harec

commit ae4c3c71a23f1b9d496c106a43aa434b2b0562f4
parent af16fa5d315b6f30b0e999e31c18d763839b7d93
Author: Drew DeVault <sir@cmpwn.com>
Date:   Sat, 16 Jan 2021 09:55:57 -0500

type store: implement tagged mutual assignment

Diffstat:
M
src/type_store.c
 | 
20
+++++++++++++++++++-
M
tests/13-tagged.ha
 | 
10
++++++++++

2 files changed, 29 insertions(+), 1 deletion(-)
diff --git a/src/type_store.c b/src/type_store.c
@@ -32,7 +32,22 @@ tagged_assignable(struct type_store *store,
 		const struct type *from)
 {
 	if (from->storage == TYPE_STORAGE_TAGGED_UNION) {
-		assert(0); // TODO
+		if (to->storage != TYPE_STORAGE_TAGGED_UNION) {
+			return false;
+		}
+		// Only assignable if 'to' is a superset of 'from'
+		// Invariant: type_tagged_union is sorted by type tag
+		const struct type_tagged_union *to_t = &to->tagged;
+		const struct type_tagged_union *from_t = &from->tagged;
+		while (to_t && from_t) {
+			if (to_t->type->id == from_t->type->id) {
+				to_t = to_t->next;
+				from_t = from_t->next;
+			} else {
+				from_t = from_t->next;
+			}
+		}
+		return from_t == NULL;
 	}
 
 	size_t nassignable = 0;
@@ -171,6 +186,9 @@ static bool
 tagged_castable(const struct type *to, const struct type *from)
 {
 	if (to->storage == TYPE_STORAGE_TAGGED_UNION) {
+		if (from->storage == TYPE_STORAGE_TAGGED_UNION) {
+			return true;
+		}
 		assert(0); // TODO
 	}
 
diff --git a/tests/13-tagged.ha b/tests/13-tagged.ha
@@ -40,9 +40,19 @@ fn operators() void = {
 	assert(x is u64);
 };
 
+fn reduction() void = {
+	let a: (i8 | i16) = 42i8;
+	let b: (i16 | i8) = a;
+	let c: (i8 | i16 | i32) = a;
+	assert(a is i8);
+	assert(b is i8);
+	assert(c is i8);
+};
+
 export fn main() void = {
 	measurements();
 	storage();
 	operators();
+	reduction();
 	// TODO: Expand this as other tagged union features become available
 };