test.cs

private static List<FieldInfo> FindMergeFields(string input)
{
	const string pattern = @"\{\{(?!#|/)(.*?)\}\}";
	var matches = new List<FieldInfo>();

	foreach (Match match in Regex.Matches(input, pattern))
	{
		matches.Add(new FieldInfo
		{
			StartIndex = match.Index,
			EndIndex = match.Index + match.Length,
			FieldName = Regex.Replace(match.Groups[1].Value, @"\s+", "")
		});
	}

	return matches;
}