Mercurial > hg
changeset 50974:c950fdba7472
rust: add `UncheckedRevision` type
This is the start of a series whose aim is to separate "checked" and
"unchecked" revision numbers. A "checked" revision number is valid for a given
index, allowing us to have faster algorithms that don't do redundant checks
all the time and have a clearer view of the kinds of revisions
we're working with.
| author | Raphaël Gomès <rgomes@octobus.net> |
|---|---|
| date | Mon, 07 Aug 2023 12:53:43 +0200 |
| parents | fd6c748eb8a6 |
| children | 3aca98a35727 |
| files | rust/hg-core/src/revlog/mod.rs |
| diffstat | 1 files changed, 20 insertions(+), 0 deletions(-) [+] |
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--- a/rust/hg-core/src/revlog/mod.rs Mon Aug 21 17:57:48 2023 -0400 +++ b/rust/hg-core/src/revlog/mod.rs Mon Aug 07 12:53:43 2023 +0200 @@ -39,6 +39,16 @@ /// 4 bytes, and are liberally converted to ints, whence the i32 pub type Revision = i32; +/// Unchecked Mercurial revision numbers. +/// +/// Values of this type have no guarantee of being a valid revision number +/// in any context. Use method `check_revision` to get a valid revision within +/// the appropriate index object. +/// +/// As noted in revlog.c, revision numbers are actually encoded in +/// 4 bytes, and are liberally converted to ints, whence the i32 +pub type UncheckedRevision = i32; + /// Marker expressing the absence of a parent /// /// Independently of the actual representation, `NULL_REVISION` is guaranteed @@ -85,6 +95,16 @@ /// /// `NULL_REVISION` is not considered to be out of bounds. fn node(&self, rev: Revision) -> Option<&Node>; + + /// Return a [`Revision`] if `rev` is a valid revision number for this + /// index + fn check_revision(&self, rev: UncheckedRevision) -> Option<Revision> { + if rev == NULL_REVISION || (rev >= 0 && (rev as usize) < self.len()) { + Some(rev) + } else { + None + } + } } const REVISION_FLAG_CENSORED: u16 = 1 << 15;