//! This example builds similar functions where one deals with a Trivial static
//! fraction that (by its parameters and number sizes) doesn't have any illegal
//! values, and a NotTrivial one that has. This program's (--release) code can
//! be viewed with `objudump -d --demangle` or similar.

#![feature(associated_consts)]

extern crate staticfraction;

#[derive(Default)]
struct TrivialDescription;
impl staticfraction::StaticFractionDescription<u32> for TrivialDescription {
    const NUM_OFFSET: u32 = 0;
    const NUM_FACTOR: u32 = 1;
    const DENOM: u32 = 100;
}

/// For this type, every value is OK
type Trivial = staticfraction::StaticFraction<u16, u32, TrivialDescription>;

#[derive(Default)]
struct NotTrivialDescription;
impl staticfraction::StaticFractionDescription<u32> for NotTrivialDescription {
    const NUM_OFFSET: u32 = 0;
    const NUM_FACTOR: u32 = 65536 * 2;
    const DENOM: u32 = 99;
}

/// For this type, only about half the values are valid
type NotTrivial = staticfraction::StaticFraction<u16, u32, NotTrivialDescription>;

/// With release builds, this produces only a few bytes of machine code --
/// looks like it's really just returning the input value.
#[inline(never)]
fn should_be_small(raw: u16) -> Trivial {
    Trivial::new_from_stored_checked(raw).unwrap()
}

/// This needs to (and does) produce more complex code. I'd expect it to be
/// checking the input against a constant (and, failing that), panicking. What
/// it actually does with current nightlies is to run something through
/// try_from, which IMO should be constant-propagatable, so there is room for
/// enhancement here.
#[inline(never)]
fn should_be_checking(raw: u16) -> NotTrivial {
    NotTrivial::new_from_stored_checked(raw).unwrap()
}

fn main() {
    let tested = should_be_small(42);
    debug_assert!(tested != 1);

    let tested = should_be_checking(42);
    debug_assert!(tested != 1);
}