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_lex @heap (\@)
        Just like "make_heap", but in string comparison order instead of
        numerical comparison order.

    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_lex @heap, $element, ... (\@@)
        Just like "push_heap", but in string comparison order instead of
        numerical comparison order.

    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_lex @heap (\@)
        Just like "pop_heap", but in string comparison order instead of
        numerical comparison order.

    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 (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. "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 <schmorp@schmorp.de>
     http://home.schmorp.de/

