PDF4QT/PdfForQtLib/sources/pdfobjectutils.h

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2020-05-31 18:31:59 +02:00
// Copyright (C) 2020 Jakub Melka
//
// This file is part of PdfForQt.
//
// PdfForQt is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// PdfForQt is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with PDFForQt. If not, see <https://www.gnu.org/licenses/>.
#ifndef PDFOBJECTUTILS_H
#define PDFOBJECTUTILS_H
#include "pdfobject.h"
#include <set>
namespace pdf
{
class PDFObjectStorage;
/// Utilities for manipulation with objects
class PDFObjectUtils
{
public:
/// Returns list of references referenced by \p objects. So, all references, which are present
/// in objects, appear in the result set, including objects, which are referenced by referenced
/// objects (so, transitive closure above reference graph is returned).
/// \param objects Objects
/// \param storage Storage
static std::set<PDFObjectReference> getReferences(const std::vector<PDFObject>& objects, const PDFObjectStorage& storage);
static PDFObject replaceReferences(const PDFObject& object, const std::map<PDFObjectReference, PDFObjectReference>& referenceMapping);
private:
PDFObjectUtils() = delete;
};
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/// Storage, which can mark objects (for example, when we want to mark already visited objects
/// during parsing some complex structure, such as tree)
class PDFMarkedObjectsContext
{
public:
inline explicit PDFMarkedObjectsContext() = default;
inline bool isMarked(PDFObjectReference reference) const { return m_markedReferences.count(reference); }
inline void mark(PDFObjectReference reference) { m_markedReferences.insert(reference); }
inline void unmark(PDFObjectReference reference) { m_markedReferences.erase(reference); }
private:
std::set<PDFObjectReference> m_markedReferences;
};
/// Class for marking/unmarking objects functioning as guard. If not already marked, then
/// during existence of this guard, object is marked and then it is unmarked. If it is
/// already marked, then nothing happens and locked flag is set to false.
class PDFMarkedObjectsLock
{
public:
explicit inline PDFMarkedObjectsLock(PDFMarkedObjectsContext* context, PDFObjectReference reference) :
m_context(context),
m_reference(reference),
m_locked(!context->isMarked(reference))
{
if (m_locked)
{
context->mark(reference);
}
}
inline ~PDFMarkedObjectsLock()
{
if (m_locked)
{
m_context->unmark(m_reference);
}
}
explicit operator bool() const { return m_locked; }
private:
PDFMarkedObjectsContext* m_context;
PDFObjectReference m_reference;
bool m_locked;
};
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} // namespace pdf
#endif // PDFOBJECTUTILS_H