#pragma once
/*
* Copyright (C) 2024 Brett Terpstra
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see .
*/
#ifndef BLT_ITERATOR_ZIP
#define BLT_ITERATOR_ZIP
#include
#include
#include
#include
namespace blt
{
namespace iterator
{
template
class zip_wrapper : public wrapper_base>
{
public:
using iterator_category = meta::lowest_iterator_category_t;
using value_type = std::tuple...>;
using difference_type = blt::ptrdiff_t;
using pointer = value_type;
using reference = value_type;
explicit zip_wrapper(Iter... iter): iter(std::make_tuple(iter...))
{}
std::tuple...> operator*() const
{
return std::apply([](auto& ... i) { return std::tuple...>{*i...}; }, iter);
}
zip_wrapper& operator++()
{
std::apply([](auto& ... i) { ((++i), ...); }, iter);
return *this;
}
zip_wrapper& operator--()
{
std::apply([](auto& ... i) { ((--i), ...); }, this->iter);
return *this;
}
zip_wrapper& operator+=(blt::ptrdiff_t n)
{
std::apply([n](auto& ... i) { ((i += n), ...); }, this->iter);
return *this;
}
zip_wrapper& operator-=(blt::ptrdiff_t n)
{
std::apply([n](auto& ... i) { ((i -= n), ...); }, this->iter);
return *this;
}
friend blt::ptrdiff_t operator-(const zip_wrapper& a, const zip_wrapper& b)
{
return sub(a, b, std::index_sequence_for());
}
auto base()
{
return iter;
}
protected:
std::tuple iter;
template
static blt::ptrdiff_t sub(const zip_wrapper& a, const zip_wrapper& b,
std::integer_sequence)
{
blt::ptrdiff_t min = std::numeric_limits::max();
((min = std::min(min, std::get(a.iter) - std::get(b.iter))), ...);
return min;
}
};
BLT_META_MAKE_FUNCTION_CHECK(base);
template
auto get_base(Iter iter)
{
if constexpr (has_func_base_v)
{
return std::move(iter).base();
} else
{
return std::move(iter);
}
}
template
class take_impl
{
private:
template
auto take_base(blt::size_t n)
{
static_assert(!std::is_same_v,
"Cannot .take() on an input iterator!");
auto* d = static_cast(this);
auto begin = d->begin();
auto end = d->end();
// take variant for forward and bidirectional iterators
if constexpr (std::is_same_v ||
std::is_same_v)
{
// with these guys we have to loop forward to move the iterators. an unfortunate inefficiency
auto new_end = begin;
for (blt::size_t i = 0; i < n; i++)
{
if constexpr (check)
{
if (new_end == end)
break;
}
++new_end;
}
return Derived{get_base(std::move(begin)), get_base(std::move(new_end))};
} else if constexpr (std::is_same_v)
{
// random access iterators can have math directly applied to them.
if constexpr (check)
{
return Derived{get_base(begin),
get_base(begin + std::min(static_cast(n), std::distance(begin, end)))};
} else
{
return Derived{get_base(begin), get_base(begin + n)};
}
}
}
public:
auto take(blt::size_t n)
{ return take_base(n); }
auto take_or(blt::size_t n)
{ return take_base(n); }
};
template
class skip_impl
{
private:
template
auto skip_base(blt::size_t n)
{
auto* d = static_cast(this);
auto begin = d->begin();
auto end = d->end();
if constexpr (std::is_same_v)
{
if constexpr (check)
{
return Derived{begin + std::min(static_cast(n), std::distance(begin, end))};
} else
{
return Derived{begin + n, end};
}
} else
{
for (blt::size_t i = 0; i < n; i++)
{
if constexpr (check)
{
if (begin == end)
break;
}
++begin;
}
return Derived{begin, end};
}
}
public:
void skip(blt::size_t n)
{ return skip_base(n); }
void skip_or(blt::size_t n)
{ return skip_base(n); }
};
}
template
struct iterator_pair
{
using type = Iter;
iterator_pair(Iter begin, Iter end): begin(std::move(begin)), end(std::move(end))
{}
Iter begin;
Iter end;
};
template
class zip_iterator_storage;
template
class zip_iterator_storage_rev;
template
class zip_iterator_storage : public iterator::take_impl>
{
public:
using iterator_category = meta::lowest_iterator_category_t;
public:
zip_iterator_storage(iterator_pair... iterator_pairs):
m_begins(std::move(iterator_pairs.begin)...), m_ends(std::move(iterator_pairs.end)...)
{}
zip_iterator_storage(iterator::zip_wrapper begins, iterator::zip_wrapper ends):
m_begins(std::move(begins)), m_ends(std::move(ends))
{}
auto rev()
{
static_assert((std::is_same_v ||
std::is_same_v),
".rev() must be used with bidirectional (or better) iterators!");
return zip_iterator_storage_rev{m_ends, m_begins};
}
auto skip(blt::size_t n)
{
if constexpr (std::is_same_v)
{
}
}
auto begin() const
{
return m_begins;
}
auto end() const
{
return m_ends;
}
private:
iterator::zip_wrapper m_begins;
iterator::zip_wrapper m_ends;
};
template
class zip_iterator_storage_rev : public iterator::take_impl>
{
public:
using iterator_category = meta::lowest_iterator_category_t;
public:
zip_iterator_storage_rev(iterator_pair... iterator_pairs): m_begins(iterator_pairs.begin...), m_ends(iterator_pairs.end...)
{
static_assert((std::is_same_v ||
std::is_same_v),
"reverse iteration is only supported on bidirectional or better iterators!");
}
zip_iterator_storage_rev(iterator::zip_wrapper begins,
iterator::zip_wrapper ends): m_begins(std::move(begins)), m_ends(std::move(ends))
{
static_assert((std::is_same_v ||
std::is_same_v),
"reverse iteration is only supported on bidirectional or better iterators!");
}
auto rev()
{
return zip_iterator_storage{m_ends.base(), m_begins.base()};
}
auto begin() const
{
return m_begins;
}
auto end() const
{
return m_ends;
}
private:
std::reverse_iterator> m_begins;
std::reverse_iterator> m_ends;
};
/*
* CTAD for the zip containers
*/
template
zip_iterator_storage(iterator_pair...) -> zip_iterator_storage;
template
zip_iterator_storage(std::initializer_list...) -> zip_iterator_storage;
template
zip_iterator_storage_rev(iterator_pair...) -> zip_iterator_storage_rev;
template
zip_iterator_storage_rev(std::initializer_list...) -> zip_iterator_storage_rev;
/*
* Helper functions for creating zip containers
*/
template
auto zip(Container& ... container)
{
return blt::zip_iterator_storage{iterator_pair{container.begin(), container.end()}...};
}
}
#endif //BLT_ITERATOR_ZIP