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revived, beefed up and documented a old linked list implementation, UNTESTED

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Christian Thaeter 2007-09-05 02:44:23 +02:00
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/*
llist.h - simple intrusive cyclic double linked list
Copyright (C)
2003, 2005 Christian Thaeter <chth@gmx.net>
Copyright (C) CinelerraCV
2007, Christian Thaeter <ct@pipapo.org>
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 2 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, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#ifndef LLIST_H
#define LLIST_H
#include <stddef.h>
/**
* @file Intrusive cyclic double linked list
* There is only one node type which contains a forward and a backward pointer. In a empty initialized node,
* this pointers point to the node itself. Note that these pointers can never ever become NULL.
* This lists are used by using one node as 'root' node where its both pointers are the head/tail pointer to the actual list.
* Care needs to be taken to ensure not to apply any operations meant to be applied to data nodes to the root node.
* This way is the prefered way to use this lists.
* Alternatively one can store only a chain of data nodes and use a LList pointer to point to the first item
* (which might be NULL in case no data is stored). When using the 2nd approach care must be taken since most functions
* below expect lists to have a root node.
*
* This header can be used in 2 different ways:
* 1) (prerefered) just including it provides all functions as static inlined functions. This is the default
* 2) #define LLIST_INTERFACE before including this header gives only the declarations
* #define LLIST_IMPLEMENTATION before including this header yields in definitions
* this can be used to generate a library. This is currently untested and not recommended.
* The rationale for using inlined functions is that most functions are very small and likely to be used in performance critical parts.
* Inlining can give a hughe performance and optimization improvement here.
* The few functions which are slightly larger are expected to be the less common used ones, so inlining them too shouldn't be a problem either
*/
/* TODO __STDC_VERSION__ 199901L
150) This macro was not specified in ISO/IEC 9899:1990 and was specified as 199409L in
ISO/IEC 9899/AMD1:1995. The intention is that this will remain an integer constant of type long
int that is increased with each revision of this International Standard.
*/
#ifdef HAVE_INLINE
# define LLIST_MACRO static inline
#else
# ifdef __GNUC__
# define LLIST_MACRO static __inline__
# else
# define LLIST_MACRO static
# endif
#endif
#if defined(LLIST_INTERFACE)
/* only the interface is generated */
#define LLIST_FUNC(proto, ...) proto
#elif defined(LLIST_IMPLEMENTATION)
/* generate a non inlined implementation */
#define LLIST_FUNC(proto, ...) proto { __VA_ARGS__ }
#else
/* all functions are macro-like inlined */
#define LLIST_FUNC(proto, ...) LLIST_MACRO proto { __VA_ARGS__ }
#endif
/*
* Type of a llist node.
*/
struct llist_struct
{
struct llist_struct *next;
struct llist_struct *prev;
};
typedef struct llist_struct llist;
typedef llist * LList;
typedef const llist * const_LList;
typedef llist ** LList_ref;
/**
* cast back from a member of a structure to a pointer of the structure
*/
/* example:
struct foo
{
int bar;
llist l;
} x;
LLIST_TO_STRUCTP (&x.l, foo, l)->bar
*/
#define LLIST_TO_STRUCTP(llist, type, member) \
((type*)(((char*)(llist)) - offsetof(type, member)))
/**
* Iterate forward over a list.
* @param list the root node of the list to be iterated
* @param node pointer to the iterated node
*/
#define LLIST_FOREACH(list, node) \
if (!list); else \
for (LList node = llist_get_head (list); \
! llist_is_end (node, list); \
llist_forward (&node))
/**
* Iterate backward over a list.
* @param list the root node of the list to be iterated
* @param node pointer to the iterated node
*/
#define LLIST_FOREACH_REV(list, node) \
if (!list); else \
for (LList node = llist_get_tail (list); \
! llist_is_end (node, list); \
llist_backward (&node))
/**
* Consume a list from head.
* The body of this statement should remove the head from the list, else it would be a infinite loop
* @param list the root node of the list to be consumed
* @param head pointer to the head node
*/
#define LLIST_WHILE_HEAD(list, head) \
if (!list); else \
for (LList head = llist_get_head (list); \
!llist_is_empty (list); \
head = llist_get_head (list))
/**
* Consume a list from tail.
* The body of this statement should remove the tail from the list, else it would be a infinite loop
* @param list the root node of the list to be consumed
* @param tail pointer to the tail node
*/
#define LLIST_WHILE_TAIL(list, tail) \
if (!list); else \
for (LList tail = llist_get_tail (list); \
!llist_is_empty (list); \
tail = llist_get_tail (list))
/**
* Macro to instantiate a local llist.
