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#pragma once
// #################################################################################################
// everything we need to provide to lua_newstate()
class AllocatorDefinition
{
public:
// xxh64 of string "kAllocatorVersion_1" generated at https://www.pelock.com/products/hash-calculator
static constexpr uintptr_t kAllocatorVersion{ static_cast<uintptr_t>(0xCF9D321B0DFB5715ull) };
uintptr_t version{ kAllocatorVersion };
lua_Alloc allocF{ nullptr };
void* allocUD{ nullptr };
[[nodiscard]] static void* operator new(size_t size_) noexcept = delete; // can't create one outside of a Lua state
[[nodiscard]] static void* operator new(size_t size_, lua_State* L_) noexcept { return lua_newuserdatauv(L_, size_, 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* p_, [[maybe_unused]] lua_State* L_) {}
AllocatorDefinition(uintptr_t const version_, lua_Alloc const allocF_, void* const allocUD_) noexcept
: version{ version_ }
, allocF{ allocF_ }
, allocUD{ allocUD_ }
{
}
AllocatorDefinition() = default;
AllocatorDefinition(AllocatorDefinition const& rhs_) = default;
AllocatorDefinition(AllocatorDefinition&& rhs_) = default;
AllocatorDefinition& operator=(AllocatorDefinition const& rhs_) = default;
AllocatorDefinition& operator=(AllocatorDefinition&& rhs_) = default;
void initFrom(lua_State* L_)
{
allocF = lua_getallocf(L_, &allocUD);
}
void* alloc(size_t nsize_)
{
return allocF(allocUD, nullptr, 0, nsize_);
}
void free(void* ptr_, size_t osize_)
{
std::ignore = allocF(allocUD, ptr_, osize_, 0);
}
};
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