stack.c

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/* $Id$ $Revision$ */
/* vim:set shiftwidth=4 ts=8: */

/*************************************************************************
 * Copyright (c) 2011 AT&T Intellectual Property 
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors: See CVS logs. Details at http://www.graphviz.org/
 *************************************************************************/


#include        "stack.h"
#include        "circular.h"
#include        <assert.h>

nstack_t *mkStack()
{
    nstack_t *s;

    s = NEW(nstack_t);

    s->top = NULL;
    s->sz = 0;
    return s;
}

void freeStack(nstack_t * s)
{
    free(s);
}

void stackPush(nstack_t * s, Agnode_t * n)
{
    SET_ONSTACK(n);
    NEXT(n) = s->top;
    s->top = n;
    s->sz += 1;
}

Agnode_t *stackPop(nstack_t * s)
{
    Agnode_t *top = s->top;

    if (top) {
        assert(s->sz > 0);
        UNSET_ONSTACK(top);
        s->top = NEXT(top);
        s->sz -= 1;
    } else {
        assert(0);
    }

    return top;
}

int stackSize(nstack_t * s)
{
    return s->sz;
}

/* stackCheck:
 * Return true if n in on the stack.
 */
int stackCheck(nstack_t * s, Agnode_t * n)
{
    return ONSTACK(n);
#ifdef OLD
    stackitem_t *top = s->top;
    Agnode_t *node;

    while (top != NULL) {
        node = top->data;
        if (node == n)
            return 1;
        top = top->next;
    }

    return 0;
#endif
}

#ifdef DEBUG
void printStack(nstack_t * s)
{
    Agnode_t *n;
    for (n = s->top; n; n = NEXT(n))
        fprintf(stderr, " %s", n->name);
    fprintf(stderr, "\n");

}
#endif