view rust/hg-cpython/src/conversion.rs @ 42748:7cae6bc29ff9

rust-parsers: switch to parse/pack_dirstate to mutate-on-loop

Both `parse_dirstate` and `pack_dirstate` can operate directly on the data
they're passed, which prevents the creation of intermediate data structures,
simplifies the function signatures and reduces boilerplate. They are exposed
directly to the Python for now, but a later patch will make use of them inside
`hg-core`.

Differential Revision: https://phab.mercurial-scm.org/D6628

// 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, 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))
}