Get finalizers working.

test/api/foreign_class.c

@@ -3,6 +3,18 @@
 
 #include "foreign_class.h"
 
+static int finalized = 0;
+
+static void apiGC(WrenVM* vm)
+{
+  wrenCollectGarbage(vm);
+}
+
+static void apiFinalized(WrenVM* vm)
+{
+  wrenReturnDouble(vm, finalized);
+}
+
 static void counterAllocate(WrenVM* vm)
 {
   double* value = (double*)wrenAllocateForeign(vm, sizeof(double));
@@ -60,8 +72,20 @@ static void pointToString(WrenVM* vm)
   wrenReturnString(vm, result, (int)strlen(result));
 }
 
+static void resourceAllocate(WrenVM* vm)
+{
+  wrenAllocateForeign(vm, 0);
+}
+
+static void resourceFinalize(WrenVM* vm)
+{
+  finalized++;
+}
+
 WrenForeignMethodFn foreignClassBindMethod(const char* signature)
 {
+  if (strcmp(signature, "static Api.gc()") == 0) return apiGC;
+  if (strcmp(signature, "static Api.finalized") == 0) return apiFinalized;
   if (strcmp(signature, "Counter.increment(_)") == 0) return counterIncrement;
   if (strcmp(signature, "Counter.value") == 0) return counterValue;
   if (strcmp(signature, "Point.translate(_,_,_)") == 0) return pointTranslate;
@@ -84,4 +108,11 @@ void foreignClassBindClass(
     methods->allocate = pointAllocate;
     return;
   }
+
+  if (strcmp(className, "Resource") == 0)
+  {
+    methods->allocate = resourceAllocate;
+    methods->finalize = resourceFinalize;
+    return;
+  }
 }

test/api/foreign_class.wren

@@ -1,3 +1,8 @@
+class Api {
+  foreign static gc()
+  foreign static finalized
+}
+
 // Class with a default constructor.
 foreign class Counter {
   foreign increment(amount)
@@ -46,3 +51,25 @@ var error = Fiber.new {
   class Subclass is Point {}
 }.try()
 IO.print(error) // expect: Class 'Subclass' cannot inherit from foreign class 'Point'.
+
+// Class with a finalizer.
+foreign class Resource {}
+
+var resources = [
+  Resource.new(),
+  Resource.new(),
+  Resource.new()
+]
+
+Api.gc()
+IO.print(Api.finalized) // expect: 0
+
+resources.removeAt(-1)
+
+Api.gc()
+IO.print(Api.finalized) // expect: 1
+
+resources.clear()
+
+Api.gc()
+IO.print(Api.finalized) // expect: 3