// 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, PyDict, PyObject, PyResult, PyTuple, Python, PythonObject,

    ToPyObject,

};

use hg::Revision;

use std::collections::HashSet;

use std::iter::FromIterator;

/// 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>(py: Python, revs: &PyObject) -> PyResult<C>

where

    C: FromIterator<Revision>,

{

    revs.iter(py)?

        .map(|r| r.and_then(|o| o.extract::<Revision>(py)))

        .collect()

}

/// Copy and convert an `HashSet<Revision>` in a Python set

///

/// This will probably turn useless once `PySet` support lands in

/// `rust-cpython`.

///

/// This builds a Python tuple, then calls Python's "set()" on it

pub fn py_set(py: Python, set: &HashSet<Revision>) -> PyResult<PyObject> {

    let as_vec: Vec<PyObject> = set

        .iter()

        .map(|rev| rev.to_py_object(py).into_object())

        .collect();

    let as_pytuple = PyTuple::new(py, as_vec.as_slice());

    let locals = PyDict::new(py);

    locals.set_item(py, "obj", as_pytuple.to_py_object(py))?;

    py.eval("set(obj)", None, Some(&locals))

}