utlist.h

/*
Copyright (c) 2007-2013, Troy D. Hanson   http://troydhanson.github.com/uthash/
All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:

    * Redistributions of source code must retain the above copyright
      notice, this list of conditions and the following disclaimer.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 COPYRIGHT OWNER
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.
*/

#ifndef UTLIST_H
#define UTLIST_H

#define UTLIST_VERSION 1.9.8

#include <assert.h>

/* 
 * This file contains macros to manipulate singly and doubly-linked lists.
 *
 * 1. LL_ macros:  singly-linked lists.
 * 2. DL_ macros:  doubly-linked lists.
 * 3. CDL_ macros: circular doubly-linked lists.
 *
 * To use singly-linked lists, your structure must have a "next" pointer.
 * To use doubly-linked lists, your structure must "prev" and "next" pointers.
 * Either way, the pointer to the head of the list must be initialized to NULL.
 * 
 * ----------------.EXAMPLE -------------------------
 * struct item {
 *      int id;
 *      struct item *prev, *next;
 * }
 *
 * struct item *list = NULL:
 *
 * int main() {
 *      struct item *item;
 *      ... allocate and populate item ...
 *      DL_APPEND(list, item);
 * }
 * --------------------------------------------------
 *
 * For doubly-linked lists, the append and delete macros are O(1)
 * For singly-linked lists, append and delete are O(n) but prepend is O(1)
 * The sort macro is O(n log(n)) for all types of single/double/circular lists.
 */

/* These macros use decltype or the earlier __typeof GNU extension.
   As decltype is only available in newer compilers (VS2010 or gcc 4.3+
   when compiling c++ code), this code uses whatever method is needed
   or, for VS2008 where neither is available, uses casting workarounds. */
#ifdef _MSC_VER            /* MS compiler */
#if _MSC_VER >= 1600 && defined(__cplusplus)  /* VS2010 or newer in C++ mode */
#define LDECLTYPE(x) decltype(x)
#else                     /* VS2008 or older (or VS2010 in C mode) */
#define NO_DECLTYPE
#define LDECLTYPE(x) char*
#endif
#else                      /* GNU, Sun and other compilers */
#define LDECLTYPE(x) __typeof(x)
#endif

/* for VS2008 we use some workarounds to get around the lack of decltype,
 * namely, we always reassign our tmp variable to the list head if we need
 * to dereference its prev/next pointers, and save/restore the real head.*/
#ifdef NO_DECLTYPE
#define _SV(elt,list) _tmp = (char*)(list); {char **_alias = (char**)&(list); *_alias = (elt); }
#define _NEXT(elt,list,next) ((char*)((list)->next))
#define _NEXTASGN(elt,list,to,next) { char **_alias = (char**)&((list)->next); *_alias=(char*)(to); }
/* #define _PREV(elt,list,prev) ((char*)((list)->prev)) */
#define _PREVASGN(elt,list,to,prev) { char **_alias = (char**)&((list)->prev); *_alias=(char*)(to); }
#define _RS(list) { char **_alias = (char**)&(list); *_alias=_tmp; }
#define _CASTASGN(a,b) { char **_alias = (char**)&(a); *_alias=(char*)(b); }
#else 
#define _SV(elt,list)
#define _NEXT(elt,list,next) ((elt)->next)
#define _NEXTASGN(elt,list,to,next) ((elt)->next)=(to)
/* #define _PREV(elt,list,prev) ((elt)->prev) */
#define _PREVASGN(elt,list,to,prev) ((elt)->prev)=(to)
#define _RS(list)
#define _CASTASGN(a,b) (a)=(b)
#endif

/******************************************************************************
 * The sort macro is an adaptation of Simon Tatham's O(n log(n)) mergesort    *
 * Unwieldy variable names used here to avoid shadowing passed-in variables.  *
 *****************************************************************************/
#define LL_SORT(list, cmp)                                                                     \
    LL_SORT2(list, cmp, next)

