LuaRef.h

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// Copyright © 2008-2023 Pioneer Developers. See AUTHORS.txt for details
// Licensed under the terms of the GPL v3. See licenses/GPL-3.txt
 
#ifndef _LUAREF_H
#define _LUAREF_H
 
#include "JsonFwd.h"
#include <cassert>
#include <lua.hpp>
#include <vector>
 
class LuaRef {
public:
    LuaRef() :
        m_lua(0),
        m_id(LUA_NOREF),
        m_copycount(nullptr) {}
    LuaRef(lua_State *l, int index);
    LuaRef(const LuaRef &ref);
    ~LuaRef();
    const LuaRef &operator=(const LuaRef &ref);
    bool operator==(const LuaRef &ref) const;
 
    void PushCopyToStack() const;
 
    lua_State *GetLua() const { return m_lua; }
 
    bool IsValid() const { return m_lua && m_id != LUA_NOREF; }
    bool IsNil() const { return m_lua && m_id == LUA_REFNIL; }
 
    void SaveToJson(Json &jsonObj);
    void LoadFromJson(const Json &jsonObj);
    void Unref();
 
private:
    lua_State *m_lua;
    int m_id;
    int *m_copycount;
 
    // Does everything we need: get the table, or create it if it doesn't exist.
    // Yay lua aux lib !
    void PushGlobalToStack() const { luaL_getsubtable(m_lua, LUA_REGISTRYINDEX, "LuaRef"); }
 
    void CheckCopyCount();
};
 
inline void pi_lua_generic_push(lua_State *l, const LuaRef &r)
{
    assert(r.GetLua() == l);
    r.PushCopyToStack();
}
 
inline void pi_lua_generic_pull(lua_State *l, int index, LuaRef &r)
{
    r = LuaRef(l, index);
}
 
inline bool pi_lua_strict_pull(lua_State *l, int index, LuaRef &r)
{
    r = LuaRef(l, index);
    return true;
}
 
#endif