NAME

    Sort::HashKeys - Get a sorted-by-key list from a hash

SYNOPSIS

        use Sort::HashKeys;
    
        my %hash;
    
        @sorted_1 = map { ($_, $hash{$_}) } sort keys %hash;
        @sorted_2 = Sort::HashKeys::sort(%hash);
        # Same outcome, but the second is faster

DESCRIPTION

        [13:37:51]  <a3f>   Is there a better way to get a sorted list out of a hash
                            than map { ($_, $versions{$_}) } reverse sort keys @versions
                            or iterating manually?
        [13:39:06]  <a3f>   oh I could provide a compare function to sort and chunk the
                            list two by two..
        [13:40:15]  <haarg> i'd probably go with the map{} reverse sort keys
        [13:41:04]  <a3f>   I don't like it that it repeats the lookup for all keys.
                            Of course wouldn't matter in practice but still…
        [13:43:40]  <haarg> whatever other solution you find will be slower
        [13:49:05]  <a3f>   put it into a list, pass it to XS, run qsort(3) over it
                            with double the element size. and compare taking only the
                            first part into account. return it back?

BENCHMARK

    See benchmark.pl
    <https://github.com/athreef/Sort-HashKeys/blob/master/benchmark.pl> in
    this distribution. Test was run on a Haswell 2.6 GHz i5 CPU (4278U) for
    a minute each on a copy of a randomly generated hash of 1000 keys. Keys
    were alphanumeric with length between 1 and 6 and values of integers
    between 1 and 1000.

                                             Rate
        map {($_,$h{$_})} sort keys %h     1830/s        --      -27%
        Sort::HashKeys::sort(%h)           2503/s       37%        --

    37% faster.

    One could do better by operating in-place, instead of copying off the
    pointers, but I'll leave that for another time. (or leave it to you!
    Send me your patch!)

METHODS AND ARGUMENTS

    sort(@)

      Sorts a hash-like list (key1 => val1, key2 => val2>) by means of your
      libc's strcmp <http://en.cppreference.com/w/c/string/byte/strcmp> in
      ascending order. If an odd number of elements was passed in, an undef
      is appended.

      Providing a custom comparison function is not yet supported.

    reverse_sort(@)

      Sorts in descending order.

GIT REPOSITORY

    http://github.com/athreef/Sort-HashKeys

AUTHOR

    Ahmad Fatoum <athreef@cpan.org>, http://a3f.at

COPYRIGHT AND LICENSE

    Copyright (C) 2017 Ahmad Fatoum

    This library is free software; you can redistribute it and/or modify it
    under the same terms as Perl itself.