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//! Rust bindings for [libffi](https://sourceware.org/libffi/).
//!
//! The C libffi library provides two main facilities: assembling calls
//! to functions dynamically, and creating closures that can be called
//! as ordinary C functions. In Rust, the latter means that we can turn
//! a Rust lambda (or any object implementing `Fn`/`FnMut`) into an
//! ordinary C function pointer that we can pass as a callback to C.
//! The easiest way to use this library is via the
//! [`high`](high/index.html) layer module, but more flexibility (and
//! less checking) is provided by the [`middle`](middle/index.html) and
//! [`low`](low/index.html) layers.
//! # Usage/Warning
//!
//! This library is experimental/unstable and shouldn’t be used for
//! anything yet. If it does something you need or want to play with
//! then we should talk.
//!
//! It’s [on crates.io](https://crates.io/crates/libffi), so it can be
//! used by adding `libffi` to the dependencies in your project’s
//! `Cargo.toml`:
//!
//! ```toml
//! [dependencies]
//! libffi = "0.1"
//! ```
//!
//! However, to actually build it, you need to install [Rust
//! bindgen](https://crates.io/crates/bindgen) (0.18.0) and [C
//! libffi](https://sourceware.org/libffi/) (3.2.1) manually first.
//!
//! # Organization
//!
//! This library is organized in four layers, each of which attempts to
//! provide more safety and a simpler interface than the next layer
//! down. From top to bottom:
//!
//! - The [`high`](high/index.html) layer provides safe(?) and
//! automatic marshalling of Rust closures into C function pointers.
//! - The [`middle`](middle/index.html) layer provides memory-managed
//! abstractions for assembling calls and closures, but is unsafe
//! because it doesn’t check argument types.
//! - The [`low`](low/index.html) layer makes no attempts at safety,
//! but provides a more idiomatically “Rusty” API than the underlying
//! C library.
//! - The [`raw`](raw/index.html) layer is a direct mapping of the
//! C libffi library into Rust, generated by [Rust
//! Bindgen](https://github.com/crabtw/rust-bindgen).
//!
//! It should be possible to use any layer without dipping into lower
//! layers (and it will be considered a bug to the extent that it
//! isn’t).
//!
//! # Example
//!
//! In this example, we convert a Rust lambda containing a free variable
//! into an ordinary C code pointer. The type of `fun` below is
//! `extern "C" fn(u64, u64) -> u64`.
//!
//! ```
//! use libffi::high::Closure2;
//!
//! let x = 5u64;
//! let f = |y: u64, z: u64| x + y + z;
//!
//! let closure = Closure2::new(&f);
//! let fun = closure.code_ptr();
//!
//! assert_eq!(18, fun(6, 7));
//! ```
extern crate libc;
/// Unwrapped definitions imported from the C library (via bindgen).