(**
 * Copyright (c) 2013-present, Facebook, Inc.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 *)

open Type

let maybe_known f x =
  let open React.CreateClass in
  begin match x with
    | Known x' ->
        let x'' = f x' in
        if x'' == x' then x
        else Known x''
    | Unknown x -> Unknown x
  end

(* NOTE: While union flattening could be performed at any time, it is most effective when we know
   that all tvars have been resolved. *)
let union_flatten =
  let rec union_flatten cx seen ts =
    List.flatten @@ List.map (flatten cx seen) ts
  and flatten cx seen t = match t with
    | OpenT (_, id) ->
      if ISet.mem id !seen then []
      else begin
        seen := ISet.add id !seen;
        match Context.find_graph cx id with
        | Constraint.Resolved t' -> flatten cx seen t'
        | _ -> [t]
      end
    | AnnotT (t, _) -> flatten cx seen t
    | ReposT (_, t) -> flatten cx seen t
    | DefT (_, UnionT rep) -> union_flatten cx seen @@ UnionRep.members rep
    | DefT (r, MaybeT t) -> (DefT (r, NullT))::(DefT (r, VoidT))::(flatten cx seen t)
    | DefT (r, OptionalT t) -> (DefT (r, VoidT))::(flatten cx seen t)
    | DefT (_, EmptyT) -> []
    | _ -> [t]
  in
  fun cx ts -> union_flatten cx (ref ISet.empty) ts

(* This class should be used when trying to perform some mapping function on
 * a type. It will recurse through the structure of the type, applying it to
 * each sub-part.
 *)

class ['a] t = object(self)
  method type_ cx (map_cx: 'a) t =
    match t with
      | OpenT (r, id) ->
          let id' = self#tvar cx map_cx r id in
          if id' == id then t else OpenT (r, id')
      | DefT (r, t') ->
          let t'' = self#def_type cx map_cx t' in
          if t' == t'' then t else DefT (r, t'')
      | EvalT (t', dt, _) ->
          let t'' = self#type_ cx map_cx t' in
          let dt' = self#defer_use_type cx map_cx dt in
          if t' == t'' && dt == dt' then t
          else EvalT (t'', dt', Reason.mk_id ())
      | BoundT t' ->
          let t'' = self#type_param cx map_cx t' in
          if t'' == t' then t
          else BoundT t''
      | ExistsT _ -> t
      | ThisClassT (r, t') ->
          let t'' = self#type_ cx map_cx t' in
          if t'' == t' then t
          else ThisClassT (r, t'')
      | ThisTypeAppT (r, t1, t2, tlist_opt) ->
          let t1' = self#type_ cx map_cx t1 in
          let t2' = self#type_ cx map_cx t2 in
          let tlist_opt' = OptionUtils.ident_map (ListUtils.ident_map (self#type_ cx map_cx)) tlist_opt in
          if t1' == t1 && t2' == t2 && tlist_opt' == tlist_opt then t
          else ThisTypeAppT(r, t1', t2', tlist_opt')
      | ExactT (r, t') ->
          let t'' = self#type_ cx map_cx t' in
          if t'' == t' then t
          else ExactT (r, t'')
      | FunProtoT _
      | ObjProtoT _
      | NullProtoT _
      | FunProtoApplyT _
      | FunProtoBindT _
      | FunProtoCallT _ -> t
      | AnyWithLowerBoundT t' ->
          let t'' = self#type_ cx map_cx t' in
          if t'' == t' then t
          else AnyWithLowerBoundT t''
      | AnyWithUpperBoundT t' ->
          let t'' = self#type_ cx map_cx t' in
          if t'' == t' then t
          else AnyWithUpperBoundT t''
      | MergedT (r, uses) ->
          let uses' = ListUtils.ident_map (self#use_type cx map_cx) uses in
          if uses == uses' then t
          else MergedT (r, uses')
      | ShapeT t' ->
          let t'' = self#type_ cx map_cx t' in
          if t'' == t' then t
          else ShapeT t''
      | MatchingPropT (r, x, t') ->
          let t'' = self#type_ cx map_cx t' in
          if t'' == t' then t
          else MatchingPropT (r, x, t'')
      | KeysT (r, t') ->
          let t'' = self#type_ cx map_cx t' in
          if t'' == t' then t
          else KeysT (r, t'')
      | AnnotT (t', use_desc) ->
          let t'' = self#type_ cx map_cx t' in
          if t'' == t' then t
          else AnnotT (t'', use_desc)
      | OpaqueT (r, opaquetype) ->
          let underlying_t = OptionUtils.ident_map (self#type_ cx map_cx) opaquetype.underlying_t in
          let super_t = OptionUtils.ident_map (self#type_ cx map_cx) opaquetype.super_t in
          let opaque_type_args = SMap.ident_map (fun x ->
            let (r, t) = x in
            let t' = self#type_ cx map_cx t in
            if t == t' then x
            else (r, t')
          ) opaquetype.opaque_type_args in
          if underlying_t == opaquetype.underlying_t &&
            super_t == opaquetype.super_t &&
            opaque_type_args == opaquetype.opaque_type_args
          then t
          else OpaqueT (r, {opaquetype with underlying_t; super_t; opaque_type_args})
      | ModuleT (r, exporttypes, is_strict) ->
          let exporttypes' = self#export_types cx map_cx exporttypes in
          if exporttypes == exporttypes' then t
          else ModuleT (r, exporttypes', is_strict)
      | InternalT (ExtendsT (r, t1, t2)) ->
          let t1' = self#type_ cx map_cx t1 in
          let t2' = self#type_ cx map_cx t2 in
          if t1' == t1 && t2' == t2 then t
          else InternalT (ExtendsT (r, t1', t2'))
      | InternalT (ChoiceKitT _) -> t
      | TypeDestructorTriggerT (u, r, repos, d, x) ->
          let d' = self#destructor cx map_cx d in
          let x' = self#type_ cx map_cx x in
          if d == d' && x == x' then t
          else TypeDestructorTriggerT (u, r, repos, d', x')
      | CustomFunT (r, kind) ->
          let kind' = self#custom_fun_kind cx map_cx kind in
          if kind' == kind then t
          else CustomFunT (r, kind')
      | InternalT (IdxWrapper (r, t')) ->
          let t'' = self#type_ cx map_cx t' in
          if t' == t'' then t
          else InternalT (IdxWrapper (r, t''))
      | OpenPredT (r, t', map1, map2) ->
          let t'' = self#type_ cx map_cx t' in
          let map1' = Key_map.map (self#predicate cx map_cx) map1 in
          let map2' = Key_map.map (self#predicate cx map_cx) map2 in
          if t'' == t' then t
          else OpenPredT (r, t'', map1', map2')
      | ReposT (r, t') ->
          let t'' = self#type_ cx map_cx t' in
          if t'' == t' then t
          else ReposT (r, t'')
      | InternalT (ReposUpperT (r, t')) ->
          let t'' = self#type_ cx map_cx t' in
          if t'' == t' then t
          else InternalT (ReposUpperT (r, t''))

