rom/utility/clonetagitems.c

   1 /*
   2     Copyright © 1995-2001, The AROS Development Team. All rights reserved.
   3     $Id$
   4
   5     Desc: CloneTagItems()
   6     Lang: english
   7 */
   8 #include "intern.h"
   9
  10 /*****************************************************************************
  11
  12     NAME */
  13 #include <utility/tagitem.h>
  14 #include <proto/utility.h>
  15
  16         AROS_LH1(struct TagItem *, CloneTagItems,
  17
  18 /*  SYNOPSIS */
  19         AROS_LHA(const struct TagItem *, tagList, A0),
  20
  21 /*  LOCATION */
  22         struct UtilityBase *, UtilityBase, 12, Utility)
  23
  24 /*  FUNCTION
  25         Duplicates a TagList. The input TagList can be NULL, in which
  26         case an empty TagList will be returned.
  27
  28     INPUTS
  29         tagList     -   The TagList that you want to clone
  30
  31     RESULT
  32         A TagList which contains a copy of the TagItems contained in the
  33         original list. The list is cloned so that calling FindTagItem()
  34         on a tag in the clone will return the same value as that in the
  35         original list (assuming the original has not been modified).
  36
  37     NOTES
  38
  39     EXAMPLE
  40         struct TagItem *tagList, *tagListClone;
  41
  42         \* Set up the original taglist tagList *\
  43
  44         tagListClone = CloneTagItems( tagList );
  45
  46         \* Do what you want with your TagList here *\
  47
  48         FreeTagItems( tagListClone );
  49
  50     BUGS
  51
  52     SEE ALSO
  53         AllocateTagItems(), FreeTagItems(), RefreshTagItemClones()
  54
  55     INTERNALS
  56
  57     HISTORY
  58         29-10-95    digulla automatically created from
  59                             utility_lib.fd and clib/utility_protos.h
  60         11-08-96    iaint   Implemented as AROS function.
  61         01-09-96    iaint   Updated the docs to give the same warnings
  62                             as the autodocs.
  63         05-09-96    iaint   Bit of optimisation (one variable :( )
  64         23-01-97    iaint   Corrected NULL TagList handling.
  65
  66 *****************************************************************************/
  67 {
  68     AROS_LIBFUNC_INIT
  69
  70     struct TagItem *newList;
  71     LONG numTags = 1;
  72
  73     /*
  74         This is rather strange, if we have a NULL input, then we still
  75         have to allocate a list. This is to circumvent a bug in SID v2,
  76         which for some unknown reason is the only program I have seen
  77         that has this problem.
  78
  79         Had to alter RefreshTagItemClones as well.
  80         However, that is also what the autodoc says...
  81     */
  82     if (tagList)
  83     {
  84         const struct TagItem *tmp;
  85         /*
  86             We start the counter at 1 since this count will not include the
  87             TAG_DONE TagItem
  88
  89             newList is used here to save a variable. We don't need to do
  90             anything to the value of newList afterwards, since AllocateTagitems()
  91             will take care of setting it to NULL if the allocation fails.
  92         */
  93         tmp = tagList;
  94         while (NextTagItem (&tmp) != NULL)
  95             numTags++;
  96     }
  97
  98     /*
  99         Then we shall allocate the TagList.
 100         If we can actually allocate a clone tag list, then we shall copy
 101         the tag values from one tag to another, the function
 102         "RefreshTagItemClones()" is used here to help re-use code.
 103
 104         Of course we don't have to worry about the if and only if
 105         statement, since the original is guaranteed to have not
 106         been changed since CloneTagItems() :)
 107     */
 108
 109     if ((newList = AllocateTagItems(numTags)))
 110         RefreshTagItemClones(newList, tagList);
 111
 112     /* newList == 0 when allocation failed - AllocateTagItems handles this*/
 113     return newList;
 114
 115     AROS_LIBFUNC_EXIT
 116 } /* CloneTagItems */