Java bindings (#147)

bindings/java/src/lib.rs

@@ -0,0 +1,150 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT License.
+
+use anyhow::Result;
+use jni::objects::{JClass, JObject, JString};
+use jni::sys::{jlong, jstring};
+use jni::JNIEnv;
+
+use regorus::{Engine, Value};
+
+#[no_mangle]
+pub extern "system" fn Java_com_microsoft_regorus_Engine_newEngine(
+    _env: JNIEnv,
+    _class: JClass,
+) -> jlong {
+    let engine = Engine::new();
+    Box::into_raw(Box::new(engine)) as jlong
+}
+
+#[no_mangle]
+pub extern "system" fn Java_com_microsoft_regorus_Engine_addPolicy(
+    env: JNIEnv,
+    _class: JClass,
+    engine_ptr: jlong,
+    path: JString,
+    rego: JString,
+) {
+    let _ = throw_err(env, |env| {
+        let engine = unsafe { &mut *(engine_ptr as *mut Engine) };
+        let path: String = env.get_string(&path)?.into();
+        let rego: String = env.get_string(&rego)?.into();
+        engine.add_policy(path, rego)?;
+        Ok(())
+    });
+}
+
+#[no_mangle]
+pub extern "system" fn Java_com_microsoft_regorus_Engine_addPolicyFromFile(
+    env: JNIEnv,
+    _class: JClass,
+    engine_ptr: jlong,
+    path: JString,
+) {
+    let _ = throw_err(env, |env| {
+        let engine = unsafe { &mut *(engine_ptr as *mut Engine) };
+        let path: String = env.get_string(&path)?.into();
+        engine.add_policy_from_file(path)?;
+        Ok(())
+    });
+}
+
+#[no_mangle]
+pub extern "system" fn Java_com_microsoft_regorus_Engine_addDataJson(
+    env: JNIEnv,
+    _class: JClass,
+    engine_ptr: jlong,
+    data: JString,
+) {
+    let _ = throw_err(env, |env| {
+        let engine = unsafe { &mut *(engine_ptr as *mut Engine) };
+        let data: String = env.get_string(&data)?.into();
+        engine.add_data_json(&data)?;
+        Ok(())
+    });
+}
+
+#[no_mangle]
+pub extern "system" fn Java_com_microsoft_regorus_Engine_addDataJsonFromFile(
+    env: JNIEnv,
+    _class: JClass,
+    engine_ptr: jlong,
+    path: JString,
+) {
+    let _ = throw_err(env, |env| {
+        let engine = unsafe { &mut *(engine_ptr as *mut Engine) };
+        let path: String = env.get_string(&path)?.into();
+        engine.add_data(Value::from_json_file(path)?)?;
+        Ok(())
+    });
+}
+
+#[no_mangle]
+pub extern "system" fn Java_com_microsoft_regorus_Engine_setInputJson(
+    env: JNIEnv,
+    _class: JClass,
+    engine_ptr: jlong,
+    input: JString,
+) {
+    let _ = throw_err(env, |env| {
+        let engine = unsafe { &mut *(engine_ptr as *mut Engine) };
+        let input: String = env.get_string(&input)?.into();
+        engine.set_input_json(&input)?;
+        Ok(())
+    });
+}
+
+#[no_mangle]
+pub extern "system" fn Java_com_microsoft_regorus_Engine_setInputJsonFromFile(
+    env: JNIEnv,
+    _class: JClass,
+    engine_ptr: jlong,
+    path: JString,
+) {
+    let _ = throw_err(env, |env| {
+        let engine = unsafe { &mut *(engine_ptr as *mut Engine) };
+        let path: String = env.get_string(&path)?.into();
+        engine.set_input(Value::from_json_file(&path)?);
+        Ok(())
+    });
+}
+
+#[no_mangle]
+pub extern "system" fn Java_com_microsoft_regorus_Engine_evalQuery(
+    env: JNIEnv,
+    _class: JClass,
+    engine_ptr: jlong,
+    query: JString,
+) -> jstring {
+    let res = throw_err(env, |env| {
+        let engine = unsafe { &mut *(engine_ptr as *mut Engine) };
+        let query: String = env.get_string(&query)?.into();
+        let results = engine.eval_query(query, false)?;
+        let output = env.new_string(serde_json::to_string(&results)?)?;
+        Ok(output.into_raw())
+    });
+
+    match res {
+        Ok(val) => val,
+        Err(_) => JObject::null().into_raw(),
+    }
+}
+
+#[no_mangle]
+pub unsafe extern "system" fn Java_com_microsoft_regorus_Engine_destroyEngine(
+    _env: JNIEnv,
+    _class: JClass,
+    engine_ptr: jlong,
+) {
+    let _engine = Box::from_raw(engine_ptr as *mut Engine);
+}
+
+fn throw_err<T>(mut env: JNIEnv, mut f: impl FnMut(&mut JNIEnv) -> Result<T>) -> Result<T> {
+    match f(&mut env) {
+        Ok(val) => Ok(val),
+        Err(err) => {
+            env.throw(err.to_string())?;
+            Err(err)
+        }
+    }
+}