Code action: Expand catch all variant (rescript-lang#987)

* code action for expanding catch all with variants

* make work with polyvariants

* extend to work on options

* changelog + fix

CHANGELOG.md

@@ -34,6 +34,7 @@
 - Emit `%todo` instead of `failwith("TODO")` when we can (ReScript >= v11.1). https://github.com/rescript-lang/rescript-vscode/pull/981
 - Complete `%todo`. https://github.com/rescript-lang/rescript-vscode/pull/981
 - Add code action for extracting a locally defined module into its own file. https://github.com/rescript-lang/rescript-vscode/pull/983
+- Add code action for expanding catch-all patterns. https://github.com/rescript-lang/rescript-vscode/pull/987
 
 ## 1.50.0
 

analysis/src/CompletionFrontEnd.ml

@@ -1005,7 +1005,9 @@ let completionWithParser1 ~currentFile ~debug ~offset ~path ~posCursor
     typedCompletionExpr expr;
     match expr.pexp_desc with
     | Pexp_match (expr, cases)
-      when cases <> [] && locHasCursor expr.pexp_loc = false ->
+      when cases <> []
+           && locHasCursor expr.pexp_loc = false
+           && Option.is_none findThisExprLoc ->
       if Debug.verbose () then
         print_endline "[completionFrontend] Checking each case";
       let ctxPath = exprToContextPath expr in

analysis/src/Xform.ml

@@ -11,6 +11,42 @@ let rangeOfLoc (loc : Location.t) =
   let end_ = loc |> Loc.end_ |> mkPosition in
   {Protocol.start; end_}
 
+let extractTypeFromExpr expr ~debug ~path ~currentFile ~full ~pos =
+  match
+    expr.Parsetree.pexp_loc
+    |> CompletionFrontEnd.findTypeOfExpressionAtLoc ~debug ~path ~currentFile
+         ~posCursor:(Pos.ofLexing expr.Parsetree.pexp_loc.loc_start)
+  with
+  | Some (completable, scope) -> (
+    let env = SharedTypes.QueryEnv.fromFile full.SharedTypes.file in
+    let completions =
+      completable
+      |> CompletionBackEnd.processCompletable ~debug ~full ~pos ~scope ~env
+           ~forHover:true
+    in
+    let rawOpens = Scope.getRawOpens scope in
+    match completions with
+    | {env} :: _ -> (
+      let opens =
+        CompletionBackEnd.getOpens ~debug ~rawOpens ~package:full.package ~env
+      in
+      match
+        CompletionBackEnd.completionsGetCompletionType2 ~debug ~full ~rawOpens
+          ~opens ~pos completions
+      with
+      | Some (typ, _env) ->
+        let extractedType =
+          match typ with
+          | ExtractedType t -> Some t
+          | TypeExpr t ->
+            TypeUtils.extractType t ~env ~package:full.package
+            |> TypeUtils.getExtractedType
+        in
+        extractedType
+      | None -> None)
+    | _ -> None)
+  | _ -> None
+
 module IfThenElse = struct
   (* Convert if-then-else to switch *)
 
@@ -324,6 +360,196 @@ module AddTypeAnnotation = struct
         | _ -> ()))
 end
 
