[flow][match] Add AST visitor for match as pattern target

Summary:
Add AST visitor for match as pattern target.

Changelog: [internal]

Reviewed By: SamChou19815

Differential Revision: D69949443

fbshipit-source-id: 247f72b7a97f379e4e15b230513ec44f0e28318d

src/parser/flow_ast_mapper.ml

@@ -2740,19 +2740,21 @@ class ['loc] mapper =
       let open Ast.MatchPattern.AsPattern in
       let { pattern; target; comments } = as_pattern in
       let pattern' = this#match_pattern pattern in
-      let target' =
-        match target with
-        | Binding (loc, binding) ->
-          id_loc this#match_binding_pattern loc binding target (fun x -> Binding (loc, x))
-        | Identifier ident ->
-          id (this#pattern_identifier ~kind:Ast.Variable.Const) ident target (fun x -> Identifier x)
-      in
+      let target' = this#match_as_pattern_target target in
       let comments' = this#syntax_opt comments in
       if pattern == pattern' && target == target' && comments == comments' then
         as_pattern
       else
         { pattern = pattern'; target = target'; comments = comments' }
 
+    method match_as_pattern_target (target : ('loc, 'loc) Ast.MatchPattern.AsPattern.target) =
+      let open Ast.MatchPattern.AsPattern in
+      match target with
+      | Binding (loc, binding) ->
+        id_loc this#match_binding_pattern loc binding target (fun x -> Binding (loc, x))
+      | Identifier ident ->
+        id (this#pattern_identifier ~kind:Ast.Variable.Const) ident target (fun x -> Identifier x)
+
     method member _loc (expr : ('loc, 'loc) Ast.Expression.Member.t) =
       let open Ast.Expression.Member in
       let { _object; property; comments } = expr in

src/parser_utils/flow_polymorphic_ast_mapper.ml

@@ -2251,15 +2251,17 @@ class virtual ['M, 'T, 'N, 'U] mapper =
       let open Ast.MatchPattern.AsPattern in
       let { pattern; target; comments } = as_pattern in
       let pattern' = this#match_pattern pattern in
-      let target' =
-        match target with
-        | Binding (loc, binding) ->
-          Binding (this#on_loc_annot loc, this#match_binding_pattern binding)
-        | Identifier id -> Identifier (this#pattern_identifier ~kind:Ast.Variable.Const id)
-      in
+      let target' = this#match_as_pattern_target target in
       let comments' = this#syntax_opt comments in
       { pattern = pattern'; target = target'; comments = comments' }
 
+    method match_as_pattern_target (target : ('M, 'T) Ast.MatchPattern.AsPattern.target)
+        : ('N, 'U) Ast.MatchPattern.AsPattern.target =
+      let open Ast.MatchPattern.AsPattern in
+      match target with
+      | Binding (loc, binding) -> Binding (this#on_loc_annot loc, this#match_binding_pattern binding)
+      | Identifier id -> Identifier (this#pattern_identifier ~kind:Ast.Variable.Const id)
+
     method member (_annot : 'T) (expr : ('M, 'T) Ast.Expression.Member.t)
         : ('N, 'U) Ast.Expression.Member.t =
       let open Ast.Expression.Member in

src/parser_utils/flow_polymorphic_ast_mapper.mli

@@ -600,6 +600,9 @@ class virtual ['M, 'T, 'N, 'U] mapper :
     method match_as_pattern :
       ('M, 'T) Ast.MatchPattern.AsPattern.t -> ('N, 'U) Ast.MatchPattern.AsPattern.t
 
+    method match_as_pattern_target :
+      ('M, 'T) Ast.MatchPattern.AsPattern.target -> ('N, 'U) Ast.MatchPattern.AsPattern.target
+
     method member : 'T -> ('M, 'T) Ast.Expression.Member.t -> ('N, 'U) Ast.Expression.Member.t
 
     method member_private_name : 'M Flow_ast.PrivateName.t -> 'N Ast.PrivateName.t