| Submitter | phabricator |
|---|---|
| Date | Jan. 24, 2020, 10:12 a.m. |
| Message ID | <differential-rev-PHID-DREV-7u3jpjzcsehx2llc7x7g-req@mercurial-scm.org> |
| Download | mbox | patch |
| Permalink | /patch/44603/ |
| State | Superseded |
| Headers | show |
Comments
This revision now requires changes to proceed. martinvonz added a comment. martinvonz requested changes to this revision. Sorry to be dismissive, but please hold on to it until it becomes needed then. I'm strongly against adding dead code unless we know we're at least going to use it soon. REPOSITORY rHG Mercurial CHANGES SINCE LAST ACTION https://phab.mercurial-scm.org/D7982/new/ REVISION DETAIL https://phab.mercurial-scm.org/D7982 To: Alphare, #hg-reviewers, martinvonz Cc: martinvonz, kevincox, mercurial-devel
Alphare added a comment. Sure, that is completely fine, I'll remove it from the stack. REPOSITORY rHG Mercurial CHANGES SINCE LAST ACTION https://phab.mercurial-scm.org/D7982/new/ REVISION DETAIL https://phab.mercurial-scm.org/D7982 To: Alphare, #hg-reviewers, martinvonz Cc: martinvonz, kevincox, mercurial-devel
Alphare added a comment. Alphare abandoned this revision. I was certain to have pruned this one. I'll do it. REPOSITORY rHG Mercurial CHANGES SINCE LAST ACTION https://phab.mercurial-scm.org/D7982/new/ REVISION DETAIL https://phab.mercurial-scm.org/D7982 To: Alphare, #hg-reviewers, martinvonz Cc: martinvonz, kevincox, mercurial-devel
Patch
diff --git a/rust/hg-core/src/utils.rs b/rust/hg-core/src/utils.rs --- a/rust/hg-core/src/utils.rs +++ b/rust/hg-core/src/utils.rs @@ -61,6 +61,36 @@ } } +/// Find the offset of the subslice relative to the original collection +/// +/// This function panics for zero-sized types. +/// # Examples: +/// +/// ``` +/// use crate::hg::utils::subslice_offset; +/// let mut line = b"Subslice me!".to_vec(); +/// assert_eq!(subslice_offset(&line, &line[8..]), Some(8)); +/// +/// assert_eq!(subslice_offset(&line, b"hahaha"), None); +/// +/// // Empty array +/// let v: [u8; 0] = []; +/// assert_eq!(subslice_offset(&v, &v), Some(0)); +/// assert_eq!(subslice_offset(&v, b"hehe"), None); +/// ``` +pub fn subslice_offset<T: Sized>(outer: &[T], inner: &[T]) -> Option<usize> { + let pointee_size = std::mem::size_of::<T>(); + assert!(0 < pointee_size && pointee_size <= isize::max_value() as usize); + + let outer_start = outer.as_ptr() as usize; + let inner = inner.as_ptr() as usize; + if inner < outer_start || inner > outer_start.wrapping_add(outer.len()) { + None + } else { + Some(inner.wrapping_sub(outer_start)) + } +} + pub trait SliceExt { fn trim_end(&self) -> &Self; fn trim_start(&self) -> &Self;