Merge of #5455

docs/docs/03-language-reference.md

@@ -813,6 +813,11 @@ Here's a quick summary of how optionality works in Wing:
 * The `x ?? y` notation will return the value in `x` if there is one, `y` otherwise.
 * The keyword `nil` can be used in assignment scenarios to indicate that an optional doesn't have a
   value. It cannot be used to test if an optional has a value or not.
+* A type annotation in Wing can always be enclosed in parentheses: `num` and `(num)` are the same type.
+  This is useful when you want to denote an optional function type. For example `((str):num)?` means
+  an **optional function** receiving a `str` and returning a `num`, while the similarly written 
+  `(str):num?` means a function receiving a `str` and returning an **optional `num`**.
+
 
 #### 1.7.1 Declaration
 

examples/tests/invalid/function_type.test.w

@@ -1,10 +1,3 @@
-// function type with no return type
-let my_func = (callback: (num)) => {  };
-//                       ^^^^^ Expected function return type
-let my_func2 = (callback: ((num)): (str)) => {  };
-//                                 ^^^^^ Expected function return type
-//                         ^^^^^ Expected function return type
-
 // interface methods with no return type
 interface IFace {
   my_method(x: num);

examples/tests/invalid/optionals.test.w

@@ -96,4 +96,10 @@ optionalFunction();
 //^ Cannot call optional function (unless it's part of a reference)
 
 let optionalFunctionWithNoRetType: ()? = () => {};
-//                                 ^^ Expected function return type
+//                                 ^^ Unexpected syntax
+
+// Pass incorrect optional function type to a function
+let functionWithOptionalFuncParam1: ((num):void)? = (x: str):void => {};
+//                                                  ^^^^^^^^^^^^^^^^^^^ Expected type to be "(preflight (num): void)?", but got "preflight (x: str): void" instead
+let functionWithOptionalFuncParam2: (():num)? = ():str => { return "s"; };
+//                                              ^^^^^^^^^^^^^^^^^^^^^^^^^ Expected type to be "(preflight (): num)?", but got "preflight (): str" instead

examples/tests/valid/optionals.test.w

@@ -204,3 +204,18 @@ if let s1 = str1 {
 } elif let s2 = str2 {
   assert(true);
 }
+
+// Optional function return type
+let var fn: (): ((): num)? = () => { return () => { return 1337; }; };
+if let f = fn() {
+  assert(f() == 1337);
+} else {
+  assert(false);
+}
+fn = () => { return nil; };
+if let f = fn() {
+  assert(false);
+} else {
+  assert(true);
+}
+

libs/tree-sitter-wing/grammar.js

@@ -91,13 +91,13 @@ module.exports = grammar({
               $.json_container_type
             )
           ),
-          field("accessor_type", $._accessor),
+          field("accessor_type", $.accessor),
           // While the "property" identifier is optional in this grammar, upstream parsing will fail if it is not present
           optional(field("property", $._member_identifier))
         )
       ),
 
-    _accessor: ($) => choice(".", "?."),
+    accessor: ($) => choice(".", "?."),
 
     inflight_specifier: ($) => "inflight",
 
@@ -442,15 +442,17 @@ module.exports = grammar({
         )
       ),
 
-    _type: ($) =>
-      choice(
-        $.custom_type,
-        $.builtin_type,
-        $._builtin_container_type,
-        $.json_container_type,
-        $.function_type,
-        $.optional
-      ),
+    _type: ($) => choice(
+      $.custom_type,
+      $.builtin_type,
+      $._builtin_container_type,
+      $.json_container_type,
+      $.function_type,
+      $.optional,
+      $._parenthesized_type,
+    ),
+
+    _parenthesized_type: ($) => seq("(", $._type, ")"),
 
     optional: ($) => seq($._type, "?"),
 
@@ -459,7 +461,7 @@ module.exports = grammar({
         seq(
           optional(field("inflight", $.inflight_specifier)),
           field("parameter_types", $.parameter_type_list),
-          optional(seq(":", field("return_type", $._type)))
+          seq(":", field("return_type", $._type))
         )
       ),
 

libs/tree-sitter-wing/test/corpus/expressions.txt

@@ -111,6 +111,7 @@ obj.method();
         (nested_identifier
           object: (reference
             (reference_identifier))
+          accessor_type: (accessor)
           property: (member_identifier)))
       args: (argument_list))))
 
