/*	$OpenBSD: queue.h,v 1.45 2018/07/12 14:22:54 sashan Exp $	*/
/*	$NetBSD: queue.h,v 1.11 1996/05/16 05:17:14 mycroft Exp $	*/

/*
 * Copyright (c) 1991, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *	@(#)queue.h	8.5 (Berkeley) 8/20/94
 */
module libressl_d.compat.sys.queue;


//#include <sys/_null.h>

extern (C):
nothrow @nogc:

/*
 * This file defines five types of data structures: singly-linked lists,
 * lists, simple queues, tail queues and XOR simple queues.
 *
 *
 * A singly-linked list is headed by a single forward pointer. The elements
 * are singly linked for minimum space and pointer manipulation overhead at
 * the expense of O(n) removal for arbitrary elements. New elements can be
 * added to the list after an existing element or at the head of the list.
 * Elements being removed from the head of the list should use the explicit
 * macro for this purpose for optimum efficiency. A singly-linked list may
 * only be traversed in the forward direction.  Singly-linked lists are ideal
 * for applications with large datasets and few or no removals or for
 * implementing a LIFO queue.
 *
 * A list is headed by a single forward pointer (or an array of forward
 * pointers for a hash table header). The elements are doubly linked
 * so that an arbitrary element can be removed without a need to
 * traverse the list. New elements can be added to the list before
 * or after an existing element or at the head of the list. A list
 * may only be traversed in the forward direction.
 *
 * A simple queue is headed by a pair of pointers, one to the head of the
 * list and the other to the tail of the list. The elements are singly
 * linked to save space, so elements can only be removed from the
 * head of the list. New elements can be added to the list before or after
 * an existing element, at the head of the list, or at the end of the
 * list. A simple queue may only be traversed in the forward direction.
 *
 * A tail queue is headed by a pair of pointers, one to the head of the
 * list and the other to the tail of the list. The elements are doubly
 * linked so that an arbitrary element can be removed without a need to
 * traverse the list. New elements can be added to the list before or
 * after an existing element, at the head of the list, or at the end of
 * the list. A tail queue may be traversed in either direction.
 *
 * An XOR simple queue is used in the same way as a regular simple queue.
 * The difference is that the head structure also includes a "cookie" that
 * is XOR'd with the queue pointer (first, last or next) to generate the
 * real pointer value.
 *
 * For details on the use of these macros, see the queue(3) manual page.
 */

//#if defined(QUEUE_MACRO_DEBUG) || (defined(_KERNEL) && defined(DIAGNOSTIC))
version (none) {
	enum _Q_INVALID = cast(void*)(-1);

	pragma(inline, true)
	pure nothrow @trusted @nogc @live
	void _Q_INVALIDATE(scope void* a)

		in
		{
			assert(a != null);
		}

		do
		{
			a = ._Q_INVALID;
		}
} else {
	pragma(inline, true)
	pure nothrow @trusted @nogc @live
	void _Q_INVALIDATE(scope void* a)

		do
		{
		}
}

/*
 * Singly-linked List definitions.
 */
template SLIST_HEAD(string name, string type)
{
	enum SLIST_HEAD = "struct " ~ name ~ " { " ~ type ~ "* slh_first; /* first element */ }";
}

pragma(inline, true)
pure nothrow @safe @nogc @live
HEAD SLIST_HEAD_INITIALIZER(HEAD)(scope const HEAD* head)
	if (is(HEAD == struct))

	do
	{
		return HEAD.init;
	}

template SLIST_ENTRY(string type)
{
	enum SLIST_ENTRY = "struct { " ~ type ~ "* sle_next; /* next element */ }";
}

/*
 * Singly-linked List access methods.
 */
//#define SLIST_FIRST(head) ((head)->slh_first)
//#define SLIST_END(head) NULL
//#define SLIST_EMPTY(head) (SLIST_FIRST(head) == SLIST_END(head))
//#define SLIST_NEXT(elm, field) ((elm)->field.sle_next)

//#define SLIST_FOREACH(var, head, field) for ((var) = SLIST_FIRST(head); (var) != SLIST_END(head); (var) = SLIST_NEXT(var, field))

//#define SLIST_FOREACH_SAFE(var, head, field, tvar) for ((var) = SLIST_FIRST(head); (var) && ((tvar) = SLIST_NEXT(var, field), 1); (var) = (tvar))

