Adding upstream version 1:7.0.4.upstream/1%7.0.4upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1603 insertions, 0 deletions

diff --git a/sfx2/source/doc/Metadatable.cxx b/sfx2/source/doc/Metadatable.cxx
new file mode 100644
index 000000000..22aeb4277
--- /dev/null
+++ b/sfx2/source/doc/Metadatable.cxx
@@ -0,0 +1,1603 @@
+/* -*- 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 .
+ */
+
+#include <sal/config.h>
+#include <sal/log.hxx>
+
+#include <osl/diagnose.h>
+#include <sfx2/Metadatable.hxx>
+#include <sfx2/XmlIdRegistry.hxx>
+
+#include <vcl/svapp.hxx>
+#include <com/sun/star/frame/XModel.hpp>
+#include <com/sun/star/lang/IllegalArgumentException.hpp>
+#include <comphelper/random.hxx>
+
+#include <algorithm>
+#include <memory>
+#include <unordered_map>
+#if OSL_DEBUG_LEVEL > 0
+#include <typeinfo>
+#endif
+
+
+/** XML ID handling.
+
+    There is an abstract base class <type>XmlIdRegistry</type>, with
+    2 subclasses <type>XmlIdRegistryDocument</type> for "normal" documents,
+    and <type>XmlIdRegistryClipboard</type> for clipboard documents.
+    These classes are responsible for managing XML IDs for all elements
+    of the model. Only the implementation of the <type>Metadatable</type>
+    base class needs to know the registries, so they are not in the header.
+
+    The handling of XML IDs differs between clipboard and non-clipboard
+    documents in several aspects. Most importantly, non-clipboard documents
+    can have several elements associated with one XML ID.
+    This is necessary because of the weird undo implementation:
+    deleting a text node moves the deleted node to the undo array, but
+    executing undo will then create a <em>copy</em> of that node in the
+    document array. These 2 nodes must have the same XML ID, because
+    we cannot know whether the user will do a redo next, or something else.
+
+    Because we need to have a mechanism for several objects per XML ID anyway,
+    we use that also to enable some usability features:
+    The document registry has a list of Metadatables per XML ID.
+    This list is sorted by priority, i.e., the first element has highest
+    priority. When inserting copies, care must be taken that they are inserted
+    at the right position: either before or after the source.
+    This is done by <method>Metadatable::RegisterAsCopyOf</method>.
+    When a text node is split, then both resulting text nodes are inserted
+    into the list. If the user then deletes one text node, the other one
+    will have the XML ID.
+    Also, when a Metadatable is copied to the clipboard and then pasted,
+    the copy is inserted into the list. If the user then deletes the source,
+    the XML ID is not lost.
+    The goal is that it should be hard to lose an XML ID by accident, which
+    is especially important as long as we do not have an UI that displays them.
+
+    There are two subclasses of <type>Metadatable</type>:
+    <ul><li><type>MetadatableClipboard</type>: for copies in the clipboard</li>
+        <li><type>MetadatableUndo</type>: for undo, because a Metadatable
+        may be destroyed on delete and a new one created on undo.</li></ul>
+    These serve only to track the position in an XML ID list in a document
+    registry, so that future actions can insert objects at the right position.
+    Unfortunately, inserting dummy objects seems to be necessary:
+    <ul><li>it is not sufficient to just remember the saved id, because then
+            the relative priorities might change when executing the undo</li>
+        <li>it is not sufficient to record the position as an integer, because
+            if we delete a text node and then undo, the node will be copied(!),
+            and we will have one more node in the list.<li>
+        <li>it is not sufficient to record the pointer of the previous/next
+            Metadatable, because if we delete a text node, undo, and then
+            do something to clear the redo array, the original text node is
+            destroyed, and is replaced by the copy created by undo</li></ul>
+
+    If content from a non-clipboard document is copied into a clipboard
+    document, a dummy <type>MetadatableClipboard</type> is inserted into the
+    non-clipboard document registry in order to track the position of the
+    source element.  When the clipboard content is pasted back into the source
+    document, this dummy object is used to associate the pasted element with
+    that same XML ID.
+
+    If a <type>Metadatable</type> is deleted or merged,
+    <method>Metadatable::CreateUndo</method> is called, and returns a
+    <type>MetadatableUndo<type> instance, which can be used to undo the action
+    by passing it to <method>Metadatable::RestoreMetadata</method>.
+
+ */
+
+
+using namespace ::com::sun::star;
+
+using ::sfx2::isValidXmlId;
+
+
+namespace sfx2 {
+
+static const char s_content [] = "content.xml";
+static const char s_styles  [] = "styles.xml";
+
+static bool isContentFile(OUString const & i_rPath)
+{
+    return i_rPath == s_content;
+}
+
+static bool isStylesFile (OUString const & i_rPath)
+{
+    return i_rPath == s_styles;
+}
+
+
+// XML ID handling ---------------------------------------------------
+
+/** handles registration of XMetadatable.
+
+    This class is responsible for guaranteeing that XMetadatable objects
+    always have XML IDs that are unique within a stream.
+
+    This is an abstract base class; see subclasses XmlIdRegistryDocument and
+    XmlIdRegistryClipboard.
+
+    @see SwDoc::GetXmlIdRegistry
+    @see SwDocShell::GetXmlIdRegistry
+ */
+class XmlIdRegistry : public sfx2::IXmlIdRegistry
+{
+
+public:
+    XmlIdRegistry();
+
+    /** get the ODF element with the given metadata reference. */
+    virtual css::uno::Reference< css::rdf::XMetadatable >
+        GetElementByMetadataReference(
+            const css::beans::StringPair & i_rReference) const
+        override;
+
+    /** register an ODF element at a newly generated, unique metadata reference.
+
+        <p>
+        Find a fresh XML ID, and register it for the element.
+        The generated ID does not occur in any stream of the document.
+        </p>
+     */
+    virtual void RegisterMetadatableAndCreateID(Metadatable& i_xObject) = 0;
+
+    /** try to register an ODF element at a given XML ID, or update its
+        registration to a different XML ID.
+
+        <p>
+        If the given new metadata reference is not already occupied in the
+        document, unregister the element at its old metadata reference if
+        it has one, and register the new metadata reference for the element.
+        Note that this method only ensures that XML IDs are unique per stream,
+        so using the same XML ID in both content.xml and styles.xml is allowed.
+        </p>
+
+        @returns
+            true iff the element has successfully been registered
+     */
+    virtual bool TryRegisterMetadatable(Metadatable& i_xObject,
+        OUString const& i_rStreamName, OUString const& i_rIdref)
+        = 0;
+
+    /** unregister an ODF element.
+
+        <p>
+        Unregister the element at its metadata reference.
+        Does not remove the metadata reference from the element.
