = self->pending;
	pwrt = multibytecodec_encode(self->codec, &self->state,
			&pending, self->pendingsize, self->errors,
			MBENC_FLUSH | MBENC_RESET);
	/* some pending buffer can be truncated when UnicodeEncodeError is
	 * raised on 'strict' mode. but, 'reset' method is designed to
	 * reset the pending buffer or states so failed string sequence
	 * ought to be missed */
	self->pendingsize = 0;
	if (pwrt == NULL)
		return NULL;

        assert(PyBytes_Check(pwrt));
	if (PyBytes_Size(pwrt) > 0) {
		PyObject *wr;
		wr = PyObject_CallMethod(self->stream, "write", "O", pwrt);
		if (wr == NULL) {
			Py_DECREF(pwrt);
			return NULL;
		}
	}
	Py_DECREF(pwrt);

	Py_RETURN_NONE;
}

static PyObject *
mbstreamwriter_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
{
	MultibyteStreamWriterObject *self;
	PyObject *stream, *codec = NULL;
	char *errors = NULL;

	if (!PyArg_ParseTupleAndKeywords(args, kwds, "O|s:StreamWriter",
				streamkwarglist, &stream, &errors))
		return NULL;

	self = (MultibyteStreamWriterObject *)type->tp_alloc(type, 0);
	if (self == NULL)
		return NULL;

	codec = PyObject_GetAttrString((PyObject *)type, "codec");
	if (codec == NULL)
		goto errorexit;
	if (!MultibyteCodec_Check(codec)) {
		PyErr_SetString(PyExc_TypeError, "codec is unexpected type");
		goto errorexit;
	}

	self->codec = ((MultibyteCodecObject *)codec)->codec;
	self->stream = stream;
	Py_INCREF(stream);
	self->pendingsize = 0;
	self->errors = internal_error_callback(errors);
	if (self->errors == NULL)
		goto errorexit;
	if (self->codec->encinit != NULL &&
	    self->codec->encinit(&self->state, self->codec->config) != 0)
		goto errorexit;

	Py_DECREF(codec);
	return (PyObject *)self;

errorexit:
	Py_XDECREF(self);
	Py_XDECREF(codec);
	return NULL;
}

static int
mbstreamwriter_init(PyObject *self, PyObject *args, PyObject *kwds)
{
	return 0;
}

static int
mbstreamwriter_traverse(MultibyteStreamWriterObject *self,
			visitproc visit, void *arg)
{
	if (ERROR_ISCUSTOM(self->errors))
		Py_VISIT(self->errors);
	Py_VISIT(self->stream);
	return 0;
}

static void
mbstreamwriter_dealloc(MultibyteStreamWriterObject *self)
{
	PyObject_GC_UnTrack(self);
	ERROR_DECREF(self->errors);
	Py_DECREF(self->stream);
	Py_Type(self)->tp_free(self);
}

static struct PyMethodDef mbstreamwriter_methods[] = {
	{"write",	(PyCFunction)mbstreamwriter_write,
			METH_O, NULL},
	{"writelines",	(PyCFunction)mbstreamwriter_writelines,
			METH_O, NULL},
	{"reset",	(PyCFunction)mbstreamwriter_reset,
			METH_NOARGS, NULL},
	{NULL,		NULL},
};

static PyMemberDef mbstreamwriter_members[] = {
	{"stream",	T_OBJECT,
			offsetof(MultibyteStreamWriterObject, stream),
			READONLY, NULL},
	{NULL,}
};

static PyTypeObject MultibyteStreamWriter_Type = {
	PyVarObject_HEAD_INIT(NULL, 0)
	"MultibyteStreamWriter",	/* tp_name */
	sizeof(MultibyteStreamWriterObject), /* tp_basicsize */
	0,				/* tp_itemsize */
	/*  methods  */
	(destructor)mbstreamwriter_dealloc, /* tp_dealloc */
	0,				/* tp_print */
	0,				/* tp_getattr */
	0,				/* tp_setattr */
	0,				/* tp_compare */
	0,				/* tp_repr */
	0,				/* tp_as_number */
	0,				/* tp_as_sequence */
	0,				/* tp_as_mapping */
	0,				/* tp_hash */
	0,				/* tp_call */
	0,				/* tp_str */
	PyObject_GenericGetAttr,	/* tp_getattro */
	0,				/* tp_setattro */
	0,				/* tp_as_buffer */
	Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC
		| Py_TPFLAGS_BASETYPE,	/* tp_flags */
	0,				/* tp_doc */
	(traverseproc)mbstreamwriter_traverse,	/* tp_traverse */
	0,				/* tp_clear */
	0,				/* tp_richcompare */
	0,				/* tp_weaklistoffset */
	0,				/* tp_iter */
	0,				/* tp_iterext */
	mbstreamwriter_methods,		/* tp_methods */
	mbstreamwriter_members,		/* tp_members */
	codecctx_getsets,		/* tp_getset */
	0,				/* tp_base */
	0,				/* tp_dict */
	0,				/* tp_descr_get */
	0,				/* tp_descr_set */
	0,				/* tp_dictoffset */
	mbstreamwriter_init,		/* tp_init */
	0,				/* tp_alloc */
	mbstreamwriter_new,		/* tp_new */
};


/**
 * Exposed factory function
 */

static PyObject *
__create_codec(PyObject *ignore, PyObject *arg)
{
	MultibyteCodecObject *self;
	MultibyteCodec *codec;

	if (!PyCObject_Check(arg)) {
		PyErr_SetString(PyExc_ValueError, "argument type invalid");
		return NULL;
	}

	codec = PyCObject_AsVoidPtr(arg);
	if (codec->codecinit != NULL && codec->codecinit(codec->config) != 0)
		return NULL;

	self = PyObject_New(MultibyteCodecObject, &MultibyteCodec_Type);
	if (self == NULL)
		return NULL;
	self->codec = codec;

	return (PyObject *)self;
}

static struct PyMethodDef __methods[] = {
	{"__create_codec", (PyCFunction)__create_codec, METH_O},
	{NULL, NULL},
};

PyMODINIT_FUNC
init_multibytecodec(void)
{
	int i;
	PyObject *m;
	PyTypeObject *typelist[] = {
		&MultibyteIncrementalEncoder_Type,
		&MultibyteIncrementalDecoder_Type,
		&MultibyteStreamReader_Type,
		&MultibyteStreamWriter_Type,
		NULL
	};

	if (PyType_Ready(&MultibyteCodec_Type) < 0)
		return;

	m = Py_InitModule("_multibytecodec", __methods);
	if (m == NULL)
		return;

	for (i = 0; typelist[i] != NULL; i++) {
		if (PyType_Ready(typelist[i]) < 0)
			return;
		Py_INCREF(typelist[i]);
		PyModule_AddObject(m, typelist[i]->tp_name,
				   (PyObject *)typelist[i]);
	}

	if (PyErr_Occurred())
		Py_FatalError("can't initialize the _multibytecodec module");
}