Lib.rs

This project allows you to use rust objects like part of jvm objects.

JVM

• add native constructor with Long return and private Long property

• implement AutoCloseable as native method

• add finalizer

• add native methods

class Sample extends AutoCloseable {
  @native private def nnew(): Long
  @native def close: Unit
  @native def test: Unit
  private val ptr = nnew()
  override def finalize = close
}

• use try-with-resource (java) / Using (scala) or call close() implicitly (don't trust to finalization — it's a thin red line)

Rust

• mark structure as JFace

#[derive(JFace)]
pub struct Sample { … }

• use throw(JNIEnv, default_function) for converting rust Jr<_> (Result<_, Box> to default JVM exception

• use JFace::jni() for converting to raw heap pointer

• provide native constructor to JNI

#[no_mangle]
pub extern "system" fn Java_package_Sample_nnew(
  jenv: JNIEnv,
  _jclass: JClass,
) -> *mut Sample {
  Sample::new().jni().throw(jenv, null_mut)
}

• use unit for Result<(), _>::throw() or hide for Result<T, _>::throw for unneeded T

• use JFace::mut_raw and map/and_then for native methods

#[no_mangle]
pub extern "system" fn Java_org_apqm_jni_Sample_test(
  jenv: JNIEnv,
  jclass: JClass,
) {
  Sample::mut_raw(&jenv, jclass).map(|it| {
    todo!()
  }).throw(jenv, unit);
}

• use JFace::box_raw for destructor

#[no_mangle]
pub extern "system" fn Java_org_apqm_jni_Sample_close(
  jenv: JNIEnv,
  jclass: JClass,
) {
  Sample::box_raw(&jenv, jclass).map(hide).throw(jenv, unit)
}

License

Licensed under either of

• Apache License, Version 2.0 (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
• MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT) at your option.