  method tvar _cx _map_cx _r id = id

  method def_type cx map_cx t =
    match t with
      | NumT _
      | StrT _
      | BoolT _
      | EmptyT
      | MixedT _
      | NullT
      | VoidT -> t
      | FunT (s, p, f) ->
          let s' = self#type_ cx map_cx s in
          let p' = self#type_ cx map_cx p in
          let f' = self#fun_type cx map_cx f in
          if s == s' && p == p' && f == f' then t
          else FunT (s', p', f')
      | ObjT objtype ->
          let objtype' = self#obj_type cx map_cx objtype in
          if objtype' == objtype then t
          else ObjT objtype'
      | ArrT arrtype ->
          let arrtype' = self#arr_type cx map_cx arrtype in
          if arrtype == arrtype' then t
          else ArrT arrtype'
      | CharSetT _ -> t
      | ClassT t' ->
          let t'' = self#type_ cx map_cx t' in
          if t'' == t' then t
          else ClassT t''
      | InstanceT (st, su, impl, instt) ->
          let st' = self#type_ cx map_cx st in
          let su' = self#type_ cx map_cx su in
          let impl' = ListUtils.ident_map (self#type_ cx map_cx) impl in
          let instt' = self#inst_type cx map_cx instt in
          if st' == st && su' == su && impl' == impl && instt' == instt then t
          else InstanceT (st', su', impl', instt')
      | SingletonStrT _
      | SingletonNumT _
      | SingletonBoolT _ -> t
      | TypeT t' ->
          let t'' = self#type_ cx map_cx t' in
          if t'' == t' then t
          else TypeT t''
      | AnyT -> t
      | OptionalT t' ->
          let t'' = self#type_ cx map_cx t' in
          if t'' == t' then t
          else OptionalT t''
      | PolyT (tparamlist, t', _) ->
          let tparamlist' = ListUtils.ident_map (self#type_param cx map_cx) tparamlist in
          let t'' = self#type_ cx map_cx t' in
          if tparamlist == tparamlist' && t' == t'' then t
          else PolyT (tparamlist', t'', Reason.mk_id ())
      | TypeAppT (op, t', ts) ->
          let t'' = self#type_ cx map_cx t' in
          let ts' = ListUtils.ident_map (self#type_ cx map_cx) ts in
          if t' == t'' && ts == ts' then t
          else TypeAppT (op, t'', ts')
      | MaybeT t' ->
          let t'' = self#type_ cx map_cx t' in
          if t'' == t' then t
          else MaybeT t''
      | IntersectionT irep ->
          let irep' = InterRep.ident_map (self#type_ cx map_cx) irep in
          if irep == irep' then t
          else IntersectionT irep'
      | UnionT urep ->
          let urep' = UnionRep.ident_map (self#type_ cx map_cx) urep in
          if urep' == urep then t
          else UnionT urep'
      | AnyObjT
      | AnyFunT -> t

  method defer_use_type cx map_cx t =
    match t with
    | DestructuringT (r, s) ->
        let s' = self#selector cx map_cx s in
        if s' == s then t
        else DestructuringT (r, s')
    | TypeDestructorT (u, r, d) ->
        let d' = self#destructor cx map_cx d in
        if d == d' then t
        else TypeDestructorT (u, r, d')

  method export_types cx map_cx ({exports_tmap; cjs_export; has_every_named_export} as t) =
    let exports_tmap' = self#exports cx map_cx exports_tmap in
    let cjs_export' = OptionUtils.ident_map (self#type_ cx map_cx) cjs_export in
    if exports_tmap == exports_tmap' && cjs_export == cjs_export' then t
    else {exports_tmap = exports_tmap'; cjs_export = cjs_export'; has_every_named_export}

  method fun_type cx map_cx ({ this_t;
                       params;
                       rest_param;
                       return_t;
                       closure_t;
                       is_predicate;
                       changeset;
                       def_reason } as t) =
    let this_t' = self#type_ cx map_cx this_t in
    let return_t' = self#type_ cx map_cx return_t in
    let params' = ListUtils.ident_map (fun ((name, t) as param) ->
      let t' = self#type_ cx map_cx t in
      if t' == t then param else (name, t')
    ) params in
    let rest_param' = match rest_param with
    | None -> rest_param
    | Some (name, loc, t) ->
        let t' = self#type_ cx map_cx t in
        if t' == t then rest_param else Some (name, loc, t')
    in
    if this_t' == this_t &&
       return_t' == return_t &&
       params' == params &&
       rest_param' == rest_param then t
    else
      let this_t = this_t' in
      let return_t = return_t' in
      let params = params' in
      let rest_param = rest_param' in
      {this_t; params; rest_param; return_t;
       closure_t; is_predicate; changeset; def_reason}

  method inst_type cx map_cx i =
    let {
      class_id;
      type_args;
      arg_polarities;
      fields_tmap;
      initialized_field_names;
      initialized_static_field_names;
      methods_tmap;
      has_unknown_react_mixins;
      structural
    } = i in
    let type_args' = SMap.ident_map (fun x ->
      let (r, t) = x in
      let t' = self#type_ cx map_cx t in
      if t == t' then x
      else (r, t')
    ) type_args in
    let f_tmap = Context.find_props cx fields_tmap in
    let f_tmap' = SMap.ident_map (Property.ident_map_t (self#type_ cx map_cx)) f_tmap in
    let fields_tmap' =
      if f_tmap == f_tmap' then fields_tmap
      else Context.make_property_map cx f_tmap' in
    let m_tmap = Context.find_props cx methods_tmap in
    let m_tmap' = SMap.ident_map (Property.ident_map_t (self#type_ cx map_cx)) m_tmap in
    let methods_tmap' =
      if m_tmap == m_tmap' then methods_tmap
      else Context.make_property_map cx m_tmap' in
    if type_args == type_args' && methods_tmap == methods_tmap' && fields_tmap == fields_tmap'
    then i
    else {
      class_id;
      type_args = type_args';
      arg_polarities;
      fields_tmap = fields_tmap';
      initialized_field_names;
      initialized_static_field_names;
      methods_tmap = methods_tmap';
      has_unknown_react_mixins;
      structural;
    }

  method type_param cx map_cx ({reason; name; bound; polarity; default} as t) =
    let bound' = self#type_ cx map_cx bound in
    let default' = OptionUtils.ident_map (self#type_ cx map_cx) default in
    if bound == bound' && default == default' then t
    else
      let bound = bound' in
      let default = default' in
      {reason; name; bound; polarity; default}

  method selector cx map_cx t =
    match t with
      | Prop _ -> t
      | Elem t' ->
          let t'' = self#type_ cx map_cx t' in
          if t'' == t' then t
          else Elem t''
      | ObjRest _
      | ArrRest _
      | Default
      | Become -> t
      | Refine p ->
          let p' = self#predicate cx map_cx p in
          if p' == p then t
          else Refine p'

  method destructor cx map_cx t =
    match t with
      | NonMaybeType
      | PropertyType _ -> t
      | ElementType t' ->
          let t'' = self#type_ cx map_cx t' in
          if t'' == t' then t
          else ElementType t''
      | Bind t' ->
          let t'' = self#type_ cx map_cx t' in
          if t'' == t' then t
          else Bind t''
      | ReadOnlyType -> t
      | SpreadType (options, tlist) ->
          let tlist' = ListUtils.ident_map (self#type_ cx map_cx) tlist in
          if tlist' == tlist then t
          else SpreadType (options, tlist')
      | RestType (options, x) ->
          let x' = self#type_ cx map_cx x in
          if x' == x then t
          else RestType (options, x')
      | ValuesType -> t
      | CallType args ->
          let args' = ListUtils.ident_map (self#type_ cx map_cx) args in
          if args' == args then t
          else CallType args'
      | TypeMap tmap ->
          let tmap' = self#type_map cx map_cx tmap in
          if tmap' == tmap then t
          else TypeMap tmap'
      | ReactElementPropsType
      | ReactElementConfigType
      | ReactElementRefType
        -> t

  method private custom_fun_kind cx map_cx kind =
    match kind with
    | ReactPropType (React.PropType.Primitive (b, t)) ->
      let t' = self#type_ cx map_cx t in
      if t' == t then kind
      else ReactPropType (React.PropType.Primitive (b, t'))
    | ReactElementFactory t ->
      let t' = self#type_ cx map_cx t in
      if t' == t then kind
      else ReactElementFactory t'
    | ObjectAssign
    | ObjectGetPrototypeOf
    | ObjectSetPrototypeOf
    | Compose _
    | ReactPropType _
    | ReactCreateClass
    | ReactCreateElement
    | ReactCloneElement
    | Idx
    | DebugPrint
    | DebugThrow
    | DebugSleep
      -> kind

  method exports cx map_cx id =
    let exps = Context.find_exports cx id in
    let map_loc_type_pair ((loc, t) as orig) =
      let t' = self#type_ cx map_cx t in
      if t == t' then orig else (loc, t')
    in
    let exps' = SMap.ident_map map_loc_type_pair exps in
    if exps == exps' then id
    else Context.make_export_map cx exps'

  method obj_type cx map_cx ({ flags; dict_t; props_tmap; proto_t} as t) =
    let dict_t' = OptionUtils.ident_map (self#dict_type cx map_cx) dict_t in
    let p_tmap = Context.find_props cx props_tmap in
    let p_tmap' = SMap.ident_map (Property.ident_map_t (self#type_ cx map_cx)) p_tmap in
    let props_tmap' = if p_tmap == p_tmap' then props_tmap
          else Context.make_property_map cx p_tmap' in
    let proto_t' = self#type_ cx map_cx proto_t in
    if dict_t' == dict_t && props_tmap' == props_tmap && proto_t' == proto_t then t
    else
      { flags; dict_t = dict_t'; props_tmap = props_tmap'; proto_t = proto_t' }

