From: Jean-Christophe Beaupré <jcbrinfo@users.noreply.github.com>
Date: Fri, 9 Jun 2017 15:06:44 +0000 (-0400)
Subject: model: Add a class kind for class subsets
X-Git-Url: http://nitlanguage.org

model: Add a class kind for class subsets

Signed-off-by: Jean-Christophe Beaupré <jcbrinfo@users.noreply.github.com>
---

diff --git a/src/model/model.nit b/src/model/model.nit
index 28303d0..58fe944 100644
--- a/src/model/model.nit
+++ b/src/model/model.nit
@@ -2595,10 +2595,16 @@ class MClassKind
 	# Can a class of kind `self` specializes a class of kind `other`?
 	fun can_specialize(other: MClassKind): Bool
 	do
-		if other == interface_kind then return true # everybody can specialize interfaces
-		if self == interface_kind or self == enum_kind then
-			# no other case for interfaces
+		if other == interface_kind then
+			# everybody can specialize interfaces
+			return true
+		else if self == interface_kind or self == enum_kind then
+			# no other case for interfaces and enums
 			return false
+		else if self == subset_kind then
+			# A subset may specialize anything, except another subset.
+			# TODO: Allow sub-subsets once we can handle them.
+			return other != subset_kind
 		else if self == extern_kind then
 			# only compatible with themselves
 			return self == other
@@ -2619,6 +2625,8 @@ fun interface_kind: MClassKind do return once new MClassKind("interface", false,
 fun enum_kind: MClassKind do return once new MClassKind("enum", false, true, false)
 # The class kind `extern`
 fun extern_kind: MClassKind do return once new MClassKind("extern class", false, true, false)
+# The class kind `subset`
+fun subset_kind: MClassKind do return once new MClassKind("subset", true, false, false)
 
 # A standalone pre-constructed model used to test various model-related methods.
 #