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# -*- perl -*-
#
# DBD::Mem - A DBI driver for in-memory tables
#
# This module is currently maintained by
#
# Jens Rehsack
#
# Copyright (C) 2016,2017 by Jens Rehsack
#
# All rights reserved.
#
# You may distribute this module under the terms of either the GNU
# General Public License or the Artistic License, as specified in
# the Perl README file.
require 5.008;
use strict;
#################
package DBD::Mem;
#################
use base qw( DBI::DBD::SqlEngine );
use vars qw($VERSION $ATTRIBUTION $drh);
$VERSION = '0.001';
$ATTRIBUTION = 'DBD::Mem by Jens Rehsack';
# no need to have driver() unless you need private methods
#
sub driver ($;$)
{
my ( $class, $attr ) = @_;
return $drh if ($drh);
# do the real work in DBI::DBD::SqlEngine
#
$attr->{Attribution} = 'DBD::Mem by Jens Rehsack';
$drh = $class->SUPER::driver($attr);
return $drh;
}
sub CLONE
{
undef $drh;
}
#####################
package DBD::Mem::dr;
#####################
$DBD::Mem::dr::imp_data_size = 0;
@DBD::Mem::dr::ISA = qw(DBI::DBD::SqlEngine::dr);
# you could put some :dr private methods here
# you may need to over-ride some DBI::DBD::SqlEngine::dr methods here
# but you can probably get away with just letting it do the work
# in most cases
#####################
package DBD::Mem::db;
#####################
$DBD::Mem::db::imp_data_size = 0;
@DBD::Mem::db::ISA = qw(DBI::DBD::SqlEngine::db);
use Carp qw/carp/;
sub set_versions
{
my $this = $_[0];
$this->{mem_version} = $DBD::Mem::VERSION;
return $this->SUPER::set_versions();
}
sub init_valid_attributes
{
my $dbh = shift;
# define valid private attributes
#
# attempts to set non-valid attrs in connect() or
# with $dbh->{attr} will throw errors
#
# the attrs here *must* start with mem_ or foo_
#
# see the STORE methods below for how to check these attrs
#
$dbh->{mem_valid_attrs} = {
mem_version => 1, # verbose DBD::Mem version
mem_valid_attrs => 1, # DBD::Mem::db valid attrs
mem_readonly_attrs => 1, # DBD::Mem::db r/o attrs
mem_meta => 1, # DBD::Mem public access for f_meta
mem_tables => 1, # DBD::Mem public access for f_meta
};
$dbh->{mem_readonly_attrs} = {
mem_version => 1, # verbose DBD::Mem version
mem_valid_attrs => 1, # DBD::Mem::db valid attrs
mem_readonly_attrs => 1, # DBD::Mem::db r/o attrs
mem_meta => 1, # DBD::Mem public access for f_meta
};
$dbh->{mem_meta} = "mem_tables";
return $dbh->SUPER::init_valid_attributes();
}
sub get_mem_versions
{
my ( $dbh, $table ) = @_;
$table ||= '';
my $meta;
my $class = $dbh->{ImplementorClass};
$class =~ s/::db$/::Table/;
$table and ( undef, $meta ) = $class->get_table_meta( $dbh, $table, 1 );
$meta or ( $meta = {} and $class->bootstrap_table_meta( $dbh, $meta, $table ) );
return sprintf( "%s using %s", $dbh->{mem_version}, $AnyData2::VERSION );
}
package DBD::Mem::st;
use strict;
use warnings;
our $imp_data_size = 0;
our @ISA = qw(DBI::DBD::SqlEngine::st);
############################
package DBD::Mem::Statement;
############################
@DBD::Mem::Statement::ISA = qw(DBI::DBD::SqlEngine::Statement);
sub open_table ($$$$$)
{
my ( $self, $data, $table, $createMode, $lockMode ) = @_;
my $class = ref $self;
$class =~ s/::Statement/::Table/;
my $flags = {
createMode => $createMode,
lockMode => $lockMode,
};
if( defined( $data->{Database}->{mem_table_data}->{$table} ) && $data->{Database}->{mem_table_data}->{$table})
{
my $t = $data->{Database}->{mem_tables}->{$table};
$t->seek( $data, 0, 0 );
return $t;
}
return $self->SUPER::open_table($data, $table, $createMode, $lockMode);
}
# ====== DataSource ============================================================
package DBD::Mem::DataSource;
use strict;
use warnings;
use Carp;
@DBD::Mem::DataSource::ISA = "DBI::DBD::SqlEngine::DataSource";
sub complete_table_name ($$;$)
{
my ( $self, $meta, $table, $respect_case ) = @_;
$table;
}
sub open_data ($)
{
my ( $self, $meta, $attrs, $flags ) = @_;
defined $meta->{data_tbl} or $meta->{data_tbl} = [];
}
########################
package DBD::Mem::Table;
########################
# shamelessly stolen from SQL::Statement::RAM
use Carp qw/croak/;
@DBD::Mem::Table::ISA = qw(DBI::DBD::SqlEngine::Table);
use Carp qw(croak);
sub new
{
#my ( $class, $tname, $col_names, $data_tbl ) = @_;
my ( $class, $data, $attrs, $flags ) = @_;
my $self = $class->SUPER::new($data, $attrs, $flags);
my $meta = $self->{meta};
$self->{records} = $meta->{data_tbl};
$self->{index} = 0;
$self;
}
sub bootstrap_table_meta
{
my ( $self, $dbh, $meta, $table ) = @_;
defined $meta->{sql_data_source} or $meta->{sql_data_source} = "DBD::Mem::DataSource";
$meta;
}
sub fetch_row
{
my ( $self, $data ) = @_;
return $self->{row} =