  method dict_type cx map_cx ({dict_name; key; value; dict_polarity} as t) =
    let key' = self#type_ cx map_cx key in
    let value' = self#type_ cx map_cx value in
    if key' == key && value' == value then t
    else
      let key = key' in
      let value = value' in
      {dict_name; key; value; dict_polarity}

  method arr_type cx map_cx t =
    match t with
    | ArrayAT (t', tlistopt) ->
        let t'' = self#type_ cx map_cx t' in
        let tlistopt' =
          OptionUtils.ident_map (ListUtils.ident_map (self#type_ cx map_cx)) tlistopt in
        if t'' == t' && tlistopt' == tlistopt then t
        else ArrayAT (t'', tlistopt')
    | TupleAT (t', tlist) ->
        let t'' = self#type_ cx map_cx t' in
        let tlist' = ListUtils.ident_map (self#type_ cx map_cx) tlist in
        if t'' == t' && tlist' == tlist then t
        else TupleAT(t'', tlist')
    | ROArrayAT t' ->
        let t'' = self#type_ cx map_cx t' in
        if t'' == t' then t
        else ROArrayAT t''
    | EmptyAT -> t

  method bounds cx map_cx t =
    let open Constraint in
    let lower' = TypeMap.ident_map_key (self#type_ cx map_cx) t.lower in
    if lower' != t.lower then
      t.lower <- lower';
    let upper' = UseTypeMap.ident_map_key (self#use_type cx map_cx) t.upper in
    if upper' != t.upper then
      t.upper <- upper';
    t