+module ExpandCatchAllForVariants = struct
+  let mkIterator ~pos ~result =
+    let expr (iterator : Ast_iterator.iterator) (e : Parsetree.expression) =
+      (if e.pexp_loc |> Loc.hasPos ~pos then
+         match e.pexp_desc with
+         | Pexp_match (switchExpr, cases) -> (
+           let catchAllCase =
+             cases
+             |> List.find_opt (fun (c : Parsetree.case) ->
+                    match c with
+                    | {pc_lhs = {ppat_desc = Ppat_any}} -> true
+                    | _ -> false)
+           in
+           match catchAllCase with
+           | None -> ()
+           | Some catchAllCase ->
+             result := Some (switchExpr, catchAllCase, cases))
+         | _ -> ());
+      Ast_iterator.default_iterator.expr iterator e
+    in
+    {Ast_iterator.default_iterator with expr}
+
+  let xform ~path ~pos ~full ~structure ~currentFile ~codeActions ~debug =
+    let result = ref None in
+    let iterator = mkIterator ~pos ~result in
+    iterator.structure iterator structure;
+    match !result with
+    | None -> ()
+    | Some (switchExpr, catchAllCase, cases) -> (
+      if Debug.verbose () then
+        print_endline
+          "[codeAction - ExpandCatchAllForVariants] Found target switch";
+      let currentConstructorNames =
+        cases
+        |> List.filter_map (fun (c : Parsetree.case) ->
+               match c with
+               | {pc_lhs = {ppat_desc = Ppat_construct ({txt}, _)}} ->
+                 Some (Longident.last txt)
+               | {pc_lhs = {ppat_desc = Ppat_variant (name, _)}} -> Some name
+               | _ -> None)
+      in
+      match
+        switchExpr
+        |> extractTypeFromExpr ~debug ~path ~currentFile ~full
+             ~pos:(Pos.ofLexing switchExpr.pexp_loc.loc_end)
+      with
+      | Some (Tvariant {constructors}) ->
+        let missingConstructors =
+          constructors
+          |> List.filter (fun (c : SharedTypes.Constructor.t) ->
+                 currentConstructorNames |> List.mem c.cname.txt = false)
+        in
+        if List.length missingConstructors > 0 then
+          let newText =
+            missingConstructors
+            |> List.map (fun (c : SharedTypes.Constructor.t) ->
+                   c.cname.txt
+                   ^
+                   match c.args with
+                   | Args [] -> ""
+                   | Args _ | InlineRecord _ -> "(_)")
+            |> String.concat " | "
+          in
+          let range = rangeOfLoc catchAllCase.pc_lhs.ppat_loc in
+          let codeAction =
+            CodeActions.make ~title:"Expand catch-all" ~kind:RefactorRewrite
+              ~uri:path ~newText ~range
+          in
+          codeActions := codeAction :: !codeActions
+        else ()
+      | Some (Tpolyvariant {constructors}) ->
+        let missingConstructors =
+          constructors
+          |> List.filter (fun (c : SharedTypes.polyVariantConstructor) ->
+                 currentConstructorNames |> List.mem c.name = false)
+        in
+        if List.length missingConstructors > 0 then
+          let newText =
+            missingConstructors
+            |> List.map (fun (c : SharedTypes.polyVariantConstructor) ->
+                   Res_printer.polyVarIdentToString c.name
+                   ^
+                   match c.args with
+                   | [] -> ""
+                   | _ -> "(_)")
+            |> String.concat " | "
+          in
+          let range = rangeOfLoc catchAllCase.pc_lhs.ppat_loc in
+          let codeAction =
+            CodeActions.make ~title:"Expand catch-all" ~kind:RefactorRewrite
+              ~uri:path ~newText ~range
+          in
+          codeActions := codeAction :: !codeActions
+        else ()
+      | Some (Toption (env, innerType)) -> (
+        if Debug.verbose () then
+          print_endline
+            "[codeAction - ExpandCatchAllForVariants] Found option type";
+        let innerType =
+          match innerType with
+          | ExtractedType t -> Some t
+          | TypeExpr t -> (
+            match TypeUtils.extractType ~env ~package:full.package t with
+            | None -> None
+            | Some (t, _) -> Some t)
+        in
+        match innerType with
+        | Some ((Tvariant _ | Tpolyvariant _) as variant) ->
+          let currentConstructorNames =
+            cases
+            |> List.filter_map (fun (c : Parsetree.case) ->
+                   match c with
+                   | {
+                    pc_lhs =
+                      {
+                        ppat_desc =
+                          Ppat_construct
+                            ( {txt = Lident "Some"},
+                              Some {ppat_desc = Ppat_construct ({txt}, _)} );
+                      };
+                   } ->
+                     Some (Longident.last txt)
+                   | {
+                    pc_lhs =
+                      {
+                        ppat_desc =
+                          Ppat_construct
+                            ( {txt = Lident "Some"},
+                              Some {ppat_desc = Ppat_variant (name, _)} );
+                      };
+                   } ->
+                     Some name
+                   | _ -> None)
+          in
+          let hasNoneCase =
+            cases
+            |> List.exists (fun (c : Parsetree.case) ->
+                   match c.pc_lhs.ppat_desc with
+                   | Ppat_construct ({txt = Lident "None"}, _) -> true
+                   | _ -> false)
+          in
+          let missingConstructors =
+            match variant with
+            | Tvariant {constructors} ->
+              constructors
+              |> List.filter_map (fun (c : SharedTypes.Constructor.t) ->
+                     if currentConstructorNames |> List.mem c.cname.txt = false
+                     then
+                       Some
+                         ( c.cname.txt,
+                           match c.args with
+                           | Args [] -> false
+                           | _ -> true )
+                     else None)
+            | Tpolyvariant {constructors} ->
+              constructors
+              |> List.filter_map
+                   (fun (c : SharedTypes.polyVariantConstructor) ->
+                     if currentConstructorNames |> List.mem c.name = false then
+                       Some
+                         ( Res_printer.polyVarIdentToString c.name,
+                           match c.args with
+                           | [] -> false
+                           | _ -> true )
+                     else None)
+            | _ -> []
+          in
+          if List.length missingConstructors > 0 || not hasNoneCase then
+            let newText =
+              "Some("
+              ^ (missingConstructors
+                |> List.map (fun (name, hasArgs) ->
+                       name ^ if hasArgs then "(_)" else "")
+                |> String.concat " | ")
+              ^ ")"
+            in
+            let newText =
+              if hasNoneCase then newText else newText ^ " | None"
+            in
+            let range = rangeOfLoc catchAllCase.pc_lhs.ppat_loc in
+            let codeAction =
+              CodeActions.make ~title:"Expand catch-all" ~kind:RefactorRewrite
+                ~uri:path ~newText ~range
+            in
+            codeActions := codeAction :: !codeActions
+          else ()
+        | _ -> ())
+      | _ -> ())
+end
+
 module ExhaustiveSwitch = struct
   (* Expand expression to be an exhaustive switch of the underlying value *)
   type posType = Single of Pos.t | Range of Pos.t * Pos.t
@@ -336,46 +562,6 @@ module ExhaustiveSwitch = struct
       }
     | Selection of {expr: Parsetree.expression}
 
