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/*-------------------------------------------------------------------------
*
* fstack.c--
* Fixed format stack definitions.
*
* Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/lib/Attic/fstack.c,v 1.8 1998/06/15 19:28:24 momjian Exp $
*
*-------------------------------------------------------------------------
*/
#include <postgres.h>
#include <lib/fstack.h>
/*
* Internal function definitions
*/
/*
* FixedItemIsValid --
* True iff item is valid.
*/
#define FixedItemIsValid(item) PointerIsValid(item)
/*
* FixedStackGetItemBase --
* Returns base of enclosing structure.
*/
#define FixedStackGetItemBase(stack, item) \
((Pointer)((char *)(item) - (stack)->offset))
/*
* FixedStackGetItem --
* Returns item of given pointer to enclosing structure.
*/
#define FixedStackGetItem(stack, pointer) \
((FixedItem)((char *)(pointer) + (stack)->offset))
#define FixedStackIsValid(stack) ((bool)PointerIsValid(stack))
/*
* External functions
*/
void
FixedStackInit(FixedStack stack, Offset offset)
{
AssertArg(PointerIsValid(stack));
stack->top = NULL;
stack->offset = offset;
}
Pointer
FixedStackPop(FixedStack stack)
{
Pointer pointer;
AssertArg(FixedStackIsValid(stack));
if (!PointerIsValid(stack->top))
return (NULL);
pointer = FixedStackGetItemBase(stack, stack->top);
stack->top = stack->top->next;
return (pointer);
}
void
FixedStackPush(FixedStack stack, Pointer pointer)
{
FixedItem item = FixedStackGetItem(stack, pointer);
AssertArg(FixedStackIsValid(stack));
AssertArg(PointerIsValid(pointer));
item->next = stack->top;
stack->top = item;
}
#ifdef USE_ASSERT_CHECKING
/*
* FixedStackContains --
* True iff ordered stack contains given element.
*
* Note:
* This is inefficient. It is intended for debugging use only.
*
* Exceptions:
* BadArg if stack is invalid.
* BadArg if pointer is invalid.
*/
static bool
FixedStackContains(FixedStack stack, Pointer pointer)
{
FixedItem next;
FixedItem item;
AssertArg(FixedStackIsValid(stack));
AssertArg(PointerIsValid(pointer));
item = FixedStackGetItem(stack, pointer);
for (next = stack->top; FixedItemIsValid(next); next = next->next)
{
if (next == item)
return (true);
}
return (false);
}
#endif
Pointer
FixedStackGetTop(FixedStack stack)
{
AssertArg(FixedStackIsValid(stack));
if (!PointerIsValid(stack->top))
return (NULL);
return (FixedStackGetItemBase(stack, stack->top));
}
Pointer
FixedStackGetNext(FixedStack stack, Pointer pointer)
{
FixedItem item;
/* AssertArg(FixedStackIsValid(stack)); */
/* AssertArg(PointerIsValid(pointer)); */
AssertArg(FixedStackContains(stack, pointer));
item = FixedStackGetItem(stack, pointer)->next;
if (!PointerIsValid(item))
return (NULL);
return (FixedStackGetItemBase(stack, item));
}
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