  method use_type cx map_cx t =
    match t with
    | UseT (u, t') ->
        let t'' = self#type_ cx map_cx t'; in
        if t'' == t' then t
        else UseT (u, t'')
    | BindT (op, r, funcall, passthrough) ->
        let funcall' = self#fun_call_type cx map_cx funcall in
        if funcall == funcall' then t
        else BindT (op, r, funcall', passthrough)
    | CallT (op, r, funcall) ->
        let funcall' = self#fun_call_type cx map_cx funcall in
        if funcall == funcall' then t
        else CallT (op, r, funcall')
    | MethodT (op, r1, r2, prop, funcall, prop_t) ->
        let prop' = self#prop_ref cx map_cx prop in
        let funcall' = self#fun_call_type cx map_cx funcall in
        let prop_t' = OptionUtils.ident_map (self#type_ cx map_cx) prop_t in
        if prop' == prop && funcall' == funcall && prop_t' == prop_t then t
        else MethodT (op, r1, r2, prop', funcall', prop_t')
    | SetPropT (use_op, r, prop, i, t', prop_t) ->
        let prop' = self#prop_ref cx map_cx prop in
        let t'' = self#type_ cx map_cx t' in
        let prop_t' = OptionUtils.ident_map (self#type_ cx map_cx) prop_t in
        if prop' == prop && t'' == t' && prop_t' == prop_t then t
        else SetPropT (use_op, r, prop', i, t'', prop_t')
    | SetPrivatePropT (use_op, r, prop, scopes, static, t', prop_t) ->
        let t'' = self#type_ cx map_cx t' in
        let scopes' = ListUtils.ident_map (self#class_binding cx map_cx) scopes in
        let prop_t' = OptionUtils.ident_map (self#type_ cx map_cx) prop_t in
        if t'' == t' && scopes' == scopes && prop_t' == prop_t then t
        else SetPrivatePropT (use_op, r, prop, scopes', static, t'', prop_t')
    | GetPropT (use_op, r, prop, t') ->
        let prop' = self#prop_ref cx map_cx prop in
        let t'' = self#type_ cx map_cx t' in
        if prop' == prop && t'' == t' then t
        else GetPropT (use_op, r, prop', t'')
    | GetPrivatePropT (use_op, r, prop, scopes, static, t') ->
        let t'' = self#type_ cx map_cx t' in
        let scopes' = ListUtils.ident_map (self#class_binding cx map_cx) scopes in
        if t'' == t' && scopes' == scopes then t
        else GetPrivatePropT (use_op, r, prop, scopes', static, t'')
    | TestPropT (r, id, prop, t') ->
        let prop' = self#prop_ref cx map_cx prop in
        let t'' = self#type_ cx map_cx t' in
        if prop' == prop && t'' == t' then t
        else TestPropT (r, id, prop', t'')
    | SetElemT (use_op, r, t1, t2, t3) ->
        let t1' = self#type_ cx map_cx t1 in
        let t2' = self#type_ cx map_cx t2 in
        let t3' = OptionUtils.ident_map (self#type_ cx map_cx) t3 in
        if t1' == t1 && t2' == t2 && t3' == t3 then t
        else SetElemT (use_op, r, t1', t2', t3')
    | GetElemT (use_op, r, t1, t2) ->
        let t1' = self#type_ cx map_cx t1 in
        let t2' = self#type_ cx map_cx t2 in
        if t1' == t1 && t2' == t2 then t
        else GetElemT (use_op, r, t1', t2')
    | CallElemT (r1, r2, t', funcall) ->
        let t'' = self#type_ cx map_cx t' in
        let funcall' = self#fun_call_type cx map_cx funcall in
        if t' == t'' && funcall' == funcall then t
        else CallElemT (r1, r2, t'', funcall')
    | GetStaticsT (r, t') ->
        let t'' = self#type_ cx map_cx t' in
        if t'' == t' then t
        else GetStaticsT (r, t'')
    | GetProtoT (r, t') ->
        let t'' = self#type_ cx map_cx t' in
        if t'' == t' then t
        else GetProtoT (r, t'')
    | SetProtoT (r, t') ->
        let t'' = self#type_ cx map_cx t' in
        if t'' == t' then t
        else SetProtoT (r, t'')
    | ReposLowerT (r, use_desc, use) ->
        let use' = self#use_type cx map_cx use in
        if use' == use then t
        else ReposLowerT (r, use_desc, use')
    | ReposUseT (r, use_desc, use_op, t') ->
        let t'' = self#type_ cx map_cx t' in
        if t'' == t' then t
        else ReposUseT (r, use_desc, use_op, t'')
    | ConstructorT (op, r, targs, args, t') ->
        let targs' = OptionUtils.ident_map (ListUtils.ident_map (self#type_ cx map_cx)) targs in
        let args' = ListUtils.ident_map (self#call_arg cx map_cx) args in
        let t'' = self#type_ cx map_cx t' in
        if targs' == targs && args' == args && t'' == t' then t
        else ConstructorT (op, r, targs', args', t'')
    | SuperT (op, r, DerivedInstance i) ->
        let i' = self#inst_type cx map_cx i in
        if i' == i then t
        else SuperT (op, r, DerivedInstance i')
    | SuperT (op, r, DerivedStatics o) ->
        let o' = self#obj_type cx map_cx o in
        if o' == o then t
        else SuperT (op, r, DerivedStatics o')
    | ImplementsT (use_op, t') ->
        let t'' = self#type_ cx map_cx t' in
        if t'' == t' then t
        else ImplementsT (use_op, t'')
    | MixinT (r, t') ->
        let t'' = self#type_ cx map_cx t' in
        if t'' == t' then t
        else MixinT (r, t'')
    | ToStringT (r, t') ->
        let t'' = self#use_type cx map_cx t' in
        if t'' == t' then t
        else ToStringT (r, t'')
    | AdderT (op, r, flip, t1, t2) ->
        let t1' = self#type_ cx map_cx t1 in
        let t2' = self#type_ cx map_cx t2 in
        if t1' == t1 && t2' == t2 then t
        else AdderT (op, r, flip, t1', t2')
    | ComparatorT (r, flip, t') ->
        let t'' = self#type_ cx map_cx t' in
        if t'' == t' then t
        else ComparatorT (r, flip, t'')
    | UnaryMinusT (r, t') ->
        let t'' = self#type_ cx map_cx t' in
        if t'' == t' then t
        else UnaryMinusT (r, t'')
    | AssertArithmeticOperandT _
    | AssertBinaryInLHST _
    | AssertBinaryInRHST _
    | AssertForInRHST _
    | AssertRestParamT _ -> t
    | PredicateT (p, t') ->
        let p' = self#predicate cx map_cx p in
        let t'' = self#type_ cx map_cx t' in
        if p' == p && t'' == t' then t
        else PredicateT (p', t'')
    | GuardT (p, t1, t2) ->
        let p' = self#predicate cx map_cx p in
        let t1' = self#type_ cx map_cx t1 in
        let t2' = self#type_ cx map_cx t2 in
        if p' == p && t1' == t1 && t2' == t2 then t
        else GuardT (p', t1', t2')
    | EqT (r, flip, t') ->
        let t'' = self#type_ cx map_cx t' in
        if t'' == t' then t
        else EqT (r, flip, t'')
    | AndT (r, t1, t2) ->
        let t1' = self#type_ cx map_cx t1 in
        let t2' = self#type_ cx map_cx t2 in
        if t1' == t1 && t2' == t2 then t
        else AndT (r, t1', t2')
    | OrT (r, t1, t2) ->
        let t1' = self#type_ cx map_cx t1 in
        let t2' = self#type_ cx map_cx t2 in
        if t1' == t1 && t2' == t2 then t
        else OrT (r, t1', t2')
    | NullishCoalesceT (r, t1, t2) ->
        let t1' = self#type_ cx map_cx t1 in
        let t2' = self#type_ cx map_cx t2 in
        if t1' == t1 && t2' == t2 then t
        else NullishCoalesceT (r, t1', t2')
    | NotT (r, t') ->
        let t'' = self#type_ cx map_cx t' in
        if t'' == t' then t
        else NotT (r, t'')
    | SpecializeT (u, r1, r2, cache, tlist_opt, t') ->
        let tlist_opt' = OptionUtils.ident_map (ListUtils.ident_map (self#type_ cx map_cx)) tlist_opt in
        let t'' = self#type_ cx map_cx t' in
        if tlist_opt' == tlist_opt && t'' == t' then t
        else SpecializeT (u, r1, r2, cache, tlist_opt', t'')
    | ThisSpecializeT (r, t1, t2) ->
        let t1' = self#type_ cx map_cx t1 in
        let t2' = self#type_ cx map_cx t2 in
        if t1' == t1 && t2' == t2 then t
        else ThisSpecializeT (r, t1', t2')
    | VarianceCheckT (r, tlist, p) ->
        let tlist' = ListUtils.ident_map (self#type_ cx map_cx) tlist in
        if tlist' == tlist then t
        else VarianceCheckT (r, tlist', p)
    | TypeAppVarianceCheckT (use_op, r1, r2, tpairlist) ->
        let tpairlist' = ListUtils.ident_map (fun ((x,y) as z) ->
          let x' = self#type_ cx map_cx x in
          let y' = self#type_ cx map_cx y in
          if x' == x && y' == y then z
          else (x', y'))
          tpairlist in
        if tpairlist' == tpairlist then t
        else TypeAppVarianceCheckT (use_op, r1, r2, tpairlist')
    | ConcretizeTypeAppsT (use_op, (ts1, op1, r1), (t2, ts2, op2, r2), flip) ->
        let ts1' = ListUtils.ident_map (self#type_ cx map_cx) ts1 in
        let t2' = self#type_ cx map_cx t2 in
        let ts2' = ListUtils.ident_map (self#type_ cx map_cx) ts2 in
        if ts1' == ts1 && t2' == t2 && ts2' == ts2 then t
        else ConcretizeTypeAppsT (use_op, (ts1', op1, r1), (t2', ts2', op2, r2), flip)
    | LookupT (r, lookup, tlist, prop, action) ->
        let lookup' = self#lookup_kind cx map_cx lookup in
        let tlist' = ListUtils.ident_map (self#type_ cx map_cx) tlist in
        let prop' = self#prop_ref cx map_cx prop in
        let action' = self#lookup_action cx map_cx action in
        if lookup' == lookup && tlist' == tlist && prop' == prop && action' == action then t
        else LookupT (r, lookup', tlist', prop', action')
    | ObjAssignToT (r, t1, t2, obj_assign) ->
        let t1' = self#type_ cx map_cx t1 in
        let t2' = self#type_ cx map_cx t2 in
        if t1' == t1 && t2' == t2 then t
        else ObjAssignToT (r, t1', t2', obj_assign)
    | ObjAssignFromT (r, t1, t2, obj_assign) ->
        let t1' = self#type_ cx map_cx t1 in
        let t2' = self#type_ cx map_cx t2 in
        if t1' == t1 && t2' == t2 then t
        else ObjAssignFromT (r, t1', t2', obj_assign)
    | ObjFreezeT (r, t') ->
        let t'' = self#type_ cx map_cx t' in
        if t'' == t' then t
        else ObjFreezeT (r, t'')
    | ObjRestT (r, strings, t') ->
        let t'' = self#type_ cx map_cx t' in
        if t'' == t' then t
        else ObjRestT (r, strings, t'')
    | ObjSealT (r, t') ->
        let t'' = self#type_ cx map_cx t' in
        if t'' == t' then t
        else ObjSealT (r, t'')
    | ObjTestT (r, t1, t2) ->
        let t1' = self#type_ cx map_cx t1 in
        let t2' = self#type_ cx map_cx t2 in
        if t1' == t1 && t2' == t2 then t
        else ObjTestT (r, t1', t2')
    | ObjTestProtoT (r, t') ->
        let t'' = self#type_ cx map_cx t' in
        if t'' == t' then t
        else ObjTestProtoT (r, t'')
    | ArrRestT (op, r, i, t') ->
        let t'' = self#type_ cx map_cx t' in
        if t'' == t' then t
        else ArrRestT (op, r, i, t'')
    | UnifyT (t1, t2) ->
        let t1' = self#type_ cx map_cx t1 in
        let t2' = self#type_ cx map_cx t2 in
        if t1' == t1 && t2' == t2 then t
        else UnifyT (t1', t2')
    | BecomeT (r, t') ->
        let t'' = self#type_ cx map_cx t' in
        if t'' == t' then t
        else BecomeT (r, t'')
    | GetKeysT (r, t') ->
        let t'' = self#use_type cx map_cx t' in
        if t'' == t' then t
        else GetKeysT (r, t'')
    | HasOwnPropT _ -> t
    | GetValuesT (r, t') ->
        let t'' = self#type_ cx map_cx t' in
        if t'' == t' then t
        else GetValuesT (r, t'')
    | ElemT (use_op, r, t', action) ->
        let t'' = self#type_ cx map_cx t' in
        let action' = self#elem_action cx map_cx action in
        if t'' == t' && action' == action then t
        else ElemT (use_op, r, t'', action')
    | MakeExactT (r, cont) ->
        let cont' = self#cont cx map_cx cont in
        if cont' == cont then t
        else MakeExactT (r, cont')
    | CJSRequireT (r, t', is_strict) ->
        let t'' = self#type_ cx map_cx t' in
        if t'' == t' then t
        else CJSRequireT (r, t'', is_strict)
    | ImportModuleNsT (r, t', is_strict) ->
        let t'' = self#type_ cx map_cx t' in
        if t'' == t' then t
        else ImportModuleNsT (r, t'', is_strict)
    | ImportDefaultT (r, import, s, t', is_strict) ->
        let t'' = self#type_ cx map_cx t' in
        if t'' == t' then t
        else ImportDefaultT (r, import, s, t'', is_strict)
    | ImportNamedT (r, import, s, m, t', is_strict) ->
        let t'' = self#type_ cx map_cx t' in
        if t'' == t' then t
        else ImportNamedT (r, import, s, m, t'', is_strict)
    | ImportTypeT (r, s, t') ->
        let t'' = self#type_ cx map_cx t' in
        if t'' == t' then t
        else ImportTypeT (r, s, t'')
    | ImportTypeofT (r, s, t') ->
        let t'' = self#type_ cx map_cx t' in
        if t'' == t' then t
        else ImportTypeofT (r, s, t'')
    | AssertImportIsValueT _ -> t
    | CJSExtractNamedExportsT (r1, (r2, exports, is_strict), t') ->
        let exports' = self#export_types cx map_cx exports in
        let t'' = self#type_ cx map_cx t' in
        if exports' == exports && t'' == t' then t
        else CJSExtractNamedExportsT (r1, (r2, exports', is_strict), t'')
    | CopyNamedExportsT (r, t1, t2) ->
        let t1' = self#type_ cx map_cx t1 in
        let t2' = self#type_ cx map_cx t2 in
        if t1' == t1 && t2' == t2 then t
        else CopyNamedExportsT (r, t1', t2')
    | CopyTypeExportsT (r, t1, t2) ->
        let t1' = self#type_ cx map_cx t1 in
        let t2' = self#type_ cx map_cx t2 in
        if t1' == t1 && t2' == t2 then t
        else CopyTypeExportsT (r, t1', t2')
    | ExportNamedT (r, skip, tmap, t') ->
        let map_loc_type_pair ((loc, t) as orig) =
          let t' = self#type_ cx map_cx t in
          if t == t' then orig else (loc, t')
        in
        let tmap' = SMap.ident_map map_loc_type_pair tmap in
        let t'' = self#type_ cx map_cx t' in
        if tmap' == tmap && t'' == t' then t
        else ExportNamedT (r, skip, tmap', t'')
    | ExportTypeT (r, skip, name, t1, t2) ->
        let t1' = self#type_ cx map_cx t1 in
        let t2' = self#type_ cx map_cx t2 in
        if t1' == t1 && t2' == t2 then t
        else ExportTypeT (r, skip, name, t1', t2')
    | MapTypeT (r, tmap, t') ->
        let tmap' = self#type_map cx map_cx tmap in
        let t'' = self#type_ cx map_cx t' in
        if tmap' == tmap && t'' == t' then t
        else MapTypeT (r, tmap', t'')
    | ReactKitT (use_op, r, react_tool) ->
        let react_tool' = self#react_tool cx map_cx react_tool in
        if react_tool' == react_tool then t
        else ReactKitT (use_op, r, react_tool')
    | ObjKitT (use_op, r, resolve_tool, tool, tout) ->
        let resolve_tool' = self#object_kit_resolve_tool cx map_cx resolve_tool in
        let tool' = self#object_kit_tool cx map_cx tool in
        let tout' = self#type_ cx map_cx tout in
        if resolve_tool' == resolve_tool && tool' == tool && tout' == tout then t
        else ObjKitT (use_op, r, resolve_tool', tool', tout')
    | ChoiceKitUseT (r, choice_use_tool) ->
        let choice_use_tool' = self#choice_use_tool cx map_cx choice_use_tool in
        if choice_use_tool' == choice_use_tool then t
        else ChoiceKitUseT (r, choice_use_tool')
    | IntersectionPreprocessKitT (r, ipt) ->
        let ipt' = self#intersection_preprocess_tool cx map_cx ipt in
        if ipt' == ipt then t
        else IntersectionPreprocessKitT (r, ipt')
    | DebugPrintT _ -> t
    | DebugSleepT _ -> t
    | SentinelPropTestT (r, t1, key, b, sentinel, t2) ->
        let t1' = self#type_ cx map_cx t1 in
        let t2' = self#type_ cx map_cx t2 in
        if t1' == t1 && t2' == t2 then t
        else SentinelPropTestT (r, t1', key, b, sentinel, t2')
    | IdxUnwrap (r, t') ->
        let t'' = self#type_ cx map_cx t' in
        if t'' == t' then t
        else IdxUnwrap (r, t'')
    | IdxUnMaybeifyT (r, t') ->
        let t'' = self#type_ cx map_cx t' in
        if t'' == t' then t
        else IdxUnMaybeifyT (r, t'')
    | OptionalChainT (r, uses) ->
        let uses' = Nel.map (fun (use, tout) ->
          self#opt_use_type cx map_cx use,
          self#type_ cx map_cx tout
        ) uses in
        if uses' == uses then t
        else OptionalChainT (r, uses')
    | CallLatentPredT (r, b, i, t1, t2) ->
        let t1' = self#type_ cx map_cx t1 in
        let t2' = self#type_ cx map_cx t2 in
        if t1' == t1 && t2' == t2 then t
        else CallLatentPredT (r, b, i, t1', t2')
    | CallOpenPredT (r, b, key, t1, t2) ->
        let t1' = self#type_ cx map_cx t1 in
        let t2' = self#type_ cx map_cx t2 in
        if t1' == t1 && t2' == t2 then t
        else CallOpenPredT (r, b, key, t1', t2')
    | SubstOnPredT (r, sub, t') ->
        let t'' = self#type_ cx map_cx t' in
        if t'' == t' then t
        else SubstOnPredT (r, sub, t'')
    | RefineT (r, p, t') ->
        let p' = self#predicate cx map_cx p in
        let t'' = self#type_ cx map_cx t' in
        if p' == p && t'' == t' then t
        else RefineT (r, p', t'')
    | ResolveSpreadT (op, r, resolve_spread) ->
        let resolve_spread' = self#resolve_spread cx map_cx resolve_spread in
        if resolve_spread' == resolve_spread then t
        else ResolveSpreadT (op, r, resolve_spread')
    | CondT (r, alt, tout) ->
        let alt' = self#type_ cx map_cx alt in
        let tout' = self#type_ cx map_cx tout in
        if alt' == alt && tout' == tout then t
        else CondT (r, alt', tout')
    | ExtendsUseT (use_op, r, tlist, t1, t2) ->
      let tlist' = ListUtils.ident_map (self#type_ cx map_cx) tlist in
      let t1' = self#type_ cx map_cx t1 in
      let t2' = self#type_ cx map_cx t2 in
      if tlist' == tlist && t1' == t1 && t2' == t2 then t
      else ExtendsUseT (use_op, r, tlist', t1', t2')

