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Diffstat (limited to 'src/java/Ref.hxx')
| -rw-r--r-- | src/java/Ref.hxx | 181 |
1 files changed, 181 insertions, 0 deletions
diff --git a/src/java/Ref.hxx b/src/java/Ref.hxx new file mode 100644 index 000000000..e9966f1c6 --- /dev/null +++ b/src/java/Ref.hxx @@ -0,0 +1,181 @@ +/* + * Copyright (C) 2010-2011 Max Kellermann <max@duempel.org> + * + * 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 <assert.h> + +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. + */ + LocalRef(JNIEnv *_env, T _value):env(_env), value(_value) { + assert(env != nullptr); + assert(value != nullptr); + } + + ~LocalRef() { + env->DeleteLocalRef(value); + } + + LocalRef(const LocalRef &other) = delete; + LocalRef &operator=(const LocalRef &other) = delete; + + T Get() const { + return value; + } + + operator T() const { + 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):value(_value) { + assert(env != nullptr); + assert(value != nullptr); + + value = (T)env->NewGlobalRef(value); + } + + ~GlobalRef() { + 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) { + assert(_value != nullptr); + + value = (T)env->NewGlobalRef(_value); + } + + T Get() const { + return value; + } + + operator T() const { + 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: + constexpr TrivialRef() {}; + + TrivialRef(const TrivialRef &other) = delete; + TrivialRef &operator=(const TrivialRef &other) = delete; + + bool IsDefined() const { + 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) { + assert(value == nullptr); + assert(_value != nullptr); + + value = (T)env->NewGlobalRef(_value); + } + + /** + * Release the global reference and clear this object. + */ + void Clear(JNIEnv *env) { + 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) { + if (value != nullptr) + Clear(env); + } + + T Get() const { + return value; + } + + operator T() const { + return value; + } + }; +} + +#endif |