From: 7stud -- <bbxx789_05ss@...>
Date: 2011-04-28T09:08:46+09:00
Subject: Re: File position and buffers

Cee Joe wrote in post #995381:
> Hi all,
>
> In a bit of a rut. Have a file with a lot of text. I want to seperate
> the text in this file as entries. Each entry that I would be seperating,
> would be done so using IO.pos and when that cursor reaches a certain
> character in the file, it will ideally place all the content before that
> character into a buffer. Then the cursor will continue reading until it
> hits that same character again and put that content into a buffer, so on
> and so forth. (Character I'll be reading would be a greater than symbol)
>

There is absolutely no reason to use pos() to read that file.


>  Would I use a do iterator or use a while loop with a gets method? Or
> readlines perhaps?
>
> File:
>>entry 1
> rubyrubyrubyrubyrubyrubyrubyruby
> (newline here which I don't want)
>

chomp() removes one newline, if present, at the end of a string.

>
> PS. The file is huge, so I don't want to read it into memory. What is
> the best way to approach this? Any suggestions or comments would be
> helpful. Thanks!

Well, then you have to tell us what you want to do with the segments of 
the file.  If you store each chunk in a variable, then you will have 
read the whole file into memory.

You say your file looks like this:

>entry 1 <---WHAT'S AT THE END OF THIS LINE??
rubyrubyrubyrubyruby <---WHAT'S AT THE END OF THIS LINE??
(newline here which I don't want)

Those look like newlines.  Are you saying that your data is organized 
into paragraphs, i.e. separated by two newlines?  Like this:

>entry1\n
rubyrubyruby\n
\n
>entry2\n
rubyrubyruby\n
\n
>entry3

A paragraph is defined as two consective newlines between lines.  Note 
that in ruby the default line separator is one newline.  But you can 
change that to two newlines--or any other character:

require 'stringio'

str =<<ENDOFSTRING
>entry1
11111111111

>entry2
22222222222

>entry3
33333333333
ENDOFSTRING

input = StringIO.new(str)
$/ = "\n\n"

input.each do |para|
  p para.sub(/\n+ \z/xms, "")
end

--output:--
">entry1\n11111111111"
">entry2\n22222222222"
">entry3\n33333333333"

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