-  module C = struct
-    let extractTypeFromExpr expr ~debug ~path ~currentFile ~full ~pos =
-      match
-        expr.Parsetree.pexp_loc
-        |> CompletionFrontEnd.findTypeOfExpressionAtLoc ~debug ~path
-             ~currentFile
-             ~posCursor:(Pos.ofLexing expr.Parsetree.pexp_loc.loc_start)
-      with
-      | Some (completable, scope) -> (
-        let env = SharedTypes.QueryEnv.fromFile full.SharedTypes.file in
-        let completions =
-          completable
-          |> CompletionBackEnd.processCompletable ~debug ~full ~pos ~scope ~env
-               ~forHover:true
-        in
-        let rawOpens = Scope.getRawOpens scope in
-        match completions with
-        | {env} :: _ -> (
-          let opens =
-            CompletionBackEnd.getOpens ~debug ~rawOpens ~package:full.package
-              ~env
-          in
-          match
-            CompletionBackEnd.completionsGetCompletionType2 ~debug ~full
-              ~rawOpens ~opens ~pos completions
-          with
-          | Some (typ, _env) ->
-            let extractedType =
-              match typ with
-              | ExtractedType t -> Some t
-              | TypeExpr t ->
-                TypeUtils.extractType t ~env ~package:full.package
-                |> TypeUtils.getExtractedType
-            in
-            extractedType
-          | None -> None)
-        | _ -> None)
-      | _ -> None
-  end
-
   let mkIteratorSingle ~pos ~result =
     let expr (iterator : Ast_iterator.iterator) (exp : Parsetree.expression) =
       (match exp.pexp_desc with
@@ -434,7 +620,7 @@ module ExhaustiveSwitch = struct
     | Some (Selection {expr}) -> (
       match
         expr
-        |> C.extractTypeFromExpr ~debug ~path ~currentFile ~full
+        |> extractTypeFromExpr ~debug ~path ~currentFile ~full
              ~pos:(Pos.ofLexing expr.pexp_loc.loc_start)
       with
       | None -> ()
@@ -460,7 +646,7 @@ module ExhaustiveSwitch = struct
     | Some (Switch {switchExpr; completionExpr; pos}) -> (
       match
         completionExpr
-        |> C.extractTypeFromExpr ~debug ~path ~currentFile ~full ~pos
+        |> extractTypeFromExpr ~debug ~path ~currentFile ~full ~pos
       with
       | None -> ()
       | Some extractedType -> (
@@ -743,6 +929,8 @@ let extractCodeActions ~path ~startPos ~endPos ~currentFile ~debug =
       match Cmt.loadFullCmtFromPath ~path with
       | Some full ->
         AddTypeAnnotation.xform ~path ~pos ~full ~structure ~codeActions ~debug;
+        ExpandCatchAllForVariants.xform ~path ~pos ~full ~structure ~codeActions
+          ~currentFile ~debug;
         ExhaustiveSwitch.xform ~printExpr ~path
           ~pos:
             (if startPos = endPos then Single startPos

analysis/tests/src/Xform.res

@@ -1,8 +1,8 @@
-type kind = First | Second | Third
+type kind = First | Second | Third | Fourth(int)
 type r = {name: string, age: int}
 
-let ret = _ => assert false
-let kind = assert false
+let ret = _ => assert(false)
+let kind = assert(false)
 
 if kind == First {
   // ^xfm
@@ -63,7 +63,7 @@ let bar = () => {
       }
     //^xfm
   }
-  @res.partial Inner.foo(1)
+  Inner.foo(1, ...)
 }
 
 module ExtractableModule = {
@@ -72,4 +72,37 @@ module ExtractableModule = {
   // A comment here
   let doStuff = a => a + 1
   // ^xfm
-}
+}
+
+let variant = First
+
+let _x = switch variant {
+| First => "first"
+| _ => "other"
+//  ^xfm
+}
+
+let polyvariant: [#first | #second | #"illegal identifier" | #third(int)] = #first
+
+let _y = switch polyvariant {
+| #first => "first"
+| _ => "other"
+//  ^xfm
+}
+
+let variantOpt = Some(variant)
+
+let _x = switch variantOpt {
+| Some(First) => "first"
+| _ => "other"
+//  ^xfm
+}
+
+let polyvariantOpt = Some(polyvariant)
+
+let _x = switch polyvariantOpt {
+| Some(#first) => "first"
+| None => "nothing"
+| _ => "other"
+//  ^xfm
+}