( $self->{records} and ( $self->{index} < scalar( @{ $self->{records} } ) ) )
? [ @{ $self->{records}->[ $self->{index}++ ] } ]
: undef;
}
sub push_row
{
my ( $self, $data, $fields ) = @_;
my $currentRow = $self->{index};
$self->{index} = $currentRow + 1;
$self->{records}->[$currentRow] = $fields;
return 1;
}
sub truncate
{
my $self = shift;
return splice @{ $self->{records} }, $self->{index}, 1;
}
sub push_names
{
my ( $self, $data, $names ) = @_;
my $meta = $self->{meta};
$meta->{col_names} = $self->{col_names} = $names;
$self->{org_col_names} = [ @{$names} ];
$self->{col_nums} = {};
$self->{col_nums}{ $names->[$_] } = $_ for ( 0 .. scalar @$names - 1 );
}
sub drop ($)
{
my ($self, $data) = @_;
delete $data->{Database}{sql_meta}{$self->{table}};
return 1;
} # drop
sub seek
{
my ( $self, $data, $pos, $whence ) = @_;
return unless defined $self->{records};
my ($currentRow) = $self->{index};
if ( $whence == 0 )
{
$currentRow = $pos;
}
elsif ( $whence == 1 )
{
$currentRow += $pos;
}
elsif ( $whence == 2 )
{
$currentRow = @{ $self->{records} } + $pos;
}
else
{
croak $self . "->seek: Illegal whence argument ($whence)";
}
$currentRow < 0 and
croak "Illegal row number: $currentRow";
$self->{index} = $currentRow;
}
1;
=head1 NAME
DBD::Mem - a DBI driver for Mem & MLMem files
=head1 SYNOPSIS
use DBI;
$dbh = DBI->connect('dbi:Mem:', undef, undef, {});
$dbh = DBI->connect('dbi:Mem:', undef, undef, {RaiseError => 1});
# or
$dbh = DBI->connect('dbi:Mem:');
$dbh = DBI->connect('DBI:Mem(RaiseError=1):');
and other variations on connect() as shown in the L<DBI> docs and
<DBI::DBD::SqlEngine metadata|DBI::DBD::SqlEngine/Metadata>.
Use standard DBI prepare, execute, fetch, placeholders, etc.,
see L<QUICK START> for an example.
=head1 DESCRIPTION
DBD::Mem is a database management system that works right out of the box.
If you have a standard installation of Perl and DBI you can begin creating,
accessing, and modifying simple database tables without any further modules.
You can add other modules (e.g., SQL::Statement) for improved functionality.
DBD::Mem doesn't store any data persistently - all data has the lifetime of
the instantiated C<$dbh>. The main reason to use DBD::Mem is to use extended
features of L<SQL::Statement> where temporary tables are required. One can
use DBD::Mem to simulate C<VIEWS> or sub-queries.
Bundling C<DBD::Mem> with L<DBI> will allow us further compatibility checks
of L<DBI::DBD::SqlEngine> beyond the capabilities of L<DBD::File> and
L<DBD::DBM>. This will ensure DBI provided basis for drivers like
L<DBD::AnyData2> or L<DBD::Amazon> are better prepared and tested for
not-file based backends.
=head2 Metadata
There're no new meta data introduced by C<DBD::Mem>. See
L<DBI::DBD::SqlEngine/Metadata> for full description.
=head1 GETTING HELP, MAKING SUGGESTIONS, AND REPORTING BUGS
If you need help installing or using DBD::Mem, please write to the DBI
users mailing list at L<mailto:dbi-users@perl.org> or to the
comp.lang.perl.modules newsgroup on usenet. I cannot always answer
every question quickly but there are many on the mailing list or in
the newsgroup who can.
DBD developers for DBD's which rely on DBI::DBD::SqlEngine or DBD::Mem or
use one of them as an example are suggested to join the DBI developers
mailing list at L<mailto:dbi-dev@perl.org> and strongly encouraged to join our
IRC channel at L<irc://irc.perl.org/dbi>.
If you have suggestions, ideas for improvements, or bugs to report, please
report a bug as described in DBI. Do not mail any of the authors directly,
you might not get an answer.
When reporting bugs, please send the output of C<< $dbh->mem_versions($table) >>
for a table that exhibits the bug and as small a sample as you can make of
the code that produces the bug. And of course, patches are welcome, too
:-).
If you need enhancements quickly, you can get commercial support as
described at L<http://dbi.perl.org/support/> or you can contact Jens Rehsack
at rehsack@cpan.org for commercial support.
=head1 AUTHOR AND COPYRIGHT
This module is written by Jens Rehsack < rehsack AT cpan.org >.
Copyright (c) 2016- by Jens Rehsack, all rights reserved.
You may freely distribute and/or modify this module under the terms of
either the GNU General Public License (GPL) or the Artistic License, as
specified in the Perl README file.
=head1 SEE ALSO
L<DBI> for the Database interface of the Perl Programming Language.
L<SQL::Statement> and L<DBI::SQL::Nano> for the available SQL engines.
L<SQL::Statement::RAM> where the implementation is shamelessly stolen from
to allow DBI bundled Pure-Perl drivers increase the test coverage.
L<DBD::SQLite> using C<dbname=:memory:> for an incredible fast in-memory database engine.
=cut