Grepper

This repository contains an implementation of the grep tool built in C++ as part of the Codecrafters "Build Your Own Grep" Challenge. The project focuses on building a regular expression (Regex) engine from scratch, capable of searching through text with support for various Regex patterns and features.

About The Project

This project is an attempt to implement grep, a command-line utility for searching text using regular expressions, in C++. Along the way, we will dive into the workings of regex syntax, character classes, quantifiers, and more. By the end of the challenge, you will have a deeper understanding of how Regex works under the hood and be able to search and match patterns in text just like the real grep tool.

Key Features:

• Matching literal characters
• Supporting various regex features such as character classes, anchors, quantifiers, and more
• Backreference support
• Regex alternation
• Wildcard matches

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Built With

The project is developed using:

• C++: The core language for implementing our custom grep functionality.
• POSIX standard: For guiding the implementation to match grep's expected behavior.

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Getting Started

To get started with building and running your own grep implementation, follow the instructions below.

Prerequisites

Make sure you have the following installed:

• GCC or any other C++ compiler.
• Make (optional, for build automation).

Repository Setup

1. Clone the repository:

   git clone https://github.com/your_username/grep_cpp.git

2. Navigate to the project directory:

   cd grep_cpp

3. Compile the project:

   g++ -o grep_cpp main.cpp

4. Run the program with a test file:

   ./grep_cpp "pattern" test_file.txt

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Features

Match a Literal Character

The most basic functionality of grep is to search for a literal string within a text.

Match Digits

Our implementation supports matching digits (e.g., \d).

Match Alphanumeric Characters

Match alphanumeric characters using character classes.

Positive Character Groups

We can match specific groups of characters like [a-zA-Z].

Negative Character Groups

Supports negation in character groups, like [^a-z].

Combining Character Classes

You can combine character classes and patterns for complex matching.

Anchors (Start and End of String)

Use the ^ (start of string) and $ (end of string) anchors to match text at the beginning or end of a string.

Quantifiers

• +: Match one or more times
• ?: Match zero or one times

Wildcards

Supports . wildcard to match any single character.

Alternation

Supports the | operator to match alternative patterns (e.g., abc|xyz).

Backreferences

• Single Backreference: Allows matching repeated patterns.
• Multiple Backreferences: Matches more complex repeated groups.
• Nested Backreferences: Supports matching nested patterns using backreferences.

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Roadmap

• Match literal characters
• Implement digit matching and alphanumeric character groups
• Add support for character groups (positive and negative)
• Implement anchors (start/end of string)
• Add quantifiers and alternation support
• Implement backreferences
• Optimize regex matching algorithm for performance

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Contributing

Contributions are welcome! If you'd like to contribute to the project, feel free to fork the repo and submit a pull request.

1. Fork the project.
2. Create your feature branch (git checkout -b feature/newFeature).
3. Commit your changes (git commit -m 'Add some feature').
4. Push to the branch (git push origin feature/newFeature).
5. Open a pull request.

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License

Distributed under the MIT License. See LICENSE for more information.

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Contact

Your Name - @Linkedin - obidur.shawal@gmail.com

Project Link: https://github.com/Ashfinn/grepper

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