Give enums the capability to produce a role based on themselves.

rakudo · May 8, 2012 · d2e01f1 · d2e01f1
1 parent 9cdfbfa
commit d2e01f1
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Showing 2 changed files with 27 additions and 1 deletion.
diff --git a/src/Perl6/Metamodel/EnumHOW.pm b/src/Perl6/Metamodel/EnumHOW.pm
@@ -27,6 +27,10 @@ class Perl6::Metamodel::EnumHOW
 
     # Roles that we do.
     has @!does_list;
+
+    # Role'd version of the enum.
+    has $!role;
+    has int $!roled;
 
     my $archetypes := Perl6::Metamodel::Archetypes.new( :nominal(1), :composalizable(1) );
     method archetypes() {
@@ -99,8 +103,14 @@ class Perl6::Metamodel::EnumHOW
         $obj
     }
 
+    my $composalizer;
+    method set_composalizer($c) { $composalizer := $c }
     method composalize($obj) {
-        nqp::die("Cannot yet turn an enum into a role");
+        unless $!roled {
+            $!role := $composalizer($obj, self.name($obj), %!values);
+            $!roled := 1;
+        }
+        $!role
     }
 
     method does_list($obj) {

diff --git a/src/core/Enumeration.pm b/src/core/Enumeration.pm
@@ -63,3 +63,19 @@ sub ANON_ENUM(*@args) {
         nqp::getattr(%res, EnumMap, '$!storage'));
     $r;
 }
+
+Metamodel::EnumHOW.set_composalizer(-> $type, $name, %enum_values {
+    my Mu $r := Metamodel::ParametricRoleHOW.new_type(:name($name));
+    $r.HOW.add_attribute($r, Attribute.new(
+        :name('$!' ~ $name), :type(nqp::p6decont($type)),
+        :has_accessor(1), :package($r)));
+    for %enum_values.kv -> $key, $value {
+        my $meth = method () { self."$name"() === $value }
+        $meth.set_name($key);
+        $r.HOW.add_method($r, $key, $meth);
+    }
+    $r.HOW.set_body_block($r,
+        -> |$c { nqp::list($r, nqp::hash('$?CLASS', $c<$?CLASS>)) });
+    $r.HOW.compose($r);
+    $r
+});