/*

 parsers.c - efficient content parsing

 Copyright 2008 Matt Mackall <mpm@selenic.com> and others

 This software may be used and distributed according to the terms of

 the GNU General Public License, incorporated herein by reference.

*/

#include <Python.h>

#include <ctype.h>

#include <string.h>

static int hexdigit(char c)

{

	if (c >= '0' && c <= '9')

		return c - '0';

	if (c >= 'A' && c <= 'F')

		return c - 'A' + 10;

	if (c >= 'a' && c <= 'f')

		return c - 'a' + 10;

	return -1;

}

/*

 * Turn a hex-encoded string into binary.

 */

static PyObject *unhexlify(const char *str, int len)

{

	PyObject *ret = NULL;

	const char *c;

	char *d;

	if (len % 2) {

		PyErr_SetString(PyExc_ValueError,

				"input is not even in length");

		goto bail;

	}

	ret = PyString_FromStringAndSize(NULL, len / 2);

	if (!ret)

		goto bail;

	d = PyString_AsString(ret);

	if (!d)

		goto bail;

	for (c = str; c < str + len;) {

		int hi = hexdigit(*c++);

		int lo = hexdigit(*c++);

		if (hi == -1 || lo == -1) {

			PyErr_SetString(PyExc_ValueError,

					"input contains non-hex character");

			goto bail;

		}

		*d++ = (hi << 4) | lo;

	}

	goto done;

bail:

	Py_XDECREF(ret);

	ret = NULL;

done:

	return ret;

}

/*

 * This code assumes that a manifest is stitched together with newline

 * ('\n') characters.

 */

static PyObject *parse_manifest(PyObject *self, PyObject *args)

{

	PyObject *mfdict, *fdict;

	char *str, *cur, *start, *zero;

	int len;

	if (!PyArg_ParseTuple(args, "O!O!s#:parse_manifest",

			      &PyDict_Type, &mfdict,

			      &PyDict_Type, &fdict,

			      &str, &len))

		goto quit;

	for (start = cur = str, zero = NULL; cur < str + len; cur++) {

		PyObject *file = NULL, *node = NULL;

		PyObject *flags = NULL;

		int nlen;

		if (!*cur) {

			zero = cur;

			continue;

		}

		else if (*cur != '\n')

			continue;

		if (!zero) {

			PyErr_SetString(PyExc_ValueError,

					"manifest entry has no separator");

			goto quit;

		}

		file = PyString_FromStringAndSize(start, zero - start);

		if (!file)

			goto bail;

		nlen = cur - zero - 1;

		node = unhexlify(zero + 1, nlen > 40 ? 40 : nlen);

		if (!node)

			goto bail;

		if (nlen > 40) {

			PyObject *flags;

			flags = PyString_FromStringAndSize(zero + 41,

							   nlen - 40);

			if (!flags)

				goto bail;

			if (PyDict_SetItem(fdict, file, flags) == -1)

				goto bail;

		}

		if (PyDict_SetItem(mfdict, file, node) == -1)

			goto bail;

		start = cur + 1;

		zero = NULL;

		Py_XDECREF(flags);

		Py_XDECREF(node);

		Py_XDECREF(file);

		continue;

	bail:

		Py_XDECREF(flags);

		Py_XDECREF(node);

		Py_XDECREF(file);

		goto quit;

	}

	if (len > 0 && *(cur - 1) != '\n') {

		PyErr_SetString(PyExc_ValueError,

				"manifest contains trailing garbage");

		goto quit;

	}

	Py_INCREF(Py_None);

	return Py_None;

quit:

	return NULL;

}

static char parsers_doc[] = "Efficient content parsing.";

static PyMethodDef methods[] = {

	{"parse_manifest", parse_manifest, METH_VARARGS, "parse a manifest\n"},

	{NULL, NULL}

};

PyMODINIT_FUNC initparsers(void)

{

	Py_InitModule3("parsers", methods, parsers_doc);

}