Merge pull request #4914 from rescript-lang/better_visistor_pattern

optimize the generated code, introducing iter visitor

Author: bobzhang

jscomp/core/j.ml

@@ -39,38 +39,38 @@
 *)
 
 
+type mutable_flag = Js_op.mutable_flag 
 
-type label = string
+type binop = Js_op.binop
 
-and binop = Js_op.binop
+type int_op = Js_op.int_op
 
-and int_op = Js_op.int_op
- 
-and kind = Js_op.kind
+type kind = Js_op.kind
 
-and property = Js_op.property
+type property = Js_op.property
 
-and number = Js_op.number 
+type number = Js_op.number 
 
-and mutable_flag = Js_op.mutable_flag 
+type ident_info = Js_op.ident_info
 
-and ident_info = Js_op.ident_info
+type exports = Js_op.exports
 
-and exports = Js_op.exports
+type tag_info = Js_op.tag_info 
 
-and tag_info = Js_op.tag_info 
+type property_name =  Js_op.property_name
+
+type label = string
 
 and required_modules = module_id list
 
-
-
+and ident = Ident.t (* we override `method ident` *)
 
 (** object literal, if key is ident, in this case, it might be renamed by 
     Google Closure  optimizer,
     currently we always use quote
  *)
-and property_name =  Js_op.property_name
-and ident = Ident.t 
+
+
 and module_id = {
   id : ident; kind : Js_op.kind
 }
@@ -350,3 +350,4 @@ and deps_program =
     modules : required_modules ;
     side_effect : string option (* None: no, Some reason  *)
   }
+  [@@deriving]

jscomp/core/js_analyzer.ml

@@ -44,21 +44,21 @@ let add_defined_idents (x : idents_stats) ident =
    Note such shaking is done in the toplevel, so that it requires us to 
    flatten the statement first 
 *)
-let free_variables (stats : idents_stats) : Js_fold.fold = 
+let free_variables (stats : idents_stats) : Js_iter.iter = 
   object (self)
-    inherit Js_fold.fold as super
+    inherit Js_iter.iter as super
     method! variable_declaration st = 
       add_defined_idents stats st.ident; 
       match st.value with 
       |  None
-        ->  self
+        ->  ()
       | Some v
         -> 
         self # expression v
     method! ident id = 
       (if not (Set_ident.mem stats.defined_idents id )then 
-         stats.used_idents <- Set_ident.add stats.used_idents id); 
-      self
+         stats.used_idents <- Set_ident.add stats.used_idents id)
+
     method! expression exp = 
       match exp.expression_desc with
       | Fun(_, _,_, env)
@@ -67,8 +67,8 @@ let free_variables (stats : idents_stats) : Js_fold.fold =
         *)
         ->
         stats.used_idents <-
-          Set_ident.union (Js_fun_env.get_unbounded env) stats.used_idents;
-        self 
+          Set_ident.union (Js_fun_env.get_unbounded env) stats.used_idents
+
 
       | _
         ->
@@ -139,32 +139,31 @@ and no_side_effect (x : J.expression)  =
 
 let no_side_effect_expression (x : J.expression) = no_side_effect x 
 
-let no_side_effect clean : Js_fold.fold = 
+let no_side_effect clean : Js_iter.iter = 
   object (self)
-    inherit Js_fold.fold as super
+    inherit Js_iter.iter as super
     method! statement s = 
-      if not !clean then self else 
+      if !clean then 
         match s.statement_desc with 
         | Throw _ 
         | Debugger 
         | Break 
         | Variable _ 
         | Continue _ ->  
-          clean := false ; self
+          clean := false 
         | Exp e -> self#expression e 
         | Int_switch _ | String_switch _ | ForRange _ 
         | If _ | While _   | Block _ | Return _ | Try _  -> super#statement s 
     method! list f x = 
-      if not !clean then self else super#list f x 
+      if  !clean then super#list f x 
     method! expression s = 
-      (if !clean then 
-        clean := no_side_effect_expression s); 
-      self 
-    (** only expression would cause side effec *)
+      if !clean then 
+        clean := no_side_effect_expression s      
+        (** only expression would cause side effec *)
   end
 let no_side_effect_statement st = 
   let clean = ref true in   
-  let _ : Js_fold.fold  = ((no_side_effect clean)#statement st) in 
+  (no_side_effect clean)#statement st;
   !clean
 
 (* TODO: generate [fold2]