Скачать или смотреть Mastering ANTLR4: How to Change Source Code and Retrieve It Back

A comprehensive guide on using ANTLR4 for changing source code, featuring practical examples and helpful tips. Learn how to manipulate source code effectively!
---
This video is based on the question https://stackoverflow.com/q/64960966/ asked by the user 'John Smith' ( https://stackoverflow.com/u/8467909/ ) and on the answer https://stackoverflow.com/a/64961301/ provided by the user 'John Smith' ( https://stackoverflow.com/u/8467909/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: ANTLR4 - How to change source code and get it back?

Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/l...
The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license.

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
Mastering ANTLR4: How to Change Source Code and Retrieve It Back

ANTLR4 (Another Tool for Language Recognition) is a powerful parser generator widely used for processing structured text and decoding programming languages. If you've ever needed to rewrite or manipulate code programmatically, understanding how to use ANTLR4 can greatly enhance your capabilities.

In this guide, we'll tackle a specific problem: how to change source code and then retrieve the modified version. We will cover the steps needed to replace string literals and erase function names and brackets using ANTLR4, specifically in the context of JavaScript with antlr4ts. Let’s dive in!

The Problem

Imagine you have a block of code that you want to modify for various reasons. For example, you might want to:

Replace string literals:

Change occurrences of a placeholder string like %%var%% to something more meaningful, like SOMETHING.

Erase function names and brackets:

Strip down function declarations to make the code cleaner or to fit a certain coding style.

Here's what our starting code looks like:

[[See Video to Reveal this Text or Code Snippet]]

On the surface, this may seem straightforward, but doing this programmatically requires an understanding of token manipulation with ANTLR4.

The Solution

Step 1: Setup ANTLR4 Environment

To get started, ensure you have ANTLR4 and antlr4ts installed in your JavaScript environment. You will need:

ANTLR4 Runtime

ANTLR4 TypeScript target (antlr4ts)

Step 2: Create the Lexer and Parser

The first step in manipulating your source code is to create a Lexer and Parser from your code input. Here’s how you can do it:

[[See Video to Reveal this Text or Code Snippet]]

This code processes your input string (code) and prepares it for further parsing.

Step 3: Utilize TokenStreamRewriter

The core of our solution lies in TokenStreamRewriter, which allows us to modify tokens at specific indices in the stream. Here’s how to instantiate the rewriter:

[[See Video to Reveal this Text or Code Snippet]]

Step 4: Implement a Custom Visitor

Using the Visitor design pattern in ANTLR4, we can define specific actions for the nodes in our parse tree. Here’s an example of a custom visitor that handles string replacement:

[[See Video to Reveal this Text or Code Snippet]]

Here, we are specifically targeting string literals and instructing the rewriter to replace them.

Step 5: Retrieving the Rewritten Code

Finally, after all modifications, you can retrieve the modified code by calling:

[[See Video to Reveal this Text or Code Snippet]]

This command will print the modified version of your source code.

Conclusion

By using ANTLR4 along with antlr4ts, you can effectively manipulate code programmatically, whether you're replacing strings or altering function signatures. The combination of lexical analysis and token stream rewriting provides a robust framework for code transformation.

Make sure to experiment with your specific use cases and refine your visitor methods for various modifications. Happy coding with ANTLR4!