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Annotation of 43BSDReno/usr.bin/make/lst.lib/lstNext.c, revision 1.1

1.1     ! root        1: /*
        !             2:  * Copyright (c) 1988, 1989, 1990 The Regents of the University of California.
        !             3:  * All rights reserved.
        !             4:  *
        !             5:  * This code is derived from software contributed to Berkeley by
        !             6:  * Adam de Boor.
        !             7:  *
        !             8:  * Redistribution and use in source and binary forms are permitted
        !             9:  * provided that: (1) source distributions retain this entire copyright
        !            10:  * notice and comment, and (2) distributions including binaries display
        !            11:  * the following acknowledgement:  ``This product includes software
        !            12:  * developed by the University of California, Berkeley and its contributors''
        !            13:  * in the documentation or other materials provided with the distribution
        !            14:  * and in all advertising materials mentioning features or use of this
        !            15:  * software. Neither the name of the University nor the names of its
        !            16:  * contributors may be used to endorse or promote products derived
        !            17:  * from this software without specific prior written permission.
        !            18:  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
        !            19:  * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
        !            20:  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
        !            21:  */
        !            22: 
        !            23: #ifndef lint
        !            24: static char sccsid[] = "@(#)lstNext.c  5.3 (Berkeley) 6/1/90";
        !            25: #endif /* not lint */
        !            26: 
        !            27: /*-
        !            28:  * LstNext.c --
        !            29:  *     Return the next node for a list.
        !            30:  *     The sequential functions access the list in a slightly different way.
        !            31:  *     CurPtr points to their idea of the current node in the list and they
        !            32:  *     access the list based on it. Because the list is circular, Lst_Next
        !            33:  *     and Lst_Prev will go around the list forever. Lst_IsAtEnd must be
        !            34:  *     used to determine when to stop.
        !            35:  */
        !            36: 
        !            37: #include       "lstInt.h"
        !            38: 
        !            39: /*-
        !            40:  *-----------------------------------------------------------------------
        !            41:  * Lst_Next --
        !            42:  *     Return the next node for the given list.
        !            43:  *
        !            44:  * Results:
        !            45:  *     The next node or NILLNODE if the list has yet to be opened. Also
        !            46:  *     if the list is non-circular and the end has been reached, NILLNODE
        !            47:  *     is returned.
        !            48:  *
        !            49:  * Side Effects:
        !            50:  *     the curPtr field is updated.
        !            51:  *
        !            52:  *-----------------------------------------------------------------------
        !            53:  */
        !            54: LstNode
        !            55: Lst_Next (l)
        !            56:     Lst                  l;
        !            57: {
        !            58:     register ListNode  tln;
        !            59:     register List      list = (List)l;
        !            60:     
        !            61:     if ((LstValid (l) == FALSE) ||
        !            62:        (list->isOpen == FALSE)) {
        !            63:            return (NILLNODE);
        !            64:     }
        !            65:     
        !            66:     list->prevPtr = list->curPtr;
        !            67:     
        !            68:     if (list->curPtr == NilListNode) {
        !            69:        if (list->atEnd == Unknown) {
        !            70:            /*
        !            71:             * If we're just starting out, atEnd will be Unknown.
        !            72:             * Then we want to start this thing off in the right
        !            73:             * direction -- at the start with atEnd being Middle.
        !            74:             */
        !            75:            list->curPtr = tln = list->firstPtr;
        !            76:            list->atEnd = Middle;
        !            77:        } else {
        !            78:            tln = NilListNode;
        !            79:            list->atEnd = Tail;
        !            80:        }
        !            81:     } else {
        !            82:        tln = list->curPtr->nextPtr;
        !            83:        list->curPtr = tln;
        !            84: 
        !            85:        if (tln == list->firstPtr || tln == NilListNode) {
        !            86:            /*
        !            87:             * If back at the front, then we've hit the end...
        !            88:             */
        !            89:            list->atEnd = Tail;
        !            90:        } else {
        !            91:            /*
        !            92:             * Reset to Middle if gone past first.
        !            93:             */
        !            94:            list->atEnd = Middle;
        !            95:        }
        !            96:     }
        !            97:     
        !            98:     return ((LstNode)tln);
        !            99: }
        !           100: 

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