+        </p>
+
+        @see RemoveXmlIdForElement
+     */
+    virtual void UnregisterMetadatable(Metadatable const&) = 0;
+
+    /** get the metadata reference for the given element. */
+    css::beans::StringPair
+        GetXmlIdForElement(Metadatable const&) const;
+
+    /** remove the metadata reference for the given element. */
+    virtual void RemoveXmlIdForElement(Metadatable const&) = 0;
+
+protected:
+
+    virtual bool LookupXmlId(const Metadatable& i_xObject,
+        OUString & o_rStream, OUString & o_rIdref) const = 0;
+
+    virtual Metadatable* LookupElement(const OUString & i_rStreamName,
+        const OUString & i_rIdref) const = 0;
+};
+
+// XmlIdRegistryDocument ---------------------------------------------
+
+namespace {
+
+/** non-clipboard documents */
+class XmlIdRegistryDocument : public XmlIdRegistry
+{
+
+public:
+    XmlIdRegistryDocument();
+
+    virtual ~XmlIdRegistryDocument() override;
+
+    virtual void RegisterMetadatableAndCreateID(Metadatable& i_xObject) override;
+
+    virtual bool TryRegisterMetadatable(Metadatable& i_xObject,
+        OUString const& i_rStreamName, OUString const& i_rIdref) override;
+
+    virtual void UnregisterMetadatable(Metadatable const&) override;
+
+    virtual void RemoveXmlIdForElement(Metadatable const&) override;
+
+    /** register i_rCopy as a copy of i_rSource,
+        with precedence iff i_bCopyPrecedesSource is true */
+    void RegisterCopy(Metadatable const& i_rSource, Metadatable & i_rCopy,
+        const bool i_bCopyPrecedesSource);
+
+    /** create a Undo Metadatable for i_rObject. */
+    static std::shared_ptr<MetadatableUndo> CreateUndo(
+        Metadatable const& i_rObject);
+
+    /** merge i_rMerged and i_rOther into i_rMerged. */
+    void JoinMetadatables(Metadatable & i_rMerged, Metadatable const& i_rOther);
+
+    // unfortunately public, Metadatable::RegisterAsCopyOf needs this
+    virtual bool LookupXmlId(const Metadatable& i_xObject,
+        OUString & o_rStream, OUString & o_rIdref) const override;
+
+private:
+
+    virtual Metadatable* LookupElement(const OUString & i_rStreamName,
+        const OUString & i_rIdref) const override;
+
+    struct XmlIdRegistry_Impl;
+    ::std::unique_ptr<XmlIdRegistry_Impl> m_pImpl;
+};
+
+}
+
+// MetadatableUndo ---------------------------------------------------
+
+/** the horrible Undo Metadatable: is inserted into lists to track position */
+class MetadatableUndo : public Metadatable
+{
+    /// as determined by the stream of the source in original document
+    const bool m_isInContent;
+public:
+    explicit MetadatableUndo(const bool i_isInContent)
+        : m_isInContent(i_isInContent) { }
+    virtual ::sfx2::XmlIdRegistry& GetRegistry() override
+    {
+        // N.B. for Undo, m_pReg is initialized by registering this as copy in
+        // CreateUndo; it is never cleared
+        OSL_ENSURE(m_pReg, "no m_pReg in MetadatableUndo ?");
+        return *m_pReg;
+    }
+    virtual bool IsInClipboard() const override { return false; }
+    virtual bool IsInUndo() const override { return true; }
+    virtual bool IsInContent() const override { return m_isInContent; }
+    virtual css::uno::Reference< css::rdf::XMetadatable > MakeUnoObject() override
+    { OSL_FAIL("MetadatableUndo::MakeUnoObject"); throw; }
+};
+
+// MetadatableClipboard ----------------------------------------------
+
+/** the horrible Clipboard Metadatable: inserted into lists to track position */
+class MetadatableClipboard : public Metadatable
+{
+    /// as determined by the stream of the source in original document
+    const bool m_isInContent;
+public:
+    explicit MetadatableClipboard(const bool i_isInContent)
+        : m_isInContent(i_isInContent) { }
+    virtual ::sfx2::XmlIdRegistry& GetRegistry() override
+    {
+        // N.B. for Clipboard, m_pReg is initialized by registering this as copy in
+        // RegisterAsCopyOf; it is only cleared by OriginNoLongerInBusinessAnymore
+        assert(m_pReg && "no m_pReg in MetadatableClipboard ?");
+        return *m_pReg;
+    }
+    virtual bool IsInClipboard() const override { return true; }
+    virtual bool IsInUndo() const override { return false; }
+    virtual bool IsInContent() const override { return m_isInContent; }
+    virtual css::uno::Reference< css::rdf::XMetadatable > MakeUnoObject() override
+    { OSL_FAIL("MetadatableClipboard::MakeUnoObject"); throw; }
+    void OriginNoLongerInBusinessAnymore() { m_pReg = nullptr; }
+};
+
+// XmlIdRegistryClipboard --------------------------------------------
+
+namespace {
+
+class XmlIdRegistryClipboard : public XmlIdRegistry
+{
+
+public:
+    XmlIdRegistryClipboard();
+
+    virtual void RegisterMetadatableAndCreateID(Metadatable& i_xObject) override;
+
+    virtual bool TryRegisterMetadatable(Metadatable& i_xObject,
+        OUString const& i_rStreamName, OUString const& i_rIdref) override;
+
+    virtual void UnregisterMetadatable(Metadatable const&) override;
+
+    virtual void RemoveXmlIdForElement(Metadatable const&) override;
+
+    /** register i_rCopy as a copy of i_rSource */
+    MetadatableClipboard & RegisterCopyClipboard(Metadatable & i_rCopy,
+        beans::StringPair const & i_rReference,
+        const bool i_isLatent);
+
+    /** get the Metadatable that links i_rObject to its origin registry */
+    MetadatableClipboard const* SourceLink(Metadatable const& i_rObject);
+
+private:
+    virtual bool LookupXmlId(const Metadatable& i_xObject,
+        OUString & o_rStream, OUString & o_rIdref) const override;
+
+    virtual Metadatable* LookupElement(const OUString & i_rStreamName,
+        const OUString & i_rIdref) const override;
+
+    /** create a Clipboard Metadatable for i_rObject. */
+    static std::shared_ptr<MetadatableClipboard> CreateClipboard(
+        const bool i_isInContent);
+
+    struct XmlIdRegistry_Impl;
+    ::std::unique_ptr<XmlIdRegistry_Impl> m_pImpl;
+};
+
+}
+
+// XmlIdRegistry
+
+::sfx2::IXmlIdRegistry * createXmlIdRegistry(const bool i_DocIsClipboard)
+{
+    return i_DocIsClipboard
+        ? static_cast<XmlIdRegistry*>( new XmlIdRegistryClipboard )
+        : static_cast<XmlIdRegistry*>( new XmlIdRegistryDocument );
+}
+
+XmlIdRegistry::XmlIdRegistry()
+{
+}
+
+css::uno::Reference< css::rdf::XMetadatable >
+XmlIdRegistry::GetElementByMetadataReference(
+    const beans::StringPair & i_rReference) const
+{
+    Metadatable* pObject( LookupElement(i_rReference.First,
+        i_rReference.Second) );
+    return pObject ? pObject->MakeUnoObject() : nullptr;
+}
+
+beans::StringPair
+XmlIdRegistry::GetXmlIdForElement(const Metadatable& i_rObject) const
