OpenEuphoria

Re: Inserting to a sequence

• Posted by Robert Craig <rds at ATTCANADA.NET> Jul 31, 1999
• 440 views

Gabriel Boehme writes:

> What is the fastest way of inserting an item into
> a sequence? I know ED.EX uses the following
> two methods:
>1) For inserting a char into a line:

>   line = line[1..b_col-1] & char & line[b_col..length(line)]

> 2) For inserting a line into a file:

>   buffer = append(buffer, 0)
>   for i = length(buffer)-1 to b_line by -1 do
>      buffer[i+1] = buffer[i]
>   end for
>   buffer[b_line] = line

Method 1 is the simplest, and it's what I originally
used for inserting a line. As I recall, I switched to
method 2 a few years ago, after running out of memory
at this exact point, while editing a huge file.
Method 2 needs less memory, i.e. temp space,
so I thought it might help. In fact it doesn't really help
much but I left it that way.

Method 2 might be faster than method 1,
depending on the size of the sequence.
Provided the sequence is reasonably long,
you can make method 2 even faster if you replace
     for
         ...
     end for

with:

buffer[bline+1..length(buffer)] = buffer[bline..length(buffer)-1]

The performance of ed depends mainly on the
screen-writing operations, not the buffer manipulations.

Regards,
     Rob Craig
     Rapid Deployment Software
     http://members.aol.com/FilesEu/