File Coverage

blib/lib/Config/MVP/Slicer.pm

Criterion	Covered	Total	%
statement	65	67	97.0
branch	29	30	96.6
condition	23	26	88.4
subroutine	14	14	100.0
pod	4	4	100.0
total	135	141	95.7

# vim: set ts=2 sts=2 sw=2 expandtab smarttab:
#
# This file is part of Config-MVP-Slicer
#
# This software is copyright (c) 2011 by Randy Stauner.
#
# This is free software; you can redistribute it and/or modify it under
# the same terms as the Perl 5 programming language system itself.
#
use strict;
use warnings;

package Config::MVP::Slicer;
# git description: v0.302-4-g57e9836

our $AUTHORITY = 'cpan:RWSTAUNER';
# ABSTRACT: Extract embedded plugin config from parent config
$Config::MVP::Slicer::VERSION = '0.303';
use Carp (); # core
use Moose;


has config => (
  is       => 'ro',
  isa      => 'HashRef',
);


sub _build_match_name {
  # "@Bundle/Plugin" =~ "(@Bundle/)*Plugin"
  return sub { scalar $_[1] =~ m{^(@.+?/)*?\Q$_[0]\E$} };
}

sub _build_match_package {
  return sub { $_[0] eq $_[1] };
}

foreach my $which ( qw( name package ) ) {
  my $name = "match_$which";
  has $name => (
    is       => 'bare',
    isa      => 'CodeRef',
    traits   => ['Code'],
    builder  => "_build_$name",
    handles => {
      $name => 'execute',
    },
  );
}


has prefix => (
  is       => 'ro',
  isa      => 'RegexpRef | Str',
  default  => '',
);


has separator => (
  is       => 'ro',
  isa      => 'Str',
  default  => '(.+?)\.(.+?)',
);


sub separator_regexp {
  my ($self) = @_;
  return qr/^${\ $self->prefix }${\ $self->separator }(\[.*?\])?$/;
}


sub slice {
  my ($self, $plugin) = @_;
  # ignore previous config
  my ($name, $pack) = $self->plugin_info($plugin);

# TODO: do we need to do anything to handle mvp_aliases?
# TODO: can/should we check $pack->mvp_multivalue_args rather than if ref $value eq 'ARRAY'

  my $slice = {};
  my $config = $self->config;
  my $regexp = $self->separator_regexp;

  # sort to keep the bracket subscripts in order
  foreach my $key ( sort keys %$config ){
    next unless
      my ($plug, $attr, $array) = ($key =~ $regexp);
    my $value = $config->{ $key };

    next unless
      $self->match_name($plug, $name) ||
      $self->match_package($plug, $pack);

    # TODO: should we allow for clearing previous []? $slice->{$attr} = [] if $overwrite;

    # TODO: $array || ref($prev->{$attr}) eq 'ARRAY'; # or is this handled by merge?
    $self->_update_hash($slice, $attr, $value, {array => $array});
  }
  return $slice;
}


#* C<join> - A string that will be used to join a new value to any existing value instead of overwriting.
# TODO: allow option for reaching into blessed hashref?

sub merge {
  my ($self, $plugin, $opts) = @_;
  $opts ||= {};

  my $slice = $opts->{slice} || $self->slice($plugin);
  my ($name, $class, $conf) = $self->plugin_info($plugin);

  while( my ($key, $value) = each %$slice ){
    # merge into hashref
    if( ref($conf) eq 'HASH' ){
      $self->_update_hash($conf, $key, $value);
    }
    # plugin instance... attempt to update
    else {
      # call attribute writer (attribute must be 'rw'!)
      my $attr = $plugin->meta->find_attribute_by_name($key);
      if( !$attr ){
        # TODO: should we be dying here?
        Carp::croak("Attribute '$key' not found on $name/$class\n");
        next;
      }
      my $type = $attr->type_constraint;
      my $previous = $plugin->$key;
      if( $previous ){
        # FIXME: do we need to check blessed() and/or isa()?
        if( ref $previous eq 'ARRAY' ){
          push(@$previous, ref $value eq 'ARRAY' ? @$value : $value);
        }
        # if new value was specified as arrayref, attempt to merge
        elsif( ref $value eq 'ARRAY' ){
          $plugin->$key( [ $previous, @$value ] );
        }
        # is this useful?
        elsif( $type->name eq 'Str' && $opts->{join} ){
          $plugin->$key( join($opts->{join}, $previous, $value) );
        }
        # TODO: any other types?
        else {
          $plugin->$key($value);
        }
      }
      else {
        $value = [ $value ]
          if $type->name =~ /^arrayref/i && ref $value ne 'ARRAY';

        $plugin->$key($value);
      }
    }
  }
  return $plugin;
}



sub plugin_info {
  my ($self, $spec) = @_;

