Add operator overloading to challenge 140-01

1 files changed, 61 insertions, 26 deletions

diff --git a/challenge-140/alexander-pankoff/perl/ch-1.pl b/challenge-140/alexander-pankoff/perl/ch-1.pl
index 37981f5430..139791fb6b 100644
--- a/challenge-140/alexander-pankoff/perl/ch-1.pl
+++ b/challenge-140/alexander-pankoff/perl/ch-1.pl
@@ -3,7 +3,8 @@ use warnings;
 use feature qw'say signatures';
 no warnings 'experimental::signatures';
 
-use List::Util qw(max);
+use Carp;
+use List::Util;
 
 run() unless caller();
 
@@ -12,43 +13,77 @@ sub run() {
     my $b = prompt_for_binary('b');
 
     say "Result:";
-    say( add_binarys( $a, $b ) );
+    say Binary->new($a) + $b;
+}
 
+sub prompt_for_binary($name) {
+    say "Enter binary number $name";
+    chomp( my $number = <STDIN> );
+
+    if ( $number !~ m/^[01]+$/ ) {
+        say "Invalid binary number.";
+        return prompt_for_binary($name);
+    }
+
+    return $number;
 }
 
-sub add_binarys ( $a, $b ) {
+package Binary {
+    use overload '+'  => 'add';
+    use overload '""' => sub { ${ shift() } };
 
-    my @a_digits = reverse split( '', $a );
-    my @b_digits = reverse split( '', $b );
+    sub new ( $class, $number ) {
+        if ( $number !~ m/^[01]+$/ ) {
+            Carp::confess("Invalid binary number: $number");
+        }
 
-    # we walk the digits of the binary numbers starting with the least
-    # significant digit, add the digits individually, carry the carry around
-    # with us and build our result from the back
-    my ( $out, $carry ) = ( '', 0 );
-    for ( 0 .. max( $#a_digits, $#b_digits ) ) {
-        my $res;
-        ( $res, $carry ) =
-          add_binary_digits( $a_digits[$_] // 0, $b_digits[$_] // 0, $carry );
-        $out = $res . $out;
+        return bless \$number, $class;
     }
 
-    return $carry ? $carry . $out : $out;
+    sub add {
+        my ( $self, $other ) = @_;
+        if ( ref $other ) {
+            if ( UNIVERSAL::isa( $other, ref $self ) ) {
+                return Binary->new(
+                    BinaryUtil::add_binarys( ${$self}, ${other} ) );
+            }
+            else {
+                Carp::confess( "Can't add a ", ref $other, " to a ",
+                    ref $self );
+            }
+        }
+        else {
+            $self->add( Binary->new($other) );
+        }
+    }
 }
 
-sub add_binary_digits ( $a, $b, $carry ) {
-    my $c = $a + $b + $carry;
+package BinaryUtil {
 
-    return $c >= 3 ? ( 1, 1 ) : $c == 2 ? ( 0, 1 ) : ( $c, 0 );
+    sub add_binarys ( $a, $b ) {
 
-}
+        my @a_digits = reverse split( '', $a );
+        my @b_digits = reverse split( '', $b );
+
+        # we walk the digits of the binary numbers starting with the least
+        # significant digit, add the digits individually, carry the carry around
+        # with us and build our result from the back
+        my ( $out, $carry ) = ( '', 0 );
+        for ( 0 .. List::Util::max( $#a_digits, $#b_digits ) ) {
+            my $res;
+            ( $res, $carry ) = add_binary_digits( $a_digits[$_] // 0,
+                $b_digits[$_] // 0, $carry );
+            $out = $res . $out;
+        }
+
+        return $carry ? $carry . $out : $out;
+    }
+
+    sub add_binary_digits ( $a, $b, $carry ) {
+        my $c = $a + $b + $carry;
+
+        return $c >= 3 ? ( 1, 1 ) : $c == 2 ? ( 0, 1 ) : ( $c, 0 );
 
-sub prompt_for_binary($name) {
-    say "Enter binary number $name";
-    chomp( my $number = <STDIN> );
-    if ( $number !~ m/^[01]+$/ ) {
-        say "Invalid binary number.";
-        return prompt_for_binary($name);
     }
 
-    return $number;
 }