Struct evalexpr::Function

pub struct Function { /* fields omitted */ }

A user-defined function. Functions can be used in expressions by storing them in a Context.

Examples

use evalexpr::*;

let mut context = HashMapContext::new();
context.set_function("id".into(), Function::new(Some(1), Box::new(|arguments| {
    Ok(arguments[0].clone())
}))).unwrap(); // Do proper error handling here
assert_eq!(eval_with_context("id(4)", &context), Ok(Value::from(4)));

Methods

impl Function

pub fn new(
    argument_amount: Option<usize>,
    function: Box<dyn Fn(&[Value]) -> EvalexprResult<Value>>
) -> Self

Creates a user-defined function.

The argument_amount is the amount of arguments this function takes. It is verified before the actual function is executed, assuming it is not None.

The function is a boxed function that takes a slice of values and returns a EvalexprResult<Value, Error>.

Trait Implementations

impl Debug for Function

fn fmt(&self, f: &mut Formatter) -> Result<(), Error>

Formats the value using the given formatter.