Function getRangeOfEnclosingComment

internal/ls/format.go:137–181

Unlike the TS implementation, this function *will not* compute default values for `precedingToken` and `tokenAtPosition`. It is the caller's responsibility to call `astnav.GetTokenAtPosition` to compute a default `tokenAtPosition`, or `astnav.FindPrecedingToken` to compute a default `precedingToken`

(
	file *ast.SourceFile,
	position int,
	precedingToken *ast.Node,
	tokenAtPosition *ast.Node,
)

// It is the caller's responsibility to call `astnav.GetTokenAtPosition` to compute a default `tokenAtPosition`,
// or `astnav.FindPrecedingToken` to compute a default `precedingToken`.
func getRangeOfEnclosingComment(
	file *ast.SourceFile,
	position int,
	precedingToken *ast.Node,
	tokenAtPosition *ast.Node,
) *ast.CommentRange {
	jsdoc := ast.FindAncestor(tokenAtPosition, (*ast.Node).IsJSDoc)
	if jsdoc != nil {
		tokenAtPosition = jsdoc.Parent
	}
	tokenStart := astnav.GetStartOfNode(tokenAtPosition, file, false /*includeJSDoc*/)
	if tokenStart <= position && position < tokenAtPosition.End() {
		return nil
	}

	// Between two consecutive tokens, all comments are either trailing on the former
	// or leading on the latter (and none are in both lists).
	var trailingRangesOfPreviousToken iter.Seq[ast.CommentRange]
	if precedingToken != nil {
		trailingRangesOfPreviousToken = scanner.GetTrailingCommentRanges(&ast.NodeFactory{}, file.Text(), precedingToken.End())
	}
	leadingRangesOfNextToken := getLeadingCommentRangesOfNode(tokenAtPosition, file)
	commentRanges := core.ConcatenateSeq(trailingRangesOfPreviousToken, leadingRangesOfNextToken)
	for commentRange := range commentRanges {
		// The end marker of a single-line comment does not include the newline character.
		// In the following case where the cursor is at `^`, we are inside a comment:
		//
		//    // asdf   ^\n
		//
		// But for closed multi-line comments, we don't want to be inside the comment in the following case:
		//
		//    /* asdf */^
		//
		// Internally, we represent the end of the comment prior to the newline and at the '/', respectively.
		//
		// However, unterminated multi-line comments lack a `/`, end at the end of the file, and *do* contain their end.
		//
		if commentRange.ContainsExclusive(position) ||
			position == commentRange.End() &&
				(commentRange.Kind == ast.KindSingleLineCommentTrivia || position == len(file.Text())) {
			return &commentRange
		}
	}
	return nil
}