use strict;
use warnings;

package Sub::Exporter::Util;

use Data::OptList ();
use Params::Util ();

=head1 NAME

Sub::Exporter::Util - utilities to make Sub::Exporter easier

=head1 VERSION

version 0.982

=cut

our $VERSION = '0.982';

=head1 DESCRIPTION

This module provides a number of utility functions for performing common or
useful operations when setting up a Sub::Exporter configuration.  All of the
utilites may be exported, but none are by default.

=head1 THE UTILITIES

=head2 curry_method

  exports => {
    some_method => curry_method,
  }

This utility returns a generator which will produce an invocant-curried version
of a method.  In other words, it will export a method call with the exporting
class built in as the invocant.

A module importing the code some the above example might do this:

  use Some::Module qw(some_method);

  my $x = some_method;

This would be equivalent to:

  use Some::Module;

  my $x = Some::Module->some_method;

If Some::Module is subclassed and the subclass's import method is called to
import C<some_method>, the subclass will be curried in as the invocant.

If an argument is provided for C<curry_method> it is used as the name of the
curried method to export.  This means you could export a Widget constructor
like this:

  exports => { widget => curry_method('new') }

This utility may also be called as C<curry_class>, for backwards compatibility.

=cut

sub curry_method {
  my $override_name = shift;
  sub {
    my ($class, $name) = @_;
    $name = $override_name if defined $override_name;
    sub { $class->$name(@_); };
  }
}

BEGIN { *curry_class = \&curry_method; }

=head2 curry_chain

C<curry_chain> behaves like C<L</curry_method>>, but is meant for generating
exports that will call several methods in succession.

  exports => {
    reticulate => curry_chain([
      new => gather_data => analyze => [ detail => 100 ] => results
    ]),
  }

If imported from Spliner, calling the C<reticulate> routine will be equivalent
to:

  Splinter->new->gather_data->analyze(detail => 100)->results;

If any method returns something on which methods may not be called, the routine
croaks.

The arguments to C<curry_chain> form an optlist.  The names are methods to be
called and the arguments, if given, are arrayrefs to be dereferenced and passed
as arguments to those methods.  C<curry_chain> returns a generator like those
expected by Sub::Exporter.

B<Achtung!> at present, there is no way to pass arguments from the generated
routine to the method calls.  This will probably be solved in future revisions
by allowing the opt list's values to be subroutines that will be called with
the generated routine's stack.

=cut

sub curry_chain {
  # In the future, we can make \%arg an optional prepend, like the "special"
  # args to the default Sub::Exporter-generated import routine.
  my (@opt_list) = @_;

  my $pairs = Data::OptList::mkopt(\@opt_list, 'args', 'ARRAY');

  sub {
    my ($class) = @_;

    sub {
      my $next = $class;

      for my $i (0 .. $#$pairs) {
        my $pair = $pairs->[ $i ];
        
        unless (Params::Util::_INVOCANT($next)) { ## no critic Private
          my $str = defined $next ? "'$next'" : 'undef';
          Carp::croak("can't call $pair->[0] on non-invocant $str")
        }

        my ($method, $args) = @$pair;

        if ($i == $#$pairs) {
          return $next->$method($args ? @$args : ());
        } else {
          $next = $next->$method($args ? @$args : ());
        }
      }
    };
  }
}

# =head2 name_map
# 
# This utility returns an list to be used in specify export generators.  For
# example, the following:
# 
#   exports => {
#     name_map(
#       '_?_gen'  => [ qw(fee fie) ],
#       '_make_?' => [ qw(foo bar) ],
#     ),
#   }
# 
# is equivalent to:
# 
#   exports => {
#     name_map(
#       fee => \'_fee_gen',
#       fie => \'_fie_gen',
#       foo => \'_make_foo',
#       bar => \'_make_bar',
#     ),
#   }
# 
# This can save a lot of typing, when providing many exports with similarly-named
# generators.
# 
# =cut
# 
# sub name_map {
#   my (%groups) = @_;
# 
#   my %map;
# 
#   while (my ($template, $names) = each %groups) {
#     for my $name (@$names) {
#       (my $export = $template) =~ s/\?/$name/
#         or Carp::croak 'no ? found in name_map template';
# 
#       $map{ $name } = \$export;
#     }
#   }
# 
#   return %map;
# }

=head2 merge_col

  exports => {
    merge_col(defaults => {
      twiddle => \'_twiddle_gen',
      tweak   => \&_tweak_gen,
    }),
  }

This utility wraps the given generator in one that will merge the named
collection into its args before calling it.  This means that you can support a
"default" collector in multipe exports without writing the code each time.

