subsurface/core/table.h

// SPDX-License-Identifier: GPL-2.0
/* This header defines a number of macros that generate table-manipulation functions.
 * There is no design behind these macros - the functions were take as-is and transformed
 * into macros. Thus, this whole header could do with some redesign. */
#ifndef CORE_TABLE_H
#define CORE_TABLE_H

#define MAKE_GROW_TABLE(table_type, item_type, array_name) \
	item_type *grow_##table_type(struct table_type *table)				\
	{										\
		int nr = table->nr, allocated = table->allocated;			\
		item_type *items = table->array_name;					\
											\
		if (nr >= allocated) {							\
			allocated = (nr + 32) * 3 / 2;					\
			items = realloc(items, allocated * sizeof(item_type));		\
			if (!items)							\
				exit(1);						\
			table->array_name = items;					\
			table->allocated = allocated;					\
		}									\
		return items;								\
	}

/* get the index where we want to insert an object so that everything stays
 * ordered according to a comparison function() */
#define MAKE_GET_INSERTION_INDEX(table_type, item_type, array_name, fun)		\
	int table_type##_get_insertion_index(struct table_type *table, item_type item)	\
	{										\
		/* we might want to use binary search here */				\
		for (int i = 0; i < table->nr; i++) {					\
			if (fun(item, table->array_name[i]))				\
				return i;						\
		}									\
		return table->nr;							\
	}

/* add object at the given index to a table. */
#define MAKE_ADD_TO(table_type, item_type, array_name)					\
	void add_to_##table_type(struct table_type *table, int idx, item_type item)	\
	{										\
		int i;									\
		grow_##table_type(table);						\
		table->nr++;								\
											\
		for (i = idx; i < table->nr; i++) {					\
			item_type tmp = table->array_name[i];				\
			table->array_name[i] = item;					\
			item = tmp;							\
		}									\
	}

#define MAKE_REMOVE_FROM(table_type, array_name)				\
	void remove_from_##table_type(struct table_type *table, int idx)	\
	{									\
		int i;								\
		for (i = idx; i < table->nr - 1; i++)				\
			table->array_name[i] = table->array_name[i + 1];	\
		table->array_name[--table->nr] = NULL;				\
	}

#define MAKE_GET_IDX(table_type, item_type, array_name)						\
	int get_idx_in_##table_type(const struct table_type *table, const item_type item)	\
	{											\
		for (int i = 0; i < table->nr; ++i) {						\
			if (table->array_name[i] == item)					\
				return i;							\
		}										\
		return -1;									\
	}

#define MAKE_SORT(table_type, item_type, array_name, fun)					\
	static int sortfn_##table_type(const void *_a, const void *_b)				\
	{											\
		const item_type a = (const item_type)*(const void **)_a;			\
		const item_type b = (const item_type)*(const void **)_b;			\
		return fun(a, b);								\
	}											\
												\
	void sort_##table_type(struct table_type *table)					\
	{											\
		qsort(table->array_name, table->nr, sizeof(item_type), sortfn_##table_type);	\
	}

#define MAKE_REMOVE(table_type, item_type, item_name)				\
	int remove_##item_name(const item_type item, struct table_type *table)	\
	{									\
		int idx = get_idx_in_##table_type(table, item);			\
		if (idx >= 0)							\
			remove_from_##table_type(table, idx);			\
		return idx;							\
	}

#endif