annotate rust/hg-cpython/src/lib.rs @ 42609:326fdce22fb2

rust: switch hg-core and hg-cpython to rust 2018 edition

Many interesting changes have happened in Rust since the Oxidation Plan was
introduced, like the 2018 edition and procedural macros:

    - Opting in to the 2018 edition is a clear benefit in terms of future
      proofing, new (nice to have) syntactical sugar notwithstanding. It
      also has a new non-lexical, non-AST based borrow checker that has
      fewer bugs(!) and allows us to write correct code that in some cases
      would have been rejected by the old one.
    - Procedural macros allow us to use the PyO3 crate which maintainers have
      expressed the clear goal of compiling on stable, which would help in
      code maintainability compared to rust-cpython.

In this patch are the following changes:
    - Removing most `extern crate` uses
    - Updating `use` clauses (`crate` keyword, nested `use`)
    - Removing `mod.rs` in favor of an aptly named module file

Like discussed in the mailing list (
https://www.mercurial-scm.org/pipermail/mercurial-devel/2019-July/132316.html
), until Rust integration in Mercurial is considered to be out of the
experimental phase, the maximum version of Rust allowed is whatever the latest
version Debian packages.

Differential Revision: https://phab.mercurial-scm.org/D6597

// lib.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.

//! Python bindings of `hg-core` objects using the `cpython` crate.
//! Once compiled, the resulting single shared library object can be placed in
//! the `mercurial` package directly as `rustext.so` or `rustext.dll`.
//! It holds several modules, so that from the point of view of Python,
//! it behaves as the `cext` package.
//!
//! Example:
//!
//! ```text
//! >>> from mercurial.rustext import ancestor
//! >>> ancestor.__doc__
//! 'Generic DAG ancestor algorithms - Rust implementation'
//! ```

/// This crate uses nested private macros, `extern crate` is still needed in
/// 2018 edition.
#[macro_use]
extern crate cpython;

pub mod ancestors;
mod cindex;
mod conversion;
pub mod dagops;
pub mod dirstate;
pub mod discovery;
pub mod exceptions;
pub mod filepatterns;

py_module_initializer!(rustext, initrustext, PyInit_rustext, |py, m| {
    m.add(
        py,
        "__doc__",
        "Mercurial core concepts - Rust implementation",
    )?;

    let dotted_name: String = m.get(py, "__name__")?.extract(py)?;
    m.add(py, "ancestor", ancestors::init_module(py, &dotted_name)?)?;
    m.add(py, "dagop", dagops::init_module(py, &dotted_name)?)?;
    m.add(py, "discovery", discovery::init_module(py, &dotted_name)?)?;
    m.add(py, "dirstate", dirstate::init_module(py, &dotted_name)?)?;
    m.add(
        py,
        "filepatterns",
        filepatterns::init_module(py, &dotted_name)?,
    )?;
    m.add(py, "GraphError", py.get_type::<exceptions::GraphError>())?;
    m.add(
        py,
        "PatternFileError",
        py.get_type::<exceptions::PatternFileError>(),
    )?;
    m.add(
        py,
        "PatternError",
        py.get_type::<exceptions::PatternError>(),
    )?;
    Ok(())
});