view rust/hg-core/src/lib.rs @ 40704:7da3729d4b45

sparse-revlog: add a `index_get_length` function in C

We are about to implement a native version of `slicechunktodensity`. For
clarity, we introduce the helper functions first. This new function provides
an efficient way to retrieve some of the information needed by
`slicechunktodensity`.

// Copyright 2018 Georges Racinet <[e-mail]>
//
// This software may be used and distributed according to the terms of the
// GNU General Public License version 2 or any later version.
mod ancestors;
pub use ancestors::AncestorsIterator;

/// Mercurial revision numbers
///
/// As noted in revlog.c, revision numbers are actually encoded in
/// 4 bytes, and are liberally converted to ints, whence the i32
pub type Revision = i32;

pub const NULL_REVISION: Revision = -1;

/// The simplest expression of what we need of Mercurial DAGs.
pub trait Graph {
    fn parents(&self, Revision) -> Result<(Revision, Revision), GraphError>;
}

#[derive(Clone, Debug, PartialEq)]
pub enum GraphError {
    ParentOutOfRange(Revision),
}