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//! Contains implementation of the `CollectDispatch` trait for every enum
//! defined in the standard library.
//!
//! Every `std` enum should additionaly have a custom trait entitled `CollectE`
//! (`E` being the name of the enum), which can be used as an iterator adapter.

use crate::prelude::*;

implement_dispatch!(Result<T, E>, Ok(T), Err(E));

/// Allows to collect values from an iterator by dispatching `Ok` variants
/// and `Err` variants in two different containers.
pub trait CollectResult<A, B> {
    /// Collects values and dispatch them.
    fn dispatch_result<C: Default + Extend<A>, D: Default + Extend<B>>(self) -> (C, D);
}

impl<T, E, I: Iterator<Item = Result<T, E>>> CollectResult<T, E> for I {
    fn dispatch_result<C: Default + Extend<T>, D: Default + Extend<E>>(self) -> (C, D) {
        use crate::prelude::*;

        Result::dispatch(self)
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn collect_result_impl() {
        let i = vec![Ok(42), Err("foo"), Ok(101), Err("bar")].into_iter();
        let (some_oks, some_errs): (Vec<_>, Vec<_>) = i.dispatch_result();

        assert_eq!(
            some_oks,
            vec![42, 101],
        );
        assert_eq!(
            some_errs,
            vec!["foo", "bar"],
        );
    }
}