# flapigen [](https://github.com/Dushistov/flapigen-rs/actions/workflows/ci.yml) [](https://github.com/Dushistov/flapigen-rs/blob/master/LICENSE) [](https://docs.rs/flapigen)
Tool for connecting programs or libraries written in Rust with other languages.
Foreign language api generator - flapigen. Former name rust_swig was changed to not confuse
with [swig](https://github.com/swig/swig).
Currently implemented support for `C++` and `Java`, but you can write support
for any language of your choice. For an instruction how to integrate flapigen with your
project look [here](https://dushistov.github.io/flapigen-rs/getting-started.html).
Suppose you have the following Rust code:
```rust
struct Foo {
data: i32
}
impl Foo {
fn new(val: i32) -> Foo {
Foo{data: val}
}
fn f(&self, a: i32, b: i32) -> i32 {
self.data + a + b
}
fn set_field(&mut self, v: i32) {
self.data = v;
}
}
fn f2(a: i32) -> i32 {
a * 2
}
```
and you want to write in Java something like this:
```Java
Foo foo = new Foo(5);
int res = foo.f(1, 2);
assert res == 8;
```
or in C++ something like this:
```C++
Foo foo(5);
int res = foo.f(1, 2);
assert(res == 8);
```
In order to implement it flapigen suggests the following functionality,
in Rust project you write (in Rust language):
```rust
foreign_class!(class Foo {
self_type Foo;
constructor Foo::new(_: i32) -> Foo;
fn Foo::set_field(&mut self, _: i32);
fn Foo::f(&self, _: i32, _: i32) -> i32;
fn f2(_: i32) -> i32;
});
```
and that's all, as a result flapigen generates JNI wrappers for Rust functions
and Java code to call these JNI functions
or generates C compatible wrappers in case of C++ and
C++ code to call these C functions.
If you want the interface file (the file containing `foreign_class!` and so on)
to be automatically generated for you, checkout [rifgen](https://crates.io/crates/rifgen).
## Users Guide
[📚 Read the `flapigen` users guide here! 📚](https://dushistov.github.io/flapigen-rs/)