Re: XMLAda & unicode symbols

[Simon Wright <simon@pushface.org>]

"196...@googlemail.com" <1963bib@googlemail.com> writes:

> I'm creating SVG files with XMLAda and I need to have a degree symbol
> within some text.
>
> I have:
> procedure Add_Min_Max (Min_Max_Str : String; X_Pos : String; Y_Pos : String) is
>       Text_Node : DOM.Core.Element;
>       Text      : DOM.Core.Text;
>    begin
>       Text_Node := DOM.Core.Documents.Create_Element (LDocument, "text");
>       DOM.Core.Elements.Set_Attribute (Text_Node, "x", X_Pos);
>       DOM.Core.Elements.Set_Attribute (Text_Node, "y", Y_Pos);
>       DOM.Core.Elements.Set_Attribute (Text_Node, "class", "def-maroon");
>       DOM.Core.Elements.Set_Attribute (Text_Node, "text-anchor", "left");
>       Text_Node := DOM.Core.Nodes.Append_Child (Root_Node, Text_Node);
>       Text := DOM.Core.Documents.Create_Text_Node (LDocument, Min_Max_Str);
>       Text := DOM.Core.Nodes.Append_Child (Text_Node, Text);
>    end Add_Min_Max;
>
> and I just pass a string in. The degree symbol is unicode 00B0 and you
> would then normally have it as &#00B0, except if I do, then XMLAda
> changes that initial '&' to '&amp' and so what is then coded is
> '&amp#00B0' and it fails to display properly.
>
> Nor can I apply Unicode.Names.Latin_1_Supplement.Degree_Sign to the
> string, since, well, strict typing...
>
> To me it seems like XMLAda is being far too eager and is not willing
> to just publish what I enter.
>
> I raised a call on the github repository, but it was closed saying
> basically use the unicode name, which fails.

Set_Attribute takes a Dom_String, which is a subtype of
Unicode.CES.Byte_Sequence, which is a subtype of String. The question
is, what encoding? I suspect it's utf-8, so we need to encode
Ada.Characters.Latin_1.Degree_Sign in utf-8, & this code using XML/Ada
support seems to do the trick:

   with Ada.Characters.Latin_1;
   with Ada.Text_IO;
   with Unicode.CES;
   with Unicode.Encodings;
   procedure Conversion is
      Fifty_Degrees_Latin1 : constant String
        := "50" & Ada.Characters.Latin_1.Degree_Sign;
      Fifty_Degrees_UTF8 : constant Unicode.CES.Byte_Sequence
        := "50"
          & Unicode.Encodings.Convert
            ((1 => Ada.Characters.Latin_1.Degree_Sign),
             From => Unicode.Encodings.Get_By_Name ("iso-8859-15"),
             To => Unicode.Encodings.Get_By_Name ("utf-8"));
   begin
      Ada.Text_IO.Put_Line (Fifty_Degrees_Latin1);
      Ada.Text_IO.Put_Line (Fifty_Degrees_UTF8);
   end Conversion;

(note that Convert's From and To parameters are the default). On this
Mac (Terminal displays utf-8 text) the first line is garbage, the second
fine.

I'm So Wildly Impressed (maybe "cast down" would be more accurate) by
all that subtyping in our wondrously safe language.

I also agree with you that suggesting you use a Unicode_Char
(Wide_Wide_Character) without saying *how* is less helpful than it could
be.