366 lines
13 KiB
C++
366 lines
13 KiB
C++
#pragma once
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/*
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* Copyright (C) 2024 Brett Terpstra
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <https://www.gnu.org/licenses/>.
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*/
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#ifndef BLT_ITERATOR_ITER_COMMON
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#define BLT_ITERATOR_ITER_COMMON
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#include <type_traits>
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#include <iterator>
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#include <blt/std/types.h>
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#include <blt/iterator/fwddecl.h>
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#include <blt/meta/meta.h>
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#include <blt/meta/iterator.h>
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namespace blt::iterator
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{
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template<typename Derived>
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struct base_wrapper
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{
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base_wrapper operator++(int)
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{
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auto tmp = *this;
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++*this;
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return tmp;
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}
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base_wrapper operator--(int)
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{
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static_assert(meta::is_bidirectional_or_better_category_v<typename Derived::iterator_category>, "Iterator must allow random access");
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auto tmp = *this;
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--*this;
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return tmp;
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}
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auto operator[](blt::ptrdiff_t n) const
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{
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static_assert(meta::is_random_access_iterator_category_v<typename Derived::iterator_category>, "Iterator must allow random access");
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return *(*this + n);
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}
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friend base_wrapper operator+(blt::ptrdiff_t n, const base_wrapper& a)
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{
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return a + n;
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}
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friend bool operator<(const base_wrapper& a, const base_wrapper& b)
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{
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static_assert(meta::is_random_access_iterator_category_v<typename Derived::iterator_category>, "Iterator must allow random access");
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return b - a > 0;
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}
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friend bool operator>(const base_wrapper& a, const base_wrapper& b)
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{
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static_assert(meta::is_random_access_iterator_category_v<typename Derived::iterator_category>, "Iterator must allow random access");
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return b < a;
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}
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friend bool operator>=(const base_wrapper& a, base_wrapper& b)
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{
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static_assert(meta::is_random_access_iterator_category_v<typename Derived::iterator_category>, "Iterator must allow random access");
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return !(a < b); // NOLINT
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}
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friend bool operator<=(const base_wrapper& a, const base_wrapper& b)
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{
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static_assert(meta::is_random_access_iterator_category_v<typename Derived::iterator_category>, "Iterator must allow random access");
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return !(a > b); // NOLINT
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}
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friend bool operator==(const base_wrapper& a, const base_wrapper& b)
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{
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return static_cast<const Derived&>(a).base() == static_cast<const Derived&>(b).base();
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}
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friend bool operator!=(const base_wrapper& a, const base_wrapper& b)
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{
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return !(static_cast<const Derived&>(a).base() == static_cast<const Derived&>(b).base()); // NOLINT
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}
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};
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template<typename Iter, typename Derived, bool dereference = false>
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struct passthrough_wrapper : public base_wrapper<Derived>
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{
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public:
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explicit passthrough_wrapper(Iter iter): iter(std::move(iter))
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{}
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auto base() const
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{
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return iter;
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}
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friend blt::ptrdiff_t operator-(const passthrough_wrapper& a, const passthrough_wrapper& b)
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{
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return a.base() - b.base();
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}
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protected:
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Iter iter;
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};
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template<typename Iter, typename Derived>
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struct passthrough_wrapper<Iter, Derived, true> : public passthrough_wrapper<Iter, Derived>
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{
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using passthrough_wrapper<Iter, Derived>::passthrough_wrapper;
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meta::deref_return_t<Iter> operator*() const
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{
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return *this->iter;
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}
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// your_class& operator++()
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// {
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// return *this;
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// }
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//
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// your_class& operator--()
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// {
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// return *this;
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// }
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//
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// friend your_class operator+(const your_class& a, blt::ptrdiff_t n)
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// {
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// static_assert(std::is_same_v<iterator_category, std::random_access_iterator_tag>,
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// "Iterator must allow random access");
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// }
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//
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// friend your_class operator-(const your_class& a, blt::ptrdiff_t n)
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// {
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// static_assert(std::is_same_v<iterator_category, std::random_access_iterator_tag>,
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// "Iterator must allow random access");
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// }
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};
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template<typename Iter, typename Func>
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class map_wrapper : public passthrough_wrapper<Iter, map_wrapper<Iter, Func>>
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{
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public:
