C++ Lox Bytecode Virtual Machine

A C++ implementation of the bytecode virtual machine from "Crafting Interpreters" by Robert Nystrom.

Philosophy

This uses some elements of the C++ standard library, but tries to stay close to the philosophy of "doing things from scratch" that the book uses.

For example, that means I use <iostream> and std::format, but wrote a simple resizable array type instead of using std::vector. It also means using C-style tagged unions instead of std::variant.

I have never written a bytecode VM before, so I'm doing it as close to the book in a more type-safe C++ way, and then refactoring into more idiomatic C++ as I go. This won't ever be a production bytecode VM, but it should eventually show my C++ version of how the book does things.

Building

This project currently uses cmake, so you can build as follows.

Use an out-of-tree build:

mkdir build
cd build
cmake ..         # Generate project
cmake --build .  # Build project
ctest            # Run unit tests

Running a .lox file

This will build the bytecode virtual machine and run the associated file:

Example:

python .\scripts\run_sample.py .\samples\expressions.lox --config Release

Acceptance Test Battery

Acceptance tests compare the standard output of running the VM on a file ending in .lox, against the expected output in a a similarly named .expected file.

The acceptance test script builds the VM and then runs the tests in Release mode.

Run the test battery like:

python .\scripts\run_acceptance_test.py