[](https://crates.io/crates/cypress)
[](https://docs.rs/cypress)
# Cypress
A parser library inspired by a scaled down derivative of the FParsec combinator library in F#.
I was also inspired by chumsky a very elegant parser combinator library which I have enjoyed using!
The goal of this project was to develop a simple parser combinator library with which people can write and parse expressive languages with ease. It is still a work in progress and there are areas that still need to be cleaned up but I believe that I have achieved my goal.
## Features
- Expressive combinators
- Labelling parser for easier debugging
- Generic over input and output
- Macros for ergonomic parsing for common tasks
## Example
I have populated `/examples` with a parser of certain simple languages, along with an evaluator for a select few, to show using this library by example. I hope to populate one or two more sophisticated implementations soon. Below is a simple parser for [BrainFuck](https://gist.github.com/roachhd/dce54bec8ba55fb17d3a) which seems to be the go to simple language parser that libraries refer to, so here it is.
```rust
use cypress::prelude::*;
#[derive(Debug, Clone, PartialEq)]
enum Instruction {
Left,
Right,
Increment,
Decrement,
Read,
Write,
Loop(Vec<Self>),
}
fn bf_parser<'a>() -> impl Parser<'a, u8, Vec<Instruction>> {
recursive(|expr| {
let instr = choice!(
select! {
'<' => Instruction::Left
'>' => Instruction::Right
'+' => Instruction::Increment
'-' => Instruction::Decrement
',' => Instruction::Read
'.' => Instruction::Write
}
expr.many()
.between(just('['), just(']'))
.map(Instruction::Loop)
);
Box::new(instr)
})
.many()
.until_end()
}
let input = b"+++++[>>+<<-]".into_input();
// parse bf input
bf_parser.parse(input);
```
## Note
This is my first published project so if you have thoughts please feel free to open an issue or a PR with ideas and fixes!
## License
cypress is licensed under the BSD 3 license (see `LICENSE` in the main repository).