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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-17 12:02:58 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-17 12:02:58 +0000 |
commit | 698f8c2f01ea549d77d7dc3338a12e04c11057b9 (patch) | |
tree | 173a775858bd501c378080a10dca74132f05bc50 /library/alloc/src/collections/btree/testing/ord_chaos.rs | |
parent | Initial commit. (diff) | |
download | rustc-698f8c2f01ea549d77d7dc3338a12e04c11057b9.tar.xz rustc-698f8c2f01ea549d77d7dc3338a12e04c11057b9.zip |
Adding upstream version 1.64.0+dfsg1.upstream/1.64.0+dfsg1
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to '')
-rw-r--r-- | library/alloc/src/collections/btree/testing/ord_chaos.rs | 81 |
1 files changed, 81 insertions, 0 deletions
diff --git a/library/alloc/src/collections/btree/testing/ord_chaos.rs b/library/alloc/src/collections/btree/testing/ord_chaos.rs new file mode 100644 index 000000000..96ce7c157 --- /dev/null +++ b/library/alloc/src/collections/btree/testing/ord_chaos.rs @@ -0,0 +1,81 @@ +use std::cell::Cell; +use std::cmp::Ordering::{self, *}; +use std::ptr; + +// Minimal type with an `Ord` implementation violating transitivity. +#[derive(Debug)] +pub enum Cyclic3 { + A, + B, + C, +} +use Cyclic3::*; + +impl PartialOrd for Cyclic3 { + fn partial_cmp(&self, other: &Self) -> Option<Ordering> { + Some(self.cmp(other)) + } +} + +impl Ord for Cyclic3 { + fn cmp(&self, other: &Self) -> Ordering { + match (self, other) { + (A, A) | (B, B) | (C, C) => Equal, + (A, B) | (B, C) | (C, A) => Less, + (A, C) | (B, A) | (C, B) => Greater, + } + } +} + +impl PartialEq for Cyclic3 { + fn eq(&self, other: &Self) -> bool { + self.cmp(&other) == Equal + } +} + +impl Eq for Cyclic3 {} + +// Controls the ordering of values wrapped by `Governed`. +#[derive(Debug)] +pub struct Governor { + flipped: Cell<bool>, +} + +impl Governor { + pub fn new() -> Self { + Governor { flipped: Cell::new(false) } + } + + pub fn flip(&self) { + self.flipped.set(!self.flipped.get()); + } +} + +// Type with an `Ord` implementation that forms a total order at any moment +// (assuming that `T` respects total order), but can suddenly be made to invert +// that total order. +#[derive(Debug)] +pub struct Governed<'a, T>(pub T, pub &'a Governor); + +impl<T: Ord> PartialOrd for Governed<'_, T> { + fn partial_cmp(&self, other: &Self) -> Option<Ordering> { + Some(self.cmp(other)) + } +} + +impl<T: Ord> Ord for Governed<'_, T> { + fn cmp(&self, other: &Self) -> Ordering { + assert!(ptr::eq(self.1, other.1)); + let ord = self.0.cmp(&other.0); + if self.1.flipped.get() { ord.reverse() } else { ord } + } +} + +impl<T: PartialEq> PartialEq for Governed<'_, T> { + fn eq(&self, other: &Self) -> bool { + assert!(ptr::eq(self.1, other.1)); + self.0.eq(&other.0) + } +} + +impl<T: Eq> Eq for Governed<'_, T> {} |