/* Copyright (C) 2001  David Decotigny
  
    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., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
    USA.
 */
 #ifndef _SOS_LIST_H_
 #define _SOS_LIST_H_
 
 /**
  * @file list.h
  *
  * Circular doubly-linked lists implementation entirely based on C
  * macros
  */
 
 
 /* *_named are used when next and prev links are not exactly next
    and prev. For instance when we have next_in_team, prev_in_team,
    prev_global and next_global */
 
 #define list_init_named(list,prev,next) \
   ((list) = NULL)
 
 #define list_singleton_named(list,item,prev,next) ({ \
   (item)->next = (item)->prev = (item); \
   (list) = (item); \
 })
 
 #define list_is_empty_named(list,prev,next) \
   ((list) == NULL)
 
 #define list_get_head_named(list,prev,next) \
   (list)
 
 #define list_get_tail_named(list,prev,next) \
   ((list)?((list)->prev):NULL)
 
 /* Internal macro : insert before the head == insert at tail */
 #define __list_insert_atleft_named(before_this,item,prev,next) ({ \
    (before_this)->prev->next = (item); \
    (item)->prev = (before_this)->prev; \
    (before_this)->prev = (item); \
    (item)->next = (before_this); \
 })
 
 /* @note Before_this and item are expected to be valid ! */
 #define list_insert_before_named(list,before_this,item,prev,next) ({ \
    __list_insert_atleft_named(before_this,item,prev,next); \
    if ((list) == (before_this)) (list) = (item); \
 })    
 
 /** @note After_this and item are expected to be valid ! */
 #define list_insert_after_named(list,after_this,item,prev,next) ({ \
    (after_this)->next->prev = (item); \
    (item)->next = (after_this)->next; \
    (after_this)->next = (item); \
    (item)->prev = (after_this); \
 })
 
 #define list_add_head_named(list,item,prev,next) ({ \
   if (list) \
     list_insert_before_named(list,list,item,prev,next); \
   else \
     list_singleton_named(list,item,prev,next); \
   (list) = (item); \
 })
 
 #define list_add_tail_named(list,item,prev,next) ({ \
   if (list) \
     __list_insert_atleft_named(list,item,prev,next); \
   else \
     list_singleton_named(list,item,prev,next); \
 })
 
 /** @note NO check whether item really is in list ! */
 #define list_delete_named(list,item,prev,next) ({ \
   if ( ((item)->next == (item)) && ((item)->prev == (item)) ) \
     (item)->next = (item)->prev = (list) = NULL; \
   else { \
     (item)->prev->next = (item)->next; \
     (item)->next->prev = (item)->prev; \
     if ((item) == (list)) (list) = (item)->next; \
     (item)->prev = (item)->next = NULL; \
   } \
 })
 
 #define list_pop_head_named(list,prev,next) ({ \
   typeof(list) __ret_elt = (list); \
   list_delete_named(list,__ret_elt,prev,next); \
   __ret_elt; })
 
 /** Loop statement that iterates through all of its elements, from
     head to tail */
 #define list_foreach_forward_named(list,iterator,nb_elements,prev,next) \
         for (nb_elements=0, (iterator) = (list) ; \
              (iterator) && (!nb_elements || ((iterator) != (list))) ; \
              nb_elements++, (iterator) = (iterator)->next )
 
 /** Loop statement that iterates through all of its elements, from
     tail back to head */
 #define list_foreach_backward_named(list,iterator,nb_elements,prev,next) \
         for (nb_elements=0, (iterator) = list_get_tail_named(list,prev,next) ; \
              (iterator) && (!nb_elements || \
                ((iterator) != list_get_tail_named(list,prev,next))) ; \
              nb_elements++, (iterator) = (iterator)->prev )
 
 #define list_foreach_named list_foreach_forward_named
 
 /** True when we exitted early from the foreach loop (ie break) */
 #define list_foreach_early_break(list,iterator,nb_elements) \
   ((list) && ( \
     ((list) != (iterator)) || \
     ( ((list) == (iterator)) && (nb_elements == 0)) ))
 
 /** Loop statement that also removes the item at each iteration */
 #define list_collapse_named(list,iterator,prev,next) \
         for ( ; ({ ((iterator) = (list)) ; \
                    if (list) list_delete_named(list,iterator,prev,next) ; \
                    (iterator); }) ; )
 
 
 /*
  * the same macros : assume that the prev and next fields are really
  * named "prev" and "next"
  */
 
 #define list_init(list) \
   list_init_named(list,prev,next)
 
 #define list_singleton(list,item) \
   list_singleton_named(list,item,prev,next)
 
 #define list_is_empty(list) \
   list_is_empty_named(list,prev,next)
 
 #define list_get_head(list) \
   list_get_head_named(list,prev,next) \
 
 #define list_get_tail(list) \
   list_get_tail_named(list,prev,next) \
 
 /* @note Before_this and item are expected to be valid ! */
 #define list_insert_after(list,after_this,item) \
   list_insert_after_named(list,after_this,item,prev,next)
 
 /* @note After_this and item are expected to be valid ! */
 #define list_insert_before(list,before_this,item) \
   list_insert_before_named(list,before_this,item,prev,next)
 
 #define list_add_head(list,item) \
   list_add_head_named(list,item,prev,next)
 
 #define list_add_tail(list,item) \
   list_add_tail_named(list,item,prev,next)
 
 /* @note NO check whether item really is in list ! */
 #define list_delete(list,item) \
   list_delete_named(list,item,prev,next)
 
 #define list_pop_head(list) \
   list_pop_head_named(list,prev,next)
 
 #define list_foreach_forward(list,iterator,nb_elements) \
   list_foreach_forward_named(list,iterator,nb_elements,prev,next)
 
 #define list_foreach_backward(list,iterator,nb_elements) \
   list_foreach_backward_named(list,iterator,nb_elements,prev,next)
 
 #define list_foreach list_foreach_forward
 
 #define list_collapse(list,iterator) \
   list_collapse_named(list,iterator,prev,next)
 
 #endif /* _SOS_LIST_H_ */