EntityComponentMetaSystem/src/EC/Bitset.hpp

82 lines
2.3 KiB
C++

// This work derives from Vittorio Romeo's code used for cppcon 2015 licensed
// under the Academic Free License.
// His code is available here: https://github.com/SuperV1234/cppcon2015
#ifndef EC_BITSET_HPP
#define EC_BITSET_HPP
#include <bitset>
#include "Meta/TypeList.hpp"
#include "Meta/Combine.hpp"
#include "Meta/IndexOf.hpp"
#include "Meta/ForEach.hpp"
#include "Meta/Contains.hpp"
namespace EC
{
// Note bitset size is sizes of components and tags + 1
// This is to use the last extra bit as the result of a query
// with a Component or Tag not known to the Bitset.
// Those queries should return a false bit every time as long as EC::Manager
// does not change that last bit.
template <typename ComponentsList, typename TagsList>
struct Bitset :
public std::bitset<ComponentsList::size + TagsList::size + 1>
{
using Combined = EC::Meta::Combine<ComponentsList, TagsList>;
Bitset()
{
(*this)[Combined::size] = false;
}
template <typename Component>
constexpr auto getComponentBit() const
{
auto index = EC::Meta::IndexOf<Component, Combined>::value;
return (*this)[index];
}
template <typename Component>
constexpr auto getComponentBit()
{
auto index = EC::Meta::IndexOf<Component, Combined>::value;
return (*this)[index];
}
template <typename Tag>
constexpr auto getTagBit() const
{
auto index = EC::Meta::IndexOf<Tag, Combined>::value;
return (*this)[index];
}
template <typename Tag>
constexpr auto getTagBit()
{
auto index = EC::Meta::IndexOf<Tag, Combined>::value;
return (*this)[index];
}
template <typename Contents>
static constexpr Bitset<ComponentsList, TagsList> generateBitset()
{
Bitset<ComponentsList, TagsList> bitset;
EC::Meta::forEach<Contents>([&bitset] (auto t) {
if(EC::Meta::Contains<decltype(t), Combined>::value)
{
bitset[EC::Meta::IndexOf<decltype(t), Combined>::value] =
true;
}
});
return bitset;
}
};
}
#endif