/ 
Array-IntSpan-1.01
River stage one • 4 direct dependents • 9 total dependents
/ Array::IntSpan

NAME

Array::IntSpan - a Module for handling arrays using IntSpan techniques

SYNOPSIS

use Array::IntSpan;

my $foo = Array::IntSpan->new([0, 59, 'F'], [60, 69, 'D'], [80, 89, 'B']);

print "A score of 84% results in a ".$foo->lookup(84).".\n";
unless (defined($foo->lookup(70))) {
  print "The grade for the score 70% is currently undefined.\n";
}

$foo->set_range(70, 79, 'C');
print "A score of 75% now results in a ".$foo->lookup(75).".\n";

$foo->set_range(0, 59, undef);
unless (defined($foo->lookup(40))) {
  print "The grade for the score 40% is now undefined.\n";
}

$foo->set_range(87, 89, 'B+');
$foo->set_range(85, 100, 'A');
$foo->set_range(100, 1_000_000, 'A+');

DESCRIPTION

Array::IntSpan brings the speed advantages of Set::IntSpan (written by Steven McDougall) to arrays. Uses include manipulating grades, routing tables, or any other situation where you have mutually exclusive ranges of integers that map to given values.

Array::IntSpan::IP is also provided with the distribution. It lets you use IP addresses in any of three forms (dotted decimal, network string, and integer) for the indices into the array. See the POD for that module for more information.

Installation instructions

Standard Make::Maker approach or just copy Array/IntSpan.pm into site/lib/Array/IntSpan.pm and Array/IntSpan/IP.pm into site/lib/Array/IntSpan/IP.pm.

METHODS

new

The new method takes an optional list of array elements. The elements should be in the form [start_index, end_index, value]. They should be in sorted order and there should be no overlaps. The internal method _check_structure will be called to verify the data is correct. If you wish to avoid the performance penalties of checking the structure, you can use Data::Dumper to dump an object and use that code to reconstitute it.

set_range

This method takes three parameters - the start_index, the end_index, and the value. If you wish to erase a range, specify undef for the value. It properly deals with overlapping ranges and will replace existing data as appropriate. If the new range lies after the last existing range, the method will execute in O(1) time. If the new range lies within the existing ranges, the method executes in O(n) time, where n is the number of ranges. The code is not completely optimized and will make up to three calls to splice if the new range intersects with existing ranges. It does not consolidate contiguous ranges that have the same value.

If you have a large number of inserts to do, it would be beneficial to sort them first. Sorting is O(n lg(n)), and since appending is O(1), that will be considerably faster than the O(n^2) time for inserting n unsorted elements.

The method returns 0 if there were no overlapping ranges and 1 if there were.

lookup

This method takes as a single parameter the index to look up. If there is an appropriate range, the method will return the associated value. Otherwise, it returns undef.

AUTHOR

Toby Everett, teverett@alascom.att.com