@@ -132,6 +133,7 @@ x == obj.method();
           (nested_identifier
             object: (reference
               (reference_identifier))
+            accessor_type: (accessor)
             property: (member_identifier)))
         args: (argument_list)))))
 
@@ -489,7 +491,9 @@ a?;
               (nested_identifier
                 object: (reference
                   (reference_identifier))
+                accessor_type: (accessor)
                 property: (member_identifier)))
+            accessor_type: (accessor)
             property: (member_identifier)))))))
 
 ================================================================================

libs/tree-sitter-wing/test/corpus/references.txt

@@ -14,7 +14,9 @@ test1.test2.test3;
           (nested_identifier
             object: (reference
               (reference_identifier))
+            accessor_type: (accessor)
             property: (member_identifier)))
+        accessor_type: (accessor)
         property: (member_identifier)))))
 
 ================================================================================
@@ -34,6 +36,8 @@ test1.test2.test3();
             (nested_identifier
               object: (reference
                 (reference_identifier))
+              accessor_type: (accessor)
               property: (member_identifier)))
+          accessor_type: (accessor)
           property: (member_identifier)))
       args: (argument_list))))

libs/tree-sitter-wing/test/corpus/statements/statements.txt

@@ -78,6 +78,8 @@ z -= 1;
 
 let var y = "hello";
 
+let w: (((num))) = 1;
+
 --------------------------------------------------------------------------------
 
 (source
@@ -107,7 +109,11 @@ let var y = "hello";
   (variable_definition_statement
     reassignable: (reassignable)
     name: (identifier)
-    value: (string)))
+    value: (string))
+  (variable_definition_statement
+    name: (identifier)
+    type: (builtin_type)
+    value: (number)))
 
 ================================================================================
 If
@@ -472,7 +478,7 @@ if let x = y {} elif let x = z {} else {}
 (source
   (if_let_statement
     name: (identifier)
-    value: (reference 
+    value: (reference
       (reference_identifier))
     block: (block)
     elif_let_block: (elif_let_block

libs/wingc/src/lsp/completions.rs

@@ -195,8 +195,25 @@ pub fn on_completion(params: lsp_types::CompletionParams) -> CompletionResponse
 				node_to_complete_kind,
 				"." | "?." | "member_identifier" | "type_identifier"
 			) {
+				// We need to double-check for an invalid nested reference (e.g. If there are multiple dots in a row)
+				if preceding_text.ends_with("..")
+					|| preceding_text.ends_with(".?.?")
+					|| preceding_text.ends_with("..")
+					|| preceding_text.ends_with(".?.")
+					|| preceding_text.ends_with("..?")
+				{
+					return vec![];
+				}
+
 				let parent = node_to_complete.parent().expect("A dot must have a parent");
 
+				// If the parent is an accessor node (the container of the "." or ".?" nodes) then move up one more level
+				let parent = if parent.kind() == "accessor" {
+					parent.parent().expect("An accessor must have a parent")
+				} else {
+					parent
+				};
+
 				if let Some(nearest_expr) = scope_visitor.nearest_expr {
 					let mut nearest_expr_type = types.get_expr_type(nearest_expr);
 					if let ExprKind::Call { .. } = &nearest_expr.kind {
@@ -207,11 +224,6 @@ pub fn on_completion(params: lsp_types::CompletionParams) -> CompletionResponse
 
 					// If we are inside an incomplete reference, there is possibly a type error or an anything which has no completions
 					if !nearest_expr_type.is_unresolved() {
-						// We need to double-check for an invalid nested reference (e.g. If there are multiple dots in a row)
-						if preceding_text.ends_with("..") || preceding_text.ends_with(".?.?") {
-							return vec![];
-						}
-
 						let access_context = if let ExprKind::Reference(Reference::Identifier(ident)) = &nearest_expr.kind {
 							match ident.name.as_str() {
 								"this" => ObjectAccessContext::This,
@@ -739,7 +751,7 @@ fn nearest_non_reference_ancestor<'a>(start_node: &'a tree_sitter::Node<'a>) ->
 		|| !nearest_non_reference.is_named()
 		|| matches!(
 			nearest_non_reference.kind(),
-			"identifier" | "reference" | "reference_identifier" | "expression_statement"
+			"identifier" | "reference" | "reference_identifier" | "expression_statement" | "accessor"
 		) {
 		let parent = nearest_non_reference.parent();
 		if let Some(parent) = parent {