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36 * $FreeBSD: src/usr.bin/make/lst.lib/lstConcat.c,v 1.7 1999/08/28 01:03:47 peter Exp $
37 * $DragonFly: src/usr.bin/make/lst.lib/Attic/lstConcat.c,v 1.11 2005/01/06 10:53:00 okumoto Exp $
39 * @(#)lstConcat.c 8.1 (Berkeley) 6/6/93
44 * Function to concatentate two lists.
54 *-----------------------------------------------------------------------
56 * Concatenate two lists. New elements are created to hold the data
57 * elements, if specified, but the elements themselves are not copied.
58 * If the elements should be duplicated to avoid confusion with another
59 * list, the Lst_Duplicate function should be called first.
62 * SUCCESS if all went well. FAILURE otherwise.
65 * list1 The list to which list2 is to be appended
66 * list2 The list to append to list1
67 * flags LST_CONCNEW if LstNode's should be duplicated
68 * LST_CONCLINK if should just be relinked
71 * New elements are created and appended the the first list.
72 *-----------------------------------------------------------------------
75 Lst_Concat(Lst *list1, Lst *list2, int flags)
77 LstNode *ln; /* original LstNode */
78 LstNode *nln; /* new LstNode */
79 LstNode *last; /* the last element in the list. Keeps
80 * bookkeeping until the end */
82 if (list2->firstPtr == NULL)
85 if (flags == LST_CONCLINK) {
87 * Link the first element of the second list to the last element of the
88 * first list. If the first list isn't empty, we then link the
89 * last element of the list to the first element of the second list
90 * The last element of the second list, if it exists, then becomes
91 * the last element of the first list.
93 list2->firstPtr->prevPtr = list1->lastPtr;
94 if (list1->lastPtr != NULL)
95 list1->lastPtr->nextPtr = list2->firstPtr;
97 list1->firstPtr = list2->firstPtr;
98 list1->lastPtr = list2->lastPtr;
103 * The loop simply goes through the entire
104 * second list creating new LstNodes and filling in the nextPtr, and
105 * prevPtr to fit into list1 and its datum field from the
106 * datum field of the corresponding element in list2. The 'last' node
107 * follows the last of the new nodes along until the entire list2 has
108 * been appended. Only then does the bookkeeping catch up with the
109 * changes. During the first iteration of the loop, if 'last' is NULL,
110 * the first list must have been empty so the newly-created node is
111 * made the first node of the list.
113 for (last = list1->lastPtr, ln = list2->firstPtr;
117 nln = emalloc(sizeof(*nln));
118 nln->datum = ln->datum;
122 list1->firstPtr = nln;
125 nln->flags = nln->useCount = 0;
130 * Finish bookkeeping. The last new element becomes the last element
133 list1->lastPtr = last;
134 last->nextPtr = NULL;