NAME
Array::Heap2 - treat perl arrays as heaps (priority queues)
SYNOPSIS
use Array::Heap2;
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 "push", "pop" etc.
The implementation itself is in C for maximum speed (although I doubt it
makes that much of a difference).
FUNCTIONS
All of the following functions are being exported by default.
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).
make_heap_cmp { compare } @heap (&\@)
Just like "make_heap", but takes a custom comparison function.
push_heap @heap, $element, ... (\@@)
Adds the given element(s) to the heap.
push_heap_cmp { compare } @heap, $element, ... (&\@@)
Just like "push_heap", but takes a custom comparison function.
pop_heap @heap (\@)
Removes the topmost (lowest) heap element and repairs the heap.
pop_heap_cmp { compare } @heap (&\@)
Just like "pop_heap", but takes a custom comparison function.
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, 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. "1,2,3".
The custom comparison functions work similar to how "sort" works: $a and
$b are set to the elements to be compared, and the result should be
either -1 if $a is less than $b, or ">= 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 "sort", the default sort is numerical and it is not possible to
use normal subroutines.
BUGS
This module works not work with tied or magical arrays or array
elements.
AUTHOR
Marc Lehmann
http://www.goof.com/pcg/marc/