2 stable releases
new 2.0.0 | Nov 18, 2024 |
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1.0.0 | Mar 3, 2023 |
#326 in Programming languages
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13KB
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Langen
A tool to create programming languages
Please depend on langen
instead of langen_macro
for this to work correctly!
The crate provides a set of derive macros to generate a lexer and parser. All the heavy computations are done during compilation.
Look at the docs for more information on how to use this.
Usage
use langen::{Grammar, NoErr, Span, Tokens};
#[derive(Tokens, Grammar, Debug)]
#[ignored(r"[ \t]")]
enum Math {
#[token(r"\(")]
LParen,
#[token(r"\)")]
RParen,
#[token(r"\+")]
Plus,
#[token(r"-")]
Minus,
#[token(r"\*")]
Mul,
#[token(r"/")]
Div,
#[token(r"[0-9]+", |s: &str| {s.parse()})]
IntLit(i32),
#[rule(|_span: Span, expr: i32, term: i32| Ok::<i32, NoErr>(expr+term), Expression, Plus, Term)]
#[rule(|_span: Span, expr: i32, term: i32| Ok::<i32, NoErr>(expr+term), Expression, Minus, Term)]
#[rule(|_span: Span, term: i32| Ok::<i32, NoErr>(term), Term)]
#[rule(|_span: Span, term: i32| Ok::<i32, NoErr>(-term), Minus, Factor)]
Expression(i32),
#[rule(|_span: Span, term: i32, factor: i32| Ok::<i32, NoErr>(term*factor), Term, Mul, Factor)]
#[rule(|_span: Span, term: i32, factor: i32| Ok::<i32, NoErr>(term/factor), Term, Div, Factor)]
#[rule(|_span: Span, factor: i32| Ok::<i32, NoErr>(factor), Factor)]
Term(i32),
#[rule(|_span: Span, intlit: i32| Ok::<i32, NoErr>(intlit), IntLit)]
#[rule(|_span: Span, expr: i32| Ok::<i32, NoErr>(expr), LParen, Expression, RParen)]
Factor(i32),
}
let input = "(33+5) * (-34)";
let tokens = Math::scan(input).unwrap();
for (t, s) in &tokens {
println!("{}\t{:?}", s, t);
}
let result = Math::parse(tokens).unwrap();
println!("{:?}", result);
License
This project is licensed under the MIT license
Dependencies
~1.5–2.5MB
~36K SLoC