use core::ops::{Bound, Range, RangeBounds};

pub(crate) fn third<A, B, C>(t: (A, B, C)) -> C {

    t.2

}

#[track_caller]

pub(crate) fn simplify_range<R>(range: R, len: usize) -> Range<usize>

where

    R: RangeBounds<usize>,

{

    let start = match range.start_bound() {

        Bound::Unbounded => 0,

        Bound::Included(&i) if i <= len => i,

        Bound::Excluded(&i) if i < len => i + 1,

        Bound::Included(i) | Bound::Excluded(i) => {

            panic!("range start index {i} out of range for slice of length {len}")

        }

    };

    let end = match range.end_bound() {

        Bound::Unbounded => len,

        Bound::Excluded(&i) if i <= len => i,

        Bound::Included(&i) if i < len => i + 1,

        Bound::Included(i) | Bound::Excluded(i) => {

            panic!("range end index {i} out of range for slice of length {len}")

        }

    };

    if start > end {

        panic!(

            "range start index {:?} should be <= range end index {:?}",

            range.start_bound(),

            range.end_bound()

        );

    }

    start..end

}

pub(crate) fn try_simplify_range<R>(range: R, len: usize) -> Option<Range<usize>>

where

    R: RangeBounds<usize>,

{

    let start = match range.start_bound() {

        Bound::Unbounded => 0,

        Bound::Included(&i) if i <= len => i,

        Bound::Excluded(&i) if i < len => i + 1,

        _ => return None,

    };

    let end = match range.end_bound() {

        Bound::Unbounded => len,

        Bound::Excluded(&i) if i <= len => i,

        Bound::Included(&i) if i < len => i + 1,

        _ => return None,

    };

    if start > end {

        return None;

    }

    Some(start..end)

}

// Generic slice equality -- copied from the standard library but adding a custom comparator,

// allowing for our `Bucket` wrapper on either or both sides.

pub(crate) fn slice_eq<T, U>(left: &[T], right: &[U], eq: impl Fn(&T, &U) -> bool) -> bool {

    if left.len() != right.len() {

        return false;

    }

    // Implemented as explicit indexing rather

    // than zipped iterators for performance reasons.

    // See PR https://github.com/rust-lang/rust/pull/116846

    for i in 0..left.len() {

        // bound checks are optimized away

        if !eq(&left[i], &right[i]) {

            return false;

        }

    }

    true

}