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Copy pathchain.hpp
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322 lines (262 loc) · 9.42 KB
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#ifndef ITER_CHAIN_HPP_
#define ITER_CHAIN_HPP_
#include "internal/iterbase.hpp"
#include <array>
#include <initializer_list>
#include <iterator>
#include <memory>
#include <tuple>
#include <type_traits>
#include <utility>
namespace iter {
namespace impl {
template <typename TupType, std::size_t... Is>
class Chained;
template <typename Container>
class ChainedFromIterable;
// rather than a chain function, use a callable object to support
// from_iterable
class ChainMaker;
}
}
template <typename TupType, std::size_t... Is>
class iter::impl::Chained {
private:
friend class ChainMaker;
static_assert(std::tuple_size<std::decay_t<TupType>>::value == sizeof...(Is),
"tuple size != sizeof Is");
static_assert(
are_same<iterator_deref<std::tuple_element_t<Is, TupType>>...>::value,
"All chained iterables must have iterators that "
"dereference to the same type, including cv-qualifiers "
"and references.");
using IterTupType = iterator_tuple_type<TupType>;
using DerefType = iterator_deref<std::tuple_element_t<0, TupType>>;
using ArrowType = iterator_arrow<std::tuple_element_t<0, TupType>>;
template <std::size_t Idx>
static DerefType get_and_deref(IterTupType& iters) {
return *std::get<Idx>(iters);
}
template <std::size_t Idx>
static ArrowType get_and_arrow(IterTupType& iters) {
return apply_arrow(std::get<Idx>(iters));
}
template <std::size_t Idx>
static void get_and_increment(IterTupType& iters) {
++std::get<Idx>(iters);
}
template <std::size_t Idx>
static bool get_and_check_not_equal(
const IterTupType& lhs, const IterTupType& rhs) {
return std::get<Idx>(lhs) != std::get<Idx>(rhs);
}
using DerefFunc = DerefType (*)(IterTupType&);
using ArrowFunc = ArrowType (*)(IterTupType&);
using IncFunc = void (*)(IterTupType&);
using NeqFunc = bool (*)(const IterTupType&, const IterTupType&);
constexpr static std::array<DerefFunc, sizeof...(Is)> derefers{
{get_and_deref<Is>...}};
constexpr static std::array<ArrowFunc, sizeof...(Is)> arrowers{
{get_and_arrow<Is>...}};
constexpr static std::array<IncFunc, sizeof...(Is)> incrementers{
{get_and_increment<Is>...}};
constexpr static std::array<NeqFunc, sizeof...(Is)> neq_comparers{
{get_and_check_not_equal<Is>...}};
using TraitsValue = iterator_traits_deref<std::tuple_element_t<0, TupType>>;
private:
Chained(TupType&& t) : tup(std::move(t)) {}
TupType tup;
public:
Chained(Chained&&) = default;
class Iterator : public std::iterator<std::input_iterator_tag, TraitsValue> {
private:
std::size_t index;
IterTupType iters;
IterTupType ends;
void check_for_end_and_adjust() {
while (this->index < sizeof...(Is)
&& !(neq_comparers[this->index](this->iters, this->ends))) {
++this->index;
}
}
public:
Iterator(std::size_t i, IterTupType&& in_iters, IterTupType&& in_ends)
: index{i}, iters(in_iters), ends(in_ends) {
this->check_for_end_and_adjust();
}
decltype(auto) operator*() {
return derefers[this->index](this->iters);
}
decltype(auto) operator -> () {
return arrowers[this->index](this->iters);
}
Iterator& operator++() {
incrementers[this->index](this->iters);
this->check_for_end_and_adjust();
return *this;
}
Iterator operator++(int) {
auto ret = *this;
++*this;
return ret;
}
bool operator!=(const Iterator& other) const {
return this->index != other.index
|| (this->index != sizeof...(Is)
&& neq_comparers[this->index](this->iters, other.iters));
}
bool operator==(const Iterator& other) const {
return !(*this != other);
}
};
Iterator begin() {
return {0, IterTupType{std::begin(std::get<Is>(this->tup))...},
IterTupType{std::end(std::get<Is>(this->tup))...}};
}
Iterator end() {
return {sizeof...(Is), IterTupType{std::end(std::get<Is>(this->tup))...},
IterTupType{std::end(std::get<Is>(this->tup))...}};
}
};
template <typename TupType, std::size_t... Is>
constexpr std::array<typename iter::impl::Chained<TupType, Is...>::DerefFunc,
sizeof...(Is)> iter::impl::Chained<TupType, Is...>::derefers;
template <typename TupType, std::size_t... Is>
constexpr std::array<typename iter::impl::Chained<TupType, Is...>::ArrowFunc,
sizeof...(Is)> iter::impl::Chained<TupType, Is...>::arrowers;
template <typename TupType, std::size_t... Is>
