arbitrary 0.3.0

The trait for generating structured data from unstructured data
Documentation 
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//! Utilities for working with and combining the results of
//! [`Arbitrary::size_hint`][crate::Arbitrary::size_hint].

/// Take the sum of the `lhs` and `rhs` size hints.
pub fn and(lhs: (usize, Option<usize>), rhs: (usize, Option<usize>)) -> (usize, Option<usize>) {
    let lower = lhs.0 + rhs.0;
    let upper = lhs.1.and_then(|lhs| rhs.1.map(|rhs| lhs + rhs));
    (lower, upper)
}

/// Take the sum of all of the given size hints.
///
/// If `hints` is empty, returns `(0, Some(0))`, aka the size of consuming
/// nothing.
pub fn and_all(hints: &[(usize, Option<usize>)]) -> (usize, Option<usize>) {
    hints.iter().copied().fold((0, Some(0)), and)
}

/// Take the maximum of the `lhs` and `rhs` size hints.
pub fn or(lhs: (usize, Option<usize>), rhs: (usize, Option<usize>)) -> (usize, Option<usize>) {
    let lower = std::cmp::max(lhs.0, rhs.0);
    let upper = lhs
        .1
        .and_then(|lhs| rhs.1.map(|rhs| std::cmp::max(lhs, rhs)));
    (lower, upper)
}

/// Take the maximum of the `lhs` and `rhs` size hints.
///
/// If `hints` is empty, returns `(0, Some(0))`, aka the size of consuming
/// nothing.
pub fn or_all(hints: &[(usize, Option<usize>)]) -> (usize, Option<usize>) {
    hints.iter().copied().fold((0, Some(0)), or)
}

#[cfg(test)]
mod tests {
    #[test]
    fn and() {
        assert_eq!((5, Some(5)), super::and((2, Some(2)), (3, Some(3))));
        assert_eq!((5, None), super::and((2, Some(2)), (3, None)));
        assert_eq!((5, None), super::and((2, None), (3, Some(3))));
        assert_eq!((5, None), super::and((2, None), (3, None)));
    }

    #[test]
    fn or() {
        assert_eq!((3, Some(3)), super::or((2, Some(2)), (3, Some(3))));
        assert_eq!((3, None), super::or((2, Some(2)), (3, None)));
        assert_eq!((3, None), super::or((2, None), (3, Some(3))));
        assert_eq!((3, None), super::or((2, None), (3, None)));
    }

    #[test]
    fn and_all() {
        assert_eq!((0, Some(0)), super::and_all(&[]));
        assert_eq!(
            (7, Some(7)),
            super::and_all(&[(1, Some(1)), (2, Some(2)), (4, Some(4))])
        );
        assert_eq!(
            (7, None),
            super::and_all(&[(1, Some(1)), (2, Some(2)), (4, None)])
        );
        assert_eq!(
            (7, None),
            super::and_all(&[(1, Some(1)), (2, None), (4, Some(4))])
        );
        assert_eq!(
            (7, None),
            super::and_all(&[(1, None), (2, Some(2)), (4, Some(4))])
        );
    }

    #[test]
    fn or_all() {
        assert_eq!((0, Some(0)), super::or_all(&[]));
        assert_eq!(
            (4, Some(4)),
            super::or_all(&[(1, Some(1)), (2, Some(2)), (4, Some(4))])
        );
        assert_eq!(
            (4, None),
            super::or_all(&[(1, Some(1)), (2, Some(2)), (4, None)])
        );
        assert_eq!(
            (4, None),
            super::or_all(&[(1, Some(1)), (2, None), (4, Some(4))])
        );
        assert_eq!(
            (4, None),
            super::or_all(&[(1, None), (2, Some(2)), (4, Some(4))])
        );
    }
}