JSONExport.cs

using System;
using Irony.Parsing;
using System.Collections.Generic;
using Newtonsoft.Json;
using System.Linq;

namespace XLParser
{
	public class JSONExport
	{
		public JSONExport ()
		{
		}

		public string ParseToJSON (string formula)
		{

			ParseTreeNode root;
			try {
				root = XLParser.ExcelFormulaParser.Parse (formula);
			} catch (ArgumentException) {
				Type grammar = typeof(ExcelFormulaGrammar);

				var r = new Parser ((Grammar)Activator.CreateInstance (grammar)).Parse (formula);
				return (JsonConvert.SerializeObject (new
						{
							error = "Parse error",
							formula = formula,
							message = r.ParserMessages.Select (m => new
								{
									level = m.Level.ToString (),
									line = m.Location.Line + 1,
									column = m.Location.Column + 1,
									msg = m.Message
				//String.Format("{0} at {1}: {2}", m.Level, m.Location, m.Message)
								}).FirstOrDefault ()

						}));

			}

			return (JsonConvert.SerializeObject (
				ToJSON (root),
				Formatting.Indented,
				new JsonSerializerSettings {
					NullValueHandling = NullValueHandling.Ignore,
				}
			));
		}

		private JSONNode ToJSON (ParseTreeNode node)
		{
			return new JSONNode {
				name = NodeText (node),
				children = node.ChildNodes.Count == 0 ? null : node.ChildNodes.Select (ToJSON)
			};
		}

		private class JSONNode
		{
			public string name;
			public IEnumerable<JSONNode> children;
		}

		private string NodeText (ParseTreeNode node)
		{
			if (node.Term is NonTerminal)
				return node.Term.Name;

			// These are simple terminals like + or =, just print them
			// For other terminals, print the terminal name + contents
			return node.Term.Name.Length <= 2 ? ExcelFormulaParser.Print(node) : $"{node.Term.Name}[\"{ExcelFormulaParser.Print(node)}\"]";
		}

	}
}