#define LL_SORT2(list, cmp, next)                                                              \
do {                                                                                           \
  LDECLTYPE(list) _ls_p;                                                                       \
  LDECLTYPE(list) _ls_q;                                                                       \
  LDECLTYPE(list) _ls_e;                                                                       \
  LDECLTYPE(list) _ls_tail;                                                                    \
  int _ls_insize, _ls_nmerges, _ls_psize, _ls_qsize, _ls_i, _ls_looping;                       \
  if (list) {                                                                                  \
    _ls_insize = 1;                                                                            \
    _ls_looping = 1;                                                                           \
    while (_ls_looping) {                                                                      \
      _CASTASGN(_ls_p,list);                                                                   \
      list = NULL;                                                                             \
      _ls_tail = NULL;                                                                         \
      _ls_nmerges = 0;                                                                         \
      while (_ls_p) {                                                                          \
        _ls_nmerges++;                                                                         \
        _ls_q = _ls_p;                                                                         \
        _ls_psize = 0;                                                                         \
        for (_ls_i = 0; _ls_i < _ls_insize; _ls_i++) {                                         \
          _ls_psize++;                                                                         \
          _SV(_ls_q,list); _ls_q = _NEXT(_ls_q,list,next); _RS(list);                          \
          if (!_ls_q) break;                                                                   \
        }                                                                                      \
        _ls_qsize = _ls_insize;                                                                \
        while (_ls_psize > 0 || (_ls_qsize > 0 && _ls_q)) {                                    \
          if (_ls_psize == 0) {                                                                \
            _ls_e = _ls_q; _SV(_ls_q,list); _ls_q =                                            \
              _NEXT(_ls_q,list,next); _RS(list); _ls_qsize--;                                  \
          } else if (_ls_qsize == 0 || !_ls_q) {                                               \
            _ls_e = _ls_p; _SV(_ls_p,list); _ls_p =                                            \
              _NEXT(_ls_p,list,next); _RS(list); _ls_psize--;                                  \
          } else if (cmp(_ls_p,_ls_q) <= 0) {                                                  \
            _ls_e = _ls_p; _SV(_ls_p,list); _ls_p =                                            \
              _NEXT(_ls_p,list,next); _RS(list); _ls_psize--;                                  \
          } else {                                                                             \
            _ls_e = _ls_q; _SV(_ls_q,list); _ls_q =                                            \
              _NEXT(_ls_q,list,next); _RS(list); _ls_qsize--;                                  \
          }                                                                                    \
          if (_ls_tail) {                                                                      \
            _SV(_ls_tail,list); _NEXTASGN(_ls_tail,list,_ls_e,next); _RS(list);                \
          } else {                                                                             \
            _CASTASGN(list,_ls_e);                                                             \
          }                                                                                    \
          _ls_tail = _ls_e;                                                                    \
        }                                                                                      \
        _ls_p = _ls_q;                                                                         \
      }                                                                                        \
      if (_ls_tail) {                                                                          \
        _SV(_ls_tail,list); _NEXTASGN(_ls_tail,list,NULL,next); _RS(list);                     \
      }                                                                                        \
      if (_ls_nmerges <= 1) {                                                                  \
        _ls_looping=0;                                                                         \
      }                                                                                        \
      _ls_insize *= 2;                                                                         \
    }                                                                                          \
  }                                                                                            \
} while (0)


#define DL_SORT(list, cmp)                                                                     \
    DL_SORT2(list, cmp, prev, next)

