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From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Newsgroups: comp.lang.ada
Subject: Re: GNOGA - RFC UXStrings package.
Date: Tue, 12 May 2020 11:35:53 +0200
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Date: 2020-05-12T11:35:53+02:00
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On 2020-05-12 10:13, Blady wrote:

> I've checked Simple Components, it might be completed with some parsing 
> functions in order to fulfill all Gnoga needs.

You are welcome to ask.

I am not sure what kind of parsing you mean, most of nightmarish legacy 
encodings are supported already, e.g.

    http://www.dmitry-kazakov.de/ada/strings_edit.htm#7.10

> But I think that UTF-8 
> (or UTF-16) internal representation would make too much penalties in 
> term of execution time which is critical for Gnoga as server.

Well, whatever minor overhead UTF-8 may have it is in order of many 
magnitude less than Unbounded_String or what you do in your code for 
UXStrings would inflict.

> That's why I would like to experiment some data structure with smart 
> character size (1, 2 or 4 bytes) and smart string length (either static 
> or dynamic).

When I am concerned about performance:

1. I make all content in UTF-8. I convert anything to UTF-8 first, if I 
get it from outside.

2. I never use dynamically allocated strings in any form, never in the 
standard memory pool. If I really, really need a pool, I use a custom 
arena pool and allocate a String there. As a nice side effect the server 
will be resilient all sorts of something-is-too-large attacks, no space 
in the arena, drop connection, bye.

3. I never copy anything. Thus, again, never Unbounded_String, only 
String and its slices.

4. I never tokenize anything. I walk down the string in a single pass, 
notice start/stop indices of a token, pass a string slice down to a 
semantic callback, better, pass it straight to a look-up table. No 
string copies.

5. I never use Wide or Wide_Wide. They are mess and require conversions 
=> copying => a lot of resources.

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