General purpose, MongoDB-style query and update language
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NAME
    MQUL - General purpose, MongoDB-style query and update language

SYNOPSIS
            use MQUL qw/doc_matches update_doc/;

            my $doc = {
                    title => 'Freaks and Geeks',
                    genres => [qw/comedy drama/],
                    imdb_score => 9.4,
                    seasons => 1,
                    starring => ['Linda Cardellini', 'James Franco', 'Jason Segel'],
                    likes => { up => 45, down => 11 }
            };

            if (doc_matches($doc, {
                    title => qr/geeks/i,
                    genres => 'comedy',
                    imdb_score => { '$gte' => 5, '$lte' => 9.5 },
                    starring => { '$type' => 'array', '$size' => 3 },
                    'likes.up' => { '$gt' => 40 }
            })) {
                    # will be true in this example
            }

            update_doc($doc, {
                    '$set' => { title => 'Greeks and Feaks' },
                    '$pop' => { genres => 1 },
                    '$inc' => { imdb_score => 0.6 },
                    '$unset' => { seasons => 1 },
                    '$push' => { starring => 'John Francis Daley' },
            });

            # $doc will now be:
            {
                    title => 'Greeks and Feaks',
                    genres => ['comedy'],
                    imdb_score => 10,
                    starring => ['Linda Cardellini', 'James Franco', 'Jason Segel', 'John Francis Daley'],
                    likes => { up => 45, down => 11 }
            }

DESCRIPTION
    MQUL (for MongoDB-style Query & Update Language; pronounced *"umm,
    cool"*; yeah, I know, that's the dumbest thing ever), is a general
    purpose implementation of MongoDB's query and update language. The
    implementation is not 100% compatible, but it only slightly deviates
    from MongoDB's behavior, actually extending it a bit.

    The module exports two subroutines: "doc_matches()" and "update_doc()".
    The first subroutine takes a document, which is really just a hash-ref
    (of whatever complexity), and a query hash-ref built in the MQUL query
    language. It returns a true value if the document matches the query, and
    a false value otherwise. The second subroutine takes a document and an
    update hash-ref built in the MQUL update language. The subroutine
    modifies the document (in-place) according to the update hash-ref.

    You can use this module for whatever purpose you see fit. It was
    actually written for Giddy, my Git-database, and was extracted from its
    original code. Outside of the database world, I plan to use it in an
    application that performs tests (such as process monitoring for
    example), and uses the query language to determine whether the results
    are valid or not (in our monitoring example, that could be CPU usage
    above a certain threshold and stuff like that). It is also used by
    MorboDB, an in-memory clone of MongoDB.

  UPGRADE NOTES
    My distributions follow the semantic versioning scheme
    <http://semver.org/>, so whenever the major version changes, that means
    that API changes incompatible with previous versions have been made.
    Always read the Changes file before upgrading.

  THE LANGUAGE
    The language itself is described in MQUL::Reference. This document only
    describes the interface of this module.

    The reference document also details MQUL's current differences from the
    original MongoDB language.

INTERFACE
  doc_matches( \%document, [ \%query, \@defs ] )
    Receives a document hash-ref and possibly a query hash-ref, and returns
    true if the document matches the query, false otherwise. If no query is
    given (or an empty hash-ref is given), true will be returned (every
    document will match an empty query - in accordance with MongoDB).

    See "QUERY STRUCTURE" in MQUL::Reference to learn about the structure of
    query hash-refs.

    Optionally, an even-numbered array reference of dynamically calculated
    attribute definitions can be provided. For example:

            [ min_val => { '$min' => ['attr1', 'attr2', 'attr3' ] },
              max_val => { '$max' => ['attr1', 'attr2', 'attr3' ] },
              difference => { '$diff' => ['max_val', 'min_val'] } ]

    This defines three dynamic attributes: "min_val", "max_val" and
    "difference", which is made up of the first two.

    See "DYNAMICALLY CALCULATED ATTRIBUTES" in MQUL::Reference for more
    information about dynamic attributes.

  update_doc( \%document, \%update )
    Receives a document hash-ref and an update hash-ref, and updates the
    document in-place according to the update hash-ref. Also returns the
    document after the update. If the update hash-ref doesn't have any of
    the update modifiers described by the language, then the update hash-ref
    is considered as what the document should now be, and so will simply
    replace the document hash-ref (once again, in accordance with MongoDB).

    See "UPDATE STRUCTURE" in MQUL::Reference to learn about the structure
    of update hash-refs.

DIAGNOSTICS
    "MQUL::doc_matches() requires a document hash-ref."
        This error means that you've either haven't passed the
        "doc_matches()" subroutine any parameters, or given it a
        non-hash-ref document.

    "MQUL::doc_matches() expects a query hash-ref."
        This error means that you've passed the "doc_matches()" attribute a
        non-hash-ref query variable. While you don't actually have to pass a
        query variable, if you do, it has to be a hash-ref.

    "MQUL::update_doc() requires a document hash-ref."
        This error means that you've either haven't passed the
        "update_doc()" subroutine any parameters, or given it a non-hash-ref
        document.

    "MQUL::update_doc() requires an update hash-ref."
        This error means that you've passed the "update_doc()" subroutine a
        non-hash-ref update variable.

    "The %s attribute is not an array in the doc."
        This error means that your update hash-ref tries to modify an array
        attribute (with $push, $pushAll, $addToSet, $pull, $pullAll, $pop,
        $shift and $splice), but the attribute in the document provided to
        the "update_doc()" subroutine is not an array.

CONFIGURATION AND ENVIRONMENT
    MQUL requires no configuration files or environment variables.

DEPENDENCIES
    MQUL depends on the following modules:

    *   Data::Compare

    *   Data::Types

    *   DateTime::Format::W3CDTF

    *   Scalar::Util

    *   Try::Tiny

INCOMPATIBILITIES
    None reported.

BUGS AND LIMITATIONS
    No bugs have been reported.

    Please report any bugs or feature requests to "bug-MQUL@rt.cpan.org", or
    through the web interface at
    <http://rt.cpan.org/NoAuth/ReportBug.html?Queue=MQUL>.

AUTHOR
    Ido Perlmuter <ido at ido50 dot net>

LICENSE AND COPYRIGHT
    Copyright (c) 2011-2015, Ido Perlmuter "ido at ido50 dot net".

    This module is free software; you can redistribute it and/or modify it
    under the same terms as Perl itself, either version 5.8.1 or any later
    version. See perlartistic and perlgpl.

    The full text of the license can be found in the LICENSE file included
    with this module.

DISCLAIMER OF WARRANTY
    BECAUSE THIS SOFTWARE IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY
    FOR THE SOFTWARE, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN
    OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES
    PROVIDE THE SOFTWARE "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER
    EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
    WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE
    ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE SOFTWARE IS WITH
    YOU. SHOULD THE SOFTWARE PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL
    NECESSARY SERVICING, REPAIR, OR CORRECTION.

    IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
    WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR
    REDISTRIBUTE THE SOFTWARE AS PERMITTED BY THE ABOVE LICENCE, BE LIABLE
    TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL, OR
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