[parser] let/const parser cleanup

Summary: there was duplication in Statement_parser, and Declaration_parser.variable was statement-specific and didn't belong there.

Reviewed By: panagosg7

Differential Revision: D10493287

fbshipit-source-id: d848975918884f0ef68200e51545afac55e3dea9

src/parser/declaration_parser.ml

@@ -23,8 +23,6 @@ module type DECLARATION = sig
   val is_simple_function_params: (Loc.t, Loc.t) Ast.Function.Params.t -> bool
   val strict_post_check: env -> strict:bool -> simple:bool -> Loc.t Identifier.t option -> (Loc.t, Loc.t) Ast.Function.Params.t -> unit
   val concise_function_body: env -> async:bool -> generator:bool -> (Loc.t, Loc.t) Function.body * bool
-  val variable: env -> (Loc.t, Loc.t) Statement.t * (Loc.t * Error.t) list
-  val variable_declaration_list: env -> (Loc.t, Loc.t) Statement.VariableDeclaration.Declarator.t list * (Loc.t * Error.t) list
   val let_: env -> (Loc.t, Loc.t) Statement.VariableDeclaration.t * (Loc.t * Error.t) list
   val const: env -> (Loc.t, Loc.t) Statement.VariableDeclaration.t * (Loc.t * Error.t) list
   val var: env -> (Loc.t, Loc.t) Statement.VariableDeclaration.t * (Loc.t * Error.t) list
@@ -329,18 +327,4 @@ module Declaration
   let let_ env =
     let env = env |> with_no_let true in
     declarations T_LET Statement.VariableDeclaration.Let env
-
-  let variable env =
-    let loc, (decl, errs) = with_loc (fun env ->
-      let variable, errs = match Peek.token env with
-      | T_CONST -> const env
-      | T_LET   -> let_ env
-      | T_VAR   -> var env
-      | _ ->
-          error_unexpected env;
-          (* We need to return something. This is as good as anything else *)
-          var env in
-      Statement.VariableDeclaration variable, errs
-    ) env in
-    (loc, decl), errs
 end

src/parser/parser_flow.ml

@@ -148,7 +148,7 @@ module rec Parse : PARSER = struct
     (* Remember kids, these look like statements but they're not
       * statements... (see section 13) *)
     | T_LET -> let_ env
-    | T_CONST -> var_or_const env
+    | T_CONST -> const env
     | _ when Peek.is_function env -> Declaration._function env
     | _ when Peek.is_class env -> class_declaration env decorators
     | T_INTERFACE -> interface env
@@ -164,7 +164,7 @@ module rec Parse : PARSER = struct
         Peek.loc env, Ast.Statement.Empty
     | T_SEMICOLON -> empty env
     | T_LCURLY -> block env
-    | T_VAR -> var_or_const env
+    | T_VAR -> var env
     | T_BREAK -> break env
     | T_CONTINUE -> continue env
     | T_DEBUGGER -> debugger env

src/parser/statement_parser.ml

@@ -41,7 +41,8 @@ module type STATEMENT = sig
  val switch: env -> (Loc.t, Loc.t) Statement.t
  val throw: env -> (Loc.t, Loc.t) Statement.t
  val type_alias: env -> (Loc.t, Loc.t) Statement.t
- val var_or_const: env -> (Loc.t, Loc.t) Statement.t
+ val var: env -> (Loc.t, Loc.t) Statement.t
+ val const: env -> (Loc.t, Loc.t) Statement.t
 end
 
 module Statement
@@ -424,25 +425,25 @@ module Statement
     }
   )
 
-  and var_or_const = with_loc (fun env ->
-    let (_loc, declaration), errs = Declaration.variable env in
+  and var = with_loc (fun env ->
+    let declaration, errs = Declaration.var env in
     Eat.semicolon env;
     errs |> List.iter (error_at env);
-    declaration
+    Statement.VariableDeclaration declaration
+  )
+
+  and const = with_loc (fun env ->
+    let declaration, errs = Declaration.const env in
+    Eat.semicolon env;
+    errs |> List.iter (error_at env);
+    Statement.VariableDeclaration declaration
   )
 
   and let_ = with_loc (fun env ->
-    Expect.token env T_LET;
-    (* Let declaration *)
-    let declarations, errs = Declaration.variable_declaration_list (env |> with_no_let true) in
-    let declaration =
-      Ast.(Statement.VariableDeclaration Statement.VariableDeclaration.({
-        declarations;
-        kind = Let;
-      })) in
+    let declaration, errs = Declaration.let_ env in
     Eat.semicolon env;
     errs |> List.iter (error_at env);
-    declaration
+    Statement.VariableDeclaration declaration
   )
 
   and while_ = with_loc (fun env ->