view rust/hg-cpython/src/ancestors.rs @ 41052:4c25038c112c

rust-cpython: implement Graph using C parents function We introduce the `Index` struct that wraps the C index. It is not intrinsically protected by the GIL (see the lengthy discussion in its docstring). Improving on this seems prematurate at this point. A pointer to the parents function is stored on the parsers C extension module as a capsule object. This is the recommended way to export a C API for consumption from other extensions. See also: https://docs.python.org/2.7/c-api/capsule.html In our case, we use it in cindex.rs, retrieving function pointer from the capsule and storing it within the CIndex struct, alongside with a pointer to the index. From there, the implementation is very close to the one from hg-direct-ffi. The naming convention for the capsule is inspired from the one in datetime: >>> import datetime >>> datetime.datetime_CAPI <capsule object "datetime.datetime_CAPI" at 0x7fb51201ecf0> although in datetime's case, the capsule points to a struct holding several type objects and methods. Differential Revision: https://phab.mercurial-scm.org/D5438
author Georges Racinet <gracinet@anybox.fr>
date Mon, 03 Dec 2018 07:44:08 +0100
parents 5532823e8c18
children d9f439fcdb4c
line wrap: on
line source

// ancestors.rs
//
// Copyright 2018 Georges Racinet <gracinet@anybox.fr>
//
// 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::{PyDict, PyModule, PyResult, Python};

/// Create the module, with __package__ given from parent
pub fn init_module(py: Python, package: &str) -> PyResult<PyModule> {
    let dotted_name = &format!("{}.ancestor", package);
    let m = PyModule::new(py, dotted_name)?;
    m.add(py, "__package__", package)?;
    m.add(
        py,
        "__doc__",
        "Generic DAG ancestor algorithms - Rust implementation",
    )?;

    let sys = PyModule::import(py, "sys")?;
    let sys_modules: PyDict = sys.get(py, "modules")?.extract(py)?;
    sys_modules.set_item(py, dotted_name, &m)?;
    // Example C code (see pyexpat.c and import.c) will "give away the
    // reference", but we won't because it will be consumed once the
    // Rust PyObject is dropped.
    Ok(m)
}