Parsing X Reference table

PdfForQtLib/sources/pdfxreftable.h

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+//    Copyright (C) 2018 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 PDFXREFTABLE_H
+#define PDFXREFTABLE_H
+
+#include "pdfglobal.h"
+#include "pdfobject.h"
+
+#include <QtCore>
+
+#include <vector>
+
+namespace pdf
+{
+class PDFParsingContext;
+
+/// Represents table of references in the PDF file. It contains
+/// scanned table in the PDF file, together with information, if entry
+/// is occupied, or it is free.
+class PDFXRefTable
+{
+    Q_DECLARE_TR_FUNCTIONS(pdf::PDFXRefTable)
+
+public:
+    constexpr inline explicit PDFXRefTable() = default;
+
+    // Enforce default copy constructor and default move constructor
+    constexpr inline PDFXRefTable(const PDFXRefTable&) = default;
+    constexpr inline PDFXRefTable(PDFXRefTable&&) = default;
+
+    // Enforce default copy assignment operator and move assignment operator
+    constexpr inline PDFXRefTable& operator=(const PDFXRefTable&) = default;
+    constexpr inline PDFXRefTable& operator=(PDFXRefTable&&) = default;
+
+    enum class EntryType
+    {
+        Free,       ///< Entry represents a free item (no object)
+        Occupied    ///< Entry represents a occupied item (object)
+    };
+
+    struct Entry
+    {
+        PDFObjectReference reference;
+        PDFInteger offset = -1;
+        EntryType type = EntryType::Free;
+    };
+
+    /// Tries to read reference table from the byte array. If error occurs, then exception
+    /// is raised. This fuction also checks redundant entries.
+    /// \param context Current parsing context
+    /// \param byteArray Input byte array (containing the PDF file)
+    /// \param startTableOffset Offset of first reference table
+    void readXRefTable(PDFParsingContext* context, const QByteArray& byteArray, PDFInteger startTableOffset);
+
+private:
+    /// Reference table entries
+    std::vector<Entry> m_entries;
+
+    /// Trailer dictionary
+    PDFObject m_trailerDictionary;
+};
+
+}   // namespace pdf
+
+#endif // PDFXREFTABLE_H