Scripting: Add callback removing

include/mgba/script/context.h

@@ -29,6 +29,8 @@ struct mScriptContext {
 	struct Table weakrefs;
 	uint32_t nextWeakref;
 	struct Table callbacks;
+	struct Table callbackId;
+	uint32_t nextCallbackId;
 	struct mScriptValue* constants;
 	struct Table docstrings;
 };
@@ -85,7 +87,8 @@ void mScriptContextExportConstants(struct mScriptContext* context, const char* n
 void mScriptContextExportNamespace(struct mScriptContext* context, const char* nspace, struct mScriptKVPair* value);
 
 void mScriptContextTriggerCallback(struct mScriptContext*, const char* callback);
-void mScriptContextAddCallback(struct mScriptContext*, const char* callback, struct mScriptValue* value);
+uint32_t mScriptContextAddCallback(struct mScriptContext*, const char* callback, struct mScriptValue* value);
+void mScriptContextRemoveCallback(struct mScriptContext*, uint32_t cbid);
 
 void mScriptContextSetDocstring(struct mScriptContext*, const char* key, const char* docstring);
 const char* mScriptContextGetDocstring(struct mScriptContext*, const char* key);

src/script/context.c

@@ -14,6 +14,11 @@ struct mScriptFileInfo {
 	struct mScriptEngineContext* context;
 };
 
+struct mScriptCallbackInfo {
+	const char* callback;
+	size_t id;
+};
+
 static void _engineContextDestroy(void* ctx) {
 	struct mScriptEngineContext* context = ctx;
 	context->destroy(context);
@@ -56,6 +61,8 @@ void mScriptContextInit(struct mScriptContext* context) {
 	TableInit(&context->weakrefs, 0, (void (*)(void*)) mScriptValueDeref);
 	context->nextWeakref = 1;
 	HashTableInit(&context->callbacks, 0, (void (*)(void*)) mScriptValueDeref);
+	TableInit(&context->callbackId, 0, free);
+	context->nextCallbackId = 1;
 	context->constants = NULL;
 	HashTableInit(&context->docstrings, 0, NULL);
 }
@@ -66,6 +73,7 @@ void mScriptContextDeinit(struct mScriptContext* context) {
 	mScriptContextDrainPool(context);
 	mScriptListDeinit(&context->refPool);
 	HashTableDeinit(&context->callbacks);
+	TableDeinit(&context->callbackId);
 	HashTableDeinit(&context->engines);
 	HashTableDeinit(&context->docstrings);
 }
@@ -199,8 +207,11 @@ void mScriptContextTriggerCallback(struct mScriptContext* context, const char* c
 	size_t i;
 	for (i = 0; i < mScriptListSize(list->value.list); ++i) {
 		struct mScriptFrame frame;
-		mScriptFrameInit(&frame);
 		struct mScriptValue* fn = mScriptListGetPointer(list->value.list, i);
+		if (!fn->type) {
+			continue;
+		}
+		mScriptFrameInit(&frame);
 		if (fn->type->base == mSCRIPT_TYPE_WRAPPER) {
 			fn = mScriptValueUnwrap(fn);
 		}
@@ -209,16 +220,48 @@ void mScriptContextTriggerCallback(struct mScriptContext* context, const char* c
 	}
 }
 
-void mScriptContextAddCallback(struct mScriptContext* context, const char* callback, struct mScriptValue* fn) {
+uint32_t mScriptContextAddCallback(struct mScriptContext* context, const char* callback, struct mScriptValue* fn) {
 	if (fn->type->base != mSCRIPT_TYPE_FUNCTION) {
-		return;
+		return 0;
 	}
 	struct mScriptValue* list = HashTableLookup(&context->callbacks, callback);
 	if (!list) {
 		list = mScriptValueAlloc(mSCRIPT_TYPE_MS_LIST);
 		HashTableInsert(&context->callbacks, callback, list);
 	}
+	struct mScriptCallbackInfo* info = malloc(sizeof(*info));
+	// Steal the string from the table key, since it's guaranteed to outlive this struct
+	struct TableIterator iter;
+	HashTableIteratorLookup(&context->callbacks, &iter, callback);
+	info->callback = HashTableIteratorGetKey(&context->callbacks, &iter);
+	info->id = mScriptListSize(list->value.list);
 	mScriptValueWrap(fn, mScriptListAppend(list->value.list));
+	while (true) {
+		uint32_t id = context->nextCallbackId;
+		++context->nextCallbackId;
+		if (TableLookup(&context->callbackId, id)) {
+			continue;
+		}
+		TableInsert(&context->callbackId, id, info);
+		return id;
+	}
+}
+
+void mScriptContextRemoveCallback(struct mScriptContext* context, uint32_t cbid) {
+	struct mScriptCallbackInfo* info = TableLookup(&context->callbackId, cbid);
+	if (!info) {
+		return;
+	}
+	struct mScriptValue* list = HashTableLookup(&context->callbacks, info->callback);
+	if (!list) {
+		return;
+	}
+	if (info->id >= mScriptListSize(list->value.list)) {
+		return;
+	}
+	struct mScriptValue* fn = mScriptValueUnwrap(mScriptListGetPointer(list->value.list, info->id));
+	mScriptValueDeref(fn);
+	mScriptListGetPointer(list->value.list, info->id)->type = NULL;
 }
 
 void mScriptContextExportConstants(struct mScriptContext* context, const char* nspace, struct mScriptKVPair* constants) {

src/script/stdlib.c

@@ -19,16 +19,22 @@ struct mScriptCallbackManager {
 	struct mScriptContext* context;
 };
 