+{
+    OUString path;
+    OUString idref;
+    if (LookupXmlId(i_rObject, path, idref))
+    {
+        if (LookupElement(path, idref) == &i_rObject)
+        {
+            return beans::StringPair(path, idref);
+        }
+    }
+    return beans::StringPair();
+}
+
+
+/// generate unique xml:id
+template< typename T >
+static OUString create_id(const
+    std::unordered_map< OUString, T > & i_rXmlIdMap)
+{
+    static bool bHack = (getenv("LIBO_ONEWAY_STABLE_ODF_EXPORT") != nullptr);
+    static const char prefix[] = "id";  // prefix for generated xml:id
+    typename std::unordered_map< OUString, T >
+        ::const_iterator iter;
+    OUString id;
+
+    if (bHack)
+    {
+        static sal_Int64 nIdCounter = SAL_CONST_INT64(4000000000);
+        do
+        {
+            id = prefix + OUString::number(nIdCounter++);
+            iter = i_rXmlIdMap.find(id);
+        }
+        while (iter != i_rXmlIdMap.end());
+    }
+    else
+    {
+        do
+        {
+            unsigned int const n(comphelper::rng::uniform_uint_distribution(0,
+                                    std::numeric_limits<unsigned int>::max()));
+            id = prefix + OUString::number(n);
+            iter = i_rXmlIdMap.find(id);
+        }
+        while (iter != i_rXmlIdMap.end());
+    }
+    return id;
+}
+
+
+// Document XML ID Registry (_Impl)
+
+/// element list
+typedef ::std::vector< Metadatable* > XmlIdVector_t;
+
+/// Idref -> (content.xml element list, styles.xml element list)
+typedef std::unordered_map< OUString,
+    ::std::pair< XmlIdVector_t, XmlIdVector_t > > XmlIdMap_t;
+
+namespace {
+
+/// pointer hash template
+template<typename T> struct PtrHash
+{
+    size_t operator() (T const * i_pT) const
+    {
+        return reinterpret_cast<size_t>(i_pT);
+    }
+};
+
+}
+
+/// element -> (stream name, idref)
+typedef std::unordered_map< const Metadatable*,
+    ::std::pair< OUString, OUString>, PtrHash<Metadatable> >
+    XmlIdReverseMap_t;
+
+struct XmlIdRegistryDocument::XmlIdRegistry_Impl
+{
+    XmlIdRegistry_Impl()
+        : m_XmlIdMap(), m_XmlIdReverseMap() { }
+
+    bool TryInsertMetadatable(Metadatable& i_xObject,
+        const OUString & i_rStream, const OUString & i_rIdref);
+
+    bool LookupXmlId(const Metadatable& i_xObject,
+        OUString & o_rStream, OUString & o_rIdref) const;
+
+    Metadatable* LookupElement(const OUString & i_rStreamName,
+        const OUString & i_rIdref) const;
+
+    const XmlIdVector_t * LookupElementVector(
+        const OUString & i_rStreamName,
+        const OUString & i_rIdref) const;
+
+          XmlIdVector_t * LookupElementVector(
+        const OUString & i_rStreamName,
+        const OUString & i_rIdref)
+    {
+        return const_cast<XmlIdVector_t*>(
+            const_cast<const XmlIdRegistry_Impl*>(this)
+                ->LookupElementVector(i_rStreamName, i_rIdref));
+    }
+
+    XmlIdMap_t m_XmlIdMap;
+    XmlIdReverseMap_t m_XmlIdReverseMap;
+};
+
+
+static void
+rmIter(XmlIdMap_t & i_rXmlIdMap, XmlIdMap_t::iterator const& i_rIter,
+    OUString const & i_rStream, Metadatable const& i_rObject)
+{
+    if (i_rIter != i_rXmlIdMap.end())
+    {
+        XmlIdVector_t & rVector( isContentFile(i_rStream)
+            ? i_rIter->second.first : i_rIter->second.second );
+        rVector.erase(std::remove(rVector.begin(), rVector.end(), &const_cast<Metadatable&>(i_rObject)));
+        if (i_rIter->second.first.empty() && i_rIter->second.second.empty())
+        {
+            i_rXmlIdMap.erase(i_rIter);
+        }
+    }
+}
+
+
+const XmlIdVector_t *
+XmlIdRegistryDocument::XmlIdRegistry_Impl::LookupElementVector(
+    const OUString & i_rStreamName,
+    const OUString & i_rIdref) const
+{
+    const XmlIdMap_t::const_iterator iter( m_XmlIdMap.find(i_rIdref) );
+    if (iter != m_XmlIdMap.end())
+    {
+        OSL_ENSURE(!iter->second.first.empty() || !iter->second.second.empty(),
+            "null entry in m_XmlIdMap");
+        return (isContentFile(i_rStreamName))
+            ?  &iter->second.first
+            :  &iter->second.second;
+    }
+    else
+    {
+        return nullptr;
+    }
+}
+
+Metadatable*
+XmlIdRegistryDocument::XmlIdRegistry_Impl::LookupElement(
+    const OUString & i_rStreamName,
+    const OUString & i_rIdref) const
+{
+    if (!isValidXmlId(i_rStreamName, i_rIdref))
+    {
+        throw lang::IllegalArgumentException("illegal XmlId", nullptr, 0);
+    }
+
+    const XmlIdVector_t * pList( LookupElementVector(i_rStreamName, i_rIdref) );
+    if (pList)
+    {
+        const XmlIdVector_t::const_iterator iter(
+            ::std::find_if(pList->begin(), pList->end(),
+                [](Metadatable* item)->bool {
+                    return !(item->IsInUndo() || item->IsInClipboard());
+                    } ) ) ;
+        if (iter != pList->end())
+        {
+            return *iter;
+        }
+    }
+    return nullptr;
+}
+
+bool
+XmlIdRegistryDocument::XmlIdRegistry_Impl::LookupXmlId(
+    const Metadatable& i_rObject,
+    OUString & o_rStream, OUString & o_rIdref) const
+{
+    const XmlIdReverseMap_t::const_iterator iter(
+        m_XmlIdReverseMap.find(&i_rObject) );
+    if (iter != m_XmlIdReverseMap.end())
+    {
+        OSL_ENSURE(!iter->second.first.isEmpty(),
+            "null stream in m_XmlIdReverseMap");
+        OSL_ENSURE(!iter->second.second.isEmpty(),
+            "null id in m_XmlIdReverseMap");
+        o_rStream = iter->second.first;
+        o_rIdref  = iter->second.second;
+        return true;
+    }
+    else
+    {
+        return false;
+    }
+}
+
+bool
+XmlIdRegistryDocument::XmlIdRegistry_Impl::TryInsertMetadatable(
+    Metadatable & i_rObject,
+    const OUString & i_rStreamName, const OUString & i_rIdref)
+{
+    const bool bContent( isContentFile(i_rStreamName) );
+    OSL_ENSURE(isContentFile(i_rStreamName) || isStylesFile(i_rStreamName),
+        "invalid stream");
+
+    XmlIdVector_t * pList( LookupElementVector(i_rStreamName, i_rIdref) );
+    if (pList)
+    {
+        if (pList->empty())
+        {
+            pList->push_back( &i_rObject );
+            return true;
+        }
+        else
+        {
+            // this is only called from TryRegister now, so check
+            // if all elements in the list are deleted (in undo) or
+            // placeholders, then "steal" the id from them
+            if ( std::none_of(pList->begin(), pList->end(),
+                [](Metadatable* item)->bool {
+                    return !(item->IsInUndo() || item->IsInClipboard());
+                    } ) )
+            {
+                pList->insert(pList->begin(), &i_rObject );
