Logos is a lexer generator that produces ridiculously fast lexers in Rust.
The problem Logos solves is the need to write lexers that are both simple to define and performant in execution. Rather than requiring hand-written optimization, the tool combines all token definitions into a single deterministic state machine at compile time. It then applies several optimization techniques: converting branches into lookup tables or jump tables, preventing backtracking within token definitions, unwinding loops, and batching reads to minimize bounds checking. All this compilation work happens before runtime, leaving only the optimized lexer for execution.
Logos suits projects where lexing performance matters and you want to avoid the complexity of hand-optimizing a lexer. It is particularly valuable when building parsers or language tools where tokenization speed directly affects overall throughput. The tool is designed for developers working in Rust who need a straightforward way to define tokens through a declarative interface while still achieving performance that would be difficult to match through manual implementation.
The project maintains an active contribution process with a documented release procedure and welcomes bug reports, suggestions, and new features through its issue and pull request channels. A contributing guide is available to help potential contributors understand the codebase and development practices.
