BinarySerializer.h

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/* Copyright (C) 2021 Wildfire Games.
 * This file is part of 0 A.D.
 *
 * 0 A.D. is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 2 of the License, or
 * (at your option) any later version.
 *
 * 0 A.D. 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with 0 A.D.  If not, see <http://www.gnu.org/licenses/>.
 */
 
#ifndef INCLUDED_BINARYSERIALIZER
#define INCLUDED_BINARYSERIALIZER
 
#include "ISerializer.h"
 
#include "lib/byte_order.h"
 
#include "scriptinterface/ScriptExtraHeaders.h"
 
#include <ostream>
#include <streambuf>
 
/**
 * Wrapper for redirecting ostream writes to CBinarySerializer's impl
 */
template<typename T>
class CSerializerStreamBuf : public std::streambuf
{
    NONCOPYABLE(CSerializerStreamBuf);
    T& m_SerializerImpl;
    char m_Buffer[2048];
public:
    CSerializerStreamBuf(T& impl) :
        m_SerializerImpl(impl)
    {
        setp(m_Buffer, m_Buffer + ARRAY_SIZE(m_Buffer) - 1);
    }
 
protected:
    // Override overflow and sync, because older versions of libc++ streams
    // write strings as individual characters, then xsputn is never called
    int overflow(int ch)
    {
        if (ch == traits_type::eof())
            return traits_type::not_eof(ch);
 
        ENSURE(pptr() <= epptr());
        *pptr() = ch;
        pbump(1);
        sync();
        return ch;
    }
 
    int sync()
    {
        std::ptrdiff_t n = pptr() - pbase();
        if (n != 0)
        {
            pbump(-n);
            m_SerializerImpl.Put("stream", reinterpret_cast<const u8*> (pbase()), n);
        }
        return 0;
    }
 
    std::streamsize xsputn(const char* s, std::streamsize n)
    {
        m_SerializerImpl.Put("stream", reinterpret_cast<const u8*> (s), n);
        return n;
    }
};
 
/**
 * PutScriptVal implementation details.
 * (Split out from the main class because it's too big to be inlined.)
 */
class CBinarySerializerScriptImpl
{
public:
    CBinarySerializerScriptImpl(const ScriptInterface& scriptInterface, ISerializer& serializer);
    ~CBinarySerializerScriptImpl();
 
    void ScriptString(const char* name, JS::HandleString string);
    void HandleScriptVal(JS::HandleValue val);
private:
    static void Trace(JSTracer* trc, void* data);
 
    const ScriptInterface& m_ScriptInterface;
    ISerializer& m_Serializer;
 
    using ObjectTagMap = JS::GCHashMap<JS::Heap<JSObject*>, u32, js::MovableCellHasher<JSObject*>, js::SystemAllocPolicy>;
    ObjectTagMap m_ScriptBackrefTags;
    u32 m_ScriptBackrefsNext;
    u32 GetScriptBackrefTag(JS::HandleObject obj);
};
 
/**
 * Serialize to a binary stream. T must just implement the Put() method.
 * (We use this templated approach to allow compiler inlining.)
 */
template <typename T>
class CBinarySerializer : public ISerializer
{
    NONCOPYABLE(CBinarySerializer);
public:
    CBinarySerializer(const ScriptInterface& scriptInterface) :
        m_ScriptImpl(new CBinarySerializerScriptImpl(scriptInterface, *this)),
        m_RawStreamBuf(m_Impl),
        m_RawStream(&m_RawStreamBuf)
    {
    }
 
    template <typename A>
    CBinarySerializer(const ScriptInterface& scriptInterface, A& a) :
        m_ScriptImpl(new CBinarySerializerScriptImpl(scriptInterface, *this)),
        m_Impl(a),
        m_RawStreamBuf(m_Impl),
        m_RawStream(&m_RawStreamBuf)
    {
    }
 
protected:
    /*
    The Put* implementations here are designed for subclasses
    that want an efficient, portable, deserializable representation.
    (Subclasses with different requirements should override these methods.)
 
    Numbers are converted to little-endian byte strings, for portability
    and efficiency.
 
    Data is not aligned, for storage efficiency.
    */
 
    virtual void PutNumber(const char* name, uint8_t value)
    {
        m_Impl.Put(name, (const u8*)&value, sizeof(uint8_t));
    }
 
    virtual void PutNumber(const char* name, int8_t value)
    {
        m_Impl.Put(name, (const u8*)&value, sizeof(int8_t));
    }
 
    virtual void PutNumber(const char* name, uint16_t value)
    {
        uint16_t v = to_le16(value);
        m_Impl.Put(name, (const u8*)&v, sizeof(uint16_t));
    }
 
    virtual void PutNumber(const char* name, int16_t value)
    {
        int16_t v = (i16)to_le16((u16)value);
        m_Impl.Put(name, (const u8*)&v, sizeof(int16_t));
    }
 
    virtual void PutNumber(const char* name, uint32_t value)
    {
        uint32_t v = to_le32(value);
        m_Impl.Put(name, (const u8*)&v, sizeof(uint32_t));
    }
 
    virtual void PutNumber(const char* name, int32_t value)
    {
        int32_t v = (i32)to_le32((u32)value);
        m_Impl.Put(name, (const u8*)&v, sizeof(int32_t));
    }
 
    virtual void PutNumber(const char* name, float value)
    {
        m_Impl.Put(name, (const u8*)&value, sizeof(float));
    }
 
    virtual void PutNumber(const char* name, double value)
    {
        m_Impl.Put(name, (const u8*)&value, sizeof(double));
    }
 
    virtual void PutNumber(const char* name, fixed value)
    {
        int32_t v = (i32)to_le32((u32)value.GetInternalValue());
        m_Impl.Put(name, (const u8*)&v, sizeof(int32_t));
    }
 
    virtual void PutBool(const char* name, bool value)
    {
        NumberU8(name, value ? 1 : 0, 0, 1);
    }
 
    virtual void PutString(const char* name, const std::string& value)
    {
        // TODO: maybe should intern strings, particularly to save space with script property names
        PutNumber("string length", (uint32_t)value.length());
        m_Impl.Put(name, (u8*)value.data(), value.length());
    }
 
    virtual void PutScriptVal(const char* UNUSED(name), JS::MutableHandleValue value)
    {
        m_ScriptImpl->HandleScriptVal(value);
    }
 
    virtual void PutRaw(const char* name, const u8* data, size_t len)
    {
        m_Impl.Put(name, data, len);
    }
 
    virtual std::ostream& GetStream()
    {
        return m_RawStream;
    }
 
protected:
    T m_Impl;
 
private:
    std::unique_ptr<CBinarySerializerScriptImpl> m_ScriptImpl;
 
    CSerializerStreamBuf<T> m_RawStreamBuf;
    std::ostream m_RawStream;
};
 
#endif // INCLUDED_BINARYSERIALIZER