expr-lang 0.2.0

expr-lang

Implementation of expr in rust.

Usage

use expr::{Context, Parser};

fn main() {
    let mut p = Parser::new();

    let mut ctx = Context::default();
    ctx.insert("two".to_string(), 2);

    let three: i64 = p.eval("1 + two", &ctx).unwrap().as_number().unwrap();
    assert_eq!(three, 3);

    p.add_function("add", |c| {
        let mut sum = 0;
        for arg in c.args {
            sum += arg.as_number().unwrap();
        }
        Ok(sum.into())
    });

    let six: i64 = p.eval("add(1, two, 3)", &ctx).unwrap().as_number().unwrap();
    assert_eq!(six, 6);
}