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From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Newsgroups: comp.lang.ada
Subject: Re: [Slightly OT] How to process lightweight text markup languages?
Date: Mon, 19 Jan 2015 14:21:15 +0100
Organization: cbb software GmbH
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Date: 2015-01-19T14:21:15+01:00
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On Mon, 19 Jan 2015 12:09:40 +0100, G.B. wrote:

> On 18.01.15 21:21, Dmitry A. Kazakov wrote:
>> This is a pretty straightforward and simple technique.
> 
> The trouble is with expectations:
> 
> Input:
> 
>   ((){)([()[[]])]
> 
> Typical parsers will respond with such useless results
> as "error at EOF". Not something that a (close to)
> natural language processor can afford, I think.

Not with the technique I described. In your example, the operator stack
will contain:

  (  at pos. 2   <--- stack top
  (  at pos. 1

when } will try to wind it up by popping the last unmatched (. Since } does
not match ( you will easily generate "the closing curly bracket at pos. 3
does not match the opening round bracket at pos. 2"

Your experience probably come from grammar-generated parsers. The
straightforward technique is so much better for all practical purposes, and
for error messages generation especially.

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