#define DL_SORT2(list, cmp, prev, next)                                                        \
do {                                                                                           \
  LDECLTYPE(list) _ls_p;                                                                       \
  LDECLTYPE(list) _ls_q;                                                                       \
  LDECLTYPE(list) _ls_e;                                                                       \
  LDECLTYPE(list) _ls_tail;                                                                    \
  int _ls_insize, _ls_nmerges, _ls_psize, _ls_qsize, _ls_i, _ls_looping;                       \
  if (list) {                                                                                  \
    _ls_insize = 1;                                                                            \
    _ls_looping = 1;                                                                           \
    while (_ls_looping) {                                                                      \
      _CASTASGN(_ls_p,list);                                                                   \
      list = NULL;                                                                             \
      _ls_tail = NULL;                                                                         \
      _ls_nmerges = 0;                                                                         \
      while (_ls_p) {                                                                          \
        _ls_nmerges++;                                                                         \
        _ls_q = _ls_p;                                                                         \
        _ls_psize = 0;                                                                         \
        for (_ls_i = 0; _ls_i < _ls_insize; _ls_i++) {                                         \
          _ls_psize++;                                                                         \
          _SV(_ls_q,list); _ls_q = _NEXT(_ls_q,list,next); _RS(list);                          \
          if (!_ls_q) break;                                                                   \
        }                                                                                      \
        _ls_qsize = _ls_insize;                                                                \
        while (_ls_psize > 0 || (_ls_qsize > 0 && _ls_q)) {                                    \
          if (_ls_psize == 0) {                                                                \
            _ls_e = _ls_q; _SV(_ls_q,list); _ls_q =                                            \
              _NEXT(_ls_q,list,next); _RS(list); _ls_qsize--;                                  \
          } else if (_ls_qsize == 0 || !_ls_q) {                                               \
            _ls_e = _ls_p; _SV(_ls_p,list); _ls_p =                                            \
              _NEXT(_ls_p,list,next); _RS(list); _ls_psize--;                                  \
          } else if (cmp(_ls_p,_ls_q) <= 0) {                                                  \
            _ls_e = _ls_p; _SV(_ls_p,list); _ls_p =                                            \
              _NEXT(_ls_p,list,next); _RS(list); _ls_psize--;                                  \
          } else {                                                                             \
            _ls_e = _ls_q; _SV(_ls_q,list); _ls_q =                                            \
              _NEXT(_ls_q,list,next); _RS(list); _ls_qsize--;                                  \
          }                                                                                    \
          if (_ls_tail) {                                                                      \
            _SV(_ls_tail,list); _NEXTASGN(_ls_tail,list,_ls_e,next); _RS(list);                \
          } else {                                                                             \
            _CASTASGN(list,_ls_e);                                                             \
          }                                                                                    \
          _SV(_ls_e,list); _PREVASGN(_ls_e,list,_ls_tail,prev); _RS(list);                     \
          _ls_tail = _ls_e;                                                                    \
        }                                                                                      \
        _ls_p = _ls_q;                                                                         \
      }                                                                                        \
      _CASTASGN(list->prev, _ls_tail);                                                         \
      _SV(_ls_tail,list); _NEXTASGN(_ls_tail,list,NULL,next); _RS(list);                       \
      if (_ls_nmerges <= 1) {                                                                  \
        _ls_looping=0;                                                                         \
      }                                                                                        \
      _ls_insize *= 2;                                                                         \
    }                                                                                          \
  }                                                                                            \
} while (0)

#define CDL_SORT(list, cmp)                                                                    \
    CDL_SORT2(list, cmp, prev, next)

