public void AddIfMissing(
string displayText, string suffix, string description,
RegexNode parentOpt, int?positionOffset = null, string insertionText = null)
{
var replacementStart = parentOpt != null
? parentOpt.GetSpan().Start
: Position;
var replacementSpan = TextSpan.FromBounds(replacementStart, Position);
var newPosition = replacementStart + positionOffset;
insertionText ??= displayText;
var escapedInsertionText = _language.EscapeText(insertionText, StringToken);
if (escapedInsertionText != insertionText)
{
newPosition += escapedInsertionText.Length - insertionText.Length;
}
AddIfMissing(new RegexItem(
displayText, suffix, description,
CompletionChange.Create(
new TextChange(replacementSpan, escapedInsertionText),
newPosition)));
}
