arena-terms-parser 0.4.0

Parser for arena-backed, lightweight representations of Prolog-like terms
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# Arena Terms Parser

[![Crates.io](https://img.shields.io/crates/v/arena-terms-parser.svg)](https://crates.io/crates/arena-terms-parser)
[![Documentation](https://docs.rs/arena-terms-parser/badge.svg)](https://docs.rs/arena-terms-parser)
[![License: LGPL-3.0-or-later](https://img.shields.io/badge/License-LGPL%203.0--or--later-blue.svg)](https://www.gnu.org/licenses/lgpl-3.0)
[![Rust](https://img.shields.io/badge/rust-stable-brightgreen.svg)](https://www.rust-lang.org)

Parser for **arena-backed, Prolog-like terms**.

This crate provides a lexer, parser, and operator handling for Prolog-style
terms. It depends on the [`arena_terms`](https://crates.io/crates/arena_terms)
crate to store terms efficiently in an arena and is built on top of the
[`parlex`](https://crates.io/crates/parlex) core library.


## Features

- **Lexer**
  Tokenizes atoms, variables, numbers, strings, dates, and symbols.

- **Parser**
  An SLR(1) parser (generated by [`parlex-gen`](https://crates.io/crates/parlex-gen)) that
  produces `arena_terms::Term` values.

- **Operators**
  Dynamically handles operator fixity, associativity, and precedence rules.

- **Arena-backed**
  Terms are stored compactly in arenas for efficient allocation and traversal.


## Usage

Parsing a string into arena terms:

```rust
use arena_terms::Arena;
use arena_terms_parser::{TermParser, define_opers};
use try_next::{IterInput, TryNextWithContext};

const DEFS: &str = "[
    op('+'(x,y), infix, 380, left),
    op('*'(x,y), infix, 400, left),
]";

const TERMS: &str = "
    likes(mary, pizza).
    2 + 2 * 3 = 8 .
";

fn main() {
    let mut arena = Arena::try_with_default_opers().unwrap();
    define_opers(&mut arena, IterInput::from(DEFS.bytes())).unwrap();
    let mut parser = TermParser::try_new(IterInput::from(TERMS.bytes())).unwrap();

    while let Some(term) = parser.try_next_with_context(&mut arena).unwrap() {
        println!("{}", term.display(&arena));
    }
}
```


## CLI

Build the binary with:

```bash
cargo build --release --bin arena-terms-parser
```

Then run:

```bash
./target/release/parser --terms input.ax
```


## Documentation

For detailed API documentation, visit [docs.rs/arena-terms-parser](https://docs.rs/arena-terms-parser).


## License

Copyright (c) 2005–2025 IKH Software, Inc.

Released under the terms of the GNU Lesser General Public License, version 3.0 or (at your option) any later version (LGPL-3.0-or-later).

## See Also

- [parlex](https://crates.io/crates/parlex) - Parlex core core library
- [parlex-gen](https://crates.io/crates/parlex-gen) - Lexer and parser generation tools (`alex` and `aslr`)
- [arena-terms](https://crates.io/crates/arena-terms) - Arena-backed Prolog-like terms