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Annotation of 43BSDReno/usr.bin/make/lst.lib/lstRemove.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[] = "@(#)lstRemove.c        5.3 (Berkeley) 6/1/90";
        !            25: #endif /* not lint */
        !            26: 
        !            27: /*-
        !            28:  * LstRemove.c --
        !            29:  *     Remove an element from a list
        !            30:  */
        !            31: 
        !            32: #include       "lstInt.h"
        !            33: 
        !            34: /*-
        !            35:  *-----------------------------------------------------------------------
        !            36:  * Lst_Remove --
        !            37:  *     Remove the given node from the given list.
        !            38:  *
        !            39:  * Results:
        !            40:  *     SUCCESS or FAILURE.
        !            41:  *
        !            42:  * Side Effects:
        !            43:  *     The list's firstPtr will be set to NilListNode if ln is the last
        !            44:  *     node on the list. firsPtr and lastPtr will be altered if ln is
        !            45:  *     either the first or last node, respectively, on the list.
        !            46:  *
        !            47:  *-----------------------------------------------------------------------
        !            48:  */
        !            49: ReturnStatus
        !            50: Lst_Remove (l, ln)
        !            51:     Lst                        l;
        !            52:     LstNode            ln;
        !            53: {
        !            54:     register List      list = (List) l;
        !            55:     register ListNode  lNode = (ListNode) ln;
        !            56: 
        !            57:     if (!LstValid (l) ||
        !            58:        !LstNodeValid (ln, l)) {
        !            59:            return (FAILURE);
        !            60:     }
        !            61:     
        !            62:     /*
        !            63:      * unlink it from the list
        !            64:      */
        !            65:     if (lNode->nextPtr != NilListNode) {
        !            66:        lNode->nextPtr->prevPtr = lNode->prevPtr;
        !            67:     }
        !            68:     if (lNode->prevPtr != NilListNode) {
        !            69:        lNode->prevPtr->nextPtr = lNode->nextPtr;
        !            70:     }
        !            71:     
        !            72:     /*
        !            73:      * if either the firstPtr or lastPtr of the list point to this node,
        !            74:      * adjust them accordingly
        !            75:      */
        !            76:     if (list->firstPtr == lNode) {
        !            77:        list->firstPtr = lNode->nextPtr;
        !            78:     }
        !            79:     if (list->lastPtr == lNode) {
        !            80:        list->lastPtr = lNode->prevPtr;
        !            81:     }
        !            82: 
        !            83:     /*
        !            84:      * Sequential access stuff. If the node we're removing is the current
        !            85:      * node in the list, reset the current node to the previous one. If the
        !            86:      * previous one was non-existent (prevPtr == NilListNode), we set the
        !            87:      * end to be Unknown, since it is.
        !            88:      */
        !            89:     if (list->isOpen && (list->curPtr == lNode)) {
        !            90:        list->curPtr = list->prevPtr;
        !            91:        if (list->curPtr == NilListNode) {
        !            92:            list->atEnd = Unknown;
        !            93:        }
        !            94:     }
        !            95: 
        !            96:     /*
        !            97:      * the only way firstPtr can still point to ln is if ln is the last
        !            98:      * node on the list (the list is circular, so lNode->nextptr == lNode in
        !            99:      * this case). The list is, therefore, empty and is marked as such
        !           100:      */
        !           101:     if (list->firstPtr == lNode) {
        !           102:        list->firstPtr = NilListNode;
        !           103:     }
        !           104:     
        !           105:     /*
        !           106:      * note that the datum is unmolested. The caller must free it as
        !           107:      * necessary and as expected.
        !           108:      */
        !           109:     if (lNode->useCount == 0) {
        !           110:        free ((Address)ln);
        !           111:     } else {
        !           112:        lNode->flags |= LN_DELETED;
        !           113:     }
        !           114:     
        !           115:     return (SUCCESS);
        !           116: }
        !           117: 

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