From: Randy Kramer <rhkramer@...>
Date: 2005-03-03T05:26:48+09:00
Subject: How/Where is a Stream Stored?

Background: In order to do the parsing I've talked about in another thread, in 
many circumstances I need to know the number of spaces before and after the 
current token.  I'm trying to think about efficient ways to do that--one 
might be to do a preprocess pass through the text to figure out how many 
spaces separate various tokens then store the tokens and spaces between them 
in a temporary in memory data structure, or I'll need a way to backtrack from 
the found position of some token to find how many spaces separate it from the 
previous token.

I'm thinking that maybe a stream ("on" the input file?) might be a way to do 
the backtracking (by moving the pos back from the current position, either 
one character at a time or several (and then read forward to the first 
space)).  

I'm wondering how efficient an operation that is--are such stream  operations 
performed on the disk file itself, or is the stream somehow buffered in 
memory and the operations performed there.  (Or, am I hopelessly 
confused? ;-)

Randy Kramer

Aside: In another thread I'm going to ask about efficient storage for the 
other alternative.