* @param name becomes a LList handle
* the underlying instance is hidden as name_llist_, this list is statically initialized
*/
#define LLIST_AUTO(name) \
llist name##_llist_ = LLIST_STATIC_INITIALIZER(name##_llist_);\
LList name = &name##_llist_
#define LLIST_STATIC_INITIALIZER(name) {&name,&name}
/**
* Initialize a new llist.
* Must not be applied to a list node which is not empty! Lists need to be initialized
* before any other operation on them is called.
* @param self node to be initialized
*/
LLIST_FUNC (void llist_init (LList self),
self->next = self->prev = self;
);
/**
* Check if a node is not linked with some other node.
*/
LLIST_FUNC (int llist_is_empty (const_LList self),
return self->next == self;
);
/**
* Check if self is the only node in a list or self is not in a list.
* @param self node to be checked
*/
LLIST_FUNC (int llist_is_single (const_LList self),
return self->next->next == self;
);
/**
* Check for the head of a list.
* @param self root of the list
* @param head expected head of the list
*/
LLIST_FUNC (int llist_is_head (const_LList self, const_LList head),
return self->next == head;
);
/**
* Check for the tail of a list.
* @param self root of the list
* @param tail expected tail of the list
*/
LLIST_FUNC (int llist_is_tail (const_LList self, const_LList tail),
return self->prev == tail;
);
/**
* Check for the end of a list.
* The end is by definition one past the tail of a list, which is the root node itself.
* @param self root node of the list
* @param end expected end of the list
*/
LLIST_FUNC (int llist_is_end (const_LList self, const_LList end),
return self == end;
);
/**
* Check if a node is a member of a list.
* @param self root node of the list
* @param member node to be searched
*/
LLIST_FUNC (int llist_is_member (const_LList self, const_LList member),
for (const_LList i = member->next; i != member; i = i->next)
{
if (i == self)
return 1;
}
return 0;
);
/**
* Check the order of elements in a list.
* @param self root node of the list
* @param before expected to be before after
* @param after expected to be after before
*/
LLIST_FUNC (int llist_is_before_after (const_LList self, const_LList before, const_LList after),
for (const_LList i = before->next; i != self; i = i->next)
{
if (i == after)
return 1;
}
return 0;
);
/**
* Count the nodes of a list.
* @param self root node of the list
* @return number of nodes in self
*/
LLIST_FUNC (unsigned llist_count (const_LList self),
unsigned cnt = 0;
const_LList i = self;
for (; i->next != self; ++cnt, i = i->next);
return cnt;
);
/* private, unlink self some any list but leaves self in a uninitialized state */
LLIST_FUNC (void llist_unlink_fast_ (LList self),
LList nxt = self->next, pre = self->prev;
nxt->prev = pre;
pre->next = nxt;
);
/**
* Remove a node from a list.
* @param self node to be removed
* @return self
*/
LLIST_FUNC (LList llist_unlink (LList self),
llist_unlink_fast_ (self);
return self->next = self->prev = self;
);
/**
* Fix a node which got relocated in memory.
* It is supported to realloc/move list nodes in memory but one must call 'list_relocate' after doing so.
* @param self node which got relocated
* @return self
*/
LLIST_FUNC (LList llist_relocate (LList self),
return self->next->prev = self->prev->next = self;
);
/**
* Insert a node after another.
* @param self node after which we want to insert
* @param next node which shall be inserted after self. Could already linked to a list from where it will be removed.
* @return self
*/
LLIST_FUNC (LList llist_insert_next (LList self, LList next),
llist_unlink_fast_ (next);
self->next->prev = next;
next->prev = self;
next->next = self->next;
self->next = next;
return self;
);
/**
* Insert a node before another.
* @param self node before which we want to insert
* @param prev node which shall be inserted nefore self. Could already linked to a list from where it will be removed.
* @return self
*/
LLIST_FUNC (LList llist_insert_prev (LList self, LList prev),
llist_unlink_fast_ (prev);
self->prev->next = prev;
prev->next = self;
prev->prev = self->prev;
self->prev = prev;
return self;
);
/**
* Move the content of a list after a node in another list.
* @param self node after which we want to insert a list
* @param next rootnode of the list which shall be inserted after self
* @return self
* next is a empty list after this call
*/
LLIST_FUNC (LList llist_insertlist_next (LList self, LList next),
if (!llist_is_empty (next))
{
self->next->prev = next->prev;
self->next = next->next;
next->next->prev = self;
next->prev->next = self->next;
next->prev = next->next = next;
}
return self;
);
/**
* Move the content of a list before a node in another list.