  method private opt_use_type cx map_cx t = match t with
  | OptCallT (op, r, funcall) ->
    let funcall' = self#opt_fun_call_type cx map_cx funcall in
    if funcall == funcall' then t
    else OptCallT (op, r, funcall')
  | OptGetPropT (use_op, r, prop) ->
    let prop' = self#prop_ref cx map_cx prop in
    if prop' == prop then t
    else OptGetPropT (use_op, r, prop')
  | OptGetPrivatePropT (use_op, r, prop, scopes, static) ->
    let scopes' = ListUtils.ident_map (self#class_binding cx map_cx) scopes in
    if scopes' == scopes then t
    else OptGetPrivatePropT (use_op, r, prop, scopes', static)
  | OptTestPropT (r, id, prop) ->
    let prop' = self#prop_ref cx map_cx prop in
    if prop' == prop then t
    else OptTestPropT (r, id, prop')
  | OptGetElemT (use_op, r, t') ->
    let t'' = self#type_ cx map_cx t' in
    if t'' == t' then t
    else OptGetElemT (use_op, r, t'')

  method fun_call_type cx map_cx t =
    let  {
      call_this_t;
      call_targs;
      call_args_tlist;
      call_tout;
      call_closure_t;
      call_strict_arity;
    } = t in
    let call_this_t' = self#type_ cx map_cx call_this_t in
    let call_targs' = OptionUtils.ident_map (ListUtils.ident_map (self#type_ cx map_cx)) call_targs in
    let call_args_tlist' = ListUtils.ident_map (self#call_arg cx map_cx) call_args_tlist in
    let call_tout' = self#type_ cx map_cx call_tout in
    if (
      call_this_t' == call_this_t &&
      call_targs' == call_targs &&
      call_args_tlist' == call_args_tlist &&
      call_tout' == call_tout
    )
    then t
    else {
      call_this_t = call_this_t';
      call_targs = call_targs';
      call_args_tlist = call_args_tlist';
      call_tout = call_tout';
      call_closure_t;
      call_strict_arity;
    }

  method private opt_fun_call_type cx map_cx ((this, targs, args, clos, strict) as t) =
    let this' = self#type_ cx map_cx this in
    let targs' = OptionUtils.ident_map (ListUtils.ident_map (self#type_ cx map_cx)) targs in
    let args' = ListUtils.ident_map (self#call_arg cx map_cx) args in
    if this' == this && targs' == targs && args' == args
    then t
    else (this', targs', args', clos, strict)

