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From: Warren <ve3wwg@gmail.com>
Newsgroups: comp.lang.ada
Subject: Re: for S'Image use Func??
Date: Mon, 10 May 2010 20:16:37 +0000 (UTC)
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Date: 2010-05-10T20:16:37+00:00
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Niklas Holsti expounded in news:84r4k5Ftk8U1@mid.individual.net:

> Warren wrote:
>> Dmitry A. Kazakov expounded in
>> news:1qcb6z4i20dyb.1dz2hd4c0vx69.dlg@40tude.net: 
>> 
>>> On Mon, 10 May 2010 16:52:18 +0000 (UTC), Warren wrote:
>>>> But if I recall correctly, I also cannot get an
>>>> empty string as input. An empty string is still
>>>> valid input.
>>> Hmm, try this:
>> 
>> Ok, good- that at least works. 
>> 
>> But you have no way to know when you've read 
>> a empty line in a lexer routine that is reading 
>> character by character. 
> 
> Yes you do...
> 
>> What you end up having to do is to
>> test for line number changes instead-- yuk.
> 
> ... if you read character by character, use the function 
> Text_IO.End_Of_Line  to detect the end of an input line. This works
> the same way in all systems, whatever line termination character
> (sequence), if any, is used. Follow with Skip_Line to go to the start
> of the next line. 

I assume that is true before you read the next "char". If I
then Skip_Line as you say, will I also get End_Of_Line true
if the next line is empty (null)?

If true, then it may be time for me to reconsider how my
current lexer works.

> To return to the subject: I too often use 'Image for normal output,
> not just for debugging. And I find the extra blank annoying. But it is
> a very small annoyance, considering what else life offers :-)

I just now use:

    function Trim(S : String) return String is
    begin
        for X in S'Range loop
            if S(X) /= ' ' then
                return S(X..S'Last);
            end if;
        end loop;
        return "";
    end;

to trim off leading the blanks. This could be simpler, if
you only use it for S'Image. ;-)

Thanks for the tip,
Warren