Where is the definition of break_value()?

rockmen1 · August 31, 2018, 3:45pm

from the src of core library, there is this function, but its definition is nowhere to be found. any idea?

    fn find<P>(&mut self, mut predicate: P) -> Option<Self::Item> where
        Self: Sized,
        P: FnMut(&Self::Item) -> bool,
    {
        self.try_for_each(move |x| {
            if predicate(&x) { LoopState::Break(x) }
            else { LoopState::Continue(()) }
        }).break_value()
    }

matklad · August 31, 2018, 3:53pm

github.com

rust-lang/rust/blob/d767ee11616390d128853a06f5addb619e79213f/src/libcore/iter/mod.rs#L383


    }
}
#[inline]
fn from_error(v: Self::Error) -> Self { LoopState::Break(v) }
#[inline]
fn from_ok(v: Self::Ok) -> Self { LoopState::Continue(v) }
}


impl<C, B> LoopState<C, B> {
#[inline]
fn break_value(self) -> Option<B> {
    match self {
        LoopState::Continue(..) => None,
        LoopState::Break(x) => Some(x),
    }
}
}


impl<R: Try> LoopState<R::Ok, R> {
#[inline]
fn from_try(r: R) -> Self {

Found by this search: https://github.com/rust-lang/rust/search?q=LoopState&unscoped_q=LoopState

rockmen1 · August 31, 2018, 3:56pm

Ah! thanks! that’s when google is not very helping in this case!

matklad · August 31, 2018, 4:01pm

FWIW, IntelliJ also works awesome for these kind of searches:

scottmcm · September 2, 2018, 6:36am

Note that that code is equivalent to just

    fn find<P>(&mut self, mut predicate: P) -> Option<Self::Item> where
        Self: Sized,
        P: FnMut(&Self::Item) -> bool,
    {
        self.try_for_each(move |x| {
            if predicate(&x) { Err(x) }
            else { Ok(()) }
        }).err()
    }

I just got myself super confused in the more complicated cases using Err in the successful path, so ended up adding the extra isomorphic-to-Result enum to try to clarify the intent of the code.