Implement JSON Comment Interpreter

Introduction

In this project, you will learn how to implement a JSON comment interpreter. This is a useful feature when working with JSON configuration files, as it allows you to add comments to explain the reasoning behind certain settings.

👀 Preview

$ /usr/local/go/bin/go test
PASS
ok      jsonex  0.002s

🎯 Tasks

In this project, you will learn:

• How to initialize a Go module and set up the necessary environment
• How to implement a JSON comment parsing function that supports the # character as a comment
• How to handle cases where the " character is part of the string content
• How to test the JSON comment parsing function

🏆 Achievements

After completing this project, you will be able to:

• Understand how to work with Go modules and set up a development environment
• Implement a custom JSON parser that supports comments
• Write tests to ensure the correctness of your JSON comment parsing function
• Apply your newfound knowledge to enhance your JSON-based configuration files with informative comments

Skills Graph

Initialize the Project

In this step, you will learn how to initialize the project and set up the necessary environment. Follow the steps below to complete this step:

1. Open a terminal and navigate to the /home/labex/project directory.

2. Initialize the Go module using the following command:

   $ /usr/local/go/bin/go mod init jsonex

3. Install the required packages by running the following command:

   $ /usr/local/go/bin/go get github.com/stretchr/testify/assert

Implement the JSON Comment Parsing Function

In this step, you will learn how to implement the JSON comment parsing function. Follow the steps below to complete this step:

1. Open the jsonex.go file in the editor.

2. The Unmarshal function is parsing JSON encoded data and storing the result.

   • Support # as the comment character in JSON, and everything after the character should be considered as a comment.
   • When " is part of the string content, it should be represented as \", and the \ should be represented as \\.

3. Implement the trimCommentsLine function to check if a line is a comment or not. If it's not a comment, return the line itself.

4. The complete code for the trimCommentsLine functions should be as follows:

   // trimCommentsLine check the line is comment or not, if not, return the line itself
   func trimCommentsLine(line []byte) []byte {
   	var newLine []byte
   	var i, quoteCount int
   	lastIdx := len(line) - 1
   	for i = 0; i <= lastIdx; i++ {
   		// if the char is '\'
   		if line[i] == '\\' {
   			// if the index is not the last index, check if the next char is '"' or '\', if so, append it
   			if i != lastIdx && (line[i+1] == '\\' || line[i+1] == '"') {
   				newLine = append(newLine, line[i], line[i+1])
   				i++
   				continue
   			}
   		}
   
   		// if the char is '"', increase the quoteCount
   		if line[i] == '"' {
   			quoteCount++
   		}
   
   		// if the char is '#'
   		if line[i] == '#' {
   			// if the quoteCount is even, break, because the '#' is not in the string,
   			// is in the comment
   			if quoteCount%2 == 0 {
   				break
   			}
   		}
   
   		newLine = append(newLine, line[i])
   	}
   
   	return newLine
   }

Test the JSON Comment Parsing Function

In this step, you will learn how to test the JSON comment parsing function. Follow the steps below to complete this step:

1. Open a terminal and navigate to the /home/labex/project directory.

2. Run the following command to execute the tests:

   $ cd /home/labex/project
   $ /usr/local/go/bin/go test

3. If the tests pass, you will see the following output:

   PASS
   ok      jsonex  0.002s

4. If you encounter a timeout error, execute the following commands in the terminal and then click the re-inspect button to pass the check:

   $ cd /home/labex/project
   $ /usr/local/go/bin/go test

Congratulations! You have successfully implemented the JSON comment parsing function and tested it. You can now use this function in your project.

Summary

Congratulations! You have completed this project. You can practice more labs in LabEx to improve your skills.