Struct arithmetic_eval::fns::If

pub struct If;

if function that eagerly evaluates "if" / "else" terms.

Type

fn<T>(bool, T, T) -> T

Examples

let program = "x = 3; if(x == 2, -1, x + 1)";
let block = F32Grammar::parse_statements(Span::new(program)).unwrap();

let mut interpreter = Interpreter::new();
interpreter.insert_native_fn("if", If);
let ret = interpreter.evaluate(&block).unwrap();
assert_eq!(ret, Value::Number(4.0));

You can also use the lazy evaluation by returning a function and evaluating it afterwards:

let program = "x = 3; if(x == 2, || -1, || x + 1)()";
let block = F32Grammar::parse_statements(Span::new(program)).unwrap();

let mut interpreter = Interpreter::new();
interpreter.insert_native_fn("if", If);
let ret = interpreter.evaluate(&block).unwrap();
assert_eq!(ret, Value::Number(4.0));

Trait Implementations

impl Clone for If

fn clone(&self) -> If

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Copy for If

impl Debug for If

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

Formats the value using the given formatter.

impl<T> NativeFn<T> for If where
    T: Grammar,
    T::Lit: Num + Neg<Output = T::Lit> + Pow<T::Lit, Output = T::Lit>, 

fn evaluate<'a>(
    &self,
    args: Vec<SpannedValue<'a, T>>,
    ctx: &mut CallContext<'_, 'a>
) -> EvalResult<'a, T>

Executes the function on the specified arguments.