Connecting Rust with Java and C++

Aisha Patel Avatar

·

In today’s interconnected world, the ability to seamlessly integrate different programming languages provides immense benefits and opens up new opportunities for developers. Rust, known for its performance, safety, and low-level control, has gained popularity among developers. However, integrating Rust code with other languages like Java or C++ can be a challenging task. That’s where flapigen-rs comes to the rescue.

flapigen-rs is a powerful tool that facilitates the connection between programs or libraries written in Rust with other languages. Formerly known as rust_swig, flapigen-rs provides support for generating APIs for languages such as C++ and Java, with the potential to extend support to other languages of your choice. With flapigen-rs, integrating Rust code into your Java or C++ projects becomes a seamless process.

Simplifying Language Integration

Suppose you have a Rust codebase and you want to utilize certain functionalities in Java or C++. flapigen-rs simplifies this integration process by providing an intuitive and efficient workflow. Let’s take a look at how this works.

Rust Code Example

Consider the following Rust code snippet:

“`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
}
“`

Java Integration

Suppose you want to utilize the Foo struct and its methods in Java. With flapigen-rs, you can easily generate the necessary JNI wrappers for Rust functions and the corresponding Java code. Here’s how the equivalent Java code would look like:

Java
Foo foo = new Foo(5);
int res = foo.f(1, 2);
assert res == 8;

C++ Integration

Similarly, if you want to integrate the Foo struct into a C++ project, flapigen-rs generates C compatible wrappers for Rust functions along with the C++ code. Here’s an example of how you can use the Foo struct in C++:

C++
Foo foo(5);
int res = foo.f(1, 2);
assert(res == 8);

Simplified Integration Workflow

To implement this integration using flapigen-rs, you need to define the foreign class in Rust and specify its methods and constructors. Here’s how the equivalent flapigen-rs code would look like for the Foo struct:

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;
});

The beauty of flapigen-rs is that it automatically generates the necessary JNI wrappers for Rust functions and Java code, or C compatible wrappers and corresponding C++ code. This automation significantly simplifies the language integration process and reduces manual effort.

Generating the Interface File

If you want the interface file, which contains the foreign_class! definition, to be automatically generated for you, you can use the rifgen tool. It streamlines the code generation process and ensures consistency in API generation.

Conclusion

flapigen-rs is a game-changer for developers looking to integrate Rust code with other languages like Java or C++. With its ability to generate JNI wrappers for Rust functions and Java code, as well as C compatible wrappers for C++ projects, flapigen-rs simplifies the language integration process and enables developers to unlock the full potential of Rust’s performance and safety in heterogeneous development environments.

Whether you are building cross-platform applications, leveraging Rust’s powerful libraries, or seeking to combine the strengths of multiple programming languages, flapigen-rs empowers you to bridge the gap between Rust and Java or C++. Embrace the power of seamless language integration and explore the possibilities with flapigen-rs.

So, what are you waiting for? Dive into the world of flapigen-rs and unlock the potential of Rust in your Java and C++ projects!

References:

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