labwc/include/common/array.h

/* SPDX-License-Identifier: GPL-2.0-only */
#ifndef LABWC_ARRAY_H
#define LABWC_ARRAY_H
#include <wayland-server-core.h>

/*
 * Wayland's wl_array API is a bit sparse consisting only of
 *  - init
 *  - release
 *  - add
 *  - copy
 *  - for_each
 *
 * The purpose of this header is the gather any generic wl_array helpers we
 * create.
 *
 * We take the liberty of using the wl_ suffix here to make it look a bit
 * prettier. If Wayland extend the API in future, we will sort the clash then.
 */

/**
 * wl_array_len() - return length of wl_array
 * @array: wl_array for which to calculate length
 * Note: The pointer type might not be 'char' but this is the approach that
 * wl_array_for_each() takes, so we align with their style.
 */
static inline size_t
wl_array_len(struct wl_array *array)
{
	return array->size / sizeof(const char *);
}

/**
 * Iterates in reverse over an array.
 * @pos: pointer that each array element will be assigned to
 * @array: wl_array to iterate over
 */
#define wl_array_for_each_reverse(pos, array)                                          \
	for (pos = !(array)->data ? NULL                                               \
		: (void *)((const char *)(array)->data + (array)->size - sizeof(pos)); \
		pos && (const char *)pos >= (const char *)(array)->data;               \
		(pos)--)

#endif /* LABWC_ARRAY_H */