  method prop_ref cx map_cx t =
    match t with
    | Named _ -> t
    | Computed t' ->
        let t'' = self#type_ cx map_cx t' in
        if t'' == t' then t
        else Computed t''

  method call_arg cx map_cx t =
    match t with
    | Arg t' ->
        let t'' = self#type_ cx map_cx t' in
        if t'' == t' then t
        else Arg t''
    | SpreadArg t' ->
        let t'' = self#type_ cx map_cx t' in
        if t'' == t' then t
        else SpreadArg t''

  method predicate cx map_cx p =
    match p with
    | AndP (p1, p2) ->
        let p1' = self#predicate cx map_cx p1 in
        let p2' = self#predicate cx map_cx p2 in
        if p1' == p1 && p2' == p2 then p
        else AndP (p1', p2')
    | OrP (p1, p2) ->
        let p1' = self#predicate cx map_cx p1 in
        let p2' = self#predicate cx map_cx p2 in
        if p1' == p1 && p2' == p2 then p
        else OrP (p1', p2')
    | NotP p' ->
        let p'' = self#predicate cx map_cx p' in
        if p'' == p' then p
        else NotP p''
    | LeftP (test, t) ->
        let t' = self#type_ cx map_cx t in
        if t' == t then p
        else LeftP (test, t')
    | RightP (test, t) ->
        let t' = self#type_ cx map_cx t in
        if t' == t then p
        else RightP (test, t')
    | ExistsP _
    | NullP
    | MaybeP
    | SingletonBoolP _
    | SingletonStrP _
    | SingletonNumP _
    | BoolP
    | FunP
    | NumP
    | ObjP
    | StrP
    | VoidP
    | ArrP
    | PropExistsP _ -> p
    | LatentP (t, i) ->
        let t' = self#type_ cx map_cx t in
        if t' == t then p
        else LatentP (t', i)

  method lookup_kind cx map_cx t =
    match t with
    | Strict _ -> t
    | NonstrictReturning (tpairopt, testopt) ->
        begin match tpairopt with
        | Some (t1, t2) ->
            let t1' = self#type_ cx map_cx t1 in
            let t2' = self#type_ cx map_cx t2 in
            if t1' == t1 && t2' == t2 then t
            else NonstrictReturning (Some (t1', t2'), testopt)
        | None -> t
        end
    | ShadowRead (r, pidlist) ->
        let pidlist' = Nel.ident_map (fun property_id ->
          let tmap = Context.find_props cx property_id in
          let tmap' = SMap.ident_map (Property.ident_map_t (self#type_ cx map_cx)) tmap in
          if tmap' == tmap then property_id
          else Context.make_property_map cx tmap'
        ) pidlist in
        if pidlist == pidlist' then t
        else ShadowRead (r, pidlist')
    | ShadowWrite pidlist ->
        let pidlist' = Nel.ident_map (fun property_id ->
          let tmap = Context.find_props cx property_id in
          let tmap' = SMap.ident_map (Property.ident_map_t (self#type_ cx map_cx)) tmap in
          if tmap' == tmap then property_id
          else Context.make_property_map cx tmap'
        ) pidlist in
        if pidlist == pidlist' then t
        else ShadowWrite pidlist'

  method lookup_action cx map_cx t =
    match t with
    | RWProp (use_op, t1, t2, rw) ->
        let t1' = self#type_ cx map_cx t1 in
        let t2' = self#type_ cx map_cx t2 in
        let rw' = self#read_write cx map_cx rw in
        if t1' == t1 && t2' == t2 && rw' == rw then t
        else RWProp (use_op, t1', t2', rw')
    | LookupProp (use, prop) ->
        let prop' = Property.ident_map_t (self#type_ cx map_cx) prop in
        if prop == prop' then t
        else LookupProp (use, prop')
    | SuperProp (op, prop) ->
        let prop' = Property.ident_map_t (self#type_ cx map_cx) prop in
        if prop == prop' then t
        else SuperProp (op, prop')
    | MatchProp t' ->
      let t'' = self#type_ cx map_cx t' in
      if t'' == t' then t
      else MatchProp t'

  method private read_write cx map_cx rw =
    match rw with
    | Read -> rw
    | Write (wr_ctx, prop_t) ->
      let prop_t' = OptionUtils.ident_map (self#type_ cx map_cx) prop_t in
      if prop_t' == prop_t then rw
      else Write (wr_ctx, prop_t')

  method elem_action cx map_cx t =
    match t with
    | ReadElem t' ->
        let t'' = self#type_ cx map_cx t' in
        if t'' == t' then t
        else ReadElem t''
    | WriteElem (tin, tout) ->
        let tin' = self#type_ cx map_cx tin in
        let tout' = OptionUtils.ident_map (self#type_ cx map_cx) tout in
        if tin' == tin && tout' == tout then t
        else WriteElem (tin', tout')
    | CallElem (r, funcall) ->
        let funcall' = self#fun_call_type cx map_cx funcall in
        if funcall' == funcall then t
        else CallElem (r, funcall')

  method cont cx map_cx t =
    match t with
    | Lower (use_op, t') ->
        let t'' = self#type_ cx map_cx t' in
        if t'' == t' then t
        else Lower (use_op, t'')
    | Upper use_t ->
        let use_t' = self#use_type cx map_cx use_t in
        if use_t' == use_t then t
        else Upper use_t'

  method type_map cx map_cx t =
    match t with
    | TupleMap t' ->
      let t'' = self#type_ cx map_cx t' in
      if t'' == t' then t
      else TupleMap t''
    | ObjectMap t' ->
      let t'' = self#type_ cx map_cx t' in
      if t'' == t' then t
      else ObjectMap t''
    | ObjectMapi t' ->
      let t'' = self#type_ cx map_cx t' in
      if t'' == t' then t
      else ObjectMapi t''

  method react_tool cx map_cx t =
    let open React in
    match t with
    | CreateElement0 (clone, config, (children, children_spread), tout) ->
      let config' = self#type_ cx map_cx config in
      let children' = ListUtils.ident_map (self#type_ cx map_cx) children in
      let children_spread' = OptionUtils.ident_map (self#type_ cx map_cx) children_spread in
      let tout' = self#type_ cx map_cx tout in
      if (
        config' == config &&
        children' == children &&
        children_spread' == children_spread &&
        tout' == tout
      ) then t else CreateElement0 (clone, config', (children', children_spread'), tout')
    | CreateElement (clone, component, config, (children, children_spread), tout) ->
      let component' = self#type_ cx map_cx component in
      let config' = self#type_ cx map_cx config in
      let children' = ListUtils.ident_map (self#type_ cx map_cx) children in
      let children_spread' = OptionUtils.ident_map (self#type_ cx map_cx) children_spread in
      let tout' = self#type_ cx map_cx tout in
      if (
        component' == component &&
        config' == config &&
        children' == children &&
        children_spread' == children_spread &&
        tout' == tout
      ) then t else CreateElement (clone, component', config', (children', children_spread'), tout')
    | GetProps tout ->
      let tout' = self#type_ cx map_cx tout in
      if tout' == tout then t
      else GetProps tout'
    | GetConfig tout ->
      let tout' = self#type_ cx map_cx tout in
      if tout' == tout then t
      else GetConfig tout'
    | GetRef tout ->
      let tout' = self#type_ cx map_cx tout in
      if tout' == tout then t
      else GetRef tout'
    | SimplifyPropType (tool, t') ->
        let tool' = self#simplify_prop_type_tool cx map_cx tool in
        let t'' = self#type_ cx map_cx t' in
        if tool' == tool && t'' == t' then t
        else SimplifyPropType (tool', t'')
    | CreateClass (tool, knot, t') ->
        let tool' = self#create_class_tool cx map_cx tool in
        let knot' = self#create_class_knot cx map_cx knot in
        let t'' = self#type_ cx map_cx t' in
        if tool' == tool && knot' == knot && t'' == t' then t
        else CreateClass (tool', knot', t'')

  method object_kit_resolve_tool cx map_cx t =
    let open Object in
    match t with
    | Resolve r ->
        let r' = self#resolve cx map_cx r in
        if r' == r then t
        else Resolve r'
    | Super ((reason, props, dict, flags), r) ->
        let props' = SMap.ident_map (fun (t, b) -> (self#type_ cx map_cx t, b)) props in
        let dict' = OptionUtils.ident_map (self#dict_type cx map_cx) dict in
        let r' = self#resolve cx map_cx r in
        if r' == r && props' == props then t
        else Super ((reason, props', dict', flags), r')