+                return true;
+            }
+            else
+            {
+                return false;
+            }
+        }
+    }
+    else
+    {
+        m_XmlIdMap.insert(::std::make_pair(i_rIdref, bContent
+            ? ::std::make_pair( XmlIdVector_t( 1, &i_rObject ), XmlIdVector_t() )
+            : ::std::make_pair( XmlIdVector_t(), XmlIdVector_t( 1, &i_rObject ) )));
+        return true;
+    }
+}
+
+
+// Document XML ID Registry
+
+
+XmlIdRegistryDocument::XmlIdRegistryDocument()
+    :   m_pImpl( new XmlIdRegistry_Impl )
+{
+}
+
+static void
+removeLink(Metadatable* i_pObject)
+{
+    OSL_ENSURE(i_pObject, "null in list ???");
+    if (!i_pObject) return;
+    if (i_pObject->IsInClipboard())
+    {
+        MetadatableClipboard* pLink(
+            dynamic_cast<MetadatableClipboard*>( i_pObject ) );
+        OSL_ENSURE(pLink, "IsInClipboard, but no MetadatableClipboard ?");
+        if (pLink)
+        {
+            pLink->OriginNoLongerInBusinessAnymore();
+        }
+    }
+}
+
+XmlIdRegistryDocument::~XmlIdRegistryDocument()
+{
+    // notify all list elements that are actually in the clipboard
+    for (const auto& aXmlId : m_pImpl->m_XmlIdMap) {
+        for (auto aLink : aXmlId.second.first)
+            removeLink(aLink);
+        for (auto aLink : aXmlId.second.second)
+            removeLink(aLink);
+    }
+}
+
+bool
+XmlIdRegistryDocument::LookupXmlId(
+    const Metadatable& i_rObject,
+    OUString & o_rStream, OUString & o_rIdref) const
+{
+    return m_pImpl->LookupXmlId(i_rObject, o_rStream, o_rIdref);
+}
+
+Metadatable*
+XmlIdRegistryDocument::LookupElement(
+    const OUString & i_rStreamName,
+    const OUString & i_rIdref) const
+{
+    return m_pImpl->LookupElement(i_rStreamName, i_rIdref);
+}
+
+bool
+XmlIdRegistryDocument::TryRegisterMetadatable(Metadatable & i_rObject,
+    OUString const& i_rStreamName, OUString const& i_rIdref)
+{
+    SAL_INFO("sfx", "TryRegisterMetadatable: " << &i_rObject << " (" << i_rStreamName << "#" << i_rIdref << ")");
+
+    OSL_ENSURE(!dynamic_cast<MetadatableUndo*>(&i_rObject),
+        "TryRegisterMetadatable called for MetadatableUndo?");
+    OSL_ENSURE(!dynamic_cast<MetadatableClipboard*>(&i_rObject),
+        "TryRegisterMetadatable called for MetadatableClipboard?");
+
+    if (!isValidXmlId(i_rStreamName, i_rIdref))
+    {
+        throw lang::IllegalArgumentException("illegal XmlId", nullptr, 0);
+    }
+    if (i_rObject.IsInContent()
+        ?   !isContentFile(i_rStreamName)
+        :   !isStylesFile(i_rStreamName))
+    {
+        throw lang::IllegalArgumentException("illegal XmlId: wrong stream", nullptr, 0);
+    }
+
+    OUString old_path;
+    OUString old_idref;
+    m_pImpl->LookupXmlId(i_rObject, old_path, old_idref);
+    if (old_path  == i_rStreamName && old_idref == i_rIdref)
+    {
+        return (m_pImpl->LookupElement(old_path, old_idref) == &i_rObject);
+    }
+    XmlIdMap_t::iterator old_id( m_pImpl->m_XmlIdMap.end() );
+    if (!old_idref.isEmpty())
+    {
+        old_id = m_pImpl->m_XmlIdMap.find(old_idref);
+        OSL_ENSURE(old_id != m_pImpl->m_XmlIdMap.end(), "old id not found");
+    }
+    if (m_pImpl->TryInsertMetadatable(i_rObject, i_rStreamName, i_rIdref))
+    {
+        rmIter(m_pImpl->m_XmlIdMap, old_id, old_path, i_rObject);
+        m_pImpl->m_XmlIdReverseMap[&i_rObject] =
+            ::std::make_pair(i_rStreamName, i_rIdref);
+        return true;
+    }
+    else
+    {
+        return false;
+    }
+}
+
+void
+XmlIdRegistryDocument::RegisterMetadatableAndCreateID(Metadatable & i_rObject)
+{
+    SAL_INFO("sfx", "RegisterMetadatableAndCreateID: " << &i_rObject);
+
+    OSL_ENSURE(!dynamic_cast<MetadatableUndo*>(&i_rObject),
+        "RegisterMetadatableAndCreateID called for MetadatableUndo?");
+    OSL_ENSURE(!dynamic_cast<MetadatableClipboard*>(&i_rObject),
+        "RegisterMetadatableAndCreateID called for MetadatableClipboard?");
+
+    const bool isInContent( i_rObject.IsInContent() );
+    const OUString stream( OUString::createFromAscii(
+        isInContent ? s_content : s_styles ) );
+    // check if we have a latent xmlid, and if yes, remove it
+    OUString old_path;
+    OUString old_idref;
+    m_pImpl->LookupXmlId(i_rObject, old_path, old_idref);
+
+    XmlIdMap_t::iterator old_id( m_pImpl->m_XmlIdMap.end() );
+    if (!old_idref.isEmpty())
+    {
+        old_id = m_pImpl->m_XmlIdMap.find(old_idref);
+        OSL_ENSURE(old_id != m_pImpl->m_XmlIdMap.end(), "old id not found");
+        if (m_pImpl->LookupElement(old_path, old_idref) == &i_rObject)
+        {
+            return;
+        }
+        else
+        {
+            // remove latent xmlid
+            rmIter(m_pImpl->m_XmlIdMap, old_id, old_path, i_rObject);
+        }
+    }
+
+    // create id
+    const OUString id( create_id(m_pImpl->m_XmlIdMap) );
+    OSL_ENSURE(m_pImpl->m_XmlIdMap.find(id) == m_pImpl->m_XmlIdMap.end(),
+        "created id is in use");
+    m_pImpl->m_XmlIdMap.insert(::std::make_pair(id, isInContent
+        ? ::std::make_pair( XmlIdVector_t( 1, &i_rObject ), XmlIdVector_t() )
+        : ::std::make_pair( XmlIdVector_t(), XmlIdVector_t( 1, &i_rObject ) )));
+    m_pImpl->m_XmlIdReverseMap[&i_rObject] = ::std::make_pair(stream, id);
+}
+
+void XmlIdRegistryDocument::UnregisterMetadatable(const Metadatable& i_rObject)
+{
+    SAL_INFO("sfx", "UnregisterMetadatable: " << &i_rObject);
+
+    OUString path;
+    OUString idref;
+    if (!m_pImpl->LookupXmlId(i_rObject, path, idref))
+    {
+        OSL_FAIL("unregister: no xml id?");
+        return;
+    }
+    const XmlIdMap_t::iterator iter( m_pImpl->m_XmlIdMap.find(idref) );
+    if (iter != m_pImpl->m_XmlIdMap.end())
+    {
+        rmIter(m_pImpl->m_XmlIdMap, iter, path, i_rObject);
+    }
+}
+
+void XmlIdRegistryDocument::RemoveXmlIdForElement(const Metadatable& i_rObject)
+{
+    SAL_INFO("sfx", "RemoveXmlIdForElement: " << &i_rObject);
+
+    const XmlIdReverseMap_t::iterator iter(
+        m_pImpl->m_XmlIdReverseMap.find(&i_rObject) );
+    if (iter != m_pImpl->m_XmlIdReverseMap.end())
+    {
+        OSL_ENSURE(!iter->second.second.isEmpty(),
+            "null id in m_XmlIdReverseMap");
+        m_pImpl->m_XmlIdReverseMap.erase(iter);
+    }
+}
+
+
+void XmlIdRegistryDocument::RegisterCopy(Metadatable const& i_rSource,
+    Metadatable & i_rCopy, const bool i_bCopyPrecedesSource)
+{
+    SAL_INFO("sfx", "RegisterCopy: " << &i_rSource << " -> " << &i_rCopy << " (" << i_bCopyPrecedesSource << ")");
+
+    // potential sources: clipboard, undo array, splitNode
+    // assumption: stream change can only happen via clipboard, and is handled
