feat(grainlsp): Implement inlay hints for module includes (#1793)

* Add initial capability for inlay hints

* Added inlay hint capability

* Added simple test of printing out an inline value

* Debug

* Cleaned up and formatted the code

* Nit cleanup after review

* Remove whitespace

---------

Co-authored-by: marcusroberts <marcus@marcusr.com>

compiler/src/language_server/driver.re

@@ -25,6 +25,9 @@ let process = msg => {
   | TextDocumentHover(id, params) when is_initialized^ =>
     Hover.process(~id, ~compiled_code, ~documents, params);
     Reading;
+  | TextDocumentInlayHint(id, params) when is_initialized^ =>
+    Inlayhint.process(~id, ~compiled_code, ~documents, params);
+    Reading;
   | TextDocumentCodeLens(id, params) when is_initialized^ =>
     Lenses.process(~id, ~compiled_code, ~documents, params);
     Reading;

compiler/src/language_server/initialize.re

@@ -59,6 +59,8 @@ module ResponseResult = {
     document_range_formatting_provider: bool,
     [@key "renameProvider"]
     rename_provider: bool,
+    [@key "inlayHintProvider"]
+    inlay_hint_provider: Protocol.inlay_hint_options,
   };
   [@deriving yojson]
   type t = {capabilities: lsp_capabilities};
@@ -78,6 +80,9 @@ module ResponseResult = {
     document_highlight_provider: false,
     document_range_formatting_provider: false,
     rename_provider: false,
+    inlay_hint_provider: {
+      resolve_provider: false,
+    },
   };
 };
 

compiler/src/language_server/inlayhint.re

@@ -0,0 +1,84 @@
+open Grain;
+open Compile;
+open Grain_parsing;
+open Grain_utils;
+open Grain_typed;
+open Grain_diagnostics;
+open Sourcetree;
+open Lsp_types;
+
+// https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#inlayHintParams
+module RequestParams = {
+  [@deriving yojson({strict: false})]
+  type t = {
+    [@key "textDocument"]
+    text_document: Protocol.text_document_identifier,
+    range: Protocol.range,
+  };
+};
+
+// https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#textDocument_inlayHint
+module ResponseResult = {
+  [@deriving yojson]
+  type inlay_hint = {
+    label: string,
+    position: Protocol.position,
+  };
+
+  [@deriving yojson]
+  type t = list(inlay_hint);
+};
+
+let send_no_result = (~id: Protocol.message_id) => {
+  Protocol.response(~id, `Null);
+};
+
+let find_hints = program => {
+  let hints = ref([]);
+  open Typedtree;
+  open Protocol;
+  module Iterator =
+    TypedtreeIter.MakeIterator({
+      include TypedtreeIter.DefaultIteratorArgument;
+      let enter_toplevel_stmt = (stmt: toplevel_stmt) => {
+        switch (stmt.ttop_desc) {
+        | TTopInclude(inc) =>
+          let path = inc.tinc_path;
+          let name = Path.name(inc.tinc_path);
+
+          let stmt_loc = stmt.ttop_loc;
+          let stmt_end = stmt_loc.loc_end;
+
+          let p: Protocol.position = {
+            line: stmt_end.pos_lnum - 1,
+            character: stmt_end.pos_cnum - stmt_end.pos_bol + 1 + 1,
+          };
+
+          let r: ResponseResult.inlay_hint = {
+            label: ": " ++ name,
+            position: p,
+          };
+          hints := [r, ...hints^];
+        | _ => ()
+        };
+      };
+    });
+  Iterator.iter_typed_program(program);
+  hints^;
+};
+
+let process =
+    (
+      ~id: Protocol.message_id,
+      ~compiled_code: Hashtbl.t(Protocol.uri, code),
+      ~documents: Hashtbl.t(Protocol.uri, string),
+      params: RequestParams.t,
+    ) => {
+  Trace.log("Inlay hint request received");
+  switch (Hashtbl.find_opt(compiled_code, params.text_document.uri)) {
+  | None => send_no_result(~id)
+  | Some({program, sourcetree}) =>
+    let hints = find_hints(program);
+    Protocol.response(~id, ResponseResult.to_yojson(hints));
+  };
+};

