feat(completion): Provide completion when writing fields before anoth…

…er field

Since you are likely to write the comma after the field we need to produce an AST when the comma is missing or else we have nothing to provide completion on.

completion/src/lib.rs

@@ -339,7 +339,7 @@ where
                     .merge_by(fields.iter().map(Either::Right), |l, r| {
                         l.left().unwrap().name.span.start < r.right().unwrap().name.span.start
                     });
-                let (_, selected) = self.select_spanned(iter, |either| {
+                let (on_whitespace, selected) = self.select_spanned(iter, |either| {
                     either.either(
                         |type_field| type_field.name.span,
                         |field| {
@@ -353,7 +353,10 @@ where
                         },
                     )
                 });
-                if let Some(either) = selected {
+
+                if on_whitespace {
+                    self.found = Some(None);
+                } else if let Some(either) = selected {
                     match either {
                         Either::Left(type_field) => {
                             if type_field.name.span.containment(&self.pos) == Ordering::Equal {

completion/tests/completion.rs

@@ -632,6 +632,20 @@ let { ab } = { x = 1, abc = "", abcd = 2 }
     assert_eq!(result, expected);
 }
 
+#[test]
+fn suggest_record_field_in_pattern_before_field() {
+    let _ = env_logger::init();
+
+    let text = r#"
+let { a abc } = { x = 1, abc = "", abcd = 2 }
+()
+"#;
+    let result = suggest_loc(text, 1, 7);
+    let expected = Ok(vec!["abcd".into()]);
+
+    assert_eq!(result, expected);
+}
+
 #[test]
 fn suggest_alias_field_in_pattern() {
     let _ = env_logger::init();

parser/src/grammar.lalrpop

@@ -69,8 +69,14 @@ extern {
 
 // Utils
 
+SingleComma: () = {
+    "," => (),
+    // Necessar
+    <!> => errors.push(<>.error)
+};
+
 Comma<Rule>: Vec<Rule> =
-    <rules: (<Rule> ",")*> <last: Rule?> => {
+    <rules: (<Rule> SingleComma)*> <last: Rule?> => {
         let mut rules = rules;
         rules.extend(last);
         rules