#define CDL_SORT2(list, cmp, prev, next)                                                       \
do {                                                                                           \
  LDECLTYPE(list) _ls_p;                                                                       \
  LDECLTYPE(list) _ls_q;                                                                       \
  LDECLTYPE(list) _ls_e;                                                                       \
  LDECLTYPE(list) _ls_tail;                                                                    \
  LDECLTYPE(list) _ls_oldhead;                                                                 \
  LDECLTYPE(list) _tmp;                                                                        \
  int _ls_insize, _ls_nmerges, _ls_psize, _ls_qsize, _ls_i, _ls_looping;                       \
  if (list) {                                                                                  \
    _ls_insize = 1;                                                                            \
    _ls_looping = 1;                                                                           \
    while (_ls_looping) {                                                                      \
      _CASTASGN(_ls_p,list);                                                                   \
      _CASTASGN(_ls_oldhead,list);                                                             \
      list = NULL;                                                                             \
      _ls_tail = NULL;                                                                         \
      _ls_nmerges = 0;                                                                         \
      while (_ls_p) {                                                                          \
        _ls_nmerges++;                                                                         \
        _ls_q = _ls_p;                                                                         \
        _ls_psize = 0;                                                                         \
        for (_ls_i = 0; _ls_i < _ls_insize; _ls_i++) {                                         \
          _ls_psize++;                                                                         \
          _SV(_ls_q,list);                                                                     \
          if (_NEXT(_ls_q,list,next) == _ls_oldhead) {                                         \
            _ls_q = NULL;                                                                      \
          } else {                                                                             \
            _ls_q = _NEXT(_ls_q,list,next);                                                    \
          }                                                                                    \
          _RS(list);                                                                           \
          if (!_ls_q) break;                                                                   \
        }                                                                                      \
        _ls_qsize = _ls_insize;                                                                \
        while (_ls_psize > 0 || (_ls_qsize > 0 && _ls_q)) {                                    \
          if (_ls_psize == 0) {                                                                \
            _ls_e = _ls_q; _SV(_ls_q,list); _ls_q =                                            \
              _NEXT(_ls_q,list,next); _RS(list); _ls_qsize--;                                  \
            if (_ls_q == _ls_oldhead) { _ls_q = NULL; }                                        \
          } else if (_ls_qsize == 0 || !_ls_q) {                                               \
            _ls_e = _ls_p; _SV(_ls_p,list); _ls_p =                                            \
              _NEXT(_ls_p,list,next); _RS(list); _ls_psize--;                                  \
            if (_ls_p == _ls_oldhead) { _ls_p = NULL; }                                        \
          } else if (cmp(_ls_p,_ls_q) <= 0) {                                                  \
            _ls_e = _ls_p; _SV(_ls_p,list); _ls_p =                                            \
              _NEXT(_ls_p,list,next); _RS(list); _ls_psize--;                                  \
            if (_ls_p == _ls_oldhead) { _ls_p = NULL; }                                        \
          } else {                                                                             \
            _ls_e = _ls_q; _SV(_ls_q,list); _ls_q =                                            \
              _NEXT(_ls_q,list,next); _RS(list); _ls_qsize--;                                  \
            if (_ls_q == _ls_oldhead) { _ls_q = NULL; }                                        \
          }                                                                                    \
          if (_ls_tail) {                                                                      \
            _SV(_ls_tail,list); _NEXTASGN(_ls_tail,list,_ls_e,next); _RS(list);                \
          } else {                                                                             \
            _CASTASGN(list,_ls_e);                                                             \
          }                                                                                    \
          _SV(_ls_e,list); _PREVASGN(_ls_e,list,_ls_tail,prev); _RS(list);                     \
          _ls_tail = _ls_e;                                                                    \
        }                                                                                      \
        _ls_p = _ls_q;                                                                         \
      }                                                                                        \
      _CASTASGN(list->prev,_ls_tail);                                                          \
      _CASTASGN(_tmp,list);                                                                    \
      _SV(_ls_tail,list); _NEXTASGN(_ls_tail,list,_tmp,next); _RS(list);                       \
      if (_ls_nmerges <= 1) {                                                                  \
        _ls_looping=0;                                                                         \
      }                                                                                        \
      _ls_insize *= 2;                                                                         \
    }                                                                                          \
  }                                                                                            \
} while (0)

/******************************************************************************
 * singly linked list macros (non-circular)                                   *
 *****************************************************************************/
#define LL_PREPEND(head,add)                                                                   \
    LL_PREPEND2(head,add,next)

#define LL_PREPEND2(head,add,next)                                                             \
do {                                                                                           \
  (add)->next = head;                                                                          \
  head = add;                                                                                  \
} while (0)

#define LL_CONCAT(head1,head2)                                                                 \
    LL_CONCAT2(head1,head2,next)

#define LL_CONCAT2(head1,head2,next)                                                           \
do {                                                                                           \
  LDECLTYPE(head1) _tmp;                                                                       \
  if (head1) {                                                                                 \
    _tmp = head1;                                                                              \
    while (_tmp->next) { _tmp = _tmp->next; }                                                  \
    _tmp->next=(head2);                                                                        \
  } else {                                                                                     \
    (head1)=(head2);                                                                           \
  }                                                                                            \
} while (0)

