=head1 NAME
Array::Heap2 - treat perl arrays as heaps (priority queues)
=head1 SYNOPSIS
use Array::Heap2;
=head1 DESCRIPTION
There are a multitude of heap and heap-like modules on CPAN, you might
want to search for /Heap/ and /Priority/ to find many. They implement more
or less fancy datastructures that might well be what you are looking for.
This module takes a different approach: It exports functions (i.e. not
object orientation) that are loosely modeled after the C++ STL's heap
functions. They all take an array as argument, just like perl's built-in
functions C, C etc.
The implementation itself is in C for maximum speed (although I doubt it
makes that much of a difference).
=head1 FUNCTIONS
All of the following functions are being exported by default.
=over 4
=cut
package Array::Heap2;
BEGIN {
$VERSION = "1.1";
require XSLoader;
XSLoader::load Array::Heap2, $VERSION;
}
use base Exporter;
@EXPORT = qw(make_heap make_heap_lex make_heap_cmp push_heap push_heap_lex push_heap_cmp pop_heap pop_heap_lex pop_heap_cmp);
=item make_heap @heap (\@)
Reorders the elements in the array so they form a heap, with the lowest
value "on top" of the heap (corresponding to the first array element).
=item make_heap_lex @heap (\@)
Just like C, but in string comparison order instead of numerical
comparison order.
=item make_heap_cmp { compare } @heap (&\@)
Just like C, but takes a custom comparison function.
=item push_heap @heap, $element, ... (\@@)
Adds the given element(s) to the heap.
=item push_heap_lex @heap, $element, ... (\@@)
Just like C, but in string comparison order instead of numerical
comparison order.
=item push_heap_cmp { compare } @heap, $element, ... (&\@@)
Just like C, but takes a custom comparison function.
=item pop_heap @heap (\@)
Removes the topmost (lowest) heap element and repairs the heap.
=item pop_heap_lex @heap (\@)
Just like C, but in string comparison order instead of numerical
comparison order.
=item pop_heap_cmp { compare } @heap (&\@)
Just like C, but takes a custom comparison function.
=cut
1;
=back
=head2 COMPARISON FUNCTIONS
All the functions come in two flavours: one that uses the built-in
comparison function and one that uses a custom comparison function.
The built-in comparison function can either compare scalar numerical
values (string values for *_lex functions), or array refs. If the elements
to compare are array refs, the first element of the array is used for
comparison, i.e.
1, 4, 6
will be sorted according to their numerical value,
[1 => $obj1], [2 => $obj2], [3 => $obj3]
will sort according to the first element of the arrays, i.e. C<1,2,3>.
The custom comparison functions work similar to how C works: C<$a>
and C<$b> are set to the elements to be compared, and the result should be
either C<-1> if C<$a> is less than C<$b>, or C<< >= 0 >> otherwise.
The first example above corresponds to this comparison "function":
{ $a <=> $b }
And the second example corresponds to this:
{ $a->[0] <=> $b->[0] }
Unlike C, the default sort is numerical and it is not possible to
use normal subroutines.
=head1 BUGS
This module works not work with tied or magical arrays or array elements.
=head1 AUTHOR
Marc Lehmann
http://home.schmorp.de/
=cut