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/*
* Copyright 2010-2018 Max Kellermann <max.kellermann@gmail.com>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* - Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the
* distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* FOUNDATION OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
* OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef JAVA_REF_HXX
#define JAVA_REF_HXX
#include "Global.hxx"
#include <jni.h>
#include <cassert>
#include <utility>
namespace Java {
/**
* Hold a local reference on a JNI object.
*/
template<typename T>
class LocalRef {
JNIEnv *const env;
const T value;
public:
/**
* The local reference is obtained by the caller. May
* be nullptr.
*/
LocalRef(JNIEnv *_env, T _value) noexcept
:env(_env), value(_value)
{
assert(env != nullptr);
}
LocalRef(LocalRef &&src) noexcept
:env(src.env),
value(std::exchange(src.value, nullptr)) {}
~LocalRef() noexcept {
env->DeleteLocalRef(value);
}
LocalRef(const LocalRef &other) = delete;
LocalRef &operator=(const LocalRef &other) = delete;
JNIEnv *GetEnv() const noexcept {
return env;
}
operator bool() const noexcept {
return value != nullptr;
}
T Get() const noexcept {
return value;
}
operator T() const noexcept {
return value;
}
};
/**
* Hold a global reference on a JNI object.
*/
template<typename T>
class GlobalRef {
T value;
public:
/**
* Constructs an uninitialized object. The method
* set() must be called before it is destructed.
*/
GlobalRef() = default;
GlobalRef(JNIEnv *env, T _value) noexcept
:value(_value)
{
assert(env != nullptr);
assert(value != nullptr);
value = (T)env->NewGlobalRef(value);
}
~GlobalRef() noexcept {
GetEnv()->DeleteGlobalRef(value);
}
GlobalRef(const GlobalRef &other) = delete;
GlobalRef &operator=(const GlobalRef &other) = delete;
/**
* Sets the object, ignoring the previous value. This
* is only allowed once after the default constructor
* was used.
*/
void Set(JNIEnv *env, T _value) noexcept {
assert(_value != nullptr);
value = (T)env->NewGlobalRef(_value);
}
T Get() const noexcept {
return value;
}
operator T() const noexcept {
return value;
}
};
/**
* Container for a global reference to a JNI object that gets
* initialised and deinitialised explicitly. Since there is
* no implicit initialisation in the default constructor, this
* is a trivial C++ class. It should only be used for global
* variables that are implicitly initialised with zeroes.
*/
template<typename T>
class TrivialRef {
T value;
public:
TrivialRef() = default;
TrivialRef(const TrivialRef &other) = delete;
TrivialRef &operator=(const TrivialRef &other) = delete;
bool IsDefined() const noexcept {
return value != nullptr;
}
/**
* Obtain a global reference on the specified object
* and store it. This object must not be set already.
*/
void Set(JNIEnv *env, T _value) noexcept {
assert(value == nullptr);
assert(_value != nullptr);
value = (T)env->NewGlobalRef(_value);
}
/**
* Release the global reference and clear this object.
*/
void Clear(JNIEnv *env) noexcept {
assert(value != nullptr);
env->DeleteGlobalRef(value);
value = nullptr;
}
/**
* Release the global reference and clear this object.
* It is allowed to call this method without ever
* calling Set().
*/
void ClearOptional(JNIEnv *env) noexcept {
if (value != nullptr)
Clear(env);
}
T Get() const noexcept {
return value;
}
operator T() const noexcept {
return value;
}
};
}
#endif
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