[flow][try] Signature help

Summary: Changelog: [website] We now provide signature help service in try-flow

Reviewed By: panagosg7

Differential Revision: D55652340

fbshipit-source-id: f7e51ff8953abdb1c266729b8cce43a1c4155ddf

src/flow_dot_js.ml

@@ -491,6 +491,40 @@ let infer_type filename content line col js_config_object : Loc.t * (string, str
         (loc, Ok (Ty_printer.string_of_type_at_pos_result ~exact_by_default:true result))
     end
 
+let signature_help filename content line col js_config_object :
+    ((ServerProt.Response.func_details_result list * int) option, string) result =
+  let filename = File_key.SourceFile filename in
+  let root = File_path.dummy_path in
+  match parse_content filename content with
+  | Error _ -> Error "parse error"
+  | Ok (ast, file_sig) ->
+    let (_, docblock) =
+      Docblock_parser.(
+        parse_docblock
+          ~max_tokens:docblock_max_tokens
+          ~file_options:Files.default_options
+          filename
+          content
+      )
+    in
+    let (cx, typed_ast) = infer_and_merge ~root filename js_config_object docblock ast file_sig in
+    let cursor_loc = mk_loc filename line col in
+    let func_details =
+      Signature_help.find_signatures
+        ~loc_of_aloc
+        ~get_ast_from_shared_mem:(fun _ -> None)
+        ~cx
+        ~file_sig
+        ~ast
+        ~typed_ast
+        cursor_loc
+    in
+    begin
+      match func_details with
+      | Ok details -> Ok details
+      | Error _ -> Error "Failed to normalize type"
+    end
+
 let types_to_json types ~strip_root =
   Hh_json.(
     Reason.(
@@ -607,6 +641,46 @@ let completion_item_to_json
   in
   JSON_Object props
 
+let signature_to_json { ServerProt.Response.func_documentation; param_tys; return_ty } =
+  let open Hh_json in
+  let open Utils_js in
+  let documentation_props = function
+    | None -> []
+    | Some doc -> [("documentation", JSON_Object [("value", JSON_String doc)])]
+  in
+  let props = documentation_props func_documentation in
+  let props =
+    ( "parameters",
+      JSON_Array
+        (Base.List.map
+           param_tys
+           ~f:(fun { ServerProt.Response.param_documentation; param_name; param_ty } ->
+             JSON_Object
+               (("label", JSON_String (spf "%s: %s" param_name param_ty))
+               :: documentation_props param_documentation
+               )
+         )
+        )
+    )
+    :: props
+  in
+  let props =
+    let sig_str =
+      Utils_js.spf
+        "(%s): %s"
+        (Base.List.map
+           param_tys
+           ~f:(fun { ServerProt.Response.param_documentation = _; param_name; param_ty } ->
+             spf "%s: %s" param_name param_ty
+         )
+        |> Base.String.concat ~sep:", "
+        )
+        return_ty
+    in
+    ("label", JSON_String sig_str) :: props
+  in
+  JSON_Object props
+
 let autocomplete js_file js_content js_line js_col js_config_object =
   let filename = Js.to_string js_file in
   let content = Js.to_string js_content in
@@ -634,6 +708,24 @@ let get_def js_file js_content js_line js_col js_config_object =
     |> js_of_json
   | Error msg -> failwith msg
 
+let signature_help js_file js_content js_line js_col js_config_object =
+  let filename = Js.to_string js_file in
+  let content = Js.to_string js_content in
+  let line = Js.parseInt js_line in
+  let col = Js.parseInt js_col in
+  match signature_help filename content line col js_config_object with
+  | Error msg -> failwith msg
+  | Ok None -> Js.Unsafe.inject Js.null
+  | Ok (Some (signatures, n)) ->
+    let open Hh_json in
+    JSON_Object
+      [
+        ("signatures", JSON_Array (Base.List.map signatures ~f:signature_to_json));
+        ("activeParameter", JSON_Number (string_of_int n));
+        ("activeSignature", JSON_Number "0");
+      ]
+    |> js_of_json
+
 let type_at_pos js_file js_content js_line js_col js_config_object =
   let filename = Js.to_string js_file in
   let content = Js.to_string js_content in
@@ -790,4 +882,6 @@ let () = Js.Unsafe.set exports "autocomplete" (Js.wrap_callback autocomplete)
 
 let () = Js.Unsafe.set exports "getDef" (Js.wrap_callback get_def)
 
+let () = Js.Unsafe.set exports "signatureHelp" (Js.wrap_callback signature_help)
+
 let () = Js.Unsafe.set exports "typeAtPos" (Js.wrap_callback type_at_pos)

website/libs/flow_js.js

@@ -90,5 +90,12 @@ declare type FlowJs = {
     col: number,
     options: {[string]: mixed},
   ): string,
+  signatureHelp(
+    filename: string,
+    body: string,
+    line: number,
+    col: number,
+    options: {[string]: mixed},
+  ): any,
   parse(body: string, options: FlowJsParseOptions): interface {},
 };

website/src/try-flow/TryFlow.js

@@ -20,6 +20,7 @@ import {
   setAutoCompleteFunction,
   setGetDefFunction,
   setTypeAtPosFunction,
+  setSignatureHelpFunction,
 } from './configured-monaco';
 import FlowJsServices from './flow-services';
 import createTokensProvider from './tokens-theme-provider';
@@ -159,6 +160,7 @@ export default component TryFlow(
     setAutoCompleteFunction(flowService);
     setGetDefFunction(flowService);
     setTypeAtPosFunction(flowService);
+    setSignatureHelpFunction(flowService);
 
     const model = monaco.editor.getModels()[0];
     if (model == null || flowService == null) return;

website/src/try-flow/configured-monaco.js

@@ -60,6 +60,19 @@ function setTypeAtPosFunction(flowService: ?FlowJsServices): void {
     );
 }
 
+let signatureHelpFunctionForMonaco = (value: string, position: Position): any =>
+  null;
+
+function setSignatureHelpFunction(flowService: ?FlowJsServices): void {
+  signatureHelpFunctionForMonaco = (value, position) =>
+    flowService?.signatureHelp(
+      '-',
+      value,
+      position.lineNumber,
+      position.column - 1,
+    );
+}
+
 monaco.languages.register({
   id: 'flow',
   extensions: ['.js', '.flow'],
@@ -180,11 +193,25 @@ monaco.languages.registerHoverProvider('flow', {
     };
   },
 });
+monaco.languages.registerSignatureHelpProvider('flow', {
+  signatureHelpTriggerCharacters: ['(', ','],
+  provideSignatureHelp(model, position) {
+    try {
+      const result = signatureHelpFunctionForMonaco(model.getValue(), position);
+      if (result == null) return null;
+      return {value: result, dispose() {}};
+    } catch (e) {
+      console.error(e);
+      return null;
+    }
+  },
+});
 loader.config({monaco});
 
 export {
   monaco,
   setAutoCompleteFunction,
   setGetDefFunction,
   setTypeAtPosFunction,
+  setSignatureHelpFunction,
 };

website/src/try-flow/flow-services.js

@@ -99,6 +99,15 @@ export default class FlowJsServices {
     return this._flow.typeAtPos(filename, body, line, col, this.config);
   }
 
+  signatureHelp(
+    filename: string,
+    body: string,
+    line: number,
+    col: number,
+  ): any {
+    return this._flow.signatureHelp(filename, body, line, col, this.config);
+  }
+
   parseAstToJsonString(body: string): interface {} {
     return this._flow.parse(body, PARSE_OPTIONS);
   }