  method object_kit_tool cx map_cx tool =
    let open Object in
    match tool with
    | ReadOnly -> tool
    | Spread (options, state) ->
      let open Object.Spread in
      let todo_rev' = ListUtils.ident_map (self#type_ cx map_cx) state.todo_rev in
      let acc' = ListUtils.ident_map (self#resolved cx map_cx) state.acc in
      if todo_rev' == state.todo_rev && acc' == state.acc then tool
      else Spread (options, {todo_rev = todo_rev'; acc = acc'})
    | Rest (options, state) ->
      let open Object.Rest in
      let state' = match state with
        | One t ->
          let t' = self#type_ cx map_cx t in
          if t == t' then state
          else One t'
        | Done o ->
          let o' = self#resolved cx map_cx o in
          if o == o' then state
          else Done o'
      in
      if state == state' then tool
      else Rest (options, state')
    | ReactConfig state ->
      let open Object.ReactConfig in
      let state' = match state with
        | Config { defaults; children } ->
          let defaults' = OptionUtils.ident_map (self#type_ cx map_cx) defaults in
          let children' = OptionUtils.ident_map (self#type_ cx map_cx) children in
          if defaults == defaults' && children == children' then state
          else Config { defaults = defaults'; children = children' }
        | Defaults { config; children } ->
          let config' = self#resolved cx map_cx config in
          let children' = OptionUtils.ident_map (self#type_ cx map_cx) children in
          if config == config' && children == children' then state
          else Defaults { config = config'; children = children' }
      in
      if state == state' then tool
      else ReactConfig state'

  method intersection_preprocess_tool cx map_cx t =
    match t with
    | ConcretizeTypes (tlist1, tlist2, t', use_t) ->
        let tlist1' = ListUtils.ident_map (self#type_ cx map_cx) tlist1 in
        let tlist2' = ListUtils.ident_map (self#type_ cx map_cx) tlist2 in
        let t'' = self#type_ cx map_cx t' in
        let use_t' = self#use_type cx map_cx use_t in
        if tlist1' == tlist1 && tlist2' == tlist2 && t'' == t' && use_t' == use_t then t
        else ConcretizeTypes (tlist1', tlist2', t'', use_t')
    | SentinelPropTest (b, s, t1, t2, t3) ->
        let t1' = self#type_ cx map_cx t1 in
        let t2' = self#type_ cx map_cx t2 in
        let t3' = self#type_ cx map_cx t3 in
        if t1' == t1 && t2' == t2 && t3' == t3 then t
        else SentinelPropTest (b, s, t1', t2', t3')
    | PropExistsTest (b, s, t1, t2) ->
        let t1' = self#type_ cx map_cx t1 in
        let t2' = self#type_ cx map_cx t2 in
        if t1' == t2 && t2' == t2 then t
        else PropExistsTest (b, s, t1', t2')

  method choice_use_tool cx map_cx t =
    match t with
    | FullyResolveType _ -> t
    | TryFlow (i, spec) ->
        let spec' = self#spec cx map_cx spec in
        if spec' == spec then t
        else TryFlow (i, spec')

  method resolve_spread cx map_cx ({rrt_resolved; rrt_unresolved; rrt_resolve_to} as t)=
    let rrt_resolved' = ListUtils.ident_map (self#resolved_param cx map_cx) rrt_resolved in
    let rrt_unresolved' = ListUtils.ident_map (self#unresolved_param cx map_cx) rrt_unresolved in
    let rrt_resolve_to' = self#spread_resolve cx map_cx rrt_resolve_to in
    if rrt_resolved' == rrt_resolved && rrt_unresolved' == rrt_unresolved
      && rrt_resolve_to' == rrt_resolve_to
    then t
    else {rrt_resolved = rrt_resolved'; rrt_unresolved = rrt_unresolved';
      rrt_resolve_to = rrt_resolve_to'}

  method simplify_prop_type_tool cx map_cx tool =
    let open React.SimplifyPropType in
    match tool with
    | ArrayOf
    | InstanceOf
    | ObjectOf -> tool
    | OneOf resolve_array ->
        let resolve_array' = self#resolve_array cx map_cx resolve_array in
        if resolve_array' == resolve_array then tool
        else OneOf resolve_array'
    | OneOfType resolve_array ->
        let resolve_array' = self#resolve_array cx map_cx resolve_array in
        if resolve_array' == resolve_array then tool
        else OneOfType resolve_array'
    | Shape resolve_object ->
        let resolve_object' = self#resolve_object cx map_cx resolve_object in
        if resolve_object' == resolve_object then tool
        else Shape resolve_object'

  method create_class_tool cx map_cx tool =
    let open React.CreateClass in
    match tool with
    | Spec tail ->
        let tail' = self#stack_tail cx map_cx tail in
        if tail' == tail then tool
        else Spec tail'
    | Mixins (head, tail) ->
        let head' = self#stack_head cx map_cx head in
        let tail' = self#stack_tail cx map_cx tail in
        if head' == head && tail' == tail then tool
        else Mixins (head', tail')
    | Statics (head, tail) ->
        let head' = self#stack_head cx map_cx head in
        let tail' = self#stack_tail cx map_cx tail in
        if head' == head && tail' == tail then tool
        else Statics (head', tail')
    | PropTypes ((head, tail), resolve_object) ->
        let head' = self#stack_head cx map_cx head in
        let tail' = self#stack_tail cx map_cx tail in
        let resolve_object' = self#resolve_object cx map_cx resolve_object in
        if head' == head && tail' == tail && resolve_object' == resolve_object then tool
        else PropTypes ((head', tail'), resolve_object')
    | DefaultProps (tlist, default_props) ->
        let tlist' = ListUtils.ident_map (self#type_ cx map_cx) tlist in
        let default_props' = OptionUtils.ident_map (self#default_props cx map_cx) default_props in
        if tlist' == tlist && default_props' == default_props then tool
        else DefaultProps (tlist', default_props')
    | InitialState (tlist, initial_state) ->
        let tlist' = ListUtils.ident_map (self#type_ cx map_cx) tlist in
        let initial_state' = OptionUtils.ident_map (self#initial_state cx map_cx) initial_state in
        if tlist' == tlist && initial_state' == initial_state then tool
        else InitialState (tlist', initial_state')

  method create_class_knot cx map_cx t =
    let open React.CreateClass in
    let this' = self#type_ cx map_cx t.this in
    let static' = self#type_ cx map_cx t.static in
    let state_t' = self#type_ cx map_cx t.state_t in
    let default_t' = self#type_ cx map_cx t.default_t in
    if this' == t.this && static' == t.static && state_t' == t.state_t
      && default_t' == t.default_t
    then t
    else {this = this'; static = static'; state_t = state_t'; default_t = default_t'}

  method resolve cx map_cx t =
    let open Object in
    match t with
    | Next -> t
    | List0 (tnelist, join) ->
        let tnelist' = Nel.ident_map (self#type_ cx map_cx) tnelist in
        if tnelist' == tnelist then t
        else List0 (tnelist', join)
    | List (tlist, resolvednelist, join) ->
        let tlist' = ListUtils.ident_map (self#type_ cx map_cx) tlist in
        let resolvednelist' = Nel.ident_map (self#resolved cx map_cx) resolvednelist in
        if tlist' == tlist && resolvednelist' == resolvednelist then t
        else List (tlist', resolvednelist', join)

  method resolved_prop cx map_cx ((t, own) as prop) =
    let t' = self#type_ cx map_cx t in
    if t' == t then prop
    else (t', own)

  method resolved cx map_cx t =
    let t' = Nel.ident_map (fun ((r, props, dict, flags) as slice) ->
      let props' = SMap.ident_map (self#resolved_prop cx map_cx) props in
      let dict' = OptionUtils.ident_map (self#dict_type cx map_cx) dict in
      if props' == props && dict' == dict then slice
      else (r, props', dict', flags)) t in
    if t' == t then t
    else t'

