Continue refactoring coroutines for lambda lowering

Summary: In order to correctly generate properties, etc, for coroutine closure classes we will need to classify all the locals used in a lambda into outer variables, inner variables, and formal parameters. In this refactoring, I create a tool in the lambda analyzer to do that, and fix up the closure data to be initialized from it.  Tweaks to the actual codegen will come in a subsequent diff.

Reviewed By: michaeltingley

Differential Revision: D5504520

fbshipit-source-id: 03bd16f1402b0441a9ed3575d328334360c64bb3

hphp/hack/src/parser/coroutine/coroutine_state_machine_generator.ml

@@ -852,34 +852,17 @@ let extract_parameter_declarations function_parameter_list =
       end
 
 let compute_state_machine_data
-    locals_and_params
+    (inner_variables, outer_variables, used_params)
     coroutine_result_data_variables
-    outer_variables
     function_parameter_list =
-  let parameters = extract_parameter_declarations function_parameter_list in
   (* TODO: Add a test case for "..." param. *)
-  let parameter_names =
-    parameters
-      |> Core_list.map ~f:
-        begin
-        function
-        | {
-            parameter_name =
-              {
-                syntax =
-                  Token { EditableToken.kind = TokenKind.Variable; text; _; };
-                _;
-              };
-            _;
-          } ->
-            text
-        | _ -> failwith "Parameter had unexpected token."
-        end
-      |> SSet.of_list in
-  let local_variables = SSet.diff locals_and_params parameter_names in
+  let parameters = extract_parameter_declarations function_parameter_list in
+  let local_variables = SSet.union inner_variables outer_variables in
   let local_variables = SSet.elements local_variables in
+  (* TODO: Why is this a map? *)
   let local_variables = local_variables @
     (SMap.keys coroutine_result_data_variables) in
+  let outer_variables = SSet.elements outer_variables in
   CoroutineStateMachineData.{ local_variables; parameters; outer_variables; }
 
 (**
@@ -894,15 +877,11 @@ let generate_coroutine_state_machine
     function_parameter_list =
   let new_body, coroutine_result_data_variables =
     lower_body original_body in
-  (* TODO: Refactor this so that the lambda analyzer partitions used locals
-  into parameters, inner variables and outer variables. *)
-  let outer_variables = Lambda_analyzer.outer_variables
-    context.Coroutine_context.parents original_body in
-  let used_locals = all_used_locals original_body in
+  let used_locals = Lambda_analyzer.partition_used_locals
+    context.Coroutine_context.parents function_parameter_list original_body in
   let state_machine_data = compute_state_machine_data
     used_locals
     coroutine_result_data_variables
-    outer_variables
     function_parameter_list in
   let closure_syntax =
     CoroutineClosureGenerator.generate_coroutine_closure

hphp/hack/src/parser/lambda_analyzer.ml

@@ -112,6 +112,7 @@ let get_body node =
   | AnonymousFunction { anonymous_body; _ } -> anonymous_body
   | _ -> make_missing()
 
+(* TODO: This does not consider situations like "${x}" as the use of a local.*)
 let add_local acc node =
   match syntax node with
   | VariableExpression { variable_expression =
@@ -164,3 +165,15 @@ let outer_variables parents lambda =
   let outer = SSet.inter all_outer all_used in
   SSet.elements outer
   (* Note that we are guaranteed that the list is sorted. *)
+
+let partition_used_locals parents params body =
+  let all_used = fold_no_lambdas add_local SSet.empty body in
+  let all_used = SSet.remove "$this" all_used in
+  let decls = syntax_node_to_list params in
+  let all_params = List.filter_map decls ~f:param_name in
+  let all_params = SSet.of_list all_params in
+  let used_params = SSet.inter all_used all_params in
+  let all_outer = List.fold_left parents ~f:local_variables ~init:SSet.empty in
+  let used_outer = SSet.inter all_used all_outer in
+  let inner = SSet.diff all_used (SSet.union used_params used_outer) in
+  (inner, used_outer, used_params)