# 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
# See the License for the specific language governing permissions and
# limitations under the License.
-# Supporting services for the FFI with Java
+# Supporting services for the FFI with Java and to access Java libraries
#
# 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
# 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
+# See also, the module `jvm` to control the JVM instances and access JNI functions.
+# You can use it to further customize the behavior of your code.
+module java
- private fun pop_from_local_frame_with_env(jni_env: JniEnv): SELF `{
- return (*jni_env)->PopLocalFrame(jni_env, recv);
- `}
-end
+import ffi_support
+import collections
nitlanguage / nit.git / blobdiff