#define LL_APPEND(head,add)                                                                    \
    LL_APPEND2(head,add,next)

#define LL_APPEND2(head,add,next)                                                              \
do {                                                                                           \
  LDECLTYPE(head) _tmp;                                                                        \
  (add)->next=NULL;                                                                            \
  if (head) {                                                                                  \
    _tmp = head;                                                                               \
    while (_tmp->next) { _tmp = _tmp->next; }                                                  \
    _tmp->next=(add);                                                                          \
  } else {                                                                                     \
    (head)=(add);                                                                              \
  }                                                                                            \
} while (0)

#define LL_DELETE(head,del)                                                                    \
    LL_DELETE2(head,del,next)

#define LL_DELETE2(head,del,next)                                                              \
do {                                                                                           \
  LDECLTYPE(head) _tmp;                                                                        \
  if ((head) == (del)) {                                                                       \
    (head)=(head)->next;                                                                       \
  } else {                                                                                     \
    _tmp = head;                                                                               \
    while (_tmp->next && (_tmp->next != (del))) {                                              \
      _tmp = _tmp->next;                                                                       \
    }                                                                                          \
    if (_tmp->next) {                                                                          \
      _tmp->next = ((del)->next);                                                              \
    }                                                                                          \
  }                                                                                            \
} while (0)

/* Here are VS2008 replacements for LL_APPEND and LL_DELETE */
#define LL_APPEND_VS2008(head,add)                                                             \
    LL_APPEND2_VS2008(head,add,next)

#define LL_APPEND2_VS2008(head,add,next)                                                       \
do {                                                                                           \
  if (head) {                                                                                  \
    (add)->next = head;     /* use add->next as a temp variable */                             \
    while ((add)->next->next) { (add)->next = (add)->next->next; }                             \
    (add)->next->next=(add);                                                                   \
  } else {                                                                                     \
    (head)=(add);                                                                              \
  }                                                                                            \
  (add)->next=NULL;                                                                            \
} while (0)

#define LL_DELETE_VS2008(head,del)                                                             \
    LL_DELETE2_VS2008(head,del,next)

#define LL_DELETE2_VS2008(head,del,next)                                                       \
do {                                                                                           \
  if ((head) == (del)) {                                                                       \
    (head)=(head)->next;                                                                       \
  } else {                                                                                     \
    char *_tmp = (char*)(head);                                                                \
    while ((head)->next && ((head)->next != (del))) {                                          \
      head = (head)->next;                                                                     \
    }                                                                                          \
    if ((head)->next) {                                                                        \
      (head)->next = ((del)->next);                                                            \
    }                                                                                          \
    {                                                                                          \
      char **_head_alias = (char**)&(head);                                                    \
      *_head_alias = _tmp;                                                                     \
    }                                                                                          \
  }                                                                                            \
} while (0)
#ifdef NO_DECLTYPE
#undef LL_APPEND
#define LL_APPEND LL_APPEND_VS2008
#undef LL_DELETE
#define LL_DELETE LL_DELETE_VS2008
#undef LL_DELETE2
#define LL_DELETE2_VS2008
#undef LL_APPEND2
#define LL_APPEND2 LL_APPEND2_VS2008
#undef LL_CONCAT /* no LL_CONCAT_VS2008 */
#undef DL_CONCAT /* no DL_CONCAT_VS2008 */
#endif
/* end VS2008 replacements */

#define LL_FOREACH(head,el)                                                                    \
    LL_FOREACH2(head,el,next)

#define LL_FOREACH2(head,el,next)                                                              \
    for(el=head;el;el=(el)->next)

#define LL_FOREACH_SAFE(head,el,tmp)                                                           \
    LL_FOREACH_SAFE2(head,el,tmp,next)

#define LL_FOREACH_SAFE2(head,el,tmp,next)                                                     \
  for((el)=(head);(el) && (tmp = (el)->next, 1); (el) = tmp)

