interoptopus_backend_c 0.13.0

Generates C bindings.
Documentation 
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Generates C bindings for [Interoptopus](https://github.com/ralfbiedert/interoptopus).

## Usage

Assuming you have written a crate containing your FFI logic called `example_library_ffi` and
want to generate **C bindings**, follow the instructions below.

#### Inside Your Library

Add [**Interoptopus**](https://crates.io/crates/interoptopus) attributes to the library you have
written, and define an [**inventory**](https://docs.rs/interoptopus/latest/interoptopus/macro.inventory.html)
function listing all symbols you wish to export. An overview of all supported constructs can be found in the
[**reference project**](https://github.com/ralfbiedert/interoptopus/tree/master/reference_project/src).

```rust
use interoptopus::{ffi_function, ffi_type};

#[ffi_type]
#[repr(C)]
pub struct Vec2 {
    pub x: f32,
    pub y: f32,
}

#[ffi_function]
#[no_mangle]
pub extern "C" fn my_function(input: Vec2) -> Vec2 {
    input
}

interoptopus::inventory!(my_inventory, [], [my_function], [], []);
```


Add these to your `Cargo.toml` so the attributes and the binding generator can be found
(replace `...` with the latest version):

```toml
[lib]
crate-type = ["cdylib", "rlib"]

[dependencies]
interoptopus = "..."
interoptopus_backend_c = "..."
```

Create a unit test in `tests/bindings.rs` which will generate your bindings when run
with `cargo test`. In real projects you might want to add this code to another crate instead:

```rust
use interoptopus::util::NamespaceMappings;
use interoptopus::{Error, Interop};

#[test]
fn bindings_c() -> Result<(), Error> {
    use interoptopus_backend_c::{Config, Generator};

    Generator::new(
        Config {
            ifndef: "example_library".to_string(),
            ..Config::default()
        },
        example_library_ffi::my_inventory(),
    ).write_file("bindings/c/example_complex.h")?;

    Ok(())
}
```

Now run `cargo test`.

If anything is unclear you can find a [**working sample on Github**](https://github.com/ralfbiedert/interoptopus/tree/master/examples/hello_world).

#### Generated Output

The output below is what this backend might generate. Have a look at the [`Config`] struct
if you want to customize something. If you really don't like how something is generated it is
easy to [**create your own**](https://github.com/ralfbiedert/interoptopus/blob/master/FAQ.md#new-backends).

```c
// Automatically generated by Interoptopus.

#ifndef example_library
#define example_library

#ifdef __cplusplus
extern "C" {
#endif

#include <stdint.h>
#include <stdbool.h>

typedef struct vec2
    {
    float x
    float y;
    } vec2;


vec2 my_function(vec2 input);

#ifdef __cplusplus
}
#endif

#endif /* example_library */

```