Feat: add completion toplevel decorators

CHANGELOG.md

@@ -15,6 +15,7 @@
 #### :rocket: New Feature
 
 - Add support for syntax highlighting in `%raw` and `%ffi` extension points. https://github.com/rescript-lang/rescript-vscode/pull/774
+- Add completion to top level decorators. https://github.com/rescript-lang/rescript-vscode/pull/799
 
 #### :bug: Bug Fix
 

analysis/src/CompletionBackEnd.ml

@@ -1475,7 +1475,16 @@ let rec processCompletable ~debug ~full ~scope ~env ~pos ~forHover completable =
     let mkDecorator (name, docstring) =
       {(Completion.create name ~kind:(Label "") ~env) with docstring}
     in
-    CompletionDecorators.decorators
+    let isTopLevel = String.starts_with ~prefix:"@" prefix in
+    let prefix =
+      if isTopLevel then String.sub prefix 1 (String.length prefix - 1)
+      else prefix
+    in
+    let decorators =
+      if isTopLevel then CompletionDecorators.toplevel
+      else CompletionDecorators.local
+    in
+    decorators
     |> List.filter (fun (decorator, _) -> Utils.startsWith decorator prefix)
     |> List.map (fun (decorator, doc) ->
            let parts = String.split_on_char '.' prefix in

analysis/src/CompletionDecorators.ml

@@ -1,4 +1,4 @@
-let decorators =
+let local =
   [
     ( "as",
       [
@@ -221,3 +221,26 @@ Note: The `@react.component` decorator requires the react-jsx config to be set i
 [Read more and see examples in the documentation](https://rescript-lang.org/syntax-lookup#variadic-decorator).|};
       ] );
   ]
+
+let toplevel =
+  [
+    ( "deprecated",
+      [
+        {|The `@@deprecated` decorator is used to add a deprecation note to the file-level of a module. The compiler and editor tooling will yield a warning whenever a deprecated file module is being used.
+
+[Read more and see examples in the documentation](https://rescript-lang.org/syntax-lookup#module-deprecated-decorator).|};
+      ] );
+    ( "directive",
+      [
+        {|The `@@directive` decorator will output that string verbatim at the very top of the generated JavaScript file, before any imports.
+
+[Read more and see examples in the documentation](https://rescript-lang.org/syntax-lookup#directive-decorator).|};
+      ] );
+    ( "warning",
+      [
+        {|The `@@warning` decorator is used to modify the enabled compiler warnings for the current module. See here for all available warning numbers.
+
+[Read more and see examples in the documentation](https://rescript-lang.org/syntax-lookup#module-warning-decorator).
+         |};
+      ] );
+  ]