lua-in-rust

The Lua programming language, implemented in Rust.

Overview

The code is primarily grouped into three modules:

• compiler deals with parsing lua code and converting it into bytecode.
  • lexer converts Lua source code into tokens.
  • parser converts those tokens into bytecode.
  • exp_desc and token are type definitions.
• vm is the largest module. It deals with actually evaluating lua code, and the Rust API.
  • vm itself holds the core functionality of the interpreter.
  • frame deals with evaluating bytecode.
  • lua_val defines the type for values in the VM.
  • object deals with garbage collection.
  • table implements Lua tables.
• lua_std is where any functions in the lua standard library are implemented.
• Other modules:
  • error defines the Error type used throughout the crate.
  • instr defines the VM's instruction set.
  • lib and main are the basic entrypoints for the library/interpreter.

Goals

The goals, in rough order of priority, are:

• Basic comparisons and equality
• and/or expressions with proper short-circuiting
• Basic strings
• if/else/elseif
• while and repeat ... until loops
• Local variables with proper scoping
• Numeric for loops
• Multiple assignment
• Single-line comments
• Function calls
• Function definition
• Tables
• Garbage Collection
• Full table literals
• Error when line starts with left paren and parses as function call
• Multiple return values
• break and continue
• Interned strings
• Unparenthesized function calls
• Better error messages
• Closures
• Lua's next function
• Generic for loops
• Metatables
• Separate array part of tables for integer keys
• Lua's standard library
• A Rust API to parallel Lua's C API
• Coroutines
• Multi-line comments
• Use actual bytecode with variable-length instructions
• Separate luac executable

Building

Like the real Lua, this project currently has zero dependencies. Just run cargo run in the root to launch the interpreter.

Debug options

There are a few environment options which enable debug features. These are all disabled by default. To enable an option, just set it in the environment before compiling (e.g. export LUA_DEBUG_VM=1; cargo build). For details on a debug option, look in the corresponding module.

The options are:

• LUA_DEBUG_PARSER
• LUA_DEBUG_VM
• LUA_DEBUG_GC