sol2/sol/stack_reference.hpp

// The MIT License (MIT) 

// Copyright (c) 2013-2016 Rapptz, ThePhD and contributors

// Permission is hereby granted, free of charge, to any person obtaining a copy of
// this software and associated documentation files (the "Software"), to deal in
// the Software without restriction, including without limitation the rights to
// use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
// the Software, and to permit persons to whom the Software is furnished to do so,
// subject to the following conditions:

// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.

// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
// FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
// COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
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// CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

#ifndef SOL_STACK_REFERENCE_HPP
#define SOL_STACK_REFERENCE_HPP

namespace sol {
class stack_reference {
private:
    lua_State* L = nullptr;
    int index = 0;

protected:
    int registry_index () const noexcept {
        return LUA_NOREF;
    }

public:
    stack_reference() noexcept = default;
    stack_reference(lua_State* L, int i) noexcept : L(L), index(lua_absindex(L, i)) {}
    stack_reference(stack_reference&& o) noexcept = default;
    stack_reference& operator=(stack_reference&&) noexcept = default;
    stack_reference(const stack_reference&) noexcept = default;
    stack_reference& operator=(const stack_reference&) noexcept = default;

    int push() const noexcept {
        lua_pushvalue(L, index);
        return 1;
    }

    void pop(int n = 1) const noexcept {
        lua_pop(lua_state( ), n);
    }

    int stack_index () const noexcept {
        return index;
    }

    type get_type() const noexcept {
        int result = lua_type(L, index);
        return static_cast<type>(result);
    }

    lua_State* lua_state() const noexcept {
        return L;
    }

    bool valid () const noexcept {
        type t = get_type();
        return t != type::nil && t != type::none;
    }
};

inline bool operator== (const stack_reference& l, const stack_reference& r) {
    return lua_compare(l.lua_state(), l.stack_index(), l.stack_index(), LUA_OPEQ) == 0;
}

inline bool operator!= (const stack_reference& l, const stack_reference& r) {
    return !operator==(l, r);
}
} // sol

#endif // SOL_STACK_REFERENCE_HPP