Re: Ada bench : count words

[Jeff C <jcreem@yahoo.com>]

Dmitry A. Kazakov wrote:
> On Tue, 22 Mar 2005 01:16:09 +0000, Marius Amado Alves wrote:
> 
> 
>>I took a shot at the count-words benchmark, a program to count lines, 
>>words and characters. The Ada program currently published there is 
>>broken. My program is correct and portable but:
>>
>>- the speed is circa 1/3 of the GCC C version
>>
>>- it fails to comply with the requirement that the input be taken from 
>>standard input. To implement buffering, I have resorted to 
>>Ada.Direct_IO, which I think cannot apply to standard input.
> 
> 
> Is Text_IO that bad?


It can be. It does a few  things that real programs often do not need to 
do (counting pages) and may not do buffering that is optimal for the job 
here. The problem is of course that it is a requirement to read from 
standard input and if I were running the website I would reject a 
program that does not.

Perhaps this could be done by using ada.text_io.text_streams to get 
access to a stream based on standard input and then use the "Read" 
procedure (v.s. 'read attribute) to get 4k blocks of data (recommended 
chunking size from problem definition). The Read procedure uses an 
"Item" and "Last" approach so you can look for Last to see how much you 
actually read.


Note since Ada 95 came out I hardly ever use direct_io anymore because 
even problems that seem to line up well with direct IO over time degrade 
  as file formats change.

I tend to jump (perhaps to soon) to ada.streams.stream_io approaches and 
or approaches like getting access to text_io streams. Note in this case 
I am not saying that the text_io stream approach will be faster..I dont 
really know..But at least it can be made compliant with the requirements 
of the test.

with Text_IO;
with Ada.Text_IO.Text_Streams;

use Ada.Text_IO.Text_Streams;
use Text_IO;

with Ada.Streams;
use Ada.Streams;

procedure stre_test is


S : Stream_Access := Stream(Standard_Input);

Data : Stream_Element_Array(1 .. 10);
Last : Stream_Element_Offset;
begin

Read(S.all, Data, Last);
Text_IO.Put_Line(Stream_Element_Offset'image(Last));

end stre_test;