usr/src/usr.bin/make/lst.lib/lstFirst.c

/*
 * Copyright (c) 1988, 1989, 1990 The Regents of the University of California.
 * All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Adam de Boor.
 *
 * %sccs.include.redist.c%
 */

#ifndef lint
static char sccsid[] = "@(#)lstFirst.c  5.3 (Berkeley) %G%";
#endif /* not lint */

/*-
 * LstFirst.c --
 *      Return the first node of a list
 */

#include        "lstInt.h"

/*-
 *-----------------------------------------------------------------------
 * Lst_First --
 *      Return the first node on the given list.
 *
 * Results:
 *      The first node or NILLNODE if the list is empty.
 *
 * Side Effects:
 *      None.
 *
 *-----------------------------------------------------------------------
 */
LstNode
Lst_First (l)
    Lst l;
{
    if (!LstValid (l) || LstIsEmpty (l)) {
        return (NILLNODE);
    } else {
        return ((LstNode)((List)l)->firstPtr);
    }
}