You can specify as many pairs of collection names and generators as you like.

=cut

sub merge_col {
  my (%groups) = @_;

  my %merged;

  while (my ($default_name, $group) = each %groups) {
    while (my ($export_name, $gen) = each %$group) {
      $merged{$export_name} = sub {
        my ($class, $name, $arg, $col) = @_;

        my $merged_arg = exists $col->{$default_name}
                       ? { %{ $col->{$default_name} }, %$arg }
                       : $arg;

        if (Params::Util::_CODELIKE($gen)) { ## no critic Private
          $gen->($class, $name, $merged_arg, $col);
        } else {
          $class->$$gen($name, $merged_arg, $col);
        }
      }
    }
  }

  return %merged;
}

=head2 mixin_installer

  use Sub::Exporter -setup => {
    installer => Sub::Exporter::Util::mixin_installer,
    exports   => [ qw(foo bar baz) ],
  };

This utility returns an installer that will install into a superclass and
adjust the ISA importing class to include the newly generated superclass.

If the target of importing is an object, the hierarchy is reversed: the new
class will be ISA the object's class, and the object will be reblessed.

B<Prerequisites>: This utility requires that Package::Generator be installed.

=cut

sub __mixin_class_for {
  my ($class, $mix_into) = @_;
  require Package::Generator;
  my $mixin_class = Package::Generator->new_package({
    base => "$class\:\:__mixin__",
  });

  ## no critic (ProhibitNoStrict)
  no strict 'refs';
  if (ref $mix_into) {
    unshift @{"$mixin_class" . "::ISA"}, ref $mix_into;
  } else {
    unshift @{"$mix_into" . "::ISA"}, $mixin_class;
  }
  return $mixin_class;
}

sub mixin_installer {
  sub {
    my ($arg, $to_export) = @_;

    my $mixin_class = __mixin_class_for($arg->{class}, $arg->{into});
    bless $arg->{into} => $mixin_class if ref $arg->{into};

    Sub::Exporter::default_installer(
      { %$arg, into => $mixin_class },
      $to_export,
    );
  };
}

sub mixin_exporter {
  Carp::cluck "mixin_exporter is deprecated; use mixin_installer instead; it behaves identically";
  return mixin_installer;
}

=head2 like

It's a collector that adds imports for anything like given regex.

If you provide this configuration:

  exports    => [ qw(igrep imap islurp exhausted) ],
  collectors => { -like => Sub::Exporter::Util::like },

A user may import from your module like this:

  use Your::Iterator -like => qr/^i/; # imports igre, imap, islurp

or

  use Your::Iterator -like => [ qr/^i/ => { -prefix => 'your_' } ];

The group-like prefix and suffix arguments are respected; other arguments are
passed on to the generators for matching exports.

=cut

sub like {
  sub {
    my ($value, $arg) = @_;
    Carp::croak "no regex supplied to regex group generator" unless $value;

    # Oh, qr//, how you bother me!  See the p5p thread from around now about
    # fixing this problem... too bad it won't help me. -- rjbs, 2006-04-25
    my @values = eval { $value->isa('Regexp') } ? ($value, undef)
               :                                  @$value;

    while (my ($re, $opt) = splice @values, 0, 2) {
      Carp::croak "given pattern for regex group generater is not a Regexp"
        unless eval { $re->isa('Regexp') };
      my @exports  = keys %{ $arg->{config}->{exports} };
      my @matching = grep { $_ =~ $re } @exports;

      my %merge = $opt ? %$opt : ();
      my $prefix = (delete $merge{-prefix}) || '';
      my $suffix = (delete $merge{-suffix}) || '';

      for my $name (@matching) {
        my $as = $prefix . $name . $suffix;
        push @{ $arg->{import_args} }, [ $name => { %merge, -as => $as } ];
      }
    }

    1;
  }
}

use Sub::Exporter -setup => {
  exports => [ qw(
    like
    name_map
    merge_col
    curry_method curry_class
    curry_chain
    mixin_installer mixin_exporter
  ) ]
};

=head1 AUTHOR

Ricardo SIGNES, C<< <rjbs@cpan.org> >>

=head1 BUGS

Please report any bugs or feature requests through the web interface at
L<http://rt.cpan.org>. I will be notified, and then you'll automatically be
notified of progress on your bug as I make changes.

=head1 COPYRIGHT

Copyright 2006-2007, Ricardo SIGNES.  This program is free software;  you can
redistribute it and/or modify it under the same terms as Perl itself.

=cut

1;