Evaluroll is a dice roll evaluator for tabletop games. It supports dice notation and basic arithmetic, as specified in the roll20 spec. It also supports keeping and dropping dice, as well as parenthesized expressions.

It also supports parsing into an AST, which can be used to evaluate the expression multiple times.

Parsing an expression into an AST:

let ast = evaluroll::parse("1d20")?;

Evaluating an AST:

use evaluroll::Eval;

let ast = evaluroll::parse("1d20")?;

let mut rng = rand::thread_rng();
let output = ast.eval(&mut rng)?;

assert_eq!(1, output.rolls.len());
assert!((1..=20).contains(&output.total));

Evaluating an expression directly:

let mut rng = rand::thread_rng();
let output = evaluroll::eval(&mut rng, "1d20")?;

assert_eq!(1, output.rolls.len());
assert!((1..=20).contains(&output.total));

Evaluroll has the following features:

• trace: Enables tracing of the AST and the output of the parser.

License: MIT