+    // by Metadatable::RegisterAsCopyOf
+    OSL_ENSURE(i_rSource.IsInUndo() || i_rCopy.IsInUndo() ||
+        (i_rSource.IsInContent() == i_rCopy.IsInContent()),
+        "RegisterCopy: not in same stream?");
+
+    OUString path;
+    OUString idref;
+    if (!m_pImpl->LookupXmlId( i_rSource, path, idref ))
+    {
+        OSL_FAIL("no xml id?");
+        return;
+    }
+    XmlIdVector_t * pList ( m_pImpl->LookupElementVector(path, idref) );
+    OSL_ENSURE( ::std::find( pList->begin(), pList->end(), &i_rCopy )
+        == pList->end(), "copy already registered???");
+    XmlIdVector_t::iterator srcpos(
+        ::std::find( pList->begin(), pList->end(), &i_rSource ) );
+    OSL_ENSURE(srcpos != pList->end(), "source not in list???");
+    if (srcpos == pList->end())
+    {
+        return;
+    }
+    if (i_bCopyPrecedesSource)
+    {
+        pList->insert( srcpos, &i_rCopy );
+    }
+    else
+    {
+        // for undo push_back does not work! must insert right after source
+        pList->insert( ++srcpos, &i_rCopy );
+    }
+    m_pImpl->m_XmlIdReverseMap.insert(::std::make_pair(&i_rCopy,
+        ::std::make_pair(path, idref)));
+}
+
+std::shared_ptr<MetadatableUndo>
+XmlIdRegistryDocument::CreateUndo(Metadatable const& i_rObject)
+{
+    SAL_INFO("sfx", "CreateUndo: " << &i_rObject);
+
+    return std::make_shared<MetadatableUndo>(
+                i_rObject.IsInContent() );
+}
+
+/*
+i_rMerged is both a source and the target node of the merge
+i_rOther is the other source, and will be deleted after the merge
+
+dimensions: none|latent|actual empty|nonempty
+i_rMerged(1)    i_rOther(2)        result
+     *|empty         *|empty    => 1|2 (arbitrary)
+     *|empty         *|nonempty => 2
+     *|nonempty      *|empty    => 1
+  none|nonempty   none|nonempty => none
+  none|nonempty latent|nonempty => 2
+latent|nonempty   none|nonempty => 1
+latent|nonempty latent|nonempty => 1|2
+     *|nonempty actual|nonempty => 2
+actual|nonempty      *|nonempty => 1
+actual|nonempty actual|nonempty => 1|2
+*/
+void
+XmlIdRegistryDocument::JoinMetadatables(
+    Metadatable & i_rMerged, Metadatable const & i_rOther)
+{
+    SAL_INFO("sfx", "JoinMetadatables: " << &i_rMerged << " <- " << &i_rOther);
+
+    bool mergedOwnsRef;
+    OUString path;
+    OUString idref;
+    if (m_pImpl->LookupXmlId(i_rMerged, path, idref))
+    {
+        mergedOwnsRef = (m_pImpl->LookupElement(path, idref) == &i_rMerged);
+    }
+    else
+    {
+        OSL_FAIL("JoinMetadatables: no xmlid?");
+        return;
+    }
+    if (!mergedOwnsRef)
+    {
+        i_rMerged.RemoveMetadataReference();
+        i_rMerged.RegisterAsCopyOf(i_rOther, true);
+        return;
+    }
+    // other cases: merged has actual ref and is nonempty,
+    // other has latent/actual ref and is nonempty: other loses => nothing to do
+}
+
+
+// Clipboard XML ID Registry (_Impl)
+
+namespace {
+
+struct RMapEntry
+{
+    RMapEntry() : m_xLink() { }
+    RMapEntry(OUString const& i_rStream,
+            OUString const& i_rXmlId,
+            std::shared_ptr<MetadatableClipboard> const& i_pLink
+                = std::shared_ptr<MetadatableClipboard>())
+        :   m_Stream(i_rStream), m_XmlId(i_rXmlId), m_xLink(i_pLink)
+        {}
+    OUString m_Stream;
+    OUString m_XmlId;
+    // this would have been an auto_ptr, if only that would have compiled...
+    std::shared_ptr<MetadatableClipboard> m_xLink;
+};
+
+}
+
+/// element -> (stream name, idref, source)
+typedef std::unordered_map< const Metadatable*,
+    struct RMapEntry,
+    PtrHash<Metadatable> >
+    ClipboardXmlIdReverseMap_t;
+
+/// Idref -> (content.xml element, styles.xml element)
+typedef std::unordered_map< OUString,
+    ::std::pair< Metadatable*, Metadatable* > >
+    ClipboardXmlIdMap_t;
+
+struct XmlIdRegistryClipboard::XmlIdRegistry_Impl
+{
+    XmlIdRegistry_Impl()
+        : m_XmlIdMap(), m_XmlIdReverseMap() { }
+
+    bool TryInsertMetadatable(Metadatable& i_xObject,
+        const OUString & i_rStream, const OUString & i_rIdref);
+
+    bool LookupXmlId(const Metadatable& i_xObject,
+        OUString & o_rStream, OUString & o_rIdref,
+        MetadatableClipboard const* &o_rpLink) const;
+
+    Metadatable* LookupElement(const OUString & i_rStreamName,
+        const OUString & i_rIdref) const;
+
+    Metadatable* const* LookupEntry(const OUString & i_rStreamName,
+        const OUString & i_rIdref) const;
+
+    ClipboardXmlIdMap_t m_XmlIdMap;
+    ClipboardXmlIdReverseMap_t m_XmlIdReverseMap;
+};
+
+
+static void
+rmIter(ClipboardXmlIdMap_t & i_rXmlIdMap,
+    ClipboardXmlIdMap_t::iterator const& i_rIter,
+    OUString const & i_rStream, Metadatable const& i_rObject)
+{
+    if (i_rIter == i_rXmlIdMap.end())
+        return;
+
+    Metadatable *& rMeta = isContentFile(i_rStream)
+        ? i_rIter->second.first : i_rIter->second.second;
+    if (rMeta == &i_rObject)
+    {
+        rMeta = nullptr;
+    }
+    if (!i_rIter->second.first && !i_rIter->second.second)
+    {
+        i_rXmlIdMap.erase(i_rIter);
+    }
+}
+
+
+Metadatable* const*
+XmlIdRegistryClipboard::XmlIdRegistry_Impl::LookupEntry(
+    const OUString & i_rStreamName,
+    const OUString & i_rIdref) const
+{
+    if (!isValidXmlId(i_rStreamName, i_rIdref))
+    {
+        throw lang::IllegalArgumentException("illegal XmlId", nullptr, 0);
+    }
+
+    const ClipboardXmlIdMap_t::const_iterator iter( m_XmlIdMap.find(i_rIdref) );
+    if (iter != m_XmlIdMap.end())
+    {
+        OSL_ENSURE(iter->second.first || iter->second.second,
+            "null entry in m_XmlIdMap");
+        return (isContentFile(i_rStreamName))
+            ?  &iter->second.first
+            :  &iter->second.second;
+    }
+    else
+    {
+        return nullptr;
+    }
+}
+
+Metadatable*
+XmlIdRegistryClipboard::XmlIdRegistry_Impl::LookupElement(
+    const OUString & i_rStreamName,
+    const OUString & i_rIdref) const
+{
+    Metadatable * const * ppEntry = LookupEntry(i_rStreamName, i_rIdref);
+    return ppEntry ? *ppEntry : nullptr;
+}
+
+bool
+XmlIdRegistryClipboard::XmlIdRegistry_Impl::LookupXmlId(
+    const Metadatable& i_rObject,
+    OUString & o_rStream, OUString & o_rIdref,
+    MetadatableClipboard const* &o_rpLink) const
+{
+    const ClipboardXmlIdReverseMap_t::const_iterator iter(
+        m_XmlIdReverseMap.find(&i_rObject) );
+    if (iter != m_XmlIdReverseMap.end())
+    {
+        OSL_ENSURE(!iter->second.m_Stream.isEmpty(),
+            "null stream in m_XmlIdReverseMap");
+        OSL_ENSURE(!iter->second.m_XmlId.isEmpty(),
+            "null id in m_XmlIdReverseMap");
+        o_rStream = iter->second.m_Stream;
