director.swg

/***********************************************************************
 * director.swg
 *
 *     This file contains support for director classes that proxy
 *     method calls from C++ to Java extensions.
 *
 * Author : Scott Michel (scottm@aero.org)
 *
 * This file was adapted from the python director.swg, written by
 * Mark Rose (mrose@stm.lbl.gov)
 ************************************************************************/

#ifdef __cplusplus

#if defined(DEBUG_DIRECTOR_OWNED)
#include <iostream>
#endif

namespace Swig {
  /* Java object wrapper */
  class JObjectWrapper {
  public:
    JObjectWrapper() : jthis_(NULL), weak_global_(true) {
    }

    ~JObjectWrapper() {
      jthis_ = NULL;
      weak_global_ = true;
    }

    bool set(JNIEnv *jenv, jobject jobj, bool mem_own, bool weak_global) {
      if (jthis_ == NULL) {
        weak_global_ = weak_global;
        if (jobj)
          jthis_ = ((weak_global_ || !mem_own) ? jenv->NewWeakGlobalRef(jobj) : jenv->NewGlobalRef(jobj));
#if defined(DEBUG_DIRECTOR_OWNED)
        std::cout << "JObjectWrapper::set(" << jobj << ", " << (weak_global ? "weak_global" : "global_ref") << ") -> " << jthis_ << std::endl;
#endif
        return true;
      } else {
#if defined(DEBUG_DIRECTOR_OWNED)
        std::cout << "JObjectWrapper::set(" << jobj << ", " << (weak_global ? "weak_global" : "global_ref") << ") -> already set" << std::endl;
#endif
        return false;
      }
    }

    jobject get(JNIEnv *jenv) const {
#if defined(DEBUG_DIRECTOR_OWNED)
      std::cout << "JObjectWrapper::get(";
      if (jthis_)
        std::cout << jthis_;
      else
        std::cout << "null";
      std::cout << ") -> return new local ref" << std::endl;
#endif
      return (jthis_ ? jenv->NewLocalRef(jthis_) : jthis_);
    }

    void release(JNIEnv *jenv) {
#if defined(DEBUG_DIRECTOR_OWNED)
      std::cout << "JObjectWrapper::release(" << jthis_ << "): " << (weak_global_ ? "weak global ref" : "global ref") << std::endl;
#endif
      if (jthis_ != NULL) {
        if (weak_global_) {
          if (jenv->IsSameObject(jthis_, NULL) == JNI_FALSE)
            jenv->DeleteWeakGlobalRef((jweak)jthis_);
        } else
          jenv->DeleteGlobalRef(jthis_);
      }

      jthis_ = NULL;
      weak_global_ = true;
    }

    jobject peek() {
      return jthis_;
    }

    /* Java proxy releases ownership of C++ object, C++ object is now
       responsible for destruction (creates NewGlobalRef to pin Java
       proxy) */
    void java_change_ownership(JNIEnv *jenv, jobject jself, bool take_or_release) {
      if (take_or_release) {  /* Java takes ownership of C++ object's lifetime. */
        if (!weak_global_) {
          jenv->DeleteGlobalRef(jthis_);
          jthis_ = jenv->NewWeakGlobalRef(jself);
          weak_global_ = true;
        }
      } else { /* Java releases ownership of C++ object's lifetime */
        if (weak_global_) {
          jenv->DeleteWeakGlobalRef((jweak)jthis_);
          jthis_ = jenv->NewGlobalRef(jself);
          weak_global_ = false;
        }
      }
    }

  private:
    /* pointer to Java object */
    jobject jthis_;
    /* Local or global reference flag */
    bool weak_global_;
  };

  /* director base class */
  class Director {
  private:
    /* pointer to Java virtual machine */
    JavaVM *swig_jvm_;

  protected:
    /* Java object wrapper */
    JObjectWrapper swig_self_;

    /* Acquire Java VM environment from Java VM */
    JNIEnv *swig_acquire_jenv() const {
      JNIEnv *env = NULL;
      swig_jvm_->AttachCurrentThread((void **) &env, NULL);
      return env;
    }

    /* Disconnect director from Java object */
    void swig_disconnect_director_self(const char *disconn_method) {
      JNIEnv *jenv = swig_acquire_jenv();
      jobject jobj = swig_self_.peek();
#if defined(DEBUG_DIRECTOR_OWNED)
      std::cout << "Swig::Director::disconnect_director_self(" << jobj << ")" << std::endl;
#endif
      if (jobj && jenv->IsSameObject(jobj, NULL) == JNI_FALSE) {
        jmethodID disconn_meth = jenv->GetMethodID(jenv->GetObjectClass(jobj), disconn_method, "()V");
        if (disconn_meth) {
#if defined(DEBUG_DIRECTOR_OWNED)
          std::cout << "Swig::Director::disconnect_director_self upcall to " << disconn_method << std::endl;
#endif
          jenv->CallVoidMethod(jobj, disconn_meth);
        }
      }
    }

  public:
    Director(JNIEnv *jenv) : swig_jvm_((JavaVM *) NULL), swig_self_() {
      /* Acquire the Java VM pointer */
      jenv->GetJavaVM(&swig_jvm_);
    }

    virtual ~Director() {
      swig_self_.release(swig_acquire_jenv());
    }

    bool swig_set_self(JNIEnv *jenv, jobject jself, bool mem_own, bool weak_global) {
      return swig_self_.set(jenv, jself, mem_own, weak_global);
    }

    jobject swig_get_self(JNIEnv *jenv) const {
      return swig_self_.get(jenv);
    }

    // Change C++ object's ownership, relative to Java
    void swig_java_change_ownership(JNIEnv *jenv, jobject jself, bool take_or_release) {
      swig_self_.java_change_ownership(jenv, jself, take_or_release);
    }
  };
}

#endif /* __cplusplus */