#define LL_SEARCH_SCALAR(head,out,field,val)                                                   \
    LL_SEARCH_SCALAR2(head,out,field,val,next)

#define LL_SEARCH_SCALAR2(head,out,field,val,next)                                             \
do {                                                                                           \
    LL_FOREACH2(head,out,next) {                                                               \
      if ((out)->field == (val)) break;                                                        \
    }                                                                                          \
} while(0) 

#define LL_SEARCH(head,out,elt,cmp)                                                            \
    LL_SEARCH2(head,out,elt,cmp,next)

#define LL_SEARCH2(head,out,elt,cmp,next)                                                      \
do {                                                                                           \
    LL_FOREACH2(head,out,next) {                                                               \
      if ((cmp(out,elt))==0) break;                                                            \
    }                                                                                          \
} while(0) 

#define LL_REPLACE_ELEM(head, el, add)                                                         \
do {                                                                                           \
 LDECLTYPE(head) _tmp;                                                                         \
 assert(head != NULL);                                                                         \
 assert(el != NULL);                                                                           \
 assert(add != NULL);                                                                          \
 (add)->next = (el)->next;                                                                     \
 if ((head) == (el)) {                                                                         \
  (head) = (add);                                                                              \
 } else {                                                                                      \
  _tmp = head;                                                                                 \
  while (_tmp->next && (_tmp->next != (el))) {                                                 \
   _tmp = _tmp->next;                                                                          \
  }                                                                                            \
  if (_tmp->next) {                                                                            \
    _tmp->next = (add);                                                                        \
  }                                                                                            \
 }                                                                                             \
} while (0)

#define LL_PREPEND_ELEM(head, el, add)                                                         \
do {                                                                                           \
 LDECLTYPE(head) _tmp;                                                                         \
 assert(head != NULL);                                                                         \
 assert(el != NULL);                                                                           \
 assert(add != NULL);                                                                          \
 (add)->next = (el);                                                                           \
 if ((head) == (el)) {                                                                         \
  (head) = (add);                                                                              \
 } else {                                                                                      \
  _tmp = head;                                                                                 \
  while (_tmp->next && (_tmp->next != (el))) {                                                 \
   _tmp = _tmp->next;                                                                          \
  }                                                                                            \
  if (_tmp->next) {                                                                            \
    _tmp->next = (add);                                                                        \
  }                                                                                            \
 }                                                                                             \
} while (0)                                                                                    \


/******************************************************************************
 * doubly linked list macros (non-circular)                                   *
 *****************************************************************************/
#define DL_PREPEND(head,add)                                                                   \
    DL_PREPEND2(head,add,prev,next)

#define DL_PREPEND2(head,add,prev,next)                                                        \
do {                                                                                           \
 (add)->next = head;                                                                           \
 if (head) {                                                                                   \
   (add)->prev = (head)->prev;                                                                 \
   (head)->prev = (add);                                                                       \
 } else {                                                                                      \
   (add)->prev = (add);                                                                        \
 }                                                                                             \
 (head) = (add);                                                                               \
} while (0)

#define DL_APPEND(head,add)                                                                    \
    DL_APPEND2(head,add,prev,next)

#define DL_APPEND2(head,add,prev,next)                                                         \
do {                                                                                           \
  if (head) {                                                                                  \
      (add)->prev = (head)->prev;                                                              \
      (head)->prev->next = (add);                                                              \
      (head)->prev = (add);                                                                    \
      (add)->next = NULL;                                                                      \
  } else {                                                                                     \
      (head)=(add);                                                                            \
      (head)->prev = (head);                                                                   \
      (head)->next = NULL;                                                                     \
  }                                                                                            \
} while (0) 

#define DL_CONCAT(head1,head2)                                                                 \
    DL_CONCAT2(head1,head2,prev,next)

