fix(grainfmt): Handle comments within lists (#1429)

compiler/src/formatting/format.re

@@ -1066,41 +1066,146 @@ and resugar_list =
 
  let last_item_was_spread = ref(false);
 
+ let list_length = List.length(processed_list);
+
  let items =
- List.map(
- i =>
- switch (i) {
+ List.mapi(
+ (index, item) =>
+ switch (item) {
  | Regular(e) =>
  last_item_was_spread := false;
 
- Doc.group(print_expression(~original_source, ~comments, e));
+ // Do we have any comments on this line?
+ // If so, we break the whole list
+
+ // we might have a list list [1, 2 // comment
+ // 3]
+ // so need to use the comment after the last item
+ // [1,
+ // 2, //comment
+ // 3]
+
+ let end_line_comments =
+ if (index < list_length - 2) {
+ let next_item = List.nth(processed_list, index + 1);
+ Comment_utils.get_comments_between_locations(
+ ~loc1=e.pexp_loc,
+ ~loc2=
+ switch (next_item) {
+ | Regular(e)
+ | Spread(e) => e.pexp_loc
+ },
+ comments,
+ );
+ } else {
+ let (_, item_line, item_char, _) =
+ Locations.get_raw_pos_info(e.pexp_loc.loc_end);
+ Comment_utils.get_comments_on_line_end(
+ ~line=item_line,
+ ~char=item_char,
+ comments,
+ );
+ };
+
+ (
+ print_expression(
+ ~original_source,
+ ~comments=
+ Comment_utils.get_comments_inside_location(
+ ~location=e.pexp_loc,
+ comments,
+ ),
+ e,
+ ),
+ end_line_comments,
+ );
+
  | Spread(e) =>
  last_item_was_spread := true;
- Doc.group(
+
+ (
  Doc.concat([
  Doc.text("..."),
- print_expression(~original_source, ~comments, e),
+ print_expression(
+ ~original_source,
+ ~comments=
+ Comment_utils.get_comments_inside_location(
+ ~location=e.pexp_loc,
+ comments,
+ ),
+ e,
+ ),
  ]),
+ [],
  );
  },
  processed_list,
  );
 
+ // We have to compose this list by hand because of the complexity of if a list item
+ // is followed by a comment, the comma must come before the comment.
+ // It also impacts how we force a new line for a line ending comment at the end of a list
+ // without introducing an extra blank line when bringing the indentation back in again
+
+ let last_line_breaks_for_comments = ref(false);
+ let items_length = List.length(items);
+ let list_items =
+ List.mapi(
+ (i, (item, item_comments)) => {
+ let final_item = items_length - 1 == i;
+
+ let comment_doc =
+ switch (item_comments) {
+ | [] =>
+ last_line_breaks_for_comments := false;
+ if (final_item) {
+ Doc.nil;
+ } else {
+ Doc.concat([Doc.comma, Doc.line]);
+ };
+ | _ =>
+ let trailing_comments =
+ List.map(
+ (cmt: Parsetree.comment) =>
+ Doc.concat([
+ Doc.space,
+ Comment_utils.nobreak_comment_to_doc(cmt),
+ ]),
+ item_comments,
+ );
+
+ last_line_breaks_for_comments := true;
+ Doc.concat([
+ Doc.comma,
+ Doc.concat(trailing_comments),
+ if (final_item) {Doc.nil} else {Doc.hardLine},
+ ]);
+ };
+
+ Doc.concat([Doc.group(item), comment_doc]);
+ },
+ items,
+ );
+
  Doc.group(
  Doc.concat([
  Doc.lbracket,
  Doc.indent(
  Doc.concat([
  Doc.softLine,
- Doc.join(~sep=Doc.concat([Doc.comma, Doc.line]), items),
- if (last_item_was_spread^) {
+ Doc.concat(list_items),
+ if (last_item_was_spread^ || last_line_breaks_for_comments^) {
  Doc.nil;
  } else {
  Doc.ifBreaks(Doc.comma, Doc.nil);
  },
  ]),
  ),
- Doc.softLine,
+ if (last_line_breaks_for_comments^) {
+ Doc.hardLine;
+ } else {
+ Doc.softLine;
+ },
  Doc.rbracket,
  ]),
  );

compiler/test/formatter_inputs/list_sugar.gr

@@ -30,4 +30,31 @@ let list4 = [[1,2],[3,4],[5,6]]
 let list5 = [[1,2,3],[3,4,5],[5,6,7]]
 }
 
+let test = [ 1, /* a */ 
+ 2, // test 
+ 3, 
+ ]
+
+let test2 = [ 1, /* a */ 
+ 2, // test 
+ 3, // final comment
+ ]
+
+let test3 = [ 1, // comm
+
+ ]
+
+
+
+let recs = [
+ { num: 1, var: A, str: "" },
+
+
+ { num: 1, var: A, str: "foo" }, // A comment
+ { num: 1, var: A, str: "bar" },
+]
+
+let t = [ 1, /*inline*/ 2, // comment
+ 3]
+
 let cons = (a, b) => [a, ...b] // <- some long comment some long comment some long comment some long comment

compiler/test/formatter_outputs/list_sugar.gr

@@ -34,6 +34,34 @@ let inaBlock = {
  let list5 = [[1, 2, 3], [3, 4, 5], [5, 6, 7]]
 }
 
+let test = [
+ 1, /* a */
+ 2, // test
+ 3,
+]
+
+let test2 = [
+ 1, /* a */
+ 2, // test
+ 3, // final comment
+]
+
+let test3 = [
+ 1, // comm
+]
+
+let recs = [
+ { num: 1, var: A, str: "" },
+ { num: 1, var: A, str: "foo" }, // A comment
+ { num: 1, var: A, str: "bar" },
+]
+
+let t = [
+ 1, /*inline*/
+ 2, // comment
+ 3,
+]
+
 let cons = (a, b) =>
  [
  a,