Library renamed to Pdf4Qt

Pdf4QtLib/sources/pdfobjectutils.h

@@ -0,0 +1,102 @@
+//    Copyright (C) 2020 Jakub Melka
+//
+//    This file is part of Pdf4Qt.
+//
+//    Pdf4Qt 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.
+//
+//    Pdf4Qt 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 Pdf4Qt. 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;
+};
+
+/// 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(!reference.isValid() || !context->isMarked(reference))
+    {
+        if (m_locked && reference.isValid())
+        {
+            context->mark(reference);
+        }
+    }
+
+    explicit inline PDFMarkedObjectsLock(PDFMarkedObjectsContext* context, const PDFObject& object) :
+        PDFMarkedObjectsLock(context, object.isReference() ? object.getReference() : PDFObjectReference())
+    {
+
+    }
+
+    inline ~PDFMarkedObjectsLock()
+    {
+        if (m_locked && m_reference.isValid())
+        {
+            m_context->unmark(m_reference);
+        }
+    }
+
+    explicit operator bool() const { return m_locked; }
+
+private:
+    PDFMarkedObjectsContext* m_context;
+    PDFObjectReference m_reference;
+    bool m_locked;
+};
+
+} // namespace pdf
+
+#endif // PDFOBJECTUTILS_H