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From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Subject: Re: Data structures for syntax trees
Newsgroups: comp.lang.ada
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Organization: cbb software GmbH
References: <20100201213441.503839d5.tero.koskinen@iki.fi>
Date: Mon, 1 Feb 2010 21:03:44 +0100
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Date: 2010-02-01T21:03:43+01:00
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On Mon, 1 Feb 2010 21:34:41 +0200, Tero Koskinen wrote:

> And what kind of data structures others have used to present
> syntax trees?

I am using access types to non-controlled class-wide objects allocated in
an arena pool. A syntax tree is usually removed as a whole.

   Tree_Pool : Stack_Storage.Pool (2048, 128);

   type Node is abstract tagged limited null record;
   function Image (Item : Node) return String is abstract;
   type Node_Ptr is access Node'Class;
   for Node_Ptr'Storage_Pool use Tree_Pool;

   type Term is abstract new Node with record
      Location : Parsers.Multiline_Source.Location;
   end record;

   type Expression (Count : Positive) is new Node with record
      Operation : Operations;
      Location  : Parsers.Multiline_Source.Location;
      Operands  : Argument_List (1..Count);
   end record;

And so on. The example can be found here:

http://www.dmitry-kazakov.de/ada/components.htm#12.9

I cannot tell if that works with Janus, I don't have the compiler.

Alternatively I would use a directed graph. That again would be access
types to the arena pool of the graph nodes, parent-child relations
maintained implicitly by the pool.

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de