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/*
* libHX/assorted/deque2.c
* Copyright Jan Engelhardt, 2002-2007
*
* This file is part of libHX. libHX is free software; you can
* redistribute it and/or modify it under the terms of the GNU Lesser
* General Public License as published by the Free Software Foundation;
* either version 2.1 or (at your option) any later version.
*
* deque2.c:
* Assorted DEQUE functions that are not deemed to be useful in the
* (compiled) library at this time.
*/
#include <stdio.h>
#include <libHX.h>
EXPORT_SYMBOL struct HXdeque_node *HXdeque_rfind(struct HXdeque *dq,
const void *ptr)
{
struct HXdeque_node *trav;
for (trav = dq->last; trav != NULL; trav = trav->prev)
if (trav->ptr == ptr)
return trav;
return NULL;
}
EXPORT_SYMBOL void *HXdeque_rget(struct HXdeque *dq, const void *ptr)
{
struct HXdeque_node *trav;
for (trav = dq->last; trav != NULL; trav = trav->prev)
if (trav->ptr == ptr)
return trav->ptr;
return NULL;
}
EXPORT_SYMBOL void *HXdeque_sget(struct HXdeque *dq, const char *s)
{
struct HXdeque_node *trav;
for (trav = dq->first; trav != NULL; trav = trav->next)
if (strcmp(trav->ptr, s) == 0)
return trav->ptr;
return NULL;
}
EXPORT_SYMBOL struct HXdeque_node *HXdeque_dup(struct HXdeque *dq)
{
/*
* Duplicate the object on top of the stack by popping it off and
* adding it again, twice.
*/
if (dq->last == NULL)
return NULL;
/*
* The mathematical axiomatic definition is that the last element is
* popped off and pushed twice. We optimize by simply "looking" at the
* last and push it again.
*/
return HXdeque_push(dq, dq->last->ptr);
}
EXPORT_SYMBOL struct HXdeque_node *HXdeque_rdup(struct HXdeque *dq)
{
/* Same as HXdeque_dup(), but works on the bottom of the stack */
if (dq->first == NULL)
return NULL;
return HXdeque_unshift(dq, dq->first->ptr);
}
EXPORT_SYMBOL struct HXdeque_node *HXdeque_toprr(struct HXdeque *dq)
{
/*
* Rotates the topmost three items right ([bottom]...CBA[top] =>
* [bottom]...ACB[top]). Also works if there are only two items in the
* stack.
*/
struct HXdeque_node *p = dq->last;
if (p == NULL)
return NULL;
HXdeque_down(p);
HXdeque_down(p);
return p;
}
EXPORT_SYMBOL struct HXdeque_node *HXdeque_toprl(struct HXdeque *dq)
{
/* Rotates the topmost three items left (...CBA => ...BAC) */
struct HXdeque_node *p = dq->last;
if (p == NULL)
return NULL;
if (p->Prev != NULL) p = p->Prev;
if (p->Prev != NULL) p = p->Prev;
HXdeque_up(p);
HXdeque_up(p);
return p;
}
EXPORT_SYMBOL struct HXdeque_node *HXdeque_botrr(struct HXdeque *dq)
{
/* (CBA... => ...ACB) */
struct HXdeque_node *p = dq->first;
if (p == NULL)
return NULL;
if (p->Prev != NULL) p = p->Prev;
if (p->Prev != NULL) p = p->Prev;
HXdeque_down(p);
HXdeque_down(p);
return p;
}
EXPORT_SYMBOL struct HXdeque_node *HXdeque_botrl(struct HXdeque *dq)
{
struct HXdeque_node *p = dq->first;
if (p == NULL)
return NULL;
HXdeque_up(p);
HXdeque_up(p);
return p;
}
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