mirror of https://github.com/JakubMelka/PDF4QT.git
103 lines
3.5 KiB
C++
103 lines
3.5 KiB
C++
// Copyright (C) 2020 Jakub Melka
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//
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// This file is part of PdfForQt.
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//
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// PdfForQt is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// PdfForQt is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public License
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// along with PDFForQt. If not, see <https://www.gnu.org/licenses/>.
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#ifndef PDFOBJECTUTILS_H
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#define PDFOBJECTUTILS_H
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#include "pdfobject.h"
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#include <set>
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namespace pdf
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{
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class PDFObjectStorage;
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/// Utilities for manipulation with objects
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class PDFObjectUtils
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{
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public:
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/// Returns list of references referenced by \p objects. So, all references, which are present
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/// in objects, appear in the result set, including objects, which are referenced by referenced
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/// objects (so, transitive closure above reference graph is returned).
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/// \param objects Objects
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/// \param storage Storage
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static std::set<PDFObjectReference> getReferences(const std::vector<PDFObject>& objects, const PDFObjectStorage& storage);
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static PDFObject replaceReferences(const PDFObject& object, const std::map<PDFObjectReference, PDFObjectReference>& referenceMapping);
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private:
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PDFObjectUtils() = delete;
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};
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/// Storage, which can mark objects (for example, when we want to mark already visited objects
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/// during parsing some complex structure, such as tree)
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class PDFMarkedObjectsContext
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{
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public:
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inline explicit PDFMarkedObjectsContext() = default;
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inline bool isMarked(PDFObjectReference reference) const { return m_markedReferences.count(reference); }
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inline void mark(PDFObjectReference reference) { m_markedReferences.insert(reference); }
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inline void unmark(PDFObjectReference reference) { m_markedReferences.erase(reference); }
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private:
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std::set<PDFObjectReference> m_markedReferences;
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};
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/// Class for marking/unmarking objects functioning as guard. If not already marked, then
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/// during existence of this guard, object is marked and then it is unmarked. If it is
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/// already marked, then nothing happens and locked flag is set to false.
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class PDFMarkedObjectsLock
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{
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public:
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explicit inline PDFMarkedObjectsLock(PDFMarkedObjectsContext* context, PDFObjectReference reference) :
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m_context(context),
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m_reference(reference),
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m_locked(!reference.isValid() || !context->isMarked(reference))
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{
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if (m_locked && reference.isValid())
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{
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context->mark(reference);
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}
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}
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explicit inline PDFMarkedObjectsLock(PDFMarkedObjectsContext* context, const PDFObject& object) :
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PDFMarkedObjectsLock(context, object.isReference() ? object.getReference() : PDFObjectReference())
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{
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}
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inline ~PDFMarkedObjectsLock()
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{
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if (m_locked && m_reference.isValid())
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{
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m_context->unmark(m_reference);
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}
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}
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explicit operator bool() const { return m_locked; }
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private:
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PDFMarkedObjectsContext* m_context;
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PDFObjectReference m_reference;
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bool m_locked;
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};
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} // namespace pdf
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#endif // PDFOBJECTUTILS_H
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