Text::Context::EitherSide(3) Get n words either side of search keywords


use Text::Context::EitherSide;
my $text = "The quick brown fox jumped over the lazy dog";
my $context = Text::Context::EitherSide->new($text);
$context->as_string("fox") # "... quick brown fox jumped over ..."
$context->as_string("fox", "jumped")
# "... quick brown fox jumped over the ..."

my $context = Text::Context::EitherSide->new($text, context => 1);
# 1 word on either side

$context->as_string("fox", "jumped", "dog");
# "... brown fox jumped over ... lazy dog",

Or, if you don't believe in all this OO rubbish:

  use Text::Context::EitherSide qw(get_context);
  get_context(1, $text, "fox", "jumped", "dog") 
        # "... brown fox jumped over ... lazy dog"


Suppose you have a large piece of text - typically, say, a web page or a mail message. And now suppose you've done some kind of full-text search on that text for a bunch of keywords, and you want to display the context in which you found the keywords inside the body of the text.

A simple-minded way to do that would be just to get the two words either side of each keyword. But hey, don't be too simple minded, because you've got to make sure that the list doesn't overlap. If you have

    the quick brown fox jumped over the lazy dog

and you extract two words either side of ``fox'', ``jumped'' and ``dog'', you really don't want to end up with

    quick brown fox jumped over brown fox jumped over the the lazy dog

so you need a small amount of smarts. This module has a small amount of smarts.



This is primarily an object-oriented module. If you don't care about that, just import the "get_context" subroutine, and call it like so:

    get_context($num_of_words, $text, @words_to_find)

and you'll get back a string with ellipses as in the synopsis. That's all that most people need to know. But if you want to do clever stuff...



    my $c = Text::Context::EitherSite->new($text [, context=> $n]);

Create a new object storing some text to be searched, plus optionally some information about how many words on either side you want. (If you don't like the default of 2.)



Allows you to get and set the number of the words on either side.



Returns the keywords, plus n words on either side, as a sparse list; the original text is split into an array of words, and non-contextual elements are replaced with "undef"s. (That's not actually how it works, but conceptually, it's the same.)



The same as "as_sparse_list", but single or multiple "undef"s are collapsed into a single ellipsis:

    (undef, "foo", undef, undef, undef, "bar")


    ("...", "foo", "...", "bar")



Takes the "as_list" output above and joins them all together into a string. This is what most people want from "Text::Context::EitherSide".


"get_context" is available as a shortcut for

   Text::Context::EitherSide->new($text, context => $n)->as_string(@words);

but needs to be explicitly imported. Nothing is exported by default.


Current maintainer: Tony Bowden

Original author: Simon Cozens


Please direct all correspondence regarding this module to:
  [email protected]


Copyright 2002-2005 by Kasei Limited, http://www.kasei.com/

You may use and redistribute this module under the terms of the Artistic License 2.0.