🧠 Mini Interpreter for a Custom Language in Python

A simple yet complete project implementing an interpreter with lexer, parser, AST, and interpreter components in Python.
The custom mini-language supports variables, basic arithmetic operations, and commands like SET, ADD, SUB, and PRINT.

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✨ Features

• 🔤 Lexer: Recognizes keywords, numbers, operators, identifiers, etc.
• 🌳 Parser: Builds an Abstract Syntax Tree (AST)
• 🧮 Interpreter: Executes the AST (assignment, arithmetic, output)
• 🧾 Supports multiple instructions in a session

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🚀 Example

Input:
SET x = 10;
ADD x 5;
SUB x 3;
PRINT x;

Output:
Value of x: 12.0

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📄 Supported Language Elements

Element	Description
SET	Assign a value to a variable (SET x = 5;)
ADD	Add a value to a variable (ADD x 2;)
SUB	Subtract a value from a variable (SUB x 1;)
PRINT	Output the value of a variable (PRINT x;)
+ - * /	Arithmetic operations within expressions
;	End of a statement

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▶️ Running the Program

python compiler.py

You can then enter interactive code, for example:

SET a = 3 + 2 * 4;
PRINT a;

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🛠 Project Structure

main.py                 # Contains lexer, parser, AST, and interpreter  
README.md               # This file  

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🎓 Background & Purpose

This project was created during my self-study as part of the Cyber Security (B.Sc.) program to apply concepts from compiler construction, theoretical computer science, and language processing in a practical way.

The goal was to model the typical stages of a programming language:

• Lexical analysis (tokenizer)
• Syntax analysis (parser + AST)
• Semantic evaluation (interpreter)

📌 This project is especially useful for:

• Students wanting to understand compiler/interpreter concepts in Python
• Teaching purposes, e.g., to visualize language processing
• Portfolio projects, e.g., for scholarships or job applications

The codebase is designed for easy extension (see below).

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💡 Potential Extensions

• IF / ELSE / WHILE (control structures)
• Logical operators (==, >, <, AND, OR)
• PRINT x + 1; (output expressions, not just variables)
• Support for comments in the source (# ...)
• Error messages with context (line, token)

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🔒 Limitations

• No type checking (all values are float)
• No functions or scoping
• No error handling for division by zero, etc.
• Only linear program execution (no control flow branching)

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🧑‍💻 About Me

I am a Cyber Security (B.Sc.) student in a part-time study program with a strong interest in theoretical computer science, digital forensics, and compiler design.
This project was created to independently deepen practical skills in the area of language processing and serves as a portfolio example.

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📄 License

This project is licensed under the MIT License.
A LICENSE file can be added to the repository if needed.