test.cs

namespace TXTextControl.DocumentServer.Fields
{
	using System.Collections.Generic;
	using System.Text.RegularExpressions;
	using TXTextControl;

	public class TagInfo
	{
		public int StartIndex { get; set; }
		public int EndIndex { get; set; }
	}

	public class FieldInfo : TagInfo
	{
		public string FieldName { get; set; }
	}

	public class BlockInfo : TagInfo
	{
		public string BlockName { get; set; }
	}

	public class MustacheMatcher
	{
		public static void Convert(ServerTextControl textControl)
		{
			var text = textControl.Text.Replace("\r\n", "\n");

			// Process merge fields
			foreach (var field in FindMergeFields(text))
			{
				ReplaceWithMergeField(textControl, field);
			}

			// Process merge blocks
			foreach (var block in FindMergeBlocks(text))
			{
				AddSubTextPart(textControl, block);
			}

			// Process special elements
			RemoveSpecialElements(textControl, text);
		}

		private static void ReplaceWithMergeField(ServerTextControl textControl, FieldInfo field)
		{
			textControl.Select(field.StartIndex, field.EndIndex - field.StartIndex);
			var selectionText = textControl.Selection.Text;

			var mergeField = new MergeField
			{
				Name = field.FieldName,
				Text = selectionText,
				ApplicationField =
				{
					DoubledInputPosition = true,
					HighlightMode = HighlightMode.Activated
				}
			};

			textControl.Selection.Text = string.Empty;
			textControl.ApplicationFields.Add(mergeField.ApplicationField);
		}

		private static void AddSubTextPart(ServerTextControl textControl, BlockInfo block)
		{
			var subTextPart = new SubTextPart("txmb_" + block.BlockName, 1, block.StartIndex, block.EndIndex - block.StartIndex);
			textControl.SubTextParts.Add(subTextPart);
		}

		private static void RemoveSpecialElements(ServerTextControl textControl, string text)
		{
			var matchElements = FindSpecialElements(text);

			int indexOffset = 0;

			foreach (var tag in matchElements)
			{
				textControl.Select(tag.StartIndex - indexOffset, tag.EndIndex - tag.StartIndex);
				indexOffset += textControl.Selection.Length;
				textControl.Selection.Text = string.Empty;
			}
		}

		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;
		}

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

			foreach (Match match in Regex.Matches(input, pattern))
			{
				matches.Add(new TagInfo
				{
					StartIndex = match.Index,
					EndIndex = match.Index + match.Length
				});
			}

			return matches;
		}

		private static List<BlockInfo> FindMergeBlocks(string input)
		{
			const string pattern = @"\{\{(#foreach\s+\w+|\s*\/foreach\s+\w+)\}\}";
			var matches = new List<BlockInfo>();
			var stack = new Stack<Match>();

			foreach (Match match in Regex.Matches(input, pattern))
			{
				if (match.Value.StartsWith("{{#foreach"))
				{
					stack.Push(match);
				}
				else if (match.Value.StartsWith("{{/foreach") && stack.Count > 0)
				{
					var startMatch = stack.Pop();
					var startVar = ExtractVariableName(startMatch.Value);
					var endVar = ExtractVariableName(match.Value);

					if (startVar == endVar)
					{
						matches.Add(new BlockInfo
						{
							StartIndex = startMatch.Index + 1,
							EndIndex = match.Index + 1 + match.Length,
							BlockName = startVar
						});
					}
				}
			}

			matches.Sort((x, y) => x.StartIndex.CompareTo(y.StartIndex));

			return matches;
		}

		private static string ExtractVariableName(string tag)
		{
			var startIndex = tag.StartsWith("{{#foreach") ? 10 : 11;
			var length = tag.Length - startIndex - 2;
			return tag.Substring(startIndex, length).Trim();
		}
	}
}