Re: How to use Multiway_Trees

[Niklas Holsti <niklas.holsti@tidorum.invalid>]

On 17-04-09 18:36 , Mart van de Wege wrote:
> I was interested in using Ada.Containers.Multiway_Trees in another
> project, so I wrote some Proof of Concept code to see if I understood
> correctly how to use it.
>
> However, even the most simple use case, the following code, raises a
> Program_Error:
>
> raised PROGRAM_ERROR : Tree_Test.Test_Tree.Replace_Element: Position cursor designates root
>
> with Ada.Text_Io;
> with Ada.Containers.Multiway_Trees;
> procedure Test_Tree is
>    type String_Access is access String;
>    package Tr is new Ada.Containers.Multiway_Trees
>      ( Element_Type => String_Access );
>    use Tr;
>    T : Tree := Empty_Tree;
>    C : Cursor := Root(T);
> begin
>    T.Insert_Child(Parent => C,
>                   Before => No_Element,
>                   New_Item => new String'("Test"));
> end Test_Tree;
>
> How do I create a tree if I can't even insert a child under the root
> node?
>
> Mart

That code works (no exceptions, and T.Node_Count = 2 after the 
Insert_Child) on my system, which is a Mac OS X 10.8.5 with GNAT GPL 
2012 (old, yes...).

-- 
Niklas Holsti
Tidorum Ltd
niklas holsti tidorum fi
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