/*
 * Singly-linked List functions.
 */
//#define SLIST_INIT(head) { SLIST_FIRST(head) = SLIST_END(head); }

//#define SLIST_INSERT_AFTER(slistelm, elm, field) do { (elm)->field.sle_next = (slistelm)->field.sle_next; (slistelm)->field.sle_next = (elm); } while (0)

//#define SLIST_INSERT_HEAD(head, elm, field) do { (elm)->field.sle_next = (head)->slh_first; (head)->slh_first = (elm); } while (0)

//#define SLIST_REMOVE_AFTER(elm, field) do { (elm)->field.sle_next = (elm)->field.sle_next->field.sle_next; } while (0)

//#define SLIST_REMOVE_HEAD(head, field) do { (head)->slh_first = (head)->slh_first->field.sle_next; } while (0)

//#define SLIST_REMOVE(head, elm, type, field) do { if ((head)->slh_first == (elm)) { SLIST_REMOVE_HEAD((head), field); } else { struct type* curelm = (head)->slh_first; while (curelm->field.sle_next != (elm)) curelm = curelm->field.sle_next; curelm->field.sle_next = curelm->field.sle_next->field.sle_next; } _Q_INVALIDATE((elm)->field.sle_next); } while (0)

/*
 * List definitions.
 */
template LIST_HEAD(string name, string type)
{
	enum LIST_HEAD = "struct " ~ name ~ " { " ~ type ~ "* lh_first; /* first element */ }";
}

pragma(inline, true)
pure nothrow @safe @nogc @live
HEAD LIST_HEAD_INITIALIZER(HEAD)(scope const HEAD* head)
	if (is(HEAD == struct))

	do
	{
		return HEAD.init;
	}

template LIST_ENTRY(string type)
{
	enum LIST_ENTRY = "struct { " ~ type ~ "* le_next; /* next element */ " ~ type ~ "** le_prev; /* address of previous next element */ }";
}

/*
 * List access methods.
 */
//#define LIST_FIRST(head) ((head)->lh_first)
//#define LIST_END(head) NULL
//#define LIST_EMPTY(head) (LIST_FIRST(head) == LIST_END(head))
//#define LIST_NEXT(elm, field) ((elm)->field.le_next)

//#define LIST_FOREACH(var, head, field) for ((var) = LIST_FIRST(head); (var) != LIST_END(head); (var) = LIST_NEXT(var, field))

//#define LIST_FOREACH_SAFE(var, head, field, tvar) for ((var) = LIST_FIRST(head); (var) && ((tvar) = LIST_NEXT(var, field), 1); (var) = (tvar))

/*
 * List functions.
 */
//#define LIST_INIT(head) do { LIST_FIRST(head) = LIST_END(head); } while (0)

//#define LIST_INSERT_AFTER(listelm, elm, field) do { if (((elm)->field.le_next = (listelm)->field.le_next) != NULL) (listelm)->field.le_next->field.le_prev = &(elm)->field.le_next; (listelm)->field.le_next = (elm); (elm)->field.le_prev = &(listelm)->field.le_next; } while (0)

//#define LIST_INSERT_BEFORE(listelm, elm, field) do { (elm)->field.le_prev = (listelm)->field.le_prev; (elm)->field.le_next = (listelm); *(listelm)->field.le_prev = (elm); (listelm)->field.le_prev = &(elm)->field.le_next; } while (0)

//#define LIST_INSERT_HEAD(head, elm, field) do { if (((elm)->field.le_next = (head)->lh_first) != NULL) (head)->lh_first->field.le_prev = &(elm)->field.le_next; (head)->lh_first = (elm); (elm)->field.le_prev = &(head)->lh_first; } while (0)

//#define LIST_REMOVE(elm, field) do { if ((elm)->field.le_next != NULL) (elm)->field.le_next->field.le_prev = (elm)->field.le_prev; *(elm)->field.le_prev = (elm)->field.le_next; _Q_INVALIDATE((elm)->field.le_prev); _Q_INVALIDATE((elm)->field.le_next); } while (0)

//#define LIST_REPLACE(elm, elm2, field) do { if (((elm2)->field.le_next = (elm)->field.le_next) != NULL) (elm2)->field.le_next->field.le_prev = &(elm2)->field.le_next; (elm2)->field.le_prev = (elm)->field.le_prev; *(elm2)->field.le_prev = (elm2); _Q_INVALIDATE((elm)->field.le_prev); _Q_INVALIDATE((elm)->field.le_next); } while (0)

