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Copy pathiteratoriterator.hpp
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287 lines (228 loc) · 8.58 KB
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#ifndef ITERATOR_ITERATOR_HPP_
#define ITERATOR_ITERATOR_HPP_
#include "iterbase.hpp"
#include "zip.hpp"
#include <iterator>
#include <type_traits>
#include <utility>
// IterIterWrapper and IteratorIterator provide a means to have a container
// of iterators act like a container of the pointed to objects. This is useful
// for combinatorics and similar itertools which need to keep track of
// more than one element at a time.
// an IterIterWrapper<some_collection_type<collection<T>::iterator>>
// behave like some_collection<T> when iterated over or indexed
namespace iter {
template <typename T, typename =void>
struct HasConstDeref : std::false_type { };
template <typename T>
struct HasConstDeref<T, void_t<decltype(*std::declval<const T&>())>>
: std::true_type { };
template <typename Iter,
typename Diff =typename std::iterator_traits<Iter>::difference_type>
class IteratorIterator : public std::iterator<
std::random_access_iterator_tag,
typename std::iterator_traits<Iter>::value_type,
Diff,
typename std::iterator_traits<Iter>::pointer,
typename std::iterator_traits<Iter>::reference
>
{
static_assert(std::is_same<
typename std::iterator_traits<Iter>::iterator_category,
std::random_access_iterator_tag>::value,
"IteratorIterator only works with random access iterators");
private:
Iter sub_iter;
public:
IteratorIterator() = default;
IteratorIterator(const Iter& it)
: sub_iter{it}
{ }
bool operator==(const IteratorIterator& other) const {
return !(*this != other);
}
bool operator!=(const IteratorIterator& other) const {
return this->sub_iter != other.sub_iter;
}
IteratorIterator& operator++() {
++this->sub_iter;
return *this;
}
IteratorIterator operator++(int) {
auto ret = *this;
++*this;
return ret;
}
IteratorIterator& operator--() {
--this->sub_iter;
return *this;
}
IteratorIterator operator--(int) {
auto ret = *this;
--*this;
return ret;
}
auto operator*() -> decltype(**sub_iter) {
return **this->sub_iter;
}
auto operator->() -> decltype(*sub_iter) {
return *this->sub_iter;
}
IteratorIterator& operator+=(Diff n) {
this->sub_iter += n;
return *this;
}
IteratorIterator operator+(Diff n) const {
auto it = *this;
it += n;
return it;
}
friend IteratorIterator operator+(Diff n, IteratorIterator it) {
it += n;
return it;
}
IteratorIterator& operator-=(Diff n) {
this->sub_iter -= n;
return *this;
}
IteratorIterator operator-(Diff n) const {
auto it = *this;
it -= n;
return it;
}
friend IteratorIterator operator-(Diff n, IteratorIterator it) {
it -= n;
return it;
}
Diff operator-(const IteratorIterator& rhs) const {
return this->sub_iter - rhs.sub_iter;
}
auto operator[](Diff idx) -> decltype(*sub_iter[idx]) {
return *sub_iter[idx];
}
bool operator<(const IteratorIterator& rhs) const {
return this->sub_iter < rhs.sub_iter;
}
bool operator>(const IteratorIterator& rhs) const {
return this->sub_iter > rhs.sub_iter;
}
bool operator<=(const IteratorIterator& rhs) const {
return this->sub_iter <= rhs.sub_iter;
}
bool operator>=(const IteratorIterator& rhs) const {
return this->sub_iter >= rhs.sub_iter;
}
};
template <typename Container>
class IterIterWrapper {
private:
Container container;
using contained_iter = typename Container::value_type;
using size_type = typename Container::size_type;
using iterator =
IteratorIterator<typename Container::iterator>;
using const_iterator =
IteratorIterator<typename Container::const_iterator>;
using reverse_iterator =
IteratorIterator<typename Container::reverse_iterator>;
using const_reverse_iterator =
IteratorIterator<typename Container::const_reverse_iterator>;
template <typename U =Container, typename =void>
struct ConstAtTypeOrVoid : type_is<void> { };
template <typename U>
struct ConstAtTypeOrVoid <
U, void_t<decltype(*std::declval<const U&>().at(0))>>
: type_is<decltype(*std::declval<const U&>().at(0))>
{ };
using const_at_type_or_void_t = typename ConstAtTypeOrVoid<>::type;
template <typename U =Container, typename =void>
struct ConstIndexTypeOrVoid : type_is<void> { };
template <typename U>
struct ConstIndexTypeOrVoid <
U, void_t<decltype(*std::declval<const U&>()[0])>>
: type_is<decltype(*std::declval<const U&>()[0])>
{ };
using const_index_type_or_void_t =
typename ConstIndexTypeOrVoid<>::type;
public:
IterIterWrapper() = default;
explicit IterIterWrapper(size_type sz)
: container(sz)
{ }
IterIterWrapper(size_type sz, const contained_iter& val)
: container(sz, val)
{ }
auto at(size_type pos) -> decltype(*container.at(pos)) {
return *container.at(pos);
}
auto at(size_type pos) const ->
const_at_type_or_void_t
{
return *container.at(pos);
}
auto operator[](size_type pos)
noexcept(noexcept(*container[pos]))
-> decltype(*container[pos])
{
return *container[pos];
}
auto operator[](size_type pos) const
noexcept(noexcept(*container[pos]))
-> const_index_type_or_void_t
{
return *container[pos];
}
bool empty() const noexcept {
return container.empty();
}
size_type size() const noexcept {
return container.size();
}
iterator begin() noexcept {
return {container.begin()};
}
iterator end() noexcept {
return {container.end()};
}
const_iterator begin() const noexcept {
return {container.begin()};
}
const_iterator end() const noexcept {
return {container.end()};
}
const_iterator cbegin() const noexcept {
return {container.cbegin()};
}
const_iterator cend() const noexcept {
return {container.cend()};
}
reverse_iterator rbegin() noexcept {
return {container.rbegin()};
}
reverse_iterator rend() noexcept {
return {container.rend()};
}
const_reverse_iterator rbegin() const noexcept {
return {container.rbegin()};
}
const_reverse_iterator rend() const noexcept {
return {container.rend()};
}
const_reverse_iterator crbegin() const noexcept {
return {container.rbegin()};
}
const_reverse_iterator crend() const noexcept {
return {container.rend()};
}
// get() exposes the underlying container. this allows the
// itertools to manipulate the iterators in the container
// and should not be depended on anywhere else.
Container& get() noexcept {
return container;
}
const Container& get() const noexcept {
return container;
}
};
}
#endif