add snippets to constructor args when completing

Author: zth

analysis/src/CompletionBackEnd.ml

@@ -1528,6 +1528,15 @@ let filterItems items ~prefix =
     |> List.filter (fun (item : Completion.t) ->
            Utils.startsWith item.name prefix)
 
+let printConstructorArgs argsLen ~asSnippet =
+  let args = ref [] in
+  for argNum = 1 to argsLen do
+    args :=
+      !args @ [(if asSnippet then Printf.sprintf "${%i:_}" argNum else "_")]
+  done;
+  if List.length !args > 0 then "(" ^ (!args |> String.concat ", ") ^ ")"
+  else ""
+
 let completeTypedValue ~env ~envWhereCompletionStarted ~full ~prefix
     ~expandOption =
   let namesUsed = Hashtbl.create 10 in
@@ -1549,22 +1558,22 @@ let completeTypedValue ~env ~envWhereCompletionStarted ~full ~prefix
       | Some (Tvariant {env; constructors; variantDecl; variantName}) ->
         constructors
         |> List.map (fun (constructor : Constructor.t) ->
-               Completion.create
+               Completion.createWithSnippet
                  ~name:
                    (constructor.cname.txt
-                   ^
-                   if constructor.args |> List.length > 0 then
-                     "("
-                     ^ (constructor.args
-                       |> List.map (fun _ -> "_")
-                       |> String.concat ", ")
-                     ^ ")"
-                   else "")
+                   ^ printConstructorArgs
+                       (List.length constructor.args)
+                       ~asSnippet:false)
+                 ~insertText:
+                   (constructor.cname.txt
+                   ^ printConstructorArgs
+                       (List.length constructor.args)
+                       ~asSnippet:true)
                  ~kind:
                    (Constructor
                       ( constructor,
                         variantDecl |> Shared.declToString variantName ))
-                 ~env)
+                 ~env ())
         |> filterItems ~prefix
       | Some (Toption (env, t)) ->
         [

analysis/tests/src/expected/CompletionFunctionArguments.res.txt

@@ -95,19 +95,25 @@ Completable: Cargument Value[someFnTakingVariant](~config)
     "kind": 4,
     "tags": [],
     "detail": "One\n\ntype someVariant = One | Two | Three(int, string)",
-    "documentation": null
+    "documentation": null,
+    "insertText": "One",
+    "insertTextFormat": 2
   }, {
     "label": "Two",
     "kind": 4,
     "tags": [],
     "detail": "Two\n\ntype someVariant = One | Two | Three(int, string)",
-    "documentation": null
+    "documentation": null,
+    "insertText": "Two",
+    "insertTextFormat": 2
   }, {
     "label": "Three(_, _)",
     "kind": 4,
     "tags": [],
     "detail": "Three(int, string)\n\ntype someVariant = One | Two | Three(int, string)",
-    "documentation": null
+    "documentation": null,
+    "insertText": "Three(${1:_}, ${2:_})",
+    "insertTextFormat": 2
   }]
 
 Complete src/CompletionFunctionArguments.res 54:40
@@ -119,7 +125,9 @@ Completable: Cargument Value[someFnTakingVariant](~config=O)
     "kind": 4,
     "tags": [],
     "detail": "One\n\ntype someVariant = One | Two | Three(int, string)",
-    "documentation": null
+    "documentation": null,
+    "insertText": "One",
+    "insertTextFormat": 2
   }, {
     "label": "OIncludeMeInCompletions",
     "kind": 9,
@@ -151,7 +159,9 @@ Completable: Cargument Value[someFnTakingVariant](~configOpt2=O)
     "kind": 4,
     "tags": [],
     "detail": "One\n\ntype someVariant = One | Two | Three(int, string)",
-    "documentation": null
+    "documentation": null,
+    "insertText": "One",
+    "insertTextFormat": 2
   }, {
     "label": "OIncludeMeInCompletions",
     "kind": 9,