An out-of-box Lua parser written in Lark

Such parser handles a relaxed version of Lua 5.3 grammar.

This is a Python-Lark implementation of Lua 5.3 parser. It has the following features:

1. the grammar is compatible to LALR(1)/LR(1)/ALL(*)
2. the generated parser creates declarative and typed Python dataclasses instead of error-prone CSTs -- that's why we call it "out-of-box".

Fable.Sedlex, which is an F# port of OCaml sedlex project and transpiled into Python, is used in this parser to achieve high-quality lexer that avoids unnecessary collisions of lexical rules.

Motivation

This project serves as a control group of comparisons against Typed BNF. We tend to show the conciseness, declarativity, simplicity, and other advantages of TypedBNF.

Limitations

It supports full lua 5.3 syntax except

1. assignment left-hand side can take arbitrary expressions, which is invalid in real lua syntax. This can be checked after parsing.

2. support for nested literal strings is limited: only [[...]], [[=]], [=[...]=] are correctly supported.

3. comments support only -- ... form, i.e., line comments.

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