add some helpful utils for decoding a jsonrpc message into a struc

lspgenerator/go/go_generator.py

@@ -8,6 +8,7 @@
 from .enums import generate_enums
 from .notifications import generate_notifications
 from .or_types import generate_or_types
+from .registry import generate_registry
 from .requests import generate_requests
 from .structs import generate_structs
 from .tests import generate_tests
@@ -40,6 +41,7 @@ def generate_from_spec(
 			+ or_types,
 		),
 		"types_test.go": generate_tests(spec),
+		"registry.go": generate_registry(spec),
 	}
 	output_path = pathlib.Path(output_dir)
 	test_path = pathlib.Path(test_dir)

lspgenerator/go/notifications.py

@@ -46,9 +46,9 @@ def generate_notifications(
 			f'\tParams {param_type} `json:"params"`',
 		]
 		struct.append("}")
-		struct.append(f"func (t *{notification.typeName}) isMessage() {{}}")
+		struct.append(f"func (t {notification.typeName}) isMessage() {{}}")
 		struct.append(
-			f"func (t *{notification.typeName}) isNotification() {{}}"
+			f"func (t {notification.typeName}) isNotification() {{}}",
 		)
 		struct += [
 			f"func (t *{notification.typeName}) UnmarshalJSON(x []byte) error {{",

lspgenerator/go/registry.py

@@ -0,0 +1,49 @@
+from generator import model
+
+from .utils import join
+
+
+def generate_registry(spec: model.LSPModel) -> str:
+	result = [
+		"package protocol",
+		"import (",
+		'	"encoding/json"',
+		")",
+		"var MessageRegistry = map[string]func([]byte) (Message, error) {",
+	]
+
+	result.extend(
+		[
+			join(
+				[
+					f'	"{request.method}": func(data []byte) (Message, error) {{',
+					f"		var message {request.typeName}",
+					"		if err := json.Unmarshal(data, &message); err != nil {",
+					"			return nil, err",
+					"		}",
+					"		return message, nil",
+					"	},",
+				],
+			)
+			for request in spec.requests
+		],
+	)
+	result.extend(
+		[
+			join(
+				[
+					f'	"{notification.method}": func(data []byte) (Message, error) {{',
+					f"		var message {notification.typeName}",
+					"		if err := json.Unmarshal(data, &message); err != nil {",
+					"			return nil, err",
+					"		}",
+					"		return message, nil",
+					"	},",
+				],
+			)
+			for notification in spec.notifications
+		],
+	)
+	result.append("}")
+
+	return join(result)

lspgenerator/go/requests.py

@@ -50,8 +50,8 @@ def generate_requests(
 		]
 
 		struct.append("}")
-		struct.append(f"func (t *{request.typeName}) isMessage() {{}}")
-		struct.append(f"func (t *{request.typeName}) isRequest() {{}}")
+		struct.append(f"func (t {request.typeName}) isMessage() {{}}")
+		struct.append(f"func (t {request.typeName}) isRequest() {{}}")
 		struct += [
 			f"func (t *{request.typeName}) UnmarshalJSON(x []byte) error {{",
 			"   var m map[string]any",
@@ -119,7 +119,7 @@ def generate_requests(
 			"   return nil",
 			"}",
 		]
-		struct.append(f"func (t *{response_name}) isMessage() {{}}")
-		struct.append(f"func (t *{response_name}) isResponse() {{}}")
+		struct.append(f"func (t {response_name}) isMessage() {{}}")
+		struct.append(f"func (t {response_name}) isResponse() {{}}")
 		result.append(join(struct))
 	return result