/*
 * Simple queue definitions.
 */
template SIMPLEQ_HEAD(string name, string type)
{
	enum SIMPLEQ_HEAD = "struct " ~ name ~ " { " ~ type ~ "* sqh_first; /* first element */ " ~ type ~ "** sqh_last; /* addr of last next element */ }";
}

pragma(inline, true)
pure nothrow @trusted @nogc @live
HEAD LIST_HEAD_INITIALIZER(HEAD)(HEAD* head)
	if (is(HEAD == struct))

	in
	{
		assert(head != null);
	}

	do
	{
		HEAD output =
		{
			null,
			&(head).sqh_first,
		};

		return output;
	}

template SIMPLEQ_ENTRY(string type)
{
	enum SIMPLEQ_ENTRY = "struct { " ~ type ~ "* sqe_next; /* next element */ }";
}

/*
 * Simple queue access methods.
 */
//#define SIMPLEQ_FIRST(head) ((head)->sqh_first)
//#define SIMPLEQ_END(head) NULL
//#define SIMPLEQ_EMPTY(head) (SIMPLEQ_FIRST(head) == SIMPLEQ_END(head))
//#define SIMPLEQ_NEXT(elm, field) ((elm)->field.sqe_next)

//#define SIMPLEQ_FOREACH(var, head, field) for ((var) = SIMPLEQ_FIRST(head); (var) != SIMPLEQ_END(head); (var) = SIMPLEQ_NEXT(var, field))

//#define SIMPLEQ_FOREACH_SAFE(var, head, field, tvar) for ((var) = SIMPLEQ_FIRST(head); (var) && ((tvar) = SIMPLEQ_NEXT(var, field), 1); (var) = (tvar))

/*
 * Simple queue functions.
 */
//#define SIMPLEQ_INIT(head) do { (head)->sqh_first = NULL; (head)->sqh_last = &(head)->sqh_first; } while (0)

//#define SIMPLEQ_INSERT_HEAD(head, elm, field) do { if (((elm)->field.sqe_next = (head)->sqh_first) == NULL) (head)->sqh_last = &(elm)->field.sqe_next; (head)->sqh_first = (elm); } while (0)

//#define SIMPLEQ_INSERT_TAIL(head, elm, field) do { (elm)->field.sqe_next = NULL; *(head)->sqh_last = (elm); (head)->sqh_last = &(elm)->field.sqe_next; } while (0)

//#define SIMPLEQ_INSERT_AFTER(head, listelm, elm, field) do { if (((elm)->field.sqe_next = (listelm)->field.sqe_next) == NULL) (head)->sqh_last = &(elm)->field.sqe_next; (listelm)->field.sqe_next = (elm); } while (0)

//#define SIMPLEQ_REMOVE_HEAD(head, field) do { if (((head)->sqh_first = (head)->sqh_first->field.sqe_next) == NULL) (head)->sqh_last = &(head)->sqh_first; } while (0)

//#define SIMPLEQ_REMOVE_AFTER(head, elm, field) do { if (((elm)->field.sqe_next = (elm)->field.sqe_next->field.sqe_next) == NULL) (head)->sqh_last = &(elm)->field.sqe_next; } while (0)

//#define SIMPLEQ_CONCAT(head1, head2) do { if (!SIMPLEQ_EMPTY((head2))) { *(head1)->sqh_last = (head2)->sqh_first; (head1)->sqh_last = (head2)->sqh_last; SIMPLEQ_INIT((head2)); } } while (0)

/*
 * XOR Simple queue definitions.
 */
template XSIMPLEQ_HEAD(string name, string type)
{
	enum XSIMPLEQ_HEAD = "struct " ~ name ~ " { " ~ type ~ "* sqx_first; /* first element */ " ~ type ~ "** sqx_last; /* addr of last next element */ core.stdc.config.c_ulong sqx_cookie; }";
}

template XSIMPLEQ_ENTRY(string type)
{
	enum XSIMPLEQ_ENTRY = "struct { " ~ type ~ "* sqx_next; /* next element */ }";
}

