NAME
    Sort::XS - a ( very ) fast XS sort alternative for one dimension list

SYNOPSIS
      use Sort::XS qw/xsort/;

      # use it simply
      my $sorted = xsort([1, 5, 3]);
      $sorted = [ 1, 3, 5 ];
  
      # personalize your xsort with some options
      my $list = [ 1..100, 24..42 ]
      my $sorted = xsort( $list ) or ixsort( $list )
                or xsort( list => $list )
                or xsort( list => $list, algorithm => 'quick' )
                or xsort( $list, algorithm => 'quick', type => integer )
                or xsort( list => $list, algorithm => 'heap', type => 'integer' ) 
                or xsort( list => $list, algorithm => 'merge', type => 'string' );
   
       # if you [ mainly ] use very small arrays ( ~ 10 rows ) 
       #    prefer using directly one of the XS subroutines
       $sorted = Sort::XS::quick_sort( $list )
            or Sort::XS::heap_sort($list)
            or Sort::XS::merge_sort($list)
            or Sort::XS::insertion_sort($list);
    
        # sorting array of strings
        $list = [ 'kiwi', 'banana', 'apple', 'cherry' ];
        $sorted = sxsort( $list )
            or sxsort( [ $list ], algorithm => 'quick' )
            or sxsort( [ $list ], algorithm => 'heap' )
            or sxsort( [ $list ], algorithm => 'merge' );
    
        # use direct XS subroutines to sort array of strings 
        $sorted = Sort::XS::quick_sort_str( $list )
            or Sort::XS::heap_sort_str($list)
            or Sort::XS::merge_sort_str($list)
            or Sort::XS::insertion_sort_str($list);
            
DESCRIPTION
    This module provides several common sort algorithms implemented as XS.
    Sort can only be used on one dimension list of integers or strings.

    It's goal is not to replace the internal sort subroutines, but to
    provide a better alternative in some specifics cases :

    - no need to specify a comparison operator
    - sorting a mono dimension list

ALGORITHMS
    Quicksort has been chosen as the default method ( even if it s not a
    stable algorithm ), you can also consider to use heapsort which provides
    a worst case in "n log n".

    Choosing the correct algorithm depends on distribution of your values
    and size of your list. Quicksort provides an average good solution, even
    if in some case it will be better to use a different choice.

  quick sort
    This is the default algorithm. In pratice it provides the best results
    even if in worst case heap sort will be a better choice.

    read http://en.wikipedia.org/wiki/Quicksort for more informations

  heap sort
    A little slower in practice than quicksort but provide a better worst
    case runtime.

    read http://en.wikipedia.org/wiki/Heapsort for more informations

  merge sort
    Stable sort algorithm, that means that in any case the time to compute
    the result will be similar. It's still a better choice than the internal
    perl sort.

    read http://en.wikipedia.org/wiki/Mergesort for more informations

  insertion sort
    Provide one implementation of insertion sort, but prefer using either
    any of the previous algorithm or even the perl internal sort.

    read http://en.wikipedia.org/wiki/Mergesort for more informations

  perl
    this is not an algorithm by itself, but provides an easy way to disable
    all XS code by switching back to a regular sort.

    Perl 5.6 and earlier used a quicksort algorithm to implement sort. That
    algorithm was not stable, so could go quadratic. (A stable sort
    preserves the input order of elements that compare equal. Although
    quicksort's run time is O(NlogN) when averaged over all arrays of length
    N, the time can be O(N**2), quadratic behavior, for some inputs.)

    In 5.7, the quicksort implementation was replaced with a stable
    mergesort algorithm whose worst-case behavior is O(NlogN). But
    benchmarks indicated that for some inputs, on some platforms, the
    original quicksort was faster.

    5.8 has a sort pragma for limited control of the sort. Its rather blunt
    control of the underlying algorithm may not persist into future Perls,
    but the ability to characterize the input or output in implementation
    independent ways quite probably will.

    use default perl version

METHODS
  xsort
    API that allow you to use one of the XS subroutines. Prefer using this
    method. ( view optimization section for tricks )

    list
        provide a reference to an array if only one argument is provided can
        be ommit

            my $list = [ 1, 3, 2, 5, 4 ];
            xsort( $list ) or xsort( list => $list )

    algorithm [ optional, default = quick ]
        default value is quick you can use any of the following choices

            quick # quicksort
            heap  # heapsort
            merge
            insertion # not recommended ( slow )
            perl # use standard perl sort method instead of c implementation

    type [ optional, default = integer ]
        You can specify which kind of sort you are expecting ( i.e. '<=>' or
        'cmp' ) by setting this attribute to one of these two values

            integer # <=>, is the default operator if not specified
            string  # cmp, do the compare on string

  ixsort
    alias on xsort method but force type to integer comparison same usage as
    xsort

  sxsort
    alias on xsort method but force type to string comparison same usage as
    xsort

  quick_sort
    XS subroutine to perform the quicksort algorithm. No type checking
    performed. Accept only one single argument as input.

        my $list = [1, 6, 4, 2, 3, 5 ]
        Sort::XS::quick_sort($list);
    
  heap_sort
    XS subroutine to perform the heapsort algorithm. No type checking
    performed. Accept only one single argument as input.

        my $list = [1, 6, 4, 2, 3, 5 ]
        Sort::XS::heap_sort($list);
    
  merge_sort
    XS subroutine to perform the mergesort algorithm. No type checking
    performed. Accept only one single argument as input.

        my $list = [1, 6, 4, 2, 3, 5 ]
        Sort::XS::merge_sort($list)
    
  insertion_sort
    XS subroutine to perform the insertionsort algorithm. No type checking
    performed. Accept only one single argument as input.

        my $list = [1, 6, 4, 2, 3, 5 ]
        Sort::XS::insertion_sort($list);

  quick_sort_str
    XS subroutine to perform quicksort on array of strings.

        Sort::XS::quick_sort_str( [ 'aa' .. 'zz' ] );
    
  heap_sort_str
    XS subroutine to perform heapsort on array of strings.

        Sort::XS::heap_sort_str( [ 'aa' .. 'zz' ] );

  merge_sort_str
    XS subroutine to perform mergesort on array of strings.

        Sort::XS::merge_sort_str( [ 'aa' .. 'zz' ] );

  insertion_sort_str
    XS subroutine to perform insertionsort on array of strings.

        Sort::XS::insertion_sort_str( [ 'aa' .. 'zz' ] );

OPTIMIZATION
    xsort provides an api to call xs subroutines to easy change sort
    preferences and an easy way to use it ( adding minimalist type checking
    ) as it provides an extra layer on the top of xs subroutines it has a
    cost... and adds a little more slowness... This extra cost cannot be
    noticed on large arrays ( > 100 rows ), but for very small arrays ( ~ 10
    rows ) it will not a good idea to use the api ( at least at this stage
    ). In this case you will prefer to do a direct call to one of the XS
    methods to have pure performance.

    Note that all the XS subroutines are not exported by default.

        my $list = [1, 6, 4, 2, 3, 5 ]
        Sort::XS::quick_sort($list);
        Sort::XS::heap_sort($list);
        Sort::XS::merge_sort($list)
        Sort::XS::insertion_sort($list);

    Once again, if you use large arrays, it will be better to use API calls
    :

        xsort([5, 7, 1, 4]);
        ixsort([1..10]);
        sxsort(['a'..'z']);

BENCHMARK
    Here is a glance of what you can expect from this module : These results
    have been computed on a set of multiple random arrays generated by the
    benchmark test included in the dist testsuite.

    Results are splitted in two parts : integers and strings. Here is a
    short definition for each label used for these benchmarks.

        [ integers ]
        * Perl                  : reference test with perl internal sort sub : sort { $a <=> $b } @array;
        * API Perl              : use native sort perl method thru API ; xsort(list => $array, algorithm => 'perl');      
        * API quick             : use quicksort via API ; xsort($array);         
        * API quick with hash   : use xsort method with additonnal parameters ; xsort(list => $array, algorithm => 'quick', type => 'integer');
        * isort                 : use isort method from Key::Sort module ; 
        * isort radix           : use isort method from Sort::Key::Radix module ; 
        * XS heap               : direct call to the xs method ; Sort::XS::heap_sort($array);
        * XS merge              : direct call to the xs method ; Sort::XS::merge_sort($array);       
        * XS quick              : direct call to the xs method ; Sort::XS::quick_sort($array);
        * void                  : a void sub used as baseline

    Comparing "Perl" vs "API Perl" or "API quick" vs "XS quick" gives an
    idea of the extra cost of the API Perl and void bench are here as a
    baseline.

        [ strings ]
        * Perl          : native perl sort method : sort { $a cmp $b } @array;
        * API sxsort    : use sxsort method ; sxsort($array);    
        * keysort       : use keysort method from Key::Sort module ; keysort { $_ } @$array; 
        * XS heap       : direct call to the xs method ; Sort::XS::heap_sort_str($array);
        * XS merge      : direct call to the xs method ; Sort::XS::merge_sort_str($array);
        * XS quick      : direct call to the xs method ; Sort::XS::quick_sort_str($array);
    
  Small arrays
    Small arrays are arrays with around 10 elements. benchmark with 1000
    arrays of 10 rows

            [ integers ]         Rate       API quick with hash       API Perl       API quick       XS merge       isort radix       XS quick       heap       isort void       Perl
            API quick with hash 130/s                        --            -7%            -67%           -74%              -77%           -78%       -78%        -80% -83%       -84%
            API Perl            140/s                        7%             --            -64%           -72%              -75%           -76%       -76%        -78% -81%       -82%
            API quick           390/s                      200%           179%              --           -22%              -31%           -33%       -33%        -39% -48%       -51%
            XS merge            502/s                      287%           260%             29%             --              -11%           -13%       -14%        -21% -33%       -37%
            isort radix         564/s                      335%           304%             45%            12%                --            -3%        -3%        -11% -25%       -29%
            XS quick            580/s                      346%           315%             49%            15%                3%             --        -0%         -9% -23%       -27%
            heap                581/s                      348%           317%             49%            16%                3%             0%         --         -9% -23%       -27%
            isort               636/s                      390%           356%             63%            27%               13%            10%         9%          -- -15%       -20%
            void                752/s                      479%           439%             93%            50%               33%            30%        29%         18%   --        -5%
            Perl                794/s                      512%           469%            104%            58%               41%            37%        37%         25%   6%         --
        
             [ sting ]  Rate       API sxsort       keysort       Perl       XS merge       XS heap       XS quick
            API sxsort 106/s               --           -8%       -59%           -59%          -62%           -63%
            keysort    116/s               9%            --       -55%           -55%          -58%           -60%
            Perl       260/s             145%          124%         --            -0%           -7%           -10%
            XS merge   260/s             145%          124%         0%             --           -7%           -10%
            XS heap    278/s             162%          140%         7%             7%            --            -4%
            XS quick   289/s             172%          149%        11%            11%            4%             --

  Medium arrays
    A mixed of arrays with 10, 100 and 1000 rows. ( 10 arrays of each size,
    maybe this should match most common usages ? ).

            [ integers ]          Rate       API Perl       Perl       XS merge       isort       heap       API quick with hash       API quick       XS quick       isort radix void
            API Perl             429/s             --       -13%           -16%        -20%       -24%                      -25%            -33%           -35%              -40% -73%
            Perl                 493/s            15%         --            -4%         -8%       -12%                      -14%            -23%           -25%              -32% -68%
            XS merge             511/s            19%         4%             --         -5%        -9%                      -11%            -20%           -22%              -29% -67%
            isort                536/s            25%         9%             5%          --        -5%                       -7%            -16%           -18%              -26% -66%
            heap                 562/s            31%        14%            10%          5%         --                       -2%            -12%           -14%              -22% -64%
            API quick with hash  575/s            34%        17%            13%          7%         2%                        --            -10%           -12%              -20% -63%
            API quick            638/s            48%        29%            25%         19%        13%                       11%              --            -3%              -12% -59%
            XS quick             657/s            53%        33%            29%         23%        17%                       14%              3%             --               -9% -58%
            isort radix          722/s            68%        46%            41%         35%        28%                       25%             13%            10%                -- -54%
            void                1562/s           264%       217%           206%        191%       178%                      172%            145%           138%              117%   --
        
            [ sting ]    Rate       keysort       API sxsort       Perl       XS heap       XS merge       XS quick
            keysort     770/s            --             -47%       -48%          -57%           -57%           -62%
            API sxsort 1450/s           88%               --        -2%          -19%           -20%           -28%
            Perl       1476/s           92%               2%         --          -18%           -18%           -27%
            XS heap    1790/s          132%              23%        21%            --            -1%           -11%
            XS merge   1806/s          135%              25%        22%            1%             --           -10%
            XS quick   2017/s          162%              39%        37%           13%            12%             --

    Sorting arrays of 100.000 rows

                                Rate         API Perl       Perl       isort       heap       XS merge       XS quick       API quick with hash       API quick       isort radix void
            API Perl            3.03/s             --        -1%         -6%       -22%           -24%           -42%                      -42%            -43%              -59% -82%
            Perl                3.07/s             1%         --         -5%       -21%           -23%           -41%                      -41%            -43%              -58% -82%
            isort               3.21/s             6%         5%          --       -18%           -20%           -38%                      -39%            -40%              -56% -81%
            heap                3.90/s            29%        27%         21%         --            -2%           -25%                      -25%            -27%              -47% -77%
            XS merge            4.00/s            32%        30%         24%         2%             --           -23%                      -24%            -25%              -46% -76%
            XS quick            5.20/s            72%        70%         62%        33%            30%             --                       -1%             -3%              -30% -69%
            API quick with hash 5.23/s            73%        71%         63%        34%            31%             1%                        --             -2%              -29% -69%
            API quick           5.36/s            77%        75%         67%        37%            34%             3%                        2%              --              -27% -68%
            isort radix         7.39/s           144%       141%        130%        89%            85%            42%                       41%             38%                -- -56%
            void                16.9/s           459%       453%        427%       334%           323%           226%                      224%            216%              129%   --

  Large arrays
    Sorting arrays of 1.000.000 rows.

            [ integers ]          Rate       API Perl       Perl       isort       heap       XS merge       isort radix       XS quick       API quick       API quick with hash void
            API Perl            1.75/s             --        -0%        -22%       -40%           -48%              -48%           -61%            -61%                      -62% -89%
            Perl                1.76/s             0%         --        -22%       -40%           -47%              -48%           -61%            -61%                      -62% -89%
            isort               2.25/s            28%        28%          --       -23%           -33%              -33%           -49%            -50%                      -51% -86%
            heap                2.94/s            67%        67%         30%         --           -12%              -13%           -34%            -35%                      -36% -82%
            XS merge            3.35/s            91%        90%         49%        14%             --               -1%           -25%            -25%                      -27% -79%
            isort radix         3.37/s            92%        92%         50%        15%             1%                --           -24%            -25%                      -26% -79%
            XS quick            4.46/s           154%       154%         98%        52%            33%               32%             --             -1%                       -3% -73%
            API quick           4.48/s           156%       155%         99%        53%            34%               33%             1%              --                       -2% -72%
            API quick with hash 4.57/s           161%       160%        103%        56%            37%               36%             3%              2%                        -- -72%
            void                16.2/s           826%       824%        621%       453%           385%              382%           264%            262%                      255%   --

           [ sting ]      Rate       Perl       XS heap       XS merge       API sxsort       XS quick
            Perl       0.698/s         --          -17%           -47%             -52%           -52%
            XS heap    0.836/s        20%            --           -37%             -43%           -43%
            XS merge    1.32/s        90%           58%             --             -10%           -10%
            API sxsort  1.46/s       110%           75%            11%               --            -0%
            XS quick    1.47/s       110%           76%            11%               0%             --
  
CONTRIBUTE
    You can contribute to this project via GitHub :
    https://github.com/atoomic/Sort-XS

TODO
    Implementation of float comparison... At this time only implement sort
    of integers and strings

    Improve API performance for small set of arrays : could use enum and
    array to speedup API. C algorithms can be also tuned.

AUTHOR
    Nicolas R., <me@eboxr.com>

CONTRIBUTORS
    Salvador Fandi–o

SEE ALSO
    Also consider the modules Sort::Key and Sort::Key::Radix, that provide a
    different API but that can sort faster on many common usage.

COPYRIGHT AND LICENSE
    This software is copyright (c) 2011 by eboxr.

    This is free software; you can redistribute it and/or modify it under
    the same terms as the Perl 5 programming language system itself.

