--- /dev/null
+# This file is part of NIT ( http://www.nitlanguage.org ).
+#
+# Copyright 2014 Alexis Laferrière <alexis.laf@xymus.net>
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# Supporting services for the FFI with Java
+#
+# This modules relies on `Sys::jvm`, `Sys::jni_env` and
+# `Sys::create_default_jvm` to get a handle on a JVM. You can adapt the
+# behavior of the FFI and services in this module by redefing
+# `Sys::create_default_jvm` and supply your own JVM object. You can manage
+# multiple java thread by switching the current environment in a redef
+# of `Sys::jni_env`, and multiple JVM using `Sys::jvm`.
+#
+# The module `jvm` gives more control over the JVM instances and wraps
+# most of JNI functions. You can use it to further customize the behavior
+# of your code.
+module java is
+ c_compiler_option("-I $(JAVA_HOME)/include/")
+ c_linker_option("-L $(JNI_LIB_PATH) -ljvm")
+ new_annotation extra_java_files
+end
+
+import jvm
+
+redef class Sys
+ private var jvm_cache: nullable JavaVM = null
+ private var jni_env_cache: nullable JniEnv = null
+
+ # Default Java Virtual Machine to use (will be instanciated using
+ # `create_default_jvm` if not already set)
+ fun jvm: JavaVM
+ do
+ if jvm_cache == null then create_default_jvm
+ return jvm_cache.as(not null)
+ end
+
+ # Sets the current default Java Virtual Machine (use with `jni_env=`)
+ fun jvm=(jvm: JavaVM) do jvm_cache = jvm
+
+ # Current main `JniEnv`
+ fun jni_env: JniEnv
+ do
+ if jni_env_cache == null then create_default_jvm
+ return jni_env_cache.as(not null)
+ end
+
+ # Sets the current default JNI env (use with `jvm=`)
+ fun jni_env=(jni_env: JniEnv) do jni_env_cache = jni_env
+
+ # Called by `jvm` and `jni_env` to instanciate a Java Virual Machine.
+ # Used mostly for the FFI with Java.
+ protected fun create_default_jvm
+ do
+ var builder = new JavaVMBuilder
+
+ # By default, look for Java classes in a jar file the same dir as the executable
+ builder.options.add "-Djava.class.path={sys.program_name}.jar"
+
+ var jvm = builder.create_jvm
+ assert jvm != null else print "JVM creation failed"
+
+ self.jvm = jvm
+ self.jni_env = builder.jni_env.as(not null)
+ end
+
+ # Get a Java class by its name from the current `jni_env`
+ fun load_jclass(name: NativeString): JClass import jni_env `{
+ JNIEnv *nit_ffi_jni_env = Sys_jni_env(recv);
+
+ // retreive the implementation Java class
+ jclass java_class = (*nit_ffi_jni_env)->FindClass(nit_ffi_jni_env, name);
+ if (java_class == NULL) {
+ fprintf(stderr, "Nit FFI with Java error: failed to load class.\\n");
+ (*nit_ffi_jni_env)->ExceptionDescribe(nit_ffi_jni_env);
+ exit(1);
+ }
+
+ return java_class;
+ `}
+end
+
+# A standard Java string `java.lang.String`
+#
+# Converted to a Nit string using `to_s`, or to a C string with `to_cstring`.
+# Created using `String::to_java_string` or `NativeString::to_java_string`.
+extern class JavaString in "Java" `{ java.lang.String `}
+ super JavaObject
+
+ redef type SELF: JavaString
+
+ # Get the string from Java and copy it to Nit memory
+ fun to_cstring: NativeString import sys, Sys.jni_env `{
+ Sys sys = JavaString_sys(recv);
+ JNIEnv *env = Sys_jni_env(sys);
+
+ // Get the data from Java
+ const jbyte *java_cstr = (char*)(*env)->GetStringUTFChars(env, recv, NULL);
+ jsize len = (*env)->GetStringUTFLength(env, recv);
+
+ // Copy it in control of Nit
+ char *nit_cstr = (char*)malloc(len+1);
+ memcpy(nit_cstr, java_cstr, len);
+ nit_cstr[len] = '\0';
+
+ // Free JNI ref and return
+ (*env)->ReleaseStringUTFChars(env, recv, java_cstr);
+ return nit_cstr;
+ `}
+
+ redef fun to_s do return to_cstring.to_s
+end
+
+redef class NativeString
+ # Get a Java string from this C string
+ #
+ # This instance is only valid until the next execution of Java code.
+ # You can use `new_local_ref` to keep it longer.
+ fun to_java_string: JavaString import sys, Sys.jni_env `{
+ Sys sys = JavaString_sys(recv);
+ JNIEnv *env = Sys_jni_env(sys);
+ return (*env)->NewStringUTF(env, recv);
+ `}
+end
+
+redef class Text
+ fun to_java_string: JavaString do return to_cstring.to_java_string
+end
+
+redef extern class JavaObject
+ type SELF: JavaObject
+
+ # Returns a global reference to the Java object behind this reference
+ #
+ # You must use a global reference when keeping a Java object
+ # across execution of Java code, per JNI specification.
+ fun new_global_ref: SELF import sys, Sys.jni_env `{
+ Sys sys = JavaObject_sys(recv);
+ JNIEnv *env = Sys_jni_env(sys);
+ return (*env)->NewGlobalRef(env, recv);
+ `}
+
+ # Delete this global reference
+ fun delete_global_ref import sys, Sys.jni_env `{
+ Sys sys = JavaObject_sys(recv);
+ JNIEnv *env = Sys_jni_env(sys);
+ (*env)->DeleteGlobalRef(env, recv);
+ `}
+
+ # Delete this local reference
+ fun delete_local_ref import sys, Sys.jni_env `{
+ Sys sys = JavaObject_sys(recv);
+ JNIEnv *env = Sys_jni_env(sys);
+ (*env)->DeleteLocalRef(env, recv);
+ `}
+
+ # Pops the current local reference frame and return a valid reference to self
+ #
+ # Similiar to `JavaVM::pop_local_frame` but returns a value.
+ fun pop_from_local_frame: SELF
+ do
+ var jni_env = sys.jni_env
+ return pop_from_local_frame_with_env(jni_env)
+ end
+
+ private fun pop_from_local_frame_with_env(jni_env: JniEnv): SELF `{
+ return (*jni_env)->PopLocalFrame(jni_env, recv);
+ `}
+end
nitlanguage / nit.git / blobdiff