/*
 * XOR Simple queue access methods.
 */
//#define XSIMPLEQ_XOR(head, ptr) ((__typeof(ptr))((head)->sqx_cookie ^ (unsigned long) (ptr)))
//#define XSIMPLEQ_FIRST(head) XSIMPLEQ_XOR(head, ((head)->sqx_first))
//#define XSIMPLEQ_END(head) NULL
//#define XSIMPLEQ_EMPTY(head) (XSIMPLEQ_FIRST(head) == XSIMPLEQ_END(head))
//#define XSIMPLEQ_NEXT(head, elm, field) XSIMPLEQ_XOR(head, ((elm)->field.sqx_next))

//#define XSIMPLEQ_FOREACH(var, head, field) for ((var) = XSIMPLEQ_FIRST(head); (var) != XSIMPLEQ_END(head); (var) = XSIMPLEQ_NEXT(head, var, field))

//#define XSIMPLEQ_FOREACH_SAFE(var, head, field, tvar) for ((var) = XSIMPLEQ_FIRST(head); (var) && ((tvar) = XSIMPLEQ_NEXT(head, var, field), 1); (var) = (tvar))

/*
 * XOR Simple queue functions.
 */
//#define XSIMPLEQ_INIT(head) do { arc4random_buf(&(head)->sqx_cookie, sizeof((head)->sqx_cookie)); (head)->sqx_first = XSIMPLEQ_XOR(head, NULL); (head)->sqx_last = XSIMPLEQ_XOR(head, &(head)->sqx_first); } while (0)

//#define XSIMPLEQ_INSERT_HEAD(head, elm, field) do { if (((elm)->field.sqx_next = (head)->sqx_first) == XSIMPLEQ_XOR(head, NULL)) (head)->sqx_last = XSIMPLEQ_XOR(head, &(elm)->field.sqx_next); (head)->sqx_first = XSIMPLEQ_XOR(head, (elm)); } while (0)

//#define XSIMPLEQ_INSERT_TAIL(head, elm, field) do { (elm)->field.sqx_next = XSIMPLEQ_XOR(head, NULL); *(XSIMPLEQ_XOR(head, (head)->sqx_last)) = XSIMPLEQ_XOR(head, (elm)); (head)->sqx_last = XSIMPLEQ_XOR(head, &(elm)->field.sqx_next); } while (0)

//#define XSIMPLEQ_INSERT_AFTER(head, listelm, elm, field) do { if (((elm)->field.sqx_next = (listelm)->field.sqx_next) == XSIMPLEQ_XOR(head, NULL)) (head)->sqx_last = XSIMPLEQ_XOR(head, &(elm)->field.sqx_next); (listelm)->field.sqx_next = XSIMPLEQ_XOR(head, (elm)); } while (0)

//#define XSIMPLEQ_REMOVE_HEAD(head, field) do { if (((head)->sqx_first = XSIMPLEQ_XOR(head, (head)->sqx_first)->field.sqx_next) == XSIMPLEQ_XOR(head, NULL)) (head)->sqx_last = XSIMPLEQ_XOR(head, &(head)->sqx_first); } while (0)

//#define XSIMPLEQ_REMOVE_AFTER(head, elm, field) do { if (((elm)->field.sqx_next = XSIMPLEQ_XOR(head, (elm)->field.sqx_next)->field.sqx_next) == XSIMPLEQ_XOR(head, NULL)) (head)->sqx_last = XSIMPLEQ_XOR(head, &(elm)->field.sqx_next); } while (0)

/*
 * Tail queue definitions.
 */
template TAILQ_HEAD(string name, string type)
{
	enum TAILQ_HEAD = "struct " ~ name ~ " { " ~ type ~ "* tqh_first; /* first element */ " ~ type ~ "** tqh_last; /* addr of last next element */ }";
}

pragma(inline, true)
pure nothrow @trusted @nogc @live
HEAD TAILQ_HEAD_INITIALIZER(HEAD)(HEAD* head)
	if (is(HEAD == struct))

	in
	{
		assert(head != null);
	}

	do
	{
		HEAD output =
		{
			null,
			&(head).tqh_first,
		};

		return output;
	}

template TAILQ_ENTRY(string type)
{
	enum TAILQ_ENTRY = "struct { " ~ type ~ "* tqe_next; /* next element */ " ~ type ~ "** tqe_prev; /* address of previous next element */ }";
}

