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#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<uintptr_t>(0xCF9D321B0DFB5715ull) };
public:
using version_t = std::remove_const_t<decltype(kAllocatorVersion)>;
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
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