1. Inserting to a sequence
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:
-- NOTE: this is paraphrased from insert_string()
line = line[1..b_col-1] & char & line[b_col..length(line)]
2) For inserting a line into a file:
-- NOTE: this is paraphrased from insert()
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
Is it safe to assume, then, that method #1 is best for relatively short
sequences (such as program file lines), while method #2 is best for
potentially huge sequences (such as big text files)? Or are there other
sequence insertion methods which work better? Anyone done any tests on this?
The reason I ask is because I'm working on a program where I want to insert
data into a sorted sequence, and it would be very impractical for me to have
to sort the sequence every time another record is added.
Thanks in advance,
Gabriel Boehme
2. Re: Inserting to a sequence
- Posted by Robert Craig <rds at ATTCANADA.NET>
Jul 31, 1999
-
Last edited Aug 01, 1999
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/