/*
 * Tail queue access methods.
 */
//#define TAILQ_FIRST(head) ((head)->tqh_first)
//#define TAILQ_END(head) NULL
//#define TAILQ_NEXT(elm, field) ((elm)->field.tqe_next)
//#define TAILQ_LAST(head, headname) (*(((struct headname*) ((head)->tqh_last))->tqh_last))
/* XXX */
//#define TAILQ_PREV(elm, headname, field) (*(((struct headname*) ((elm)->field.tqe_prev))->tqh_last))
//#define TAILQ_EMPTY(head) (TAILQ_FIRST(head) == TAILQ_END(head))

//#define TAILQ_FOREACH(var, head, field) for ((var) = TAILQ_FIRST(head); (var) != TAILQ_END(head); (var) = TAILQ_NEXT(var, field))

//#define TAILQ_FOREACH_SAFE(var, head, field, tvar) for ((var) = TAILQ_FIRST(head); (var) != TAILQ_END(head) && ((tvar) = TAILQ_NEXT(var, field), 1); (var) = (tvar))

//#define TAILQ_FOREACH_REVERSE(var, head, headname, field) for ((var) = TAILQ_LAST(head, headname); (var) != TAILQ_END(head); (var) = TAILQ_PREV(var, headname, field))

//#define TAILQ_FOREACH_REVERSE_SAFE(var, head, headname, field, tvar) for ((var) = TAILQ_LAST(head, headname); (var) != TAILQ_END(head) && ((tvar) = TAILQ_PREV(var, headname, field), 1); (var) = (tvar))

/*
 * Tail queue functions.
 */
//#define TAILQ_INIT(head) do { (head)->tqh_first = NULL; (head)->tqh_last = &(head)->tqh_first; } while (0)

//#define TAILQ_INSERT_HEAD(head, elm, field) do { if (((elm)->field.tqe_next = (head)->tqh_first) != NULL) (head)->tqh_first->field.tqe_prev = &(elm)->field.tqe_next; else (head)->tqh_last = &(elm)->field.tqe_next; (head)->tqh_first = (elm); (elm)->field.tqe_prev = &(head)->tqh_first; } while (0)

//#define TAILQ_INSERT_TAIL(head, elm, field) do { (elm)->field.tqe_next = NULL; (elm)->field.tqe_prev = (head)->tqh_last; *(head)->tqh_last = (elm); (head)->tqh_last = &(elm)->field.tqe_next; } while (0)

//#define TAILQ_INSERT_AFTER(head, listelm, elm, field) do { if (((elm)->field.tqe_next = (listelm)->field.tqe_next) != NULL) (elm)->field.tqe_next->field.tqe_prev = &(elm)->field.tqe_next; else (head)->tqh_last = &(elm)->field.tqe_next; (listelm)->field.tqe_next = (elm); (elm)->field.tqe_prev = &(listelm)->field.tqe_next; } while (0)

//#define TAILQ_INSERT_BEFORE(listelm, elm, field) do { (elm)->field.tqe_prev = (listelm)->field.tqe_prev; (elm)->field.tqe_next = (listelm); *(listelm)->field.tqe_prev = (elm); (listelm)->field.tqe_prev = &(elm)->field.tqe_next; } while (0)

//#define TAILQ_REMOVE(head, elm, field) do { if (((elm)->field.tqe_next) != NULL) (elm)->field.tqe_next->field.tqe_prev = (elm)->field.tqe_prev; else (head)->tqh_last = (elm)->field.tqe_prev; *(elm)->field.tqe_prev = (elm)->field.tqe_next; _Q_INVALIDATE((elm)->field.tqe_prev); _Q_INVALIDATE((elm)->field.tqe_next); } while (0)

//#define TAILQ_REPLACE(head, elm, elm2, field) do { if (((elm2)->field.tqe_next = (elm)->field.tqe_next) != NULL) (elm2)->field.tqe_next->field.tqe_prev = &(elm2)->field.tqe_next; else (head)->tqh_last = &(elm2)->field.tqe_next; (elm2)->field.tqe_prev = (elm)->field.tqe_prev; *(elm2)->field.tqe_prev = (elm2); _Q_INVALIDATE((elm)->field.tqe_prev); _Q_INVALIDATE((elm)->field.tqe_next); } while (0)

//#define TAILQ_CONCAT(head1, head2, field) do { if (!TAILQ_EMPTY(head2)) { *(head1)->tqh_last = (head2)->tqh_first; (head2)->tqh_first->field.tqe_prev = (head1)->tqh_last; (head1)->tqh_last = (head2)->tqh_last; TAILQ_INIT((head2)); } } while (0)