#pragma once #include "compat.hpp" // ################################################################################################# namespace lanes { // everything we need to provide to lua_newstate() class AllocatorDefinition { private: // xxh64 of string "kAllocatorVersion_1" generated at https://www.pelock.com/products/hash-calculator static constexpr auto kAllocatorVersion{ static_cast(0xCF9D321B0DFB5715ull) }; public: using version_t = std::remove_const_t; private: // can't make these members const because we need to be able to copy an AllocatorDefinition into another // so the members are not const, but they are private to avoid accidents. version_t version{ kAllocatorVersion }; lua_Alloc allocF{ nullptr }; void* allocUD{ nullptr }; public: [[nodiscard]] static void* operator new(size_t const size_) noexcept = delete; // can't create one outside of a Lua state [[nodiscard]] static void* operator new(size_t const size_, lua_State* const L_) noexcept { return lua_newuserdatauv(L_, size_, UserValueCount{ 0 }); } // always embedded somewhere else or "in-place constructed" as a full userdata // can't actually delete the operator because the compiler generates stack unwinding code that could call it in case of exception static void operator delete([[maybe_unused]] void* const p_, [[maybe_unused]] lua_State* const L_) {} AllocatorDefinition(lua_Alloc const allocF_, void* const allocUD_) noexcept : allocF{ allocF_ } , allocUD{ allocUD_ } { } // rule of 5 AllocatorDefinition() = default; AllocatorDefinition(AllocatorDefinition const& rhs_) = default; AllocatorDefinition(AllocatorDefinition&& rhs_) = default; AllocatorDefinition& operator=(AllocatorDefinition const& rhs_) = default; AllocatorDefinition& operator=(AllocatorDefinition&& rhs_) = default; [[nodiscard]] static AllocatorDefinition& Validated(lua_State* L_, StackIndex idx_); void initFrom(lua_State* const L_) { allocF = lua_getallocf(L_, &allocUD); } void installIn(lua_State* const L_) const { if (allocF) { lua_setallocf(L_, allocF, allocUD); } } [[nodiscard]] lua_State* newState() const { return lua_newstate(allocF, allocUD); } [[nodiscard]] void* alloc(size_t const nsize_) const { return allocF(allocUD, nullptr, 0, nsize_); } [[nodiscard]] void* alloc(void* const ptr_, size_t const osize_, size_t const nsize_) const { return allocF(allocUD, ptr_, osize_, nsize_); } void free(void* const ptr_, size_t const osize_) const { std::ignore = allocF(allocUD, ptr_, osize_, 0); } }; } // namespace lanes