C# JSON Parser

This is a simple JSON Parser implementation written in c# in accordance with RFC8259 specification. This is a personal project and should not be used in production applications. Instead use the inbuilt System.Text.Json library.

Usage

You can use JSON Converter class to parse the file to a strongly typed object.

using var stream = new FileStream("parse.json", FileMode.Open, FileAccess.Read);
using var reader = new StreamReader(stream);

var converter = new JsonConverter();
var obj = converter.Convert<ImageRef>(reader);
Console.WriteLine(JsonSerializer.Serialize(obj));

The above example will convert this JSON object

{
  "Image": {
    "Width": 800,
    "Height": 600,
    "Title": "View from 15th Floor",
    "Thumbnail": {
      "Url": "http://www.example.com/image/481989943",
      "Height": 125,
      "Width": 100
    },
    "Animated": false,
    "IDs": [116, 943, 234, 38793]
  }
}

to the following strongly typed object

public class Image
{
    public int Width { get; set; }
    
    public int Height { get; set; }
    
    public string Title { get; set; }
    
    public bool Animated { get; set; }
    
    public Thumbnail Thumbnail { get; set; }
    
    public IEnumerable<int> IDs { get; set; }
}

How does it work?

The JSON parser works similarly to most parsers through the following steps

• Lexical Analysis: The JSON file is broken down into a stream of semantically meaningful tokens. This first uses a scanner to look over all the characters and then an evaluator to assign semantic meaning to the tokens. See JsonLexer.cs
• Parsing: The lexical tokens are turned into an abstract syntax tree. This process uses a stack to recursively parse the children of a given node. See JsonParser.cs. The structure of the parsed result is a JsonNode.cs.
• Converting: This stage converts the abtract syntax tree to a strongly typed object using reflection. This process essentially uses DFS to recurse over the objects typs and find equivalents in the JSON node.