#define DL_CONCAT2(head1,head2,prev,next)                                                      \
do {                                                                                           \
  LDECLTYPE(head1) _tmp;                                                                       \
  if (head2) {                                                                                 \
    if (head1) {                                                                               \
        _tmp = (head2)->prev;                                                                  \
        (head2)->prev = (head1)->prev;                                                         \
        (head1)->prev->next = (head2);                                                         \
        (head1)->prev = _tmp;                                                                  \
    } else {                                                                                   \
        (head1)=(head2);                                                                       \
    }                                                                                          \
  }                                                                                            \
} while (0) 

#define DL_DELETE(head,del)                                                                    \
    DL_DELETE2(head,del,prev,next)

#define DL_DELETE2(head,del,prev,next)                                                         \
do {                                                                                           \
  assert((del)->prev != NULL);                                                                 \
  if ((del)->prev == (del)) {                                                                  \
      (head)=NULL;                                                                             \
  } else if ((del)==(head)) {                                                                  \
      (del)->next->prev = (del)->prev;                                                         \
      (head) = (del)->next;                                                                    \
  } else {                                                                                     \
      (del)->prev->next = (del)->next;                                                         \
      if ((del)->next) {                                                                       \
          (del)->next->prev = (del)->prev;                                                     \
      } else {                                                                                 \
          (head)->prev = (del)->prev;                                                          \
      }                                                                                        \
  }                                                                                            \
} while (0) 


#define DL_FOREACH(head,el)                                                                    \
    DL_FOREACH2(head,el,next)

#define DL_FOREACH2(head,el,next)                                                              \
    for(el=head;el;el=(el)->next)

/* this version is safe for deleting the elements during iteration */
#define DL_FOREACH_SAFE(head,el,tmp)                                                           \
    DL_FOREACH_SAFE2(head,el,tmp,next)

#define DL_FOREACH_SAFE2(head,el,tmp,next)                                                     \
  for((el)=(head);(el) && (tmp = (el)->next, 1); (el) = tmp)

/* these are identical to their singly-linked list counterparts */
#define DL_SEARCH_SCALAR LL_SEARCH_SCALAR
#define DL_SEARCH LL_SEARCH
#define DL_SEARCH_SCALAR2 LL_SEARCH_SCALAR2
#define DL_SEARCH2 LL_SEARCH2

#define DL_REPLACE_ELEM(head, el, add)                                                         \
do {                                                                                           \
 assert(head != NULL);                                                                         \
 assert(el != NULL);                                                                           \
 assert(add != NULL);                                                                          \
 if ((head) == (el)) {                                                                         \
  (head) = (add);                                                                              \
  (add)->next = (el)->next;                                                                    \
  if ((el)->next == NULL) {                                                                    \
   (add)->prev = (add);                                                                        \
  } else {                                                                                     \
   (add)->prev = (el)->prev;                                                                   \
   (add)->next->prev = (add);                                                                  \
  }                                                                                            \
 } else {                                                                                      \
  (add)->next = (el)->next;                                                                    \
  (add)->prev = (el)->prev;                                                                    \
  (add)->prev->next = (add);                                                                   \
  if ((el)->next == NULL) {                                                                    \
   (head)->prev = (add);                                                                       \
  } else {                                                                                     \
   (add)->next->prev = (add);                                                                  \
  }                                                                                            \
 }                                                                                             \
} while (0)

#define DL_PREPEND_ELEM(head, el, add)                                                         \
do {                                                                                           \
 assert(head != NULL);                                                                         \
 assert(el != NULL);                                                                           \
 assert(add != NULL);                                                                          \
 (add)->next = (el);                                                                           \
 (add)->prev = (el)->prev;                                                                     \
 (el)->prev = (add);                                                                           \
 if ((head) == (el)) {                                                                         \
  (head) = (add);                                                                              \
 } else {                                                                                      \
  (add)->prev->next = (add);                                                                   \
 }                                                                                             \
} while (0)                                                                                    \


/******************************************************************************
 * circular doubly linked list macros                                         *
 *****************************************************************************/
#define CDL_PREPEND(head,add)                                                                  \
    CDL_PREPEND2(head,add,prev,next)