+        o_rIdref  = iter->second.m_XmlId;
+        o_rpLink  = iter->second.m_xLink.get();
+        return true;
+    }
+    else
+    {
+        return false;
+    }
+}
+
+bool
+XmlIdRegistryClipboard::XmlIdRegistry_Impl::TryInsertMetadatable(
+    Metadatable & i_rObject,
+    const OUString & i_rStreamName, const OUString & i_rIdref)
+{
+    bool bContent( isContentFile(i_rStreamName) );
+    OSL_ENSURE(isContentFile(i_rStreamName) || isStylesFile(i_rStreamName),
+        "invalid stream");
+
+    Metadatable ** ppEntry = const_cast<Metadatable**>(LookupEntry(i_rStreamName, i_rIdref));
+    if (ppEntry)
+    {
+        if (*ppEntry)
+        {
+            return false;
+        }
+        else
+        {
+            *ppEntry = &i_rObject;
+            return true;
+        }
+    }
+    else
+    {
+        m_XmlIdMap.insert(::std::make_pair(i_rIdref, bContent
+            ? ::std::make_pair( &i_rObject, static_cast<Metadatable*>(nullptr) )
+            : ::std::make_pair( static_cast<Metadatable*>(nullptr), &i_rObject )));
+        return true;
+    }
+}
+
+
+// Clipboard XML ID Registry
+
+
+XmlIdRegistryClipboard::XmlIdRegistryClipboard()
+    :   m_pImpl( new XmlIdRegistry_Impl )
+{
+}
+
+bool
+XmlIdRegistryClipboard::LookupXmlId(
+    const Metadatable& i_rObject,
+    OUString & o_rStream, OUString & o_rIdref) const
+{
+    const MetadatableClipboard * pLink;
+    return m_pImpl->LookupXmlId(i_rObject, o_rStream, o_rIdref, pLink);
+}
+
+Metadatable*
+XmlIdRegistryClipboard::LookupElement(
+    const OUString & i_rStreamName,
+    const OUString & i_rIdref) const
+{
+    return m_pImpl->LookupElement(i_rStreamName, i_rIdref);
+}
+
+bool
+XmlIdRegistryClipboard::TryRegisterMetadatable(Metadatable & i_rObject,
+    OUString const& i_rStreamName, OUString const& i_rIdref)
+{
+    SAL_INFO("sfx", "TryRegisterMetadatable: " << &i_rObject << " (" << i_rStreamName << "#" << i_rIdref <<")");
+
+    OSL_ENSURE(!dynamic_cast<MetadatableUndo*>(&i_rObject),
+        "TryRegisterMetadatable called for MetadatableUndo?");
+    OSL_ENSURE(!dynamic_cast<MetadatableClipboard*>(&i_rObject),
+        "TryRegisterMetadatable called for MetadatableClipboard?");
+
+    if (!isValidXmlId(i_rStreamName, i_rIdref))
+    {
+        throw lang::IllegalArgumentException("illegal XmlId", nullptr, 0);
+    }
+    if (i_rObject.IsInContent()
+        ?   !isContentFile(i_rStreamName)
+        :   !isStylesFile(i_rStreamName))
+    {
+        throw lang::IllegalArgumentException("illegal XmlId: wrong stream", nullptr, 0);
+    }
+
+    OUString old_path;
+    OUString old_idref;
+    const MetadatableClipboard * pLink;
+    m_pImpl->LookupXmlId(i_rObject, old_path, old_idref, pLink);
+    if (old_path  == i_rStreamName && old_idref == i_rIdref)
+    {
+        return (m_pImpl->LookupElement(old_path, old_idref) == &i_rObject);
+    }
+    ClipboardXmlIdMap_t::iterator old_id( m_pImpl->m_XmlIdMap.end() );
+    if (!old_idref.isEmpty())
+    {
+        old_id = m_pImpl->m_XmlIdMap.find(old_idref);
+        OSL_ENSURE(old_id != m_pImpl->m_XmlIdMap.end(), "old id not found");
+    }
+    if (m_pImpl->TryInsertMetadatable(i_rObject, i_rStreamName, i_rIdref))
+    {
+        rmIter(m_pImpl->m_XmlIdMap, old_id, old_path, i_rObject);
+        m_pImpl->m_XmlIdReverseMap[&i_rObject] =
+            RMapEntry(i_rStreamName, i_rIdref);
+        return true;
+    }
+    else
+    {
+        return false;
+    }
+}
+
+void
+XmlIdRegistryClipboard::RegisterMetadatableAndCreateID(Metadatable & i_rObject)
+{
+    SAL_INFO("sfx", "RegisterMetadatableAndCreateID: " << &i_rObject);
+
+    OSL_ENSURE(!dynamic_cast<MetadatableUndo*>(&i_rObject),
+        "RegisterMetadatableAndCreateID called for MetadatableUndo?");
+    OSL_ENSURE(!dynamic_cast<MetadatableClipboard*>(&i_rObject),
+        "RegisterMetadatableAndCreateID called for MetadatableClipboard?");
+
+    bool isInContent( i_rObject.IsInContent() );
+    OUString stream( OUString::createFromAscii(
+        isInContent ? s_content : s_styles ) );
+
+    OUString old_path;
+    OUString old_idref;
+    LookupXmlId(i_rObject, old_path, old_idref);
+    if (!old_idref.isEmpty() &&
+        (m_pImpl->LookupElement(old_path, old_idref) == &i_rObject))
+    {
+        return;
+    }
+
+    // create id
+    const OUString id( create_id(m_pImpl->m_XmlIdMap) );
+    OSL_ENSURE(m_pImpl->m_XmlIdMap.find(id) == m_pImpl->m_XmlIdMap.end(),
+        "created id is in use");
+    m_pImpl->m_XmlIdMap.insert(::std::make_pair(id, isInContent
+        ? ::std::make_pair( &i_rObject, static_cast<Metadatable*>(nullptr) )
+        : ::std::make_pair( static_cast<Metadatable*>(nullptr), &i_rObject )));
+    // N.B.: if i_rObject had a latent XmlId, then we implicitly delete the
+    // MetadatableClipboard and thus the latent XmlId here
+    m_pImpl->m_XmlIdReverseMap[&i_rObject] = RMapEntry(stream, id);
+}
+
+void XmlIdRegistryClipboard::UnregisterMetadatable(const Metadatable& i_rObject)
+{
+    SAL_INFO("sfx", "UnregisterMetadatable: " << &i_rObject);
+
+    OUString path;
+    OUString idref;
+    const MetadatableClipboard * pLink;
+    if (!m_pImpl->LookupXmlId(i_rObject, path, idref, pLink))
+    {
+        OSL_FAIL("unregister: no xml id?");
+        return;
+    }
+    const ClipboardXmlIdMap_t::iterator iter( m_pImpl->m_XmlIdMap.find(idref) );
+    if (iter != m_pImpl->m_XmlIdMap.end())
+    {
+        rmIter(m_pImpl->m_XmlIdMap, iter, path, i_rObject);
+    }
+}
+
+
+void XmlIdRegistryClipboard::RemoveXmlIdForElement(const Metadatable& i_rObject)
+{
+    SAL_INFO("sfx", "RemoveXmlIdForElement: " << &i_rObject);
+
+    ClipboardXmlIdReverseMap_t::iterator iter(
+        m_pImpl->m_XmlIdReverseMap.find(&i_rObject) );
+    if (iter != m_pImpl->m_XmlIdReverseMap.end())
+    {
+        OSL_ENSURE(!iter->second.m_XmlId.isEmpty(),
+            "null id in m_XmlIdReverseMap");
+        m_pImpl->m_XmlIdReverseMap.erase(iter);
+    }
+}
+
+
+std::shared_ptr<MetadatableClipboard>
+XmlIdRegistryClipboard::CreateClipboard(const bool i_isInContent)
+{
+    SAL_INFO("sfx", "CreateClipboard:");
+
+    return std::make_shared<MetadatableClipboard>(
+        i_isInContent );
+}
+
+MetadatableClipboard &
+XmlIdRegistryClipboard::RegisterCopyClipboard(Metadatable & i_rCopy,
+    beans::StringPair const & i_rReference,
+    const bool i_isLatent)
+{
+    SAL_INFO("sfx", "RegisterCopyClipboard: " << &i_rCopy
+              << " -> (" << i_rReference.First << "#" << i_rReference.Second << ") (" << i_isLatent << ")");
+
+    // N.B.: when copying to the clipboard, the selection is always inserted
+    //       into the body, even if the source is a header/footer!
