Minimal JSON Parser written in go

Purpose

This project is a solution for Write Your Own JSON Parser build for my personal educational purposes

Features

• Parse json into interface{}
• TODO: implement json stringify

Implementation Details

The implementation is based on the json specification Introducing JSON.

Lexical analysis

This step is responsible to create the tokens. A json scanner was implemented from scratch to accomplish this task.

Syntax analysis

This step is responsible to validate the correct structure that matches the formal grammar and create the syntax tree. The parser implemented in this project is a recursive descent parser based on the json context free grammar seen in the specification Introducing JSON.

Syntax tree

The json is parsed directly as an interface{}. Can be used exactly like go manipulates Generic JSON

Example Usage

package main

import (
	"JSONParser/JSONParser"
	"JSONParser/Util"
	"log"
	"os"
)

func main() {
	input, err := os.ReadFile("tests/step4/valid2.json")

	if err != nil {
		log.Fatal(err)
	}

	parsed, err := JSONParser.Parse(input)
	if err != nil {
		log.Fatal(err)
	}

	Util.Printify(parsed)
}

File tests/step4/valid2.json

{
  "key": "value",
  "y": "\u0020",
  "e": 12.5e-4,
  "e2": 12e+4,
  "e3": 12e-4,
  "key-n": 101000,
  "n" : -12445.1,
  "key-o": {
    "inner key": "inner value"
  },
  "key-l": [
    "list value"
  ],
  "l" : [1, 2, "dd", 3],
  "nested": {
    "n": {
      "attr": true
    }
  }
}

Output

{
  "key-n": 101000,
  "n": -12445.1,
  "key-l": ["list value"],
  "e": 0.00125,
  "e2": 120000,
  "e3": 0.0012,
  "key-o": {
    "inner key": "inner value"
  },
  "l": [1, 2, "dd", 3],
  "nested": {
    "n": {
      "attr": true
    }
  },
  "key": "value",
  "y": " "
}

How to run

1. clone the repo git clone https://github.com/Leonardpepa/JSONParser
2. build go build
3. run on windows JSONParser.exe
4. run on linux ./JSONParser
5. test go test ./...

Tests

The parser is tested comparing the results against the native go json package. Run the tests go test ./...