  method spec cx map_cx t =
    match t with
    | UnionCases (use_op, t', rep, tlist) ->
        let t'' = self#type_ cx map_cx t' in
        let tlist' = ListUtils.ident_map (self#type_ cx map_cx) tlist in
        if t'' == t' && tlist' == tlist then t
        else UnionCases (use_op, t'', rep, tlist')
    | IntersectionCases (tlist, use_t) ->
        let tlist' = ListUtils.ident_map (self#type_ cx map_cx) tlist in
        let use_t' = self#use_type cx map_cx use_t in
        if tlist' == tlist && use_t' == use_t then t
        else IntersectionCases (tlist', use_t')

  method resolved_param cx map_cx t =
    match t with
    | ResolvedArg t' ->
        let t'' = self#type_ cx map_cx t' in
        if t'' == t' then t
        else ResolvedArg t''
    | ResolvedSpreadArg (r, arrtype) ->
        let arrtype' = self#arr_type cx map_cx arrtype in
        if arrtype' == arrtype then t
        else ResolvedSpreadArg (r, arrtype')
    | ResolvedAnySpreadArg _ -> t


  method unresolved_param cx map_cx t =
    match t with
    | UnresolvedArg t' ->
        let t'' = self#type_ cx map_cx t' in
        if t'' == t' then t
        else UnresolvedArg t''
    | UnresolvedSpreadArg t' ->
        let t'' = self#type_ cx map_cx t' in
        if t'' == t' then t
        else UnresolvedSpreadArg t''

  method spread_resolve cx map_cx t =
    match t with
    | ResolveSpreadsToTuple (i, t1', t2') ->
        let t1'' = self#type_ cx map_cx t1' in
        let t2'' = self#type_ cx map_cx t2' in
        if t1'' == t1' && t2'' == t2' then t
        else ResolveSpreadsToTuple (i, t1'', t2'')
    | ResolveSpreadsToArrayLiteral (i, t1', t2') ->
        let t1'' = self#type_ cx map_cx t1' in
        let t2'' = self#type_ cx map_cx t2' in
        if t1'' == t1' && t2'' == t2' then t
        else ResolveSpreadsToArrayLiteral (i, t1'', t2'')
    | ResolveSpreadsToArray (t1', t2') ->
        let t1'' = self#type_ cx map_cx t1' in
        let t2'' = self#type_ cx map_cx t2' in
        if t1'' == t1' && t2'' == t2' then t
        else ResolveSpreadsToArray (t1'', t2'')
    | ResolveSpreadsToMultiflowCallFull (i, funtype) ->
        let funtype' = self#fun_type cx map_cx funtype in
        if funtype' == funtype then t
        else ResolveSpreadsToMultiflowCallFull (i, funtype')
    | ResolveSpreadsToMultiflowSubtypeFull (i, funtype) ->
        let funtype' = self#fun_type cx map_cx funtype in
        if funtype' == funtype then t
        else ResolveSpreadsToMultiflowSubtypeFull (i, funtype')
    | ResolveSpreadsToCustomFunCall (i, kind, tout) ->
        let tout' = self#type_ cx map_cx tout in
        if tout' == tout then t
        else ResolveSpreadsToCustomFunCall (i, kind, tout')
    | ResolveSpreadsToMultiflowPartial (i, funtype, r, t') ->
        let funtype' = self#fun_type cx map_cx funtype in
        let t'' = self#type_ cx map_cx t' in
        if funtype' == funtype && t'' == t' then t
        else ResolveSpreadsToMultiflowPartial (i, funtype', r, t'')
    | ResolveSpreadsToCallT (funcalltype, t') ->
        let funcalltype' = self#fun_call_type cx map_cx funcalltype in
        let t'' = self#type_ cx map_cx t' in
        if funcalltype' == funcalltype && t'' == t' then t
        else ResolveSpreadsToCallT (funcalltype', t'')

  method resolve_array cx map_cx t =
    let open React in
    match t with
    | ResolveArray -> t
    | ResolveElem (tlist1, tlist2) ->
        let tlist1' = ListUtils.ident_map (self#type_ cx map_cx) tlist1 in
        let tlist2' = ListUtils.ident_map (self#type_ cx map_cx) tlist2 in
        if tlist1' == tlist1 && tlist2' == tlist2 then t
        else ResolveElem (tlist1', tlist2')

  method resolve_object cx map_cx t =
    let open React in
    match t with
    | ResolveObject -> t
    | ResolveDict (dict, props, obj) ->
        let dict' = self#dict_type cx map_cx dict in
        let props' = SMap.ident_map (Property.ident_map_t (self#type_ cx map_cx)) props in
        let obj' = self#resolved_object cx map_cx obj in
        if dict' == dict && props' == props && obj' == obj then t
        else ResolveDict (dict', props', obj')
    | ResolveProp (s, props, obj) ->
        let props' = SMap.ident_map (Property.ident_map_t (self#type_ cx map_cx)) props in
        let obj' = self#resolved_object cx map_cx obj in
        if props' == props && obj' == obj then t
        else ResolveProp (s, props', obj')

  method stack_tail cx map_cx tail = ListUtils.ident_map (self#stack_tail_elem cx map_cx) tail

  method stack_tail_elem cx map_cx ((head, tlist, maybespeclist) as t) =
    let head' = self#stack_head cx map_cx head in
    let tlist' = ListUtils.ident_map (self#type_ cx map_cx) tlist in
    let maybespeclist' =
      ListUtils.ident_map (maybe_known (self#create_class_spec cx map_cx)) maybespeclist in
    if head' == head && tlist' == tlist && maybespeclist' == maybespeclist then t
    else (head', tlist', maybespeclist')

  method create_class_spec cx map_cx t =
    let open React.CreateClass in
    let obj = self#resolved_object cx map_cx t.obj in
    let statics = OptionUtils.ident_map (maybe_known (self#resolved_object cx map_cx)) t.statics in
    let prop_types =
      OptionUtils.ident_map (maybe_known (self#resolved_object cx map_cx)) t.prop_types in
    let get_default_props = ListUtils.ident_map (self#type_ cx map_cx) t.get_default_props in
    let get_initial_state = ListUtils.ident_map (self#type_ cx map_cx) t.get_initial_state in
    if obj == t.obj && statics == t.statics && prop_types == t.prop_types
      && get_default_props == t.get_default_props && get_initial_state == t.get_initial_state
    then t
    else {obj; statics; prop_types; get_default_props; get_initial_state;
      unknown_mixins = t.unknown_mixins}

  method stack_head cx map_cx ((obj, spec) as t) =
    let obj' = self#resolved_object cx map_cx obj in
    let spec' = self#create_class_spec cx map_cx spec in
    if obj' == obj && spec' == spec then t
    else (obj', spec')

  method default_props cx map_cx default_props =
    maybe_known (self#resolved_object cx map_cx) default_props

  method resolved_object cx map_cx ((r, props, dictopt, flags) as t) =
    let props' = SMap.ident_map (Property.ident_map_t (self#type_ cx map_cx)) props in
    let dictopt' = OptionUtils.ident_map (self#dict_type cx map_cx) dictopt in
    if props' == props && dictopt' == dictopt then t
    else (r, props', dictopt', flags)

  method initial_state cx map_cx t =
    let open React.CreateClass in
    maybe_known (fun x -> match x with
    | NotNull obj ->
        let obj' = self#resolved_object cx map_cx obj in
        if obj' == obj then x
        else NotNull obj'
    | Null _ -> x) t

  method class_binding cx map_cx binding =
    let f_tmap = Context.find_props cx binding.class_private_fields in
    let f_tmap' = SMap.ident_map (Property.ident_map_t (self#type_ cx map_cx)) f_tmap in
    let class_private_fields = if f_tmap == f_tmap' then binding.class_private_fields
          else Context.make_property_map cx f_tmap' in
    let s_tmap = Context.find_props cx binding.class_private_static_fields in
    let s_tmap' = SMap.ident_map (Property.ident_map_t (self#type_ cx map_cx)) s_tmap in
    let class_private_static_fields = if s_tmap == s_tmap' then binding.class_private_static_fields
          else Context.make_property_map cx s_tmap' in
    if class_private_fields == binding.class_private_fields &&
      class_private_static_fields == binding.class_private_static_fields
    then binding
    else {binding with class_private_fields; class_private_static_fields}
end
