Files
rgbds/include/itertools.hpp
Sylvie 17444e825a Reduce the header declarations (#1342)
- Since we have style rules to include foo.hpp at the top of its
  corresponding foo.cpp, this takes any headers included by foo.hpp
  as being also guaranteed for foo.cpp.

- Use C-style <foo.h> instead of <cfoo>, since the latter only
  guarantees putting symbols in the `std` namespace, which we are
  not using for C functions (e.g. `printf` not `std::printf`).

- Remove now-unused `__PRETTY_FUNCTION__` reporting
2024-03-09 14:55:39 -05:00

117 lines
2.8 KiB
C++

/* SPDX-License-Identifier: MIT */
#ifndef RGBDS_ITERTOOLS_HPP
#define RGBDS_ITERTOOLS_HPP
#include <tuple>
#include <utility>
template<typename T>
class EnumSeqIterator {
T _value;
public:
explicit EnumSeqIterator(T value) : _value(value) {}
EnumSeqIterator &operator++() {
_value = (T)(_value + 1);
return *this;
}
auto operator*() const { return _value; }
friend auto operator==(EnumSeqIterator const &lhs, EnumSeqIterator const &rhs) {
return lhs._value == rhs._value;
}
friend auto operator!=(EnumSeqIterator const &lhs, EnumSeqIterator const &rhs) {
return lhs._value != rhs._value;
}
};
template<typename T>
class EnumSeq {
T _start;
T _stop;
public:
explicit EnumSeq(T stop) : _start((T)0), _stop(stop) {}
explicit EnumSeq(T start, T stop) : _start(start), _stop(stop) {}
EnumSeqIterator<T> begin() { return EnumSeqIterator(_start); }
EnumSeqIterator<T> end() { return EnumSeqIterator(_stop); }
};
// This is not a fully generic implementation; its current use cases only require for-loop behavior.
// We also assume that all iterators have the same length.
template<typename... Iters>
class Zip {
std::tuple<Iters...> _iters;
public:
explicit Zip(std::tuple<Iters...> &&iters) : _iters(iters) {}
Zip &operator++() {
std::apply([](auto &&...it) { (++it, ...); }, _iters);
return *this;
}
auto operator*() const {
return std::apply(
[](auto &&...it) { return std::tuple<decltype(*it)...>(*it...); }, _iters
);
}
friend auto operator==(Zip const &lhs, Zip const &rhs) {
return std::get<0>(lhs._iters) == std::get<0>(rhs._iters);
}
friend auto operator!=(Zip const &lhs, Zip const &rhs) {
return std::get<0>(lhs._iters) != std::get<0>(rhs._iters);
}
};
namespace detail {
template<typename... Containers>
class ZipContainer {
std::tuple<Containers...> _containers;
public:
explicit ZipContainer(Containers &&...containers)
: _containers(std::forward<Containers>(containers)...) {}
auto begin() {
return Zip(std::apply(
[](auto &&...containers) {
using std::begin;
return std::make_tuple(begin(containers)...);
},
_containers
));
}
auto end() {
return Zip(std::apply(
[](auto &&...containers) {
using std::end;
return std::make_tuple(end(containers)...);
},
_containers
));
}
};
// Take ownership of objects and rvalue refs passed to us, but not lvalue refs
template<typename T>
using Holder = std::
conditional_t<std::is_lvalue_reference_v<T>, T, std::remove_cv_t<std::remove_reference_t<T>>>;
} // namespace detail
// Does the same number of iterations as the first container's iterator!
template<typename... Containers>
static constexpr auto zip(Containers &&...cs) {
return detail::ZipContainer<detail::Holder<Containers>...>(std::forward<Containers>(cs)...);
}
#endif // RGBDS_ITERTOOLS_HPP