https://github.com/rodrigorc/pomelo

Implementation of the Lemon parser generator as a Rust procedural macro
https://github.com/rodrigorc/pomelo

lemon-parser lemon-parser-generator rust-macro

Last synced: about 2 months ago
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Implementation of the Lemon parser generator as a Rust procedural macro

• Host: GitHub
• URL: https://github.com/rodrigorc/pomelo
• Owner: rodrigorc
• License: apache-2.0
• Created: 2019-06-12T16:40:05.000Z (almost 7 years ago)
• Default Branch: master
• Last Pushed: 2025-09-25T09:45:35.000Z (8 months ago)
• Last Synced: 2026-03-13T05:52:50.207Z (3 months ago)
• Topics: lemon-parser, lemon-parser-generator, rust-macro
• Language: Rust
• Size: 324 KB
• Stars: 53
• Watchers: 2
• Forks: 9
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE-APACHE

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README

          
# pomelo

A procedural macro to create Lemon-like parsers.

[![Travis-CI Status](https://travis-ci.com/rodrigorc/pomelo.svg?branch=master)](https://travis-ci.com/rodrigorc/pomelo)

[![Latest version](https://img.shields.io/crates/v/pomelo.svg)](https://crates.io/crates/pomelo)

[![Documentation](https://docs.rs/pomelo/badge.svg)](https://docs.rs/pomelo)

Pomelo is a port to Rust of the Lemon Parser Generator (from now on, Lemon\_C) originally written

by D. Richard Hipp for his SQLite parser.  It is based on a previous attempt to port Lemon to Rust

(Lemon\_Rust), but now it is written as a Rust procedural macro, so it does not contain any of the

original C code (although it uses the same algorithms). Thus the change in name to a different

citrus fruit.

## Getting Started

It is recommended to go to [crates.io](https://crates.io/crates/pomelo) for

the newest released version, as well as links to the newest builds of the docs.

Just add the following dependency to your Cargo manifest:

```toml

[dependencies]

pomelo = "*"

```

## Example

```rust

use pomelo::pomelo;

pomelo! {

    %type input Vec;

    %type numbers Vec;

    %type Number i32;

    input ::= numbers?(A) { A.unwrap_or_else(Vec::new) };

    numbers ::= Number(N) { vec![N] }

    numbers ::= numbers(mut L) Comma Number(N) { L.push(N); L }

}

fn main() -> Result<(), ()> {

    use parser::{Parser, Token};

    //Real world code would use a tokenizer

    let tokens = vec![

        Token::Number(1),

        Token::Comma,

        Token::Number(2),

        Token::Comma,

        Token::Number(3),

    ];

    let mut p = Parser::new();

    for tok in tokens.into_iter() {

        p.parse(tok)?;

    }

    let data = p.end_of_input()?;

    assert_eq!(data, vec![1, 2, 3]);

    Ok(())

}

```

See more examples in the [github repo folder](https://github.com/rodrigorc/pomelo/tree/master/examples).

## License

Licensed under either of

 * Apache License, Version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or http://www.apache.org/licenses/LICENSE-2.0)

 * MIT license ([LICENSE-MIT](LICENSE-MIT) or http://opensource.org/licenses/MIT)

at your option.

### Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted

for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any

additional terms or conditions.