File Coverage

blib/lib/Number/Tolerant/Union.pm

Criterion	Covered	Total	%
statement	44	44	100.0
branch	30	30	100.0
condition			n/a
subroutine	14	14	100.0
pod	2	2	100.0
total	90	90	100.0

use strict;
use warnings;
package Number::Tolerant::Union 1.709;
# ABSTRACT: unions of tolerance ranges

#pod =head1 SYNOPSIS
#pod
#pod  use Number::Tolerant;
#pod
#pod  my $range1 = tolerance(10 => to => 12);
#pod  my $range2 = tolerance(14 => to => 16);
#pod
#pod  my $union = $range1 | $range2;
#pod
#pod  if ($11 == $union) { ... } # this will happen
#pod  if ($12 == $union) { ... } # so will this
#pod
#pod  if ($13 == $union) { ... } # nothing will happen here
#pod
#pod  if ($14 == $union) { ... } # this will happen
#pod  if ($15 == $union) { ... } # so will this
#pod
#pod =head1 DESCRIPTION
#pod
#pod Number::Tolerant::Union is used by L to represent the union
#pod of multiple tolerances.  A subset of the same operators that function on a
#pod tolerance will function on a union of tolerances, as listed below.
#pod
#pod =head1 METHODS
#pod
#pod =head2 new
#pod
#pod   my $union = Number::Tolerant::Union->new(@list_of_tolerances);
#pod
#pod There is a C method on the Number::Tolerant::Union class, but unions are
#pod meant to be created with the C<|> operator on a Number::Tolerant tolerance.
#pod
#pod The arguments to C are a list of numbers or tolerances to be unioned.
#pod
#pod Intersecting ranges are not converted into a single range, but this may change
#pod in the future.  (For example, the union of "5 to 10" and "7 to 12" is not "5 to
#pod 12.")
#pod
#pod =cut

sub new {
  my $class = shift;
  bless { options => [ @_ ] } => $class;
}

#pod =head2 options
#pod
#pod This method will return a list of all the acceptable options for the union.
#pod
#pod =cut

sub options {
  my $self = shift;
  return @{$self->{options}};
}

#pod =head2 Overloading
#pod
#pod Tolerance unions overload a few operations, mostly comparisons.
#pod
#pod =over
#pod
#pod =item numification
#pod
#pod Unions numify to undef.  If there's a better idea, I'd love to hear it.
#pod
#pod =item stringification
#pod
#pod A tolerance stringifies to a short description of itself.  This is a set of the
#pod union's options, parentheses-enclosed and joined by the word "or"
#pod
#pod =item equality
#pod
#pod A number is equal to a union if it is equal to any of its options.
#pod
#pod =item comparison
#pod
#pod A number is greater than a union if it is greater than all its options.
#pod
#pod A number is less than a union if it is less than all its options.
#pod
#pod =item union intersection
#pod
#pod An intersection (C<&>) with a union is commutted across all options.  In other
#pod words:
#pod
#pod  (a | b | c) & d  ==yields==> ((a & d) | (b & d) | (c & d))
#pod
#pod Options that have no intersection with the new element are dropped.  The
#pod intersection of a constant number and a union yields that number, if the number
#pod was in the union's ranges and otherwise yields nothing.
#pod
#pod =back
#pod
#pod =cut

use overload
  '0+' => sub { undef },
  '""' => sub { join(' or ', map { "($_)" } $_[0]->options) },
  '==' => sub { for ($_[0]->options) { return 1 if $_ == $_[1] } return 0 },
  '!=' => sub { for ($_[0]->options) { return 0 if $_ == $_[1] } return 1 },
  '>'  =>
    sub {
      if ($_[2]) { for ($_[0]->options) { return 0 unless $_[1] > $_ } return 1 }
      else       { for ($_[0]->options) { return 0 unless $_[1] < $_ } return 1 }
    },
  '<'  =>
    sub {
      if ($_[2]) { for ($_[0]->options) { return 0 unless $_[1] < $_ } return 1 }
      else       { for ($_[0]->options) { return 0 unless $_[1] > $_ } return 1 }
    },
  '<=>' =>
    sub {
      if ($_[2]) { $_[0] < $_[1] ? 1 : $_[0] > $_[1] ? -1 : 0 }
      else       { $_[0] > $_[1] ? 1 : $_[0] < $_[1] ? -1 : 0 }
    },
  '|' => sub { __PACKAGE__->new($_[0]->options,$_[1]); },
  '&' => sub {
    eval { $_[1]->isa('Number::Tolerant') }
      ? __PACKAGE__->new(map { $_ & $_[1] } $_[0]->options )
      : $_[1] == $_[0]
        ? $_[1]
        : ();
    },
  fallback => 1;

#pod =head1 TODO
#pod
#pod Who knows.  Collapsing overlapping options, probably.
#pod
#pod =cut

1;

__END__