  # plugin bundles: ['name', 'class', {con => 'fig'}]
  return @$spec
    if ref $spec eq 'ARRAY';

  # plugin instances
  return ($spec->plugin_name, ref($spec), $spec)
    if eval { $spec->can('plugin_name') };

  Carp::croak(qq[Don't know how to handle $spec]);
}

sub _update_hash {
  my ($self, $hash, $key, $value, $options) = @_;

  # concatenate array if
  if(
    # we know it should be an array
    $options->{array} ||
    # it already is an array
    (exists($hash->{ $key }) && ref($hash->{ $key }) eq 'ARRAY') ||
    # the new value is an array
    ref($value) eq 'ARRAY'
  ){
    # if there is an initial value but it's not an array ref, convert it
    $hash->{ $key } = [ $hash->{ $key } ]
      if exists $hash->{ $key } && ref $hash->{ $key } ne 'ARRAY';

    push @{ $hash->{ $key } }, ref($value) eq 'ARRAY' ? @$value : $value;
  }
  # else overwrite
  else {
    $hash->{ $key } = $value;
  }
}

no Moose;
__PACKAGE__->meta->make_immutable;
1;

__END__

=pod

=encoding UTF-8

=for :stopwords Randy Stauner ACKNOWLEDGEMENTS cpan testmatrix url annocpan anno bugtracker
rt cpants kwalitee diff irc mailto metadata placeholders metacpan

=head1 NAME

Config::MVP::Slicer - Extract embedded plugin config from parent config

=head1 VERSION

version 0.303

=for test_synopsis my ($parent, $plugin);

=head1 SYNOPSIS

  my $slicer = Config::MVP::Slicer->new({
    config => $parent->config,
  });

  # extract a hashref from the parent config without modifying the plugin
  my $plugin_config = $slicer->slice($plugin);

  # from plugin bundles:
  my $plugin_spec = ['Name', 'Package::Name', {default => 'config'}];
  # update the hashref
  $slicer->merge($plugin_spec);

  # with object instances:
  my $plugger = App::Plugin::Plugger->new({some => 'config'});
  # update 'rw' attributes
  $slicer->merge($plugger);

=head1 DESCRIPTION

This can be used to extract embedded configurations for other plugins
out of larger (parent) configurations.

A example where this can be useful is plugin bundles
(see L<Config::MVP::Assembler::WithBundles>).

A bundle loads other plugins with a default configuration
that works most of the time, but sometimes you wish you could
customize the configuration for one of those plugins
without having to remove the plugin from the bundle
and re-specify it separately.

  # mvp config file
  [@MyBundle]
  Other::Plugin.setting = new value

Now you can accept customizations to plugins into your
bundle config and separate them out using this module.

=head1 ATTRIBUTES

=head2 config

This is the main/parent configuration hashref
that contains embedded plugin configurations.

=head2 match_name

This is coderef that determines if a configuration line
matches a plugin's name.

It can be customized by passing an alternate subroutine reference
to the constructor.

The sub will receive two arguments:

=over 4

=item *

The plugin name portion of the configuration line

=item *

The name of the plugin being worked on (provided to L</slice>, for instance).

=back

The default returns true if the current plugin name matches
the name from the config line
regardless of any leading "@Bundle/" prefixes in the plugin name
(as this is a common convention for bundles).

Obviously if the "@Bundle/" prefix is specified in the configuration
then it is required to be there for the default sub to match
(but multiple other "@Bundle/" prefixes will be allowed before it).

  # configuration line: "Foo.attr = value"

  $slicer->match_name("Foo", "Foo");            # true
  $slicer->match_name("Foo", "@Bar/Foo");       # true
  $slicer->match_name("Foo", "Bar");            # false

  # configuration line: "@Bar/Foo.attr = value"

  $slicer->match_name("@Bar/Foo", "Foo");           # false
  $slicer->match_name("@Bar/Foo", "@Bar/Foo");      # true
  $slicer->match_name("@Bar/Foo", "@Baz/@Bar/Foo"); # true
  $slicer->match_name("@Bar/Foo", "@Baz/Foo");      # false

Subclasses can define C<_build_match_name>
(which should return a C<sub>) to overwrite the default.

=head2 match_package

This works like L</match_name>
except that the configuration line is compared
to the plugin's package (class).

The default returns true if the two values are equal and false otherwise.

If you want to match by package rather than name
and you expand packages with (for example) a string prefix
you may need to set this to something like:

  match_package => sub { rewrite_prefix($_[0]) eq $_[1] }

Subclasses can define C<_build_match_package>
(which should return a C<sub>) to overwrite the default.

=head2 prefix

Regular expression that should match at the beginning of a key
before the module name and attribute:

  # prefix => 'dynamic\.'
  # { 'dynamic.Module::Name.attr' => 'value' }

This can be a string or a compiled regular expression (C<qr//>).

The default is no prefix (empty string C<''>).

=head2 separator

A regular expression that will capture
the package name in C<$1> and
the attribute name in C<$2>.

