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,
[email protected]
