Document builder basics

PdfForQtLib/sources/pdfdocumentbuilder.h

@@ -0,0 +1,119 @@
+//    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 PDFDOCUMENTBUILDER_H
+#define PDFDOCUMENTBUILDER_H
+
+#include "pdfobject.h"
+
+namespace pdf
+{
+
+/// Factory for creating various PDF objects, such as simple objects,
+/// dictionaries, arrays etc.
+class PDFObjectFactory
+{
+public:
+    inline explicit PDFObjectFactory() = default;
+
+    void beginArray();
+    void endArray();
+
+    void beginDictionary();
+    void endDictionary();
+
+    void beginDictionaryItem(const QByteArray& name);
+    void endDictionaryItem();
+
+    PDFObjectFactory& operator<<(std::nullptr_t);
+    PDFObjectFactory& operator<<(bool value);
+    PDFObjectFactory& operator<<(PDFReal value);
+    PDFObjectFactory& operator<<(PDFInteger value);
+    PDFObjectFactory& operator<<(PDFObjectReference value);
+
+    /// Treat containers - write them as array
+    template<typename Container, typename ValueType = decltype(*std::begin(std::declval<Container>()))>
+    PDFObjectFactory& operator<<(Container container)
+    {
+        beginArray();
+
+        auto it = std::begin(container);
+        auto itEnd = std::end(container);
+        for (; it != itEnd; ++it)
+        {
+            *this << *it;
+        }
+
+        endArray();
+
+        return *this;
+    }
+
+private:
+    void addObject(PDFObject object);
+
+    enum class ItemType
+    {
+        Object,
+        Dictionary,
+        DictionaryItem,
+        Array
+    };
+
+    /// What is stored in this structure, depends on the type.
+    /// If type is 'Object', then single simple object is in object,
+    /// if type is dictionary, then PDFDictionary is stored in object,
+    /// if type is dictionary item, then object and item name is stored
+    /// in the data, if item is array, then array is stored in the data.
+    struct Item
+    {
+        inline Item() = default;
+
+        template<typename T>
+        inline Item(ItemType type, T&& data) :
+            type(type),
+            object(qMove(data))
+        {
+
+        }
+
+        template<typename T>
+        inline Item(ItemType type, const QByteArray& itemName, T&& data) :
+            type(type),
+            itemName(qMove(itemName)),
+            object(qMove(data))
+        {
+
+        }
+
+        ItemType type = ItemType::Object;
+        QByteArray itemName;
+        std::variant<PDFObject, PDFArray, PDFDictionary> object;
+    };
+
+    std::vector<Item> m_items;
+};
+
+class PDFDocumentBuilder
+{
+public:
+    PDFDocumentBuilder();
+};
+
+}   // namespace pdf
+
+#endif // PDFDOCUMENTBUILDER_H