* @param self node before which we want to insert a list
* @param prev rootnode of the list which shall be inserted before self
* @return self
* prev is a empty list after this call
*/
LLIST_FUNC (LList llist_insertlist_prev (LList self, LList prev),
if (!llist_is_empty (prev))
{
self->prev->next = prev->next;
self->prev = prev->prev;
prev->prev->next = self;
prev->next->prev = self->prev;
prev->prev = prev->next = prev;
}
return self;
);
#if 0 //BUG("needs temporary")
/**
* Move a range of nodes after a given node.
* @param self node after which the range shall be inserted
* @param start first node in range to be moved
* @param end node after the last node of the range
*/
LLIST_FUNC (LList llist_insertafter_range (LList self, LList start, LList end),
self->next->prev = end->prev;
end->prev->next = self->next;
end->prev = start->prev;
start->prev->next = end;
self->next = start;
start->prev = self;
return self;
);
#endif
#if 0 //BUG("needs temporary")
/**
* Move a range of nodes before a given node.
* @param self node before which the range shall be inserted
* @param start first node in range to be moved
* @param end node after the last node of the range
*/
LLIST_FUNC (LList llist_inserbefore_range (LList self, LList start, LList end),
self->prev->next = start;
start->prev->next = end;
end->prev = start->prev;
start->prev = self->prev;
self->prev = end->prev;
end->prev->next = self;
return self;
);
#endif
/**
* Swap a node with its next node.
* @param self node to be advaced
* @return self
* advancing will not stop at tail, one has to check that if this is intended
*/
LLIST_FUNC (LList llist_advance (LList self),
LList tmp = self->next->next;
tmp->prev = self;
self->next->prev = self->prev;
self->prev->next = self->next;
self->prev = self->next;
self->next->next = self;
self->next = tmp;
return self;
);
/**
* Swap a node with its previous node.
* @param self node to be retreated
* @return self
* retreating will not stop at head, one has to check that if this is intended
*/
LLIST_FUNC (LList llist_retreat (LList self),
LList tmp = self->prev->prev;
tmp->next = self;
self->prev->next = self->next;
self->next->prev = self->prev;
self->next = self->prev;
self->prev->prev = self;
self->prev = tmp;
return self;
);
/**
* Get next node.
* @param self current node
* @return node after self
* Will not stop at tail
*/
LLIST_FUNC (LList llist_next (const_LList self),
return self->next;
);
/**
* Get previous node.
* @param self current node
* @return node before self
* Will not stop at head
*/
LLIST_FUNC (LList llist_prev (const_LList self),
return self->prev;
);
/**
* Advance a pointer to a node to its next node.
* @param self pointer-to-pointer to the current node
* *self will point to the next node after this call
*/
LLIST_FUNC (void llist_forward (LList_ref self),
*self = (*self)->next;
);
/**
* Retreat a pointer to a node to its previous node.
* @param self pointer-to-pointer to the current node
* *self will point to the previous node after this call
*/
LLIST_FUNC (void llist_backward (LList_ref self),
*self = (*self)->prev;
);
/**
* Get the nth element of a list.
* @param self list to be queried
* @param n nth element after (positive n) or before (negative n) self
* this function does not stop at head/tail.
*/
LLIST_FUNC (LList llist_nth (LList self, int n),
if (n>0)
while (n--)
self = llist_get_next (self);
else
while (n++)
self = llist_get_prev (self);
return self;
);
/**
* Get the nth element of a list with a stop node.
* @param self list to be queried
* @param n nth element after (positive n) or before (negative n) self
* @param stop node which will abort the iteration
*/
LLIST_FUNC (LList llist_get_nth_stop (LList self, int n, const_LList stop),
if (n>0)
while (n--)
{
self = llist_get_next (self);
if (self == stop)
return NULL;
}
else
while (n++)
{
self = llist_get_prev (self);
if (self == stop)
return NULL;
}
return self;
);
/*
some macros for convenience
*/
#define llist_insert_head(list, element) llist_insert_next (list, element)
#define llist_insert_tail(list, element) llist_insert_prev (list, element)
#define llist_head llist_next
#define llist_tail llist_prev
#endif /* LLIST_H */
/*
// Local Variables:
// mode: C
// c-file-style: "gnu"
// End:
// arch-tag: e8fe4a59-fd55-4c45-b860-5cd1e0771213
// end_of_file
*/