+    //       so we do not check whether the stream is right in this function
+
+    if (!isValidXmlId(i_rReference.First, i_rReference.Second))
+    {
+        throw lang::IllegalArgumentException("illegal XmlId", nullptr, 0);
+    }
+
+    if (!i_isLatent)
+    {
+        // this should succeed assuming clipboard has a single source document
+        const bool success( m_pImpl->TryInsertMetadatable(i_rCopy,
+                i_rReference.First, i_rReference.Second) );
+        OSL_ENSURE(success, "RegisterCopyClipboard: TryInsert failed?");
+    }
+    const std::shared_ptr<MetadatableClipboard> xLink(
+        CreateClipboard( isContentFile(i_rReference.First)) );
+    m_pImpl->m_XmlIdReverseMap.insert(::std::make_pair(&i_rCopy,
+        RMapEntry(i_rReference.First, i_rReference.Second, xLink)));
+    return *xLink;
+}
+
+MetadatableClipboard const*
+XmlIdRegistryClipboard::SourceLink(Metadatable const& i_rObject)
+{
+    OUString path;
+    OUString idref;
+    const MetadatableClipboard * pLink( nullptr );
+    m_pImpl->LookupXmlId(i_rObject, path, idref, pLink);
+    return pLink;
+}
+
+
+// Metadatable mixin
+
+
+Metadatable::~Metadatable()
+{
+    RemoveMetadataReference();
+}
+
+void Metadatable::RemoveMetadataReference()
+{
+    try
+    {
+        if (m_pReg)
+        {
+            m_pReg->UnregisterMetadatable( *this );
+            m_pReg->RemoveXmlIdForElement( *this );
+            m_pReg = nullptr;
+        }
+    }
+    catch (const uno::Exception &)
+    {
+        OSL_FAIL("Metadatable::RemoveMetadataReference: exception");
+    }
+}
+
+// css::rdf::XMetadatable:
+beans::StringPair
+Metadatable::GetMetadataReference() const
+{
+    if (m_pReg)
+    {
+        return m_pReg->GetXmlIdForElement(*this);
+    }
+    return beans::StringPair();
+}
+
+void Metadatable::SetMetadataReference( const css::beans::StringPair & i_rReference)
+{
+    if (i_rReference.Second.isEmpty())
+    {
+        RemoveMetadataReference();
+    }
+    else
+    {
+        OUString streamName( i_rReference.First );
+        if (streamName.isEmpty())
+        {
+            // handle empty stream name as auto-detect.
+            // necessary for importing flat file format.
+            streamName = OUString::createFromAscii(
+                            IsInContent() ? s_content : s_styles );
+        }
+        XmlIdRegistry & rReg( dynamic_cast<XmlIdRegistry&>( GetRegistry() ) );
+        if (!rReg.TryRegisterMetadatable(*this, streamName, i_rReference.Second))
+        {
+            throw lang::IllegalArgumentException(
+                "Metadatable::SetMetadataReference: argument is invalid", /*this*/nullptr, 0);
+        }
+
+        m_pReg = &rReg;
+    }
+}
+
+void Metadatable::EnsureMetadataReference()
+{
+    XmlIdRegistry& rReg(
+        m_pReg ? *m_pReg : dynamic_cast<XmlIdRegistry&>( GetRegistry() ) );
+    rReg.RegisterMetadatableAndCreateID( *this );
+    m_pReg = &rReg;
+}
+
+static const ::sfx2::IXmlIdRegistry& GetRegistryConst(Metadatable const& i_rObject)
+{
+    return const_cast< Metadatable& >( i_rObject ).GetRegistry();
+}
+
+void
+Metadatable::RegisterAsCopyOf(Metadatable const & i_rSource,
+    const bool i_bCopyPrecedesSource)
+{
+    OSL_ENSURE(typeid(*this) == typeid(i_rSource)
+        || typeid(i_rSource) == typeid(MetadatableUndo)
+        || typeid(*this)     == typeid(MetadatableUndo)
+        || typeid(i_rSource) == typeid(MetadatableClipboard)
+        || typeid(*this)     == typeid(MetadatableClipboard),
+        "RegisterAsCopyOf element with different class?");
+    OSL_ENSURE(!m_pReg, "RegisterAsCopyOf called on element with XmlId?");
+
+    if (m_pReg)
+    {
+        RemoveMetadataReference();
+    }
+
+    try
+    {
+        if (i_rSource.m_pReg)
+        {
+            XmlIdRegistry & rReg(
+                dynamic_cast<XmlIdRegistry&>( GetRegistry() ) );
+            if (i_rSource.m_pReg == &rReg)
+            {
+                OSL_ENSURE(!IsInClipboard(),
+                    "RegisterAsCopy: both in clipboard?");
+                if (!IsInClipboard())
+                {
+                    XmlIdRegistryDocument & rRegDoc(
+                        dynamic_cast<XmlIdRegistryDocument&>( rReg ) );
+                    rRegDoc.RegisterCopy(i_rSource, *this,
+                        i_bCopyPrecedesSource);
+                    m_pReg = &rRegDoc;
+                }
+                return;
+            }
+            // source is in different document
+            XmlIdRegistryDocument  * pRegDoc(
+                dynamic_cast<XmlIdRegistryDocument *>(&rReg) );
+            XmlIdRegistryClipboard * pRegClp(
+                dynamic_cast<XmlIdRegistryClipboard*>(&rReg) );
+
+            if (pRegClp)
+            {
+                beans::StringPair SourceRef(
+                    i_rSource.m_pReg->GetXmlIdForElement(i_rSource) );
+                bool isLatent( SourceRef.Second.isEmpty() );
+                XmlIdRegistryDocument * pSourceRegDoc(
+                    dynamic_cast<XmlIdRegistryDocument*>(i_rSource.m_pReg) );
+                OSL_ENSURE(pSourceRegDoc, "RegisterAsCopyOf: 2 clipboards?");
+                if (!pSourceRegDoc) return;
+                // this is a copy _to_ the clipboard
+                if (isLatent)
+                {
+                    pSourceRegDoc->LookupXmlId(i_rSource,
+                        SourceRef.First, SourceRef.Second);
+                }
+                Metadatable & rLink(
+                    pRegClp->RegisterCopyClipboard(*this, SourceRef, isLatent));
+                m_pReg = pRegClp;
+                // register as copy in the non-clipboard registry
+                pSourceRegDoc->RegisterCopy(i_rSource, rLink,
+                    false); // i_bCopyPrecedesSource);
+                rLink.m_pReg = pSourceRegDoc;
+            }
+            else if (pRegDoc)
+            {
+                XmlIdRegistryClipboard * pSourceRegClp(
+                    dynamic_cast<XmlIdRegistryClipboard*>(i_rSource.m_pReg) );
+                OSL_ENSURE(pSourceRegClp,
+                    "RegisterAsCopyOf: 2 non-clipboards?");
+                if (!pSourceRegClp) return;
+                const MetadatableClipboard * pLink(
+                    pSourceRegClp->SourceLink(i_rSource) );
+                // may happen if src got its id via UNO call
+                if (!pLink) return;
+                // only register copy if clipboard content is from this SwDoc!