-static void _mScriptCallbackAdd(struct mScriptCallbackManager* adapter, struct mScriptString* name, struct mScriptValue* fn) {
+static uint32_t _mScriptCallbackAdd(struct mScriptCallbackManager* adapter, struct mScriptString* name, struct mScriptValue* fn) {
 	if (fn->type->base == mSCRIPT_TYPE_WRAPPER) {
 		fn = mScriptValueUnwrap(fn);
 	}
-	mScriptContextAddCallback(adapter->context, name->buffer, fn);
+	uint32_t id = mScriptContextAddCallback(adapter->context, name->buffer, fn);
 	mScriptValueDeref(fn);
+	return id;
+}
+
+static void _mScriptCallbackRemove(struct mScriptCallbackManager* adapter, uint32_t id) {
+	mScriptContextRemoveCallback(adapter->context, id);
 }
 
 mSCRIPT_DECLARE_STRUCT(mScriptCallbackManager);
-mSCRIPT_DECLARE_STRUCT_VOID_METHOD(mScriptCallbackManager, add, _mScriptCallbackAdd, 2, STR, callback, WRAPPER, function);
+mSCRIPT_DECLARE_STRUCT_METHOD(mScriptCallbackManager, U32, add, _mScriptCallbackAdd, 2, STR, callback, WRAPPER, function);
+mSCRIPT_DECLARE_STRUCT_VOID_METHOD(mScriptCallbackManager, remove, _mScriptCallbackRemove, 1, U32, cbid);
 
 static uint64_t mScriptMakeBitmask(struct mScriptList* list) {
 	size_t i;
@@ -76,8 +82,10 @@ mSCRIPT_DEFINE_STRUCT(mScriptCallbackManager)
 		"- **start**: The emulation has started\n"
 		"- **stop**: The emulation has voluntarily shut down\n"
 	)
-	mSCRIPT_DEFINE_DOCSTRING("Add a callback of the named type")
+	mSCRIPT_DEFINE_DOCSTRING("Add a callback of the named type. The returned id can be used to remove it later")
 	mSCRIPT_DEFINE_STRUCT_METHOD(mScriptCallbackManager, add)
+	mSCRIPT_DEFINE_DOCSTRING("Remove a callback with the previously retuned id")
+	mSCRIPT_DEFINE_STRUCT_METHOD(mScriptCallbackManager, remove)
 mSCRIPT_DEFINE_END;
 
 void mScriptContextAttachStdlib(struct mScriptContext* context) {

src/script/test/stdlib.c

@@ -7,6 +7,7 @@
 
 #include <mgba/internal/script/lua.h>
 #include <mgba/script/context.h>
+#include <mgba/script/macros.h>
 #include <mgba/script/types.h>
 
 #define SETUP_LUA \
@@ -85,7 +86,36 @@ M_TEST_DEFINE(bitUnmask) {
 	mScriptContextDeinit(&context);
 }
 
+M_TEST_DEFINE(callbacks) {
+	SETUP_LUA;
+
+	TEST_PROGRAM(
+		"val = 0\n"
+		"function cb()\n"
+		"	val = val + 1\n"
+		"end\n"
+		"id = callbacks:add('test', cb)\n"
+		"assert(id)"
+	);
+
+	TEST_VALUE(S32, "val", 0);
+
+	mScriptContextTriggerCallback(&context, "test");
+	TEST_VALUE(S32, "val", 1);
+
+	mScriptContextTriggerCallback(&context, "test");
+	TEST_VALUE(S32, "val", 2);
+
+	TEST_PROGRAM("callbacks:remove(id)");
+
+	mScriptContextTriggerCallback(&context, "test");
+	TEST_VALUE(S32, "val", 2);
+
+	mScriptContextDeinit(&context);
+}
+
 M_TEST_SUITE_DEFINE_SETUP_TEARDOWN(mScriptStdlib,
 	cmocka_unit_test(bitMask),
 	cmocka_unit_test(bitUnmask),
+	cmocka_unit_test(callbacks),
 )

src/script/types.c

@@ -249,6 +249,9 @@ void _allocList(struct mScriptValue* val) {
 void _freeList(struct mScriptValue* val) {
 	size_t i;
 	for (i = 0; i < mScriptListSize(val->value.list); ++i) {
+		if (val->type) {
+			continue;
+		}
 		struct mScriptValue* unwrapped = mScriptValueUnwrap(mScriptListGetPointer(val->value.list, i));
 		if (unwrapped) {
 			mScriptValueDeref(unwrapped);