compiler/src/language_server/inlayhint.rei

@@ -0,0 +1,22 @@
+open Grain_typed;
+
+// https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#inlayHintParams
+module RequestParams: {
+  [@deriving yojson({strict: false})]
+  type t;
+};
+
+// https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#textDocument_inlayHint
+module ResponseResult: {
+  [@deriving yojson]
+  type t;
+};
+
+let process:
+  (
+    ~id: Protocol.message_id,
+    ~compiled_code: Hashtbl.t(Protocol.uri, Lsp_types.code),
+    ~documents: Hashtbl.t(Protocol.uri, string),
+    RequestParams.t
+  ) =>
+  unit;

compiler/src/language_server/message.re

@@ -8,6 +8,7 @@ type t =
   | Exit(Protocol.message_id, Exit.RequestParams.t)
   | TextDocumentDidOpen(Protocol.uri, Code_file.DidOpen.RequestParams.t)
   | TextDocumentDidChange(Protocol.uri, Code_file.DidChange.RequestParams.t)
+  | TextDocumentInlayHint(Protocol.message_id, Inlayhint.RequestParams.t)
   | Formatting(Protocol.message_id, Formatting.RequestParams.t)
   | SetTrace(Protocol.trace_value)
   | Unsupported
@@ -25,6 +26,11 @@ let of_request = (msg: Protocol.request_message): t => {
     | Ok(params) => TextDocumentHover(id, params)
     | Error(msg) => Error(msg)
     }
+  | {method: "textDocument/inlayHint", id: Some(id), params: Some(params)} =>
+    switch (Inlayhint.RequestParams.of_yojson(params)) {
+    | Ok(params) => TextDocumentInlayHint(id, params)
+    | Error(msg) => Error(msg)
+    }
   | {method: "textDocument/codeLens", id: Some(id), params: Some(params)} =>
     switch (Lenses.RequestParams.of_yojson(params)) {
     | Ok(params) => TextDocumentCodeLens(id, params)

compiler/src/language_server/message.rei

@@ -6,6 +6,7 @@ type t =
   | Exit(Protocol.message_id, Exit.RequestParams.t)
   | TextDocumentDidOpen(Protocol.uri, Code_file.DidOpen.RequestParams.t)
   | TextDocumentDidChange(Protocol.uri, Code_file.DidChange.RequestParams.t)
+  | TextDocumentInlayHint(Protocol.message_id, Inlayhint.RequestParams.t)
   | Formatting(Protocol.message_id, Formatting.RequestParams.t)
   | SetTrace(Protocol.trace_value)
   | Unsupported

compiler/src/language_server/protocol.re

@@ -5,6 +5,13 @@ let uri_to_yojson = (uri: Uri.t): Yojson.Safe.t =>
 let uri_of_yojson = (json: Yojson.Safe.t) =>
   json |> [%of_yojson: string] |> Result.map(Uri.of_string);
 
+//https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#inlayHintOptions
+[@deriving yojson]
+type inlay_hint_options = {
+  [@key "resolveProvider"]
+  resolve_provider: bool,
+};
+
 type uri = [@to_yojson uri_to_yojson] [@of_yojson uri_of_yojson] Uri.t;
 
 [@deriving yojson]

compiler/src/language_server/protocol.rei

@@ -1,5 +1,12 @@
 open Grain_utils;
 
+//https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#inlayHintOptions
+[@deriving yojson]
+type inlay_hint_options = {
+  [@key "resolveProvider"]
+  resolve_provider: bool,
+};
+
 [@deriving yojson]
 type version;