taskrambler/include/class.h

/**
 * \file
 * My own class implementation for C. It combines a data structure
 * with a set of dynamically linked methods defined by an interface. A
 * dynamically linked method will be called via a selector method which in
 * turn gets the implementation stored in the class.
 *
 * \author	Georg Hopp
 *
 * \copyright
 * Copyright (C) 2012  Georg Hopp
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#ifndef __CLASS_H__
#define __CLASS_H__

#include <stdarg.h>
#include <sys/types.h>
#include <string.h>
#include <assert.h>

#include "interface.h"

#ifndef _ISOC99_SOURCE
#define _ISOC99_SOURCE
#endif

#define CLASS_MAGIC    0xFEFE

#define CLASS(name)                    \
	struct c_##name;                   \
	typedef struct c_##name * name;    \
	extern struct class * const _##name; \
	struct c_##name

#define EXTENDS(parent) \
	const char _[sizeof(struct c_##parent)]

#define _NULL	NULL
#define CREATE_CLASS(name,_parent,...) \
	static struct class c_##name;      \
	static void _classInit_(void) {    \
		c_##name.parent = _##_parent;  \
		c_##name.init   = NULL;        \
	}                                  \
	static struct class c_##name = {   \
		CLASS_MAGIC,                   \
		NULL,                          \
		sizeof(struct c_##name),       \
		_classInit_,                   \
		INIT_IMPL(__VA_ARGS__)         \
	}; struct class * const _##name = &c_##name

#define GET_CLASS(object)			(*(class_ptr *)((object) - sizeof(void*)))
#define IFACE_GET(class,iface)		(interfaceGet(&((class)->impl),(iface)))
#define IFACE_EXISTS(class,iface)	(NULL != IFACE_GET((class),(iface)))

/**
 * \todo actually i use gcc feature ## for variadoc... think about
 * a way to make this standard.
 */
#define _CALL(object,_iface,method,...)                                           \
	do {                                                                          \
		class_ptr class = GET_CLASS((object));                                \
		if (class->init) class->init();                                           \
		iface = (struct i_##_iface *)IFACE_GET(class, &i_##_iface);      \
		while ((NULL == iface || NULL == iface->method) && HAS_PARENT(class)) {   \
			class = class->parent;                                                \
			if (class->init) class->init();                                       \
			iface = (struct i_##_iface *)IFACE_GET(class, &i_##_iface);  \
		};                                                                        \
		assert(NULL != iface->method);                                            \
	} while(0)

#define CALL(object,_iface,method,...)                \
	do {                                              \
		struct i_##_iface * iface;                    \
		_CALL(object, _iface, method, ##__VA_ARGS__); \
		iface->method(object, ##__VA_ARGS__);         \
	} while(0)

#define RETCALL(object,_iface,method,ret,...)         \
	do {                                              \
		struct i_##_iface * iface;                    \
		_CALL(object, _iface, method, ##__VA_ARGS__); \
		ret = iface->method(object, ##__VA_ARGS__);   \
	} while(0)

#define PARENTCALL(object,_iface,method,...)                                  \
	do {                                                                      \
		struct i_##_iface * iface;                                            \
		class_ptr class = GET_CLASS((object));                            \
		if (class->init) class->init();                                       \
		assert(HAS_PARENT(class));                                            \
		class = class->parent;                                                \
		if (class->init) class->init();                                       \
		iface = (struct i_##_iface *)IFACE_GET(class, &i_##_iface);  \
		assert(NULL != iface->method);                                        \
		iface->method(object, ##__VA_ARGS__);                                 \
	} while(0)


#define HAS_PARENT(class)			(NULL != ((class)->parent))

typedef void (* fptr_classInit)(void);

struct class;
typedef struct class * class_ptr;
struct class {
	const int         magic;
	class_ptr         parent;
	size_t            object_size;
	fptr_classInit    init;
	struct iface_impl impl;
};

#endif // __CLASS_H__

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