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=over 4

=item $class

A class with a C<make_limit> method.

=item $name

Name of a class in the C<Class::DBI::Plugin::Pager::> namespace, which has a
C<make_limit> method.

=item $coderef

Will be called as a method on the pager object, so receives the pager as its
argument.

=item (no args)

Called without args, will default to C<LimitOffset>, which causes
L<Class::DBI::Plugin::Pager::LimitOffset|Class::DBI::Plugin::Pager::LimitOffset>
to be used.

=back

=cut

sub set_syntax {
    my ( $proto, $syntax ) = @_;

    # pick up default from subclass, or load from LimitOffset
    $syntax ||= $proto->can( 'make_limit' );
    $syntax ||= 'LimitOffset';

    if ( ref( $syntax ) eq 'CODE' )
    {
        $proto->_syntax( $syntax );
        return $syntax;
    }

    my $format_class = $syntax =~ '::' ? $syntax : "Class::DBI::Plugin::Pager::$syntax";

    $format_class->require || croak "error loading $format_class: $UNIVERSAL::require::ERROR";

    my $formatter = $format_class->can( 'make_limit' ) || croak "no make_limit method in $format_class";

    $proto->_syntax( $formatter );

    return $formatter;
}

=item auto_set_syntax

This is called automatically when you call C<pager>, and attempts to set the
syntax automatically.

If you are using a subclass of the pager, this method will not be called.

Will C<die> if using Oracle or DB2, since there is no simple syntax for limiting
the results set. DB2 has a C<FETCH> keyword, but that seems to apply to a
cursor and I don't know if there is a cursor available to the pager. There
should probably be others to add to the unsupported list.

Supports the following drivers:

                      DRIVER        CDBI::P::Pager subclass
    my %supported = ( pg        => 'LimitOffset',
                      mysql     => 'LimitOffset', # older versions need LimitXY
                      sqlite    => 'LimitOffset', # or LimitYX
                      interbase => 'RowsTo',
                      firebird  => 'RowsTo',
                      );

Older versions of MySQL should use the LimitXY syntax. You'll need to set it
manually, either by C<use CDBI::P::Pager::LimitXY>, or by passing
C<syntax =E<gt> 'LimitXY'> to a method call, or call C<set_syntax> directly.

Any driver not in the supported or unsupported lists defaults to LimitOffset.

Any additions to the supported and unsupported lists gratefully received.

=cut

sub auto_set_syntax {
    my ( $self ) = @_;

    # not an exhaustive list
    my %not_supported = ( oracle => 'Oracle',
                          db2    => 'DB2',
                          );

    # additions welcome
    my %supported = ( pg        => 'LimitOffset',
                      mysql     => 'LimitOffset', # older versions need LimitXY
                      sqlite    => 'LimitOffset', # or LimitYX
                      interbase => 'RowsTo',
                      firebird  => 'RowsTo',
                      );

    my $cdbi = $self->_cdbi_app;

    my $driver = lc( $cdbi->__driver );

    die __PACKAGE__ . " can't build limit clauses for $not_supported{ $driver }"
        if $not_supported{ $driver };

    $self->set_syntax( $supported{ $driver } || 'LimitOffset' );
}

1;

__END__

#=for notes
#
#Would this work?
#
#with $limit and $offset defined.
#
#my $last = $limit + $offset
#