constexpr std::array<typename iter::impl::Chained<TupType, Is...>::IncFunc,
sizeof...(Is)> iter::impl::Chained<TupType, Is...>::incrementers;
template <typename TupType, std::size_t... Is>
constexpr std::array<typename iter::impl::Chained<TupType, Is...>::NeqFunc,
sizeof...(Is)> iter::impl::Chained<TupType, Is...>::neq_comparers;
template <typename Container>
class iter::impl::ChainedFromIterable {
private:
Container container;
friend class ChainMaker;
ChainedFromIterable(Container&& in_container)
: container(std::forward<Container>(in_container)) {}
public:
ChainedFromIterable(ChainedFromIterable&&) = default;
class Iterator : public std::iterator<std::input_iterator_tag,
iterator_traits_deref<iterator_deref<Container>>> {
private:
using SubContainer = iterator_deref<Container>;
using SubIter = iterator_type<SubContainer>;
iterator_type<Container> top_level_iter;
iterator_type<Container> top_level_end;
std::unique_ptr<SubIter> sub_iter_p;
std::unique_ptr<SubIter> sub_end_p;
static std::unique_ptr<SubIter> clone_sub_pointer(const SubIter* sub_iter) {
return sub_iter ? std::make_unique<SubIter>(*sub_iter) : nullptr;
}
bool sub_iters_differ(const Iterator& other) const {
if (this->sub_iter_p == other.sub_iter_p) {
return false;
}
if (this->sub_iter_p == nullptr || other.sub_iter_p == nullptr) {
// since the first check tests if they're the same,
// this will return if only one is nullptr
return true;
}
return *this->sub_iter_p != *other.sub_iter_p;
}
public:
Iterator(
iterator_type<Container>&& top_iter, iterator_type<Container>&& top_end)
: top_level_iter{std::move(top_iter)},
top_level_end{std::move(top_end)},
sub_iter_p{!(top_iter != top_end)
? // iter == end ?
nullptr
: std::make_unique<SubIter>(std::begin(*top_iter))},
sub_end_p{!(top_iter != top_end)
? // iter == end ?
nullptr
: std::make_unique<SubIter>(std::end(*top_iter))} {}
Iterator(const Iterator& other)
: top_level_iter{other.top_level_iter},
top_level_end{other.top_level_end},
sub_iter_p{clone_sub_pointer(other.sub_iter_p.get())},
sub_end_p{clone_sub_pointer(other.sub_end_p.get())} {}
Iterator& operator=(const Iterator& other) {
if (this == &other) { return *this; }
this->top_level_iter = other.top_level_iter;
this->top_level_end = other.top_level_end;
this->sub_iter_p = clone_sub_pointer(other.sub_iter_p.get());
this->sub_end_p = clone_sub_pointer(other.sub_end_p.get());
return *this;
}
Iterator(Iterator&&) = default;
Iterator& operator=(Iterator&&) = default;
~Iterator() = default;
Iterator& operator++() {
++*this->sub_iter_p;
if (!(*this->sub_iter_p != *this->sub_end_p)) {
++this->top_level_iter;
if (this->top_level_iter != this->top_level_end) {
sub_iter_p =
std::make_unique<SubIter>(std::begin(*this->top_level_iter));
sub_end_p =
std::make_unique<SubIter>(std::end(*this->top_level_iter));
} else {
sub_iter_p.reset();
sub_end_p.reset();
}
}
return *this;
}
Iterator operator++(int) {
auto ret = *this;
++*this;
return ret;
}
bool operator!=(const Iterator& other) const {
return this->top_level_iter != other.top_level_iter
|| this->sub_iters_differ(other);
}
bool operator==(const Iterator& other) const {
return !(*this != other);
}
iterator_deref<iterator_deref<Container>> operator*() {
return **this->sub_iter_p;
}
iterator_arrow<iterator_deref<Container>> operator->() {
return apply_arrow(*this->sub_iter_p);
}
};
Iterator begin() {
return {std::begin(this->container), std::end(this->container)};
}
Iterator end() {
return {std::end(this->container), std::end(this->container)};
}
};
class iter::impl::ChainMaker {
private:
template <typename TupleType, std::size_t... Is>
Chained<TupleType, Is...> chain_impl(
TupleType&& in_containers, std::index_sequence<Is...>) const {
return {std::move(in_containers)};
}
public:
// expose regular call operator to provide usual chain()
template <typename... Containers>
auto operator()(Containers&&... cs) const {
return this->chain_impl(
std::tuple<Containers...>{std::forward<Containers>(cs)...},
std::index_sequence_for<Containers...>{});
}
// chain.from_iterable
template <typename Container>
ChainedFromIterable<Container> from_iterable(Container&& container) const {
return {std::forward<Container>(container)};
}
};
namespace iter {
namespace {
constexpr auto chain = iter::impl::ChainMaker{};
}
}
#endif