The default (C<(.+?)\.(.+?)>)
separates plugin name from attribute name with a dot:

  'Module::Name.attribute'
  '-Plugin.attr'

B<NOTE>: The regexp should B<not> be anchored since L</separator_regexp>
uses it as the middle piece of a larger regexp
(to add L</prefix> and the possible array bracket suffix).
Also beware of using a regexp that greedily matches the array bracket suffix
as that can confuse things as well.

=head1 METHODS

=head2 separator_regexp

Returns a compiled regular expression (C<qr//>)
combining L</prefix>, L</separator>,
and the possible trailing array specification (C<\[.*?\]>).

=head2 slice

  $slicer->slice($plugin);

Return a hashref of the config arguments for the plugin
determined by C<$plugin>.

This is a slice of the L</config> attribute
appropriate for the plugin passed to the method.

Starting with a config hashref of:

  {
    'APlug:attr1'   => 'value1',
    'APlug:second'  => '2nd',
    'OtherPlug:attr => '0'
  }

Passing a plugin instance of C<'APlug'>
(or an arrayref of C<< ['APlug', 'Full::Package::APlug', {}] >>)
would return:

  {
    'attr1'   => 'value1',
    'second'  => '2nd'
  }

=head2 merge

  $slicer->merge($plugin, \%opts);

Get the config slice (see L</slice>),
then attempt to merge it into the plugin.

If C<$plugin> is an arrayref the hashref will be modified.
If it is an object it's attributes should be writable (C<'rw'>).

This will append to array references
if it was specified as an array
or if a preexisting value is an arrayref.

Returns the modified C<$plugin> for convenience.

Possible options:

=over 4

=item *

C<slice> - A hashref like that returned from L</slice>.  If not present, L</slice> will be called.

=back

=head2 plugin_info

  $slicer->plugin_info($plugin);

Used by other methods to normalize the information about a plugin.
Returns a list of C<< ($name, $package, \%config) >>.

If C<$plugin> is an arrayref it will simply dereference it.
This can be useful for processing the results of plugin bundles.

If C<$plugin> is an instance of a plugin that has a C<plugin_name>
method it will construct the list from that method, C<ref>,
and the instance itself.

=head1 CONFIGURATION SYNTAX

Often configurations come from an C<ini> file and look like this:

  [PluginName]
  option = value

This gets converted to a hashref:

  PluginName->new({ option => 'value' });

To embed configuration for other plugins:

  [@BigBundle]
  bundle_option = value
  Bundled::Plugin.option = other value

The simple 'bundle_option' attribute is for C<@BigBundle>,
and the bundle can slice out the C<Bundled::Plugin> configuration
and merge it in to that plugin's configuration.

Prefixes can be used (see L</prefix>).
In this example the prefix is set as C<"plug.">.

  [@Foo]
  plug.Bundled::Plugin.attr = value

Due to limitations of this dynamic passing of unknown options
(otherwise known as a I<hack>)
values that are arrays cannot be declared ahead of time by the bundle.
You can help out by specifying that an attribute should be an array:

  [@Bar]
  Baz.quux[0] = part 1
  Baz.quux[1] = part 2

This is required because each line will end up in a hashref:

  { "quux[0]" => "part 1", "quxx[1]" => "part 2" }

The subscripts inside the brackets are used for sorting but otherwise ignored.
The L</slice> method will sort the keys (B<alphabetically>) to produce:

  { quux => ["part 1", "part 2"] }

For simplicity the keys are sorted B<alphabetically>
because C<quux[1.9]> and C<quux[1.10]>
probably won't sort the way you intended anyway,
so just keep things simple:

  [@Bundle]
  Plug.attr[0] = part 1
  Plug.attr[1] = part 2
  Plug.other[09] = part 1
  Plug.other[10] = part 2
  Plug.alpha[a] = part 1
  Plug.alpha[b] = part 2
  Plug.alpha[bc] = part 3
  Plug.single[] = subscript not required; only used for sorting

=head1 SUPPORT

=head2 Perldoc

You can find documentation for this module with the perldoc command.

  perldoc Config::MVP::Slicer

=head2 Websites

The following websites have more information about this module, and may be of help to you. As always,
in addition to those websites please use your favorite search engine to discover more resources.

=over 4

=item *

MetaCPAN

A modern, open-source CPAN search engine, useful to view POD in HTML format.

L<http://metacpan.org/release/Config-MVP-Slicer>

=back

=head2 Bugs / Feature Requests

Please report any bugs or feature requests by email to C<bug-config-mvp-slicer at rt.cpan.org>, or through
the web interface at L<https://rt.cpan.org/Public/Bug/Report.html?Queue=Config-MVP-Slicer>. You will be automatically notified of any
progress on the request by the system.

=head2 Source Code


L<https://github.com/rwstauner/Config-MVP-Slicer>

  git clone https://github.com/rwstauner/Config-MVP-Slicer.git

=head1 AUTHOR

Randy Stauner <[e-mail]>

=head1 COPYRIGHT AND LICENSE

This software is copyright (c) 2011 by Randy Stauner.

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

=cut