#define CDL_PREPEND2(head,add,prev,next)                                                       \
do {                                                                                           \
 if (head) {                                                                                   \
   (add)->prev = (head)->prev;                                                                 \
   (add)->next = (head);                                                                       \
   (head)->prev = (add);                                                                       \
   (add)->prev->next = (add);                                                                  \
 } else {                                                                                      \
   (add)->prev = (add);                                                                        \
   (add)->next = (add);                                                                        \
 }                                                                                             \
(head)=(add);                                                                                  \
} while (0)

#define CDL_DELETE(head,del)                                                                   \
    CDL_DELETE2(head,del,prev,next)

#define CDL_DELETE2(head,del,prev,next)                                                        \
do {                                                                                           \
  if ( ((head)==(del)) && ((head)->next == (head))) {                                          \
      (head) = 0L;                                                                             \
  } else {                                                                                     \
     (del)->next->prev = (del)->prev;                                                          \
     (del)->prev->next = (del)->next;                                                          \
     if ((del) == (head)) (head)=(del)->next;                                                  \
  }                                                                                            \
} while (0) 

#define CDL_FOREACH(head,el)                                                                   \
    CDL_FOREACH2(head,el,next)

#define CDL_FOREACH2(head,el,next)                                                             \
    for(el=head;el;el=((el)->next==head ? 0L : (el)->next)) 

#define CDL_FOREACH_SAFE(head,el,tmp1,tmp2)                                                    \
    CDL_FOREACH_SAFE2(head,el,tmp1,tmp2,prev,next)

#define CDL_FOREACH_SAFE2(head,el,tmp1,tmp2,prev,next)                                         \
  for((el)=(head), ((tmp1)=(head)?((head)->prev):NULL);                                        \
      (el) && ((tmp2)=(el)->next, 1);                                                          \
      ((el) = (((el)==(tmp1)) ? 0L : (tmp2))))

#define CDL_SEARCH_SCALAR(head,out,field,val)                                                  \
    CDL_SEARCH_SCALAR2(head,out,field,val,next)

#define CDL_SEARCH_SCALAR2(head,out,field,val,next)                                            \
do {                                                                                           \
    CDL_FOREACH2(head,out,next) {                                                              \
      if ((out)->field == (val)) break;                                                        \
    }                                                                                          \
} while(0) 

#define CDL_SEARCH(head,out,elt,cmp)                                                           \
    CDL_SEARCH2(head,out,elt,cmp,next)

#define CDL_SEARCH2(head,out,elt,cmp,next)                                                     \
do {                                                                                           \
    CDL_FOREACH2(head,out,next) {                                                              \
      if ((cmp(out,elt))==0) break;                                                            \
    }                                                                                          \
} while(0) 

#define CDL_REPLACE_ELEM(head, el, add)                                                        \
do {                                                                                           \
 assert(head != NULL);                                                                         \
 assert(el != NULL);                                                                           \
 assert(add != NULL);                                                                          \
 if ((el)->next == (el)) {                                                                     \
  (add)->next = (add);                                                                         \
  (add)->prev = (add);                                                                         \
  (head) = (add);                                                                              \
 } else {                                                                                      \
  (add)->next = (el)->next;                                                                    \
  (add)->prev = (el)->prev;                                                                    \
  (add)->next->prev = (add);                                                                   \
  (add)->prev->next = (add);                                                                   \
  if ((head) == (el)) {                                                                        \
   (head) = (add);                                                                             \
  }                                                                                            \
 }                                                                                             \
} while (0)

#define CDL_PREPEND_ELEM(head, el, add)                                                        \
do {                                                                                           \
 assert(head != NULL);                                                                         \
 assert(el != NULL);                                                                           \
 assert(add != NULL);                                                                          \
 (add)->next = (el);                                                                           \
 (add)->prev = (el)->prev;                                                                     \
 (el)->prev = (add);                                                                           \
 (add)->prev->next = (add);                                                                    \
 if ((head) == (el)) {                                                                         \
  (head) = (add);                                                                              \
 }                                                                                             \
} while (0)                                                                                    \

#endif /* UTLIST_H */