json_writer.hxx

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/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4; fill-column: 100 -*- */
/*
 * This file is part of the LibreOffice project.
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/.
 */
#pragma once
 
#include <sal/config.h>
 
#include <tools/toolsdllapi.h>
#include <rtl/string.hxx>
#include <rtl/ustring.hxx>
#include <sal/types.h>
 
#include <string>
#include <string_view>
#include <utility>
 
namespace tools
{
class ScopedJsonWriterNode;
class ScopedJsonWriterArray;
class ScopedJsonWriterStruct;
 
class TOOLS_DLLPUBLIC JsonWriter
{
    friend class ScopedJsonWriterNode;
    friend class ScopedJsonWriterArray;
    friend class ScopedJsonWriterStruct;
 
    char* mpBuffer;
    char* mPos;
    int mSpaceAllocated;
    int mStartNodeCount;
    bool mbFirstFieldInNode;
    bool mbClosed; // cannot add to it anymore
 
public:
    JsonWriter();
    ~JsonWriter();
 
    [[nodiscard]] ScopedJsonWriterNode startNode(std::string_view);
    [[nodiscard]] ScopedJsonWriterArray startArray(std::string_view);
    [[nodiscard]] ScopedJsonWriterStruct startStruct();
 
    void put(std::u16string_view pPropName, const OUString& rPropValue);
 
    void put(std::string_view pPropName, const OUString& rPropValue);
    // Assumes utf-8 property value encoding
    void put(std::string_view pPropName, std::string_view rPropValue);
    void put(std::string_view pPropName, const char* pPropVal)
    {
        put(pPropName, std::string_view(pPropVal));
    }
    template <size_t N> void put(std::string_view pPropName, const char (&pPropVal)[N])
    {
        put(pPropName, std::string_view(pPropVal, N));
    }
 
    template <typename N, std::enable_if_t<std::is_arithmetic_v<N>, int> = 0>
    void put(std::string_view pPropName, N n)
    {
        putLiteral(pPropName, OString::number(n));
    }
    void put(std::string_view pPropName, bool);
 
    void putSimpleValue(const OUString& rPropValue);
 
    void putRaw(std::string_view);
 
    OString finishAndGetAsOString();
 
    bool isDataEquals(std::string_view) const;
 
private:
    void endNode();
    void endArray();
    void endStruct();
    void addCommaBeforeField();
    void writeEscapedOUString(const OUString& rPropVal);
    void closeDocument();
    void ensureSpace(int noMoreBytesRequired);
    void ensureSpaceAndWriteNameColon(std::string_view name, int valSize);
    void putLiteral(std::string_view propName, std::string_view propValue);
 
    // overflow validation in debug mode
    static constexpr unsigned char JSON_WRITER_DEBUG_MARKER = 0xde;
 
    inline void addValidationMark()
    {
#ifndef NDEBUG
        *(mpBuffer + mSpaceAllocated - 1) = JSON_WRITER_DEBUG_MARKER;
#endif
    }
 
    inline void validate()
    {
#ifndef NDEBUG
        unsigned char c = *(mpBuffer + mSpaceAllocated - 1);
        assert(c == JSON_WRITER_DEBUG_MARKER);
#endif
    }
};
 
class ScopedJsonWriterNode
{
    friend class JsonWriter;
 
    JsonWriter& mrWriter;
 
    ScopedJsonWriterNode(JsonWriter& rWriter)
        : mrWriter(rWriter)
    {
    }
 
public:
    ~ScopedJsonWriterNode() { mrWriter.endNode(); }
};
 
class ScopedJsonWriterArray
{
    friend class JsonWriter;
 
    JsonWriter& mrWriter;
 
    ScopedJsonWriterArray(JsonWriter& rWriter)
        : mrWriter(rWriter)
    {
    }
 
public:
    ~ScopedJsonWriterArray() { mrWriter.endArray(); }
};
 
class ScopedJsonWriterStruct
{
    friend class JsonWriter;
 
    JsonWriter& mrWriter;
 
    ScopedJsonWriterStruct(JsonWriter& rWriter)
        : mrWriter(rWriter)
    {
    }
 
public:
    ~ScopedJsonWriterStruct() { mrWriter.endStruct(); }
};
}
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