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162 lines
2.9 KiB
C
162 lines
2.9 KiB
C
/*-------------------------------------------------------------------------
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*
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* oset.c--
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* Fixed format ordered set definitions.
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*
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* Copyright (c) 1994, Regents of the University of California
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*
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*
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* IDENTIFICATION
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* $Header: /cvsroot/pgsql/src/backend/utils/mmgr/Attic/oset.c,v 1.8 1998/06/15 19:29:53 momjian Exp $
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*
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* NOTE
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* XXX This is a preliminary implementation which lacks fail-fast
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* XXX validity checking of arguments.
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*
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*-------------------------------------------------------------------------
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*/
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#include "c.h"
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#include "utils/memutils.h" /* where declarations of this file goes */
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static Pointer OrderedElemGetBase(OrderedElem elem);
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static void OrderedElemPush(OrderedElem elem);
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static void OrderedElemPushHead(OrderedElem elem);
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/*
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* OrderedElemGetBase --
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* Returns base of enclosing structure.
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*/
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static Pointer
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OrderedElemGetBase(OrderedElem elem)
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{
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if (elem == (OrderedElem) NULL)
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return (Pointer) NULL;
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return ((Pointer) ((char *) (elem) - (elem)->set->offset));
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}
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/*
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* OrderedSetInit --
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*/
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void
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OrderedSetInit(OrderedSet set, Offset offset)
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{
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set->head = (OrderedElem) &set->dummy;
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set->dummy = NULL;
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set->tail = (OrderedElem) &set->head;
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set->offset = offset;
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}
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/*
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* OrderedSetContains --
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* True iff ordered set contains given element.
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*/
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bool
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OrderedSetContains(OrderedSet set, OrderedElem elem)
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{
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return ((bool) (elem->set == set && (elem->next || elem->prev)));
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}
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/*
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* OrderedSetGetHead --
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*/
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Pointer
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OrderedSetGetHead(OrderedSet set)
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{
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OrderedElem elem;
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elem = set->head;
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if (elem->next)
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return (OrderedElemGetBase(elem));
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return (NULL);
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}
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/*
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* OrderedSetGetTail --
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*/
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#ifdef NOT_USED
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Pointer
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OrderedSetGetTail(OrderedSet set)
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{
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OrderedElem elem;
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elem = set->tail;
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if (elem->prev)
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return (OrderedElemGetBase(elem));
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return (NULL);
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}
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#endif
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/*
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* OrderedElemGetPredecessor --
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*/
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Pointer
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OrderedElemGetPredecessor(OrderedElem elem)
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{
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elem = elem->prev;
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if (elem->prev)
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return (OrderedElemGetBase(elem));
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return (NULL);
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}
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/*
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* OrderedElemGetSuccessor --
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*/
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Pointer
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OrderedElemGetSuccessor(OrderedElem elem)
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{
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elem = elem->next;
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if (elem->next)
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return (OrderedElemGetBase(elem));
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return (NULL);
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}
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/*
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* OrderedElemPop --
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*/
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void
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OrderedElemPop(OrderedElem elem)
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{
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elem->next->prev = elem->prev;
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elem->prev->next = elem->next;
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/* assignments used only for error detection */
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elem->next = NULL;
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elem->prev = NULL;
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}
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/*
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* OrderedElemPushInto --
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*/
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void
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OrderedElemPushInto(OrderedElem elem, OrderedSet set)
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{
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elem->set = set;
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/* mark as unattached */
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elem->next = NULL;
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elem->prev = NULL;
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OrderedElemPush(elem);
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}
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/*
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* OrderedElemPush --
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*/
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static void
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OrderedElemPush(OrderedElem elem)
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{
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OrderedElemPushHead(elem);
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}
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/*
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* OrderedElemPushHead --
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*/
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static void
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OrderedElemPushHead(OrderedElem elem)
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{
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elem->next = elem->set->head;
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elem->prev = (OrderedElem) &elem->set->head;
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elem->next->prev = elem;
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elem->prev->next = elem;
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}
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