125 lines
3.7 KiB
Rust
125 lines
3.7 KiB
Rust
//! Utilities for working with and combining the results of
|
|
//! [`Arbitrary::size_hint`][crate::Arbitrary::size_hint].
|
|
|
|
/// Protects against potential infinite recursion when calculating size hints
|
|
/// due to indirect type recursion.
|
|
///
|
|
/// When the depth is not too deep, calls `f` with `depth + 1` to calculate the
|
|
/// size hint.
|
|
///
|
|
/// Otherwise, returns the default size hint: `(0, None)`.
|
|
#[inline]
|
|
pub fn recursion_guard(
|
|
depth: usize,
|
|
f: impl FnOnce(usize) -> (usize, Option<usize>),
|
|
) -> (usize, Option<usize>) {
|
|
const MAX_DEPTH: usize = 20;
|
|
if depth > MAX_DEPTH {
|
|
(0, None)
|
|
} else {
|
|
f(depth + 1)
|
|
}
|
|
}
|
|
|
|
/// Take the sum of the `lhs` and `rhs` size hints.
|
|
#[inline]
|
|
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.
|
|
#[inline]
|
|
pub fn and_all(hints: &[(usize, Option<usize>)]) -> (usize, Option<usize>) {
|
|
hints.iter().copied().fold((0, Some(0)), and)
|
|
}
|
|
|
|
/// Take the minimum of the lower bounds and maximum of the upper bounds in the
|
|
/// `lhs` and `rhs` size hints.
|
|
#[inline]
|
|
pub fn or(lhs: (usize, Option<usize>), rhs: (usize, Option<usize>)) -> (usize, Option<usize>) {
|
|
let lower = std::cmp::min(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.
|
|
#[inline]
|
|
pub fn or_all(hints: &[(usize, Option<usize>)]) -> (usize, Option<usize>) {
|
|
if let Some(head) = hints.first().copied() {
|
|
hints[1..].iter().copied().fold(head, or)
|
|
} else {
|
|
(0, Some(0))
|
|
}
|
|
}
|
|
|
|
#[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!((2, Some(3)), super::or((2, Some(2)), (3, Some(3))));
|
|
assert_eq!((2, None), super::or((2, Some(2)), (3, None)));
|
|
assert_eq!((2, None), super::or((2, None), (3, Some(3))));
|
|
assert_eq!((2, 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!(
|
|
(1, Some(4)),
|
|
super::or_all(&[(1, Some(1)), (2, Some(2)), (4, Some(4))])
|
|
);
|
|
assert_eq!(
|
|
(1, None),
|
|
super::or_all(&[(1, Some(1)), (2, Some(2)), (4, None)])
|
|
);
|
|
assert_eq!(
|
|
(1, None),
|
|
super::or_all(&[(1, Some(1)), (2, None), (4, Some(4))])
|
|
);
|
|
assert_eq!(
|
|
(1, None),
|
|
super::or_all(&[(1, None), (2, Some(2)), (4, Some(4))])
|
|
);
|
|
}
|
|
}
|