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use 5.008;
use warnings;
use strict;

package Class::Scaffold::Util;
BEGIN {
  $Class::Scaffold::Util::VERSION = '1.102280';
}
# ABSTRACT: Exports various useful functions
use Error::Hierarchy::Util 'assert_hashref';
use Exporter qw(import);
our %EXPORT_TAGS = (util => [qw/hash_delta const/],);
our @EXPORT_OK = @{ $EXPORT_TAGS{all} = [ map { @$_ } values %EXPORT_TAGS ] };

# generates the delta for two given hashrefs.
# returns three hashrefs containing the elements of the given hashrefs
# which should be
#   1. inserted
#   2. updated
#   3. deleted
sub hash_delta {
    my ($this, $that) = @_;
    my ($insert, $delete, $update);
    $this = {} unless defined $this;
    $that = {} unless defined $that;
    assert_hashref $this,
      sprintf "hash_delta: \$this isn't a hashref, it's a %s", ref $this;
    assert_hashref $that,
      sprintf "hash_delta: \$that isn't a hashref, it's a %s", ref $that;

    # get extinct keys.
    for (keys %$this) {
        $delete->{$_} = $this->{$_} unless exists $that->{$_};
    }

    # get new keys.
    for (keys %$that) {

        # and catch updated keys also.
        if (exists $this->{$_}) {
            $update->{$_} = $that->{$_};
        } else {
            $insert->{$_} = $that->{$_};
        }
    }
    return ($insert, $update, $delete);
}

sub const ($@) {
    my $name = shift;
    my %args = @_;
    my ($pkg, $filename, $line) = (caller)[ 0 .. 2 ];
    no strict 'refs';
    my $every_hash_name = "${name}_HASH";
    $::PTAGS && $::PTAGS->add_tag($every_hash_name, $filename, $line);
    *{"${pkg}::${every_hash_name}"} = sub { %args };
    $::PTAGS && $::PTAGS->add_tag($name, $filename, $line);
    *{"${pkg}::${name}"} = sub {
        my $self = shift;
        my $hash = $self->every_hash($every_hash_name);
        if (@_) {
            my $key = shift;
            $hash->{$key}
              || $hash->{_AUTO}
              || throw Error::Hierarchy::Internal::CustomMessage(
                custom_message =>
                  "neither key [$key] nor [_AUTO] in $every_hash_name");
        } else {
            my @val = values %$hash;
            return wantarray ? @val : \@val;
        }
    };

    # have a sub that returns how many of those items there are
    my $count_name = "${name}_COUNT";
    $::PTAGS && $::PTAGS->add_tag($count_name, $filename, $line);
    *{"${pkg}::${count_name}"} = sub {
        my $self = shift;
        scalar(@{ $self->$name });
    };
    while (my ($key, $value) = each %args) {
        $::PTAGS && $::PTAGS->add_tag($key, $filename, $line);
        *{"${pkg}::${key}"} = sub { $value };
    }
}
1;


__END__
=pod

=for stopwords const

=head1 NAME

Class::Scaffold::Util - Exports various useful functions

=head1 VERSION

version 1.102280

=head1 METHODS

=head2 const

FIXME

=head2 hash_delta

FIXME

=head1 INSTALLATION