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diff --git a/include/jvmaccess/virtualmachine.hxx b/include/jvmaccess/virtualmachine.hxx
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+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/*
+ * This file is part of the LibreOffice project.
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ *
+ * This file incorporates work covered by the following license notice:
+ *
+ *   Licensed to the Apache Software Foundation (ASF) under one or more
+ *   contributor license agreements. See the NOTICE file distributed
+ *   with this work for additional information regarding copyright
+ *   ownership. The ASF licenses this file to you 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 .
+ */
+
+#ifndef INCLUDED_JVMACCESS_VIRTUALMACHINE_HXX
+#define INCLUDED_JVMACCESS_VIRTUALMACHINE_HXX
+
+#include <jvmaccess/jvmaccessdllapi.h>
+#include <rtl/ref.hxx>
+#include <salhelper/simplereferenceobject.hxx>
+
+#include <jni.h>
+
+namespace jvmaccess {
+
+/** An encapsulating wrapper around a Java virtual machine.
+ */
+class JVMACCESS_DLLPUBLIC VirtualMachine final : public salhelper::SimpleReferenceObject
+{
+public:
+    /** A helper to attach a thread to a Java virtual machine.
+
+        @descr
+        Upon construction of a guard the current thread is attached to the
+        virtual machine, and upon destruction of the guard the thread is
+        detached again.  For any one thread, multiple instances of this class
+        may be used in a stack-like fashion (care is taken to only really
+        detach the thread from the virtual machine upon destruction of the guard
+        at the bottom of the stack).
+     */
+    class JVMACCESS_DLLPUBLIC AttachGuard
+    {
+    public:
+        /** An exception indicating failure to create an AttachGuard.
+         */
+        class JVMACCESS_DLLPUBLIC CreationException final
+        {
+        public:
+            CreationException();
+
+            CreationException(CreationException const &);
+
+            ~CreationException();
+
+            CreationException & operator =(CreationException const &);
+        };
+
+        /** Attach the current thread to a virtual machine.
+
+            @param rMachine
+            The virtual machine to attach to.  Must not be a null reference.
+
+            @exception CreationException
+            Thrown in case attaching fails (due to a JNI problem).
+         */
+        explicit AttachGuard(rtl::Reference< VirtualMachine > const & rMachine);
+
+        /** Detach the current thread from the virtual machine again.
+         */
+        ~AttachGuard();
+
+        /** Get a JNI environment pointer for the current thread.
+
+            @return
+            A valid JNI environment pointer.  Will never be null.
+         */
+        JNIEnv * getEnvironment() const { return m_pEnvironment; }
+
+    private:
+        AttachGuard(AttachGuard const &) = delete;
+        AttachGuard& operator =(AttachGuard const &) = delete;
+
+        rtl::Reference< VirtualMachine > m_xMachine;
+        JNIEnv * m_pEnvironment;
+        bool m_bDetach;
+    };
+
+    /** Create a wrapper around a Java virtual machine.
+
+        @param pVm
+        A JNI pointer to virtual machine.  Must not be null.
+
+        @param nVersion
+        The JNI version of the virtual machine pointed to by pVm.  Must be at
+        least JNI_VERSION_1_2.  This parameter should be of type jint, not int,
+        but at least on some platforms the definition of jint changed from
+        JDK 1.3 (long) to JDK 1.4 (int), so that the mangled C++ name of the
+        constructor would depend on the JDK version used at compile time.
+
+        @param bDestroy
+        Whether to destroy the virtual machine when destructing the wrapper
+        (i.e., whether the wrapper owns the virtual machine pointed to by pVm).
+
+        @param pMainThreadEnv
+        A valid JNI environment pointer for the current thread; must not be
+        null.  The current thread must be "initially attached" to the virtual
+        machine while this constructor is being called (i.e., it must be the
+        thread that has called JNI_CreateJavaVM in case the virtual machine has
+        been started via the JNI Invocation API, and it must not already have
+        called DetachCurrentThread; or it must be executing native code called
+        from a "primordial" virtual machine).  This environment pointer was
+        formerly used to obtain a reference to the thread's current context
+        class loader (java.lang.Thread.getCurrentClassLoader; if later a native
+        thread was attached to the virtual machine, that thread's context class
+        loader would be null, so the AttachGuard first of all set it to the
+        saved value; this feature has been removed again for performance reasons
+        and because the default context class loader is often not useful, so
+        that code relying on a context class loader has to set one explicitly,
+        anyway).  This parameter is currently unused (but may be used again in
+        the future).
+     */
+    VirtualMachine(JavaVM * pVm, int nVersion, bool bDestroy,
+                   JNIEnv const * pMainThreadEnv);
+
+private:
+    VirtualMachine(VirtualMachine const &) = delete;
+    VirtualMachine& operator =(VirtualMachine const & ) = delete;
+
+    virtual ~VirtualMachine() override;
+
+    JNIEnv * attachThread(bool * pAttached) const;
+
+    void detachThread() const;
+
+    JavaVM * m_pVm;
+    jint m_nVersion;
+    bool m_bDestroy;
+
+    friend class AttachGuard; // to access attachThread, detachThread
+};
+
+}
+
+#endif // INCLUDED_JVMACCESS_VIRTUALMACHINE_HXX
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */