view rust/hg-cpython/src/conversion.rs @ 51225:89ce6a49bfeb

rust-index: implement common_ancestors_heads() and ancestors()

The only differences betwwen `common_ancestors_heads()` and
`find_gca_candidates()` seems to be that:

- the former accepts "overlapping" input revisions (meaning with duplicates).
- limitation to 24 inputs (in the C code), that we translate to using the
  arbitrary size bit sets in the Rust code because we cannot bail to Python.

Given that the input is expected to be small in most cases, we take the
heavy handed approach of going through a HashSet and wait for perfomance
assessment

In case this is used via `hg-cpython`, we can anyway absorb the overhead
by having `commonancestorheads` build a vector of unique values
directly, and introduce a thin wrapper over `find_gca_candidates`, to take
care of bit set type dispatching only.

As far as `ancestors` is concerneed, this is just chaining
`common_ancestors_heads()` with `find_deepest_revs`.

// conversion.rs
//
// Copyright 2019 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.

//! Bindings for the hg::ancestors module provided by the
//! `hg-core` crate. From Python, this will be seen as `rustext.ancestor`

use cpython::{ObjectProtocol, PyErr, PyObject, PyResult, Python};
use hg::{Revision, RevlogIndex, UncheckedRevision};

use crate::{exceptions::GraphError, PyRevision};

/// Utility function to convert a Python iterable into various collections
///
/// We need this in particular to feed to various methods of inner objects
/// with `impl IntoIterator<Item=Revision>` arguments, because
/// a `PyErr` can arise at each step of iteration, whereas these methods
/// expect iterables over `Revision`, not over some `Result<Revision, PyErr>`
pub fn rev_pyiter_collect<C, I>(
    py: Python,
    revs: &PyObject,
    index: &I,
) -> PyResult<C>
where
    C: FromIterator<Revision>,
    I: RevlogIndex,
{
    rev_pyiter_collect_or_else(py, revs, index, |r| {
        PyErr::new::<GraphError, _>(py, ("InvalidRevision", r.0))
    })
}

/// Same as [`rev_pyiter_collect`], giving control on returned errors
pub fn rev_pyiter_collect_or_else<C, I>(
    py: Python,
    revs: &PyObject,
    index: &I,
    invalid_rev_error: impl FnOnce(PyRevision) -> PyErr + Copy,
) -> PyResult<C>
where
    C: FromIterator<Revision>,
    I: RevlogIndex,
{
    revs.iter(py)?
        .map(|r| {
            r.and_then(|o| match o.extract::<PyRevision>(py) {
                Ok(r) => index
                    .check_revision(UncheckedRevision(r.0))
                    .ok_or_else(|| invalid_rev_error(r)),
                Err(e) => Err(e),
            })
        })
        .collect()
}