rust/hg-core/src/testing.rs

transaction: allow finalizer to add finalizer

It will make some code (persistent nodemap related) simpler to write, because
higher level code can blindly queue finalization without thinking too hard about
the context.

Differential Revision: https://phab.mercurial-scm.org/D7833

// testing.rs
//
// 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.

use crate::{Graph, GraphError, Revision, NULL_REVISION};

/// A stub `Graph`, same as the one from `test-ancestor.py`
///
/// o  13
/// |
/// | o  12
/// | |
/// | | o    11
/// | | |\
/// | | | | o  10
/// | | | | |
/// | o---+ |  9
/// | | | | |
/// o | | | |  8
///  / / / /
/// | | o |  7
/// | | | |
/// o---+ |  6
///  / / /
/// | | o  5
/// | |/
/// | o  4
/// | |
/// o |  3
/// | |
/// | o  2
/// |/
/// o  1
/// |
/// o  0
#[derive(Clone, Debug)]
pub struct SampleGraph;

impl Graph for SampleGraph {
    fn parents(&self, rev: Revision) -> Result<[Revision; 2], GraphError> {
        match rev {
            0 => Ok([NULL_REVISION, NULL_REVISION]),
            1 => Ok([0, NULL_REVISION]),
            2 => Ok([1, NULL_REVISION]),
            3 => Ok([1, NULL_REVISION]),
            4 => Ok([2, NULL_REVISION]),
            5 => Ok([4, NULL_REVISION]),
            6 => Ok([4, NULL_REVISION]),
            7 => Ok([4, NULL_REVISION]),
            8 => Ok([NULL_REVISION, NULL_REVISION]),
            9 => Ok([6, 7]),
            10 => Ok([5, NULL_REVISION]),
            11 => Ok([3, 7]),
            12 => Ok([9, NULL_REVISION]),
            13 => Ok([8, NULL_REVISION]),
            r => Err(GraphError::ParentOutOfRange(r)),
        }
    }
}

// A Graph represented by a vector whose indices are revisions
// and values are parents of the revisions
pub type VecGraph = Vec<[Revision; 2]>;

impl Graph for VecGraph {
    fn parents(&self, rev: Revision) -> Result<[Revision; 2], GraphError> {
        Ok(self[rev as usize])
    }
}