// conversion.rs

//

// Copyright 2019 Georges Racinet <georges.racinet@octobus.net>

//

// 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::{revlog::RevlogIndex, Revision, 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()

}