Python-like Interpreter (C++)

Description

This repository contains a small interpreter written in C++ with a syntax inspired by Python. It is an educational project to learn about lexical analysis (lexer), parsing, AST (abstract syntax tree) nodes, and evaluation/interpretation.

Project layout

• interpreter/ - core implementation: Lexer, Parser, Interpreter, AST Node definitions, Token, Value, and File utilities.
• main.cpp - C++ entry point.

Prerequisites

• CMake (>= 3.10 recommended)
• A recent C++ compiler (Clang or GCC with C++11/14/17 support)
• (Optional) An IDE such as CLion or VSCode, or build tools like Make/Ninja

How to build (macOS / Linux / Windows (MSYS2))

Open a terminal at the repository root and run:

mkdir -p build && cd build
cmake ..
cmake --build .

Running the interpreter

To run the interpreter on Linux and MacOS:

cd build
./python_interpreter path/to/script.py

To run the interpreter on Windows:

cd build
python_interpreter.exe path/to/script.py

Supported language features

• Variables, numbers, strings and arithmetic/comparison expressions (+ - * / > < ==, unary -)
• print(...) with multiple comma-separated arguments
• if / else
• for x in range(...), with the same signatures as Python:
  • range(end)
  • range(start, end)
  • range(start, end, step) (including negative steps, e.g. counting down)
• Functions with def, parameters and return (including recursion). Functions have their own local scope: assignments inside a function do not leak to the caller.

Example script (example.py)

# example.py
x = 0
for i in range(5):
    print(i)

print("End of loop")

def factorial(n):
    if n < 2:
        return 1
    return n * factorial(n - 1)

print(factorial(5))

Expected output (implementation-dependent):

0
1
2
3
4
End of loop
120

Code structure

• interpreter/Lexer.* - tokenization
• interpreter/Parser.* - AST construction
• interpreter/Interpreter.* - AST execution/evaluation
• interpreter/Node/ - AST node definitions (AssignNode, ForNode, PrintNode, FunctionDefNode, ReturnNode, CallNode, etc.)
• interpreter/File.* - file reading utilities