📘 Grammar Ambiguity Checker & LR(1) Parser

A full-stack application that analyzes context-free grammars (CFGs) using LR(1) parsing. The system calculates FIRST & FOLLOW sets, builds LR(1) item sets, generates the LR(1) parsing table, detects grammar ambiguity (shift/reduce or reduce/reduce conflicts), and supports parse simulation for input strings.

🚀 Project Overview

This project combines:

• 🔹 Python Backend — Grammar processing, LR(1) construction, and parsing logic
• 🔹 React + Vite Frontend — Interactive UI for entering grammars and simulating parsing

The system guides users through fundamental compiler concepts such as FIRST/FOLLOW set calculation, LR(1) table construction, and conflict detection.

🧠 What It Does

• 📌 Computes FIRST and FOLLOW sets for CFGs
• 📌 Constructs LR(1) item sets
• 📌 Generates LR(1) parsing tables
• 📌 Detects ambiguity via parsing table conflicts
• 📌 Simulates parsing of input strings
• 📌 Displays step-by-step parse actions

💻 Features

📊 Grammar Analysis

• Validates CFG input
• Handles ε (epsilon) productions
• Displays computed FIRST & FOLLOW sets

📈 LR(1) Table Generation

• Shows item sets and transitions
• Highlights shift/reduce and reduce/reduce conflicts
• Indicates ambiguity clearly

▶️ Parse Simulation

• Step through input parsing
• View stack, input, and action transitions
• Debug grammars interactively

🧠 Learning Focus

This tool is perfect for students and developers learning compilers, automata, and formal languages.

🛠️ Tech Stack

Component	Technology
Frontend	React, Vite
Backend	Python
UI Libraries	(React components you use)
Grammar Engine	Custom Python parser logic

🗂 Project Structure

CD-PROJECT/
├── backend/      # Python grammar and parser logic
├── frontend/     # React + Vite UI
├── README.md
└── .gitignore

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⚙️ How It Works

1. Enter CFG:
   Define grammar productions in the frontend.

2. Compute FIRST & FOLLOW:
   Backend calculates sets using standard CFG algorithms.

3. Build LR(1) Items:
   Generates canonical LR(1) item sets.

4. Create Parsing Table:
   Produces ACTION and GOTO tables.

5. Check Ambiguity:
   Detects shift/reduce and reduce/reduce conflicts.

6. Simulate Parsing:
   Step through stack/input transitions for given input strings.

🏃 Running the App

Clone the Repository

git clone https://github.com/tanikaaaa/CD-PROJECT.git
cd CD-PROJECT

Backend (Python)

1. Navigate to backend:

   cd backend

2. Create a virtual environment (optional but recommended):

   python -m venv venv
   source venv/bin/activate      # macOS/Linux
   .\venv\Scripts\activate       # Windows

3. Install dependencies:

   pip install -r requirements.txt

4. Run the backend server:

   python app.py

Frontend (React + Vite)

1. Navigate to frontend:

   cd frontend

2. Install node dependencies:

   npm install

3. Start dev server:

   npm run dev

   Visit the app at the URL shown in the terminal (usually http://localhost:5173).

🤝 Use Cases

• Grammar validation and debugging
• Educational tool for compilers coursework
• Visualizing parsing steps and conflicts
• Understanding FIRST/FOLLOW and LR(1) mechanics

Process:

1. FIRST/FOLLOW sets computed
2. LR(1) item sets built
3. Parsing table generated
4. Ambiguity detected
5. Input simulation executed

🛠 Future Enhancements

• Support for other parser types (LL(1), SLR(1), LALR(1))
• Visual graph representation of item sets
• Export parsing tables and reports
• Web deployment & hosting