Re: Strange crash on custom iterator

[Simon Wright <simon@pushface.org>]

Lucretia <laguest9000@googlemail.com> writes:

> On Saturday, 30 June 2018 12:32:14 UTC+1, Simon Wright  wrote:
>> Lucretia <> writes:
>>
>> > I finally got around to getting back to my iterator and on a first
>> > test implementation, i.e. to just iterate over each element of the
>> > array, the thing crashes in the Element function when accessing the
>> > array through the cursor.
>> >
>> > The source is https://bpaste.net/show/6c5fca4c0ffd and the gdb session
>> > is https://bpaste.net/show/5b0cf9d2be79
>>
>> UCA.Encoding missing?
>
> Balls! https://bpaste.net/show/a0d108820ce6

First, I think Has_Element should probably be

   function Has_Element (Position : in Cursor) return Boolean is
   begin
      return Position.Index in Position.Data'Range;
   end Has_Element;

Second, there's something odd about the Address_To_Access_Conversions:
in Iterate, the address of the passed Container (which is on the
stack!!!)  appears in I.Data, but I.Data's length is 0.

I got it to work (at first glance) with

   type Cursor is
      record
         Data  : Unicode_String_Access := null;
         Index : Positive              := Positive'Last;
      end record;

   type Code_Point_Iterator is new Limited_Controlled and Code_Point_Iterators.Forward_Iterator with
      record
         Data  : Unicode_String_Access := null;
      end record;

and in Iterate

      return I : Code_Point_Iterator :=
         (Limited_Controlled with Data => new Unicode_String'(Container)) do

but of course you probably don't want the copy.