+                if (&GetRegistryConst(*pLink) == pRegDoc)
+                {
+                    // this is a copy _from_ the clipboard; check if the
+                    // element is still in the same stream
+                    // N.B.: we check the stream of pLink, not of i_rSource!
+                    bool srcInContent( pLink->IsInContent() );
+                    bool tgtInContent( IsInContent() );
+                    if (srcInContent == tgtInContent)
+                    {
+                        pRegDoc->RegisterCopy(*pLink, *this,
+                            true); // i_bCopyPrecedesSource);
+                        m_pReg = pRegDoc;
+                    }
+                    // otherwise: stream change! do not register!
+                }
+            }
+            else
+            {
+                OSL_FAIL("neither RegDoc nor RegClp cannot happen");
+            }
+        }
+    }
+    catch (const uno::Exception &)
+    {
+        OSL_FAIL("Metadatable::RegisterAsCopyOf: exception");
+    }
+}
+
+std::shared_ptr<MetadatableUndo> Metadatable::CreateUndo() const
+{
+    OSL_ENSURE(!IsInUndo(), "CreateUndo called for object in undo?");
+    OSL_ENSURE(!IsInClipboard(), "CreateUndo called for object in clipboard?");
+    try
+    {
+        if (!IsInClipboard() && !IsInUndo() && m_pReg)
+        {
+            XmlIdRegistryDocument * pRegDoc(
+                dynamic_cast<XmlIdRegistryDocument*>( m_pReg ) );
+            assert(pRegDoc);
+            std::shared_ptr<MetadatableUndo> xUndo(
+                sfx2::XmlIdRegistryDocument::CreateUndo(*this) );
+            pRegDoc->RegisterCopy(*this, *xUndo, false);
+            xUndo->m_pReg = pRegDoc;
+            return xUndo;
+        }
+    }
+    catch (const uno::Exception &)
+    {
+        OSL_FAIL("Metadatable::CreateUndo: exception");
+    }
+    return std::shared_ptr<MetadatableUndo>();
+}
+
+std::shared_ptr<MetadatableUndo> Metadatable::CreateUndoForDelete()
+{
+    std::shared_ptr<MetadatableUndo> const xUndo( CreateUndo() );
+    RemoveMetadataReference();
+    return xUndo;
+}
+
+void Metadatable::RestoreMetadata(
+    std::shared_ptr<MetadatableUndo> const& i_pUndo)
+{
+    OSL_ENSURE(!IsInUndo(), "RestoreMetadata called for object in undo?");
+    OSL_ENSURE(!IsInClipboard(),
+        "RestoreMetadata called for object in clipboard?");
+    if (IsInClipboard() || IsInUndo()) return;
+    RemoveMetadataReference();
+    if (i_pUndo)
+    {
+        RegisterAsCopyOf(*i_pUndo, true);
+    }
+}
+
+void
+Metadatable::JoinMetadatable(Metadatable const & i_rOther,
+    const bool i_isMergedEmpty, const bool i_isOtherEmpty)
+{
+    OSL_ENSURE(!IsInUndo(), "JoinMetadatables called for object in undo?");
+    OSL_ENSURE(!IsInClipboard(),
+        "JoinMetadatables called for object in clipboard?");
+    if (IsInClipboard() || IsInUndo()) return;
+
+    if (i_isOtherEmpty && !i_isMergedEmpty)
+    {
+        // other is empty, thus loses => nothing to do
+        return;
+    }
+    if (i_isMergedEmpty && !i_isOtherEmpty)
+    {
+        RemoveMetadataReference();
+        RegisterAsCopyOf(i_rOther, true);
+        return;
+    }
+
+    if (!i_rOther.m_pReg)
+    {
+        // other doesn't have xmlid, thus loses => nothing to do
+        return;
+    }
+    if (!m_pReg)
+    {
+        RegisterAsCopyOf(i_rOther, true);
+        // assumption: i_rOther will be deleted, so don't unregister it here
+        return;
+    }
+    try
+    {
+        XmlIdRegistryDocument * pRegDoc(
+            dynamic_cast<XmlIdRegistryDocument*>( m_pReg ) );
+        OSL_ENSURE(pRegDoc, "JoinMetadatable: no pRegDoc?");
+        if (pRegDoc)
+        {
+            pRegDoc->JoinMetadatables(*this, i_rOther);
+        }
+    }
+    catch (const uno::Exception &)
+    {
+        OSL_FAIL("Metadatable::JoinMetadatable: exception");
+    }
+}
+
+
+// XMetadatable mixin
+
+// css::rdf::XNode:
+OUString SAL_CALL MetadatableMixin::getStringValue()
+{
+    return getNamespace() + getLocalName();
+}
+
+// css::rdf::XURI:
+OUString SAL_CALL MetadatableMixin::getLocalName()
+{
+    SolarMutexGuard aGuard;
+    beans::StringPair mdref( getMetadataReference() );
+    if (mdref.Second.isEmpty())
+    {
+        ensureMetadataReference(); // N.B.: side effect!
+        mdref = getMetadataReference();
+    }
+    return mdref.First + "#" + mdref.Second;
+}
+
+OUString SAL_CALL MetadatableMixin::getNamespace()
+{
+    SolarMutexGuard aGuard;
+    const uno::Reference< frame::XModel > xModel( GetModel() );
+    const uno::Reference< rdf::XURI > xDMA( xModel, uno::UNO_QUERY_THROW );
+    return xDMA->getStringValue();
+}
+
+// css::rdf::XMetadatable:
+beans::StringPair SAL_CALL
+MetadatableMixin::getMetadataReference()
+{
+    SolarMutexGuard aGuard;
+
+    Metadatable *const pObject( GetCoreObject() );
+    if (!pObject)
+    {
+        throw uno::RuntimeException(
+            "MetadatableMixin: cannot get core object; not inserted?",
+            *this);
+    }
+    return pObject->GetMetadataReference();
+}
+
+void SAL_CALL
+MetadatableMixin::setMetadataReference(
+    const beans::StringPair & i_rReference)
+{
+    SolarMutexGuard aGuard;
+
+    Metadatable *const pObject( GetCoreObject() );
+    if (!pObject)
+    {
+        throw uno::RuntimeException(
+            "MetadatableMixin: cannot get core object; not inserted?",
+            *this);
+    }
+    return pObject->SetMetadataReference(i_rReference);
+}
+
+void SAL_CALL MetadatableMixin::ensureMetadataReference()
+{
+    SolarMutexGuard aGuard;
+
+    Metadatable *const pObject( GetCoreObject() );
+    if (!pObject)
+    {
+        throw uno::RuntimeException(
+            "MetadatableMixin: cannot get core object; not inserted?",
+            *this);
+    }
+    return pObject->EnsureMetadataReference();
+}
+
+} // namespace sfx2
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */