NAME
    Array::OverlapFinder - Find/remove overlapping items among ordered
    sequences

VERSION
    This document describes version 0.005 of Array::OverlapFinder (from Perl
    distribution Array-OverlapFinder), released on 2020-01-02.

SYNOPSIS
     use Array::OverlapFinder qw(
         find_overlap
         combine_overlap
     );

     # sequence is array of strings (compared with 'eq' operator; if you have array
     # of records/structures, you can encode each record as JSON or using Data::Dmp,
     # for example)
     my @seq1 = qw(1 2 3 4 5 6);
     my @seq2 = qw(4 5 6 7 8 9);
     my @seq3 = qw(8 9 10 11);

     my @overlap_items                   = find_overlap(\@seq1, \@seq2);                           # => (4,5,6)
     my @all_overlap_items               = find_overlap(\@seq1, \@seq2, \@seq3);                   # => ([4,5,6], [8,9])
     my ($overlap_items_12, $index2_at_seq1, $overlap_items_13, $index3_at_seq1b) =
                                           find_overlap({detail=>1}, \@seq1, \@seq2, \@seq3);      # => ([4,5,6], 3, [8,9], 7)

     my @combined_seq = combine_overlap(\@seq1, \@seq2, \@seq3);                                   # => (1,2,3,4,5,6,7,8,9,10,11)
     my ($combined_seq, $overlap_items_12, $index2_at_seq1, $overlap_items_13, $index3_at_seq1b) =
                        combine_overlap({detail=>1}, \@seq1, \@seq2, \@seq3);
                                                                                                   # => ([1,2,3,4,5,6,7,8,9,10,11], [4,5,6], 3, [8,9], 7)

DESCRIPTION
    Assuming you have two ordered sequences of items that might or might not
    overlap, where the first sequence contains "earlier" items and the
    second contains possibly "later" items, the functions in this module can
    find the overlapping items for you or remove them combining the two
    sequence into one:

     # condition A, no overlaps
     sequence1: 1 2 3 4 5 6
     sequence2:              8 9 10
     overlap  :
     combined : 1 2 3 4 5 6  8 9 10

     # condition B, overlaps
     sequence1: 1 2 3 4 5 6
     sequence2:       4 5 6 7 8 9
     overlap  :       4 5 6
     combined : 1 2 3 4 5 6 7 8 9

     # condition C, overlaps
     sequence1: 1 2 3 4 5 6
     sequence2:       4 5
     overlap  : 4 5
     combined : 1 2 3 4 5 6

     # condition D, overlaps
     sequence1: 1 2 3 4 5 6
     sequence2:       4 5 6
     overlap  :       4 5 6
     combined : 1 2 3 4 5 6

     # condition E, overlaps (identical)
     sequence1: 1 2 3 4 5 6
     sequence2: 1 2 3 4 5 6
     overlap  : 1 2 3 4 5 6
     combined : 1 2 3 4 5 6

     # condition F, overlaps
     sequence1: 1 2 3 4 5 6
     sequence2: 1 2 3 4 5 6 7 8
     overlap  : 1 2 3 4 5 6
     combined : 1 2 3 4 5 6 7 8

     # condition G1, overlaps in the middle of second sequence will be assumed as non-overlapping
     sequence1: 1 2 3 4 5 6
     sequence2:   2 3 4 x x 5 6
     overlap  :
     combined : 1 2 3 4 5 6 2 3 4 x x 5 6

     # condition G2, multiple overlaps will be assumed as non-overlapping
     sequence1: 1 2 3 4 5 6
     sequence2: 2 3 4 x x 5 6 y y
     overlap  :
     combined : 1 2 3 4 5 6 2 3 4 x x 5 6 y y

    The functions can accept more than two sequences to find/remove
    overlapping items in.

    Use-cases: forming a non-overlapping sequence of items from repeated
    downloads of RSS feed or "recent" page.

FUNCTIONS
    All functions are not exported by default, but exportable.

  find_overlap
    Usage:

     find_overlap([ \%opts , ] \@seq1, \@seq2, ...)

  combine_overlap
    Usage:

     combine_overlap([ \%opts , ] \@seq1, \@seq2, ...)

HOMEPAGE
    Please visit the project's homepage at
    <https://metacpan.org/release/Array-OverlapFinder>.

SOURCE
    Source repository is at
    <https://github.com/perlancar/perl-Array-OverlapFinder>.

BUGS
    Please report any bugs or feature requests on the bugtracker website
    <https://github.com/perlancar/perl-Array-OverlapFinder/issues>

    When submitting a bug or request, please include a test-file or a patch
    to an existing test-file that illustrates the bug or desired feature.

SEE ALSO
    nauniq from App::nauniq can also sometimes be used, if you know the
    items in the sequence are unique.

    Algorithm::Diff

    Text::OverlapFinder has a similar name, but the two modules are not that
    related.

AUTHOR
    perlancar <perlancar@cpan.org>

COPYRIGHT AND LICENSE
    This software is copyright (c) 2021, 2020 by perlancar@cpan.org.

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