Open Source Rust Parser Generators

argh is a tiny, pragmatic command-line argument parsing library that favors simple, readable code over elaborate configuration. It’s designed for the case where you just want to declare a few flags, accept some positional arguments, and print helpful usage text without wiring up a heavy framework. The API is intentionally compact so you can parse arguments inline near main() and map them straight into native types. It supports short and long options, boolean switches, and key–value flags while keeping error messages and help output understandable for end users. Subcommands can be modeled without much boilerplate, letting you structure larger CLIs while keeping each command self-contained. The overall feel is “get out of your way”: minimal setup, zero magic, and a straightforward path from argv to validated inputs.

Logos is a lexer generator for Rust, designed to create fast and efficient lexers with minimal code. It leverages Rust's procedural macros to define token patterns, streamlining the process of lexical analysis.​

Parser for Rust source code is a major Rust crate for parsing Rust source code (token streams) into a syntax tree (AST) that procedural macros can inspect or transform. The primary target is macro authors: you can parse TokenStreams into syn::File, syn::Item, syn::Expr, syn::Type, etc. It offers rich data structures, fine-grained parsing, span tracking (for error reporting), traversal and mutation APIs (visit, fold, visit_mut), printing back to tokens, and strong feature-gating so you only compile what you need. The documentation emphasises that while the crate is geared for procedural macros (and custom derives), some of the APIs may be of more general use. Using syn you can effectively write code that analyzes or generates Rust code at compile time.

rust-peg is a Parsing Expression Grammar (PEG) parser generator for Rust. It allows developers to define grammars in a concise syntax and generates efficient parsers, facilitating the creation of domain-specific languages and interpreters.​

Tree-sitter is a parser generator tool and an incremental parsing library. It can build a concrete syntax tree for a source file and efficiently update the syntax tree as the source file is edited. General enough to parse any programming language. Fast enough to parse on every keystroke in a text editor. Robust enough to provide useful results even in the presence of syntax errors. Dependency-free so that the runtime library (which is written in pure C) can be embedded in any application. All of Tree-sitter’s parsing functionality is exposed through C APIs. Applications written in higher-level languages can use Tree-sitter via binding libraries like node-tree-sitter or the tree-sitter rust crate, which have their own documentation. To build the library on a POSIX system, just run make in the Tree-sitter directory. This will create a static library called libtree-sitter.a as well as dynamic libraries.