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using iterator_category = typename std::iterator_traits<Iter>::iterator_category;
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using value_type = std::invoke_result_t<Func, meta::deref_return_t<Iter>>;
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using difference_type = blt::ptrdiff_t;
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using pointer = value_type;
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using reference = value_type;
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map_wrapper(Iter iter, Func func): passthrough_wrapper<Iter, map_wrapper<Iter, Func>>(std::move(iter)), func(std::move(func))
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{}
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reference operator*() const
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{
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return func(*this->iter);
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}
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map_wrapper& operator++()
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{
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++this->iter;
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return *this;
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}
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map_wrapper& operator--()
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{
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--this->iter;
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return *this;
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}
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friend map_wrapper operator+(const map_wrapper& a, blt::ptrdiff_t n)
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{
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static_assert(meta::is_random_access_iterator_v<Iter>, "Iterator must allow random access");
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return {a.iter + n, a.func};
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}
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friend map_wrapper operator-(const map_wrapper& a, blt::ptrdiff_t n)
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{
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static_assert(meta::is_random_access_iterator_v<Iter>, "Iterator must allow random access");
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return {a.iter - n, a.func};
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}
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private:
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Func func;
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};
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namespace impl
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{
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template<typename Derived>
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class skip_t
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{
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private:
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template<bool check>
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auto skip_base(blt::size_t n)
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{
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auto* d = static_cast<Derived*>(this);
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auto begin = d->begin();
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auto end = d->end();
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if constexpr (meta::is_random_access_iterator_category_v<typename Derived::iterator_category>)
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{
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// random access iterators can have math directly applied to them.
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if constexpr (check)
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{
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return Derived{begin + std::min(static_cast<blt::ptrdiff_t>(n), std::distance(begin, end)), end};
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} else
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{
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return Derived{begin + n, end};
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}
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} else
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{
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for (blt::size_t i = 0; i < n; i++)
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{
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if constexpr (check)
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{
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if (begin == end)
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break;
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}
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++begin;
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}
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return Derived{std::move(begin), std::move(end)};
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}
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}
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public:
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auto skip(blt::size_t n)
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{ return skip_base<false>(n); }
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auto skip_or(blt::size_t n)
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{ return skip_base<true>(n); }
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};
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template<typename Derived>
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class take_t
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{
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private:
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template<bool check>
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auto take_base(blt::size_t n)
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{
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static_assert(!meta::is_input_iterator_category_v<typename Derived::iterator_category>,
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"Cannot .take() on an input iterator!");
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auto* d = static_cast<Derived*>(this);
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auto begin = d->begin();
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auto end = d->end();
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// take variant for forward and bidirectional iterators
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if constexpr (meta::is_forward_iterator_category_v<typename Derived::iterator_category> ||
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meta::is_bidirectional_iterator_category_v<typename Derived::iterator_category>)
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{
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// with these guys we have to loop forward to move the iterators. an unfortunate inefficiency
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auto new_end = begin;
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for (blt::size_t i = 0; i < n; i++)
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{
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if constexpr (check)
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{
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if (new_end == end)
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break;
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}
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++new_end;
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}
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return Derived{std::move(begin), std::move(new_end)};
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} else if constexpr (meta::is_random_access_iterator_category_v<typename Derived::iterator_category>)
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{
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// random access iterators can have math directly applied to them.
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if constexpr (check)
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{
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return Derived{begin, begin + std::min(static_cast<blt::ptrdiff_t>(n), std::distance(begin, end))};
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} else
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{
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return Derived{begin, begin + n};
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}
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}
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}
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public:
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auto take(blt::size_t n)
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{ return take_base<false>(n); }
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auto take_or(blt::size_t n)
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{ return take_base<true>(n); }
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};
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}
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template<typename IterBase>
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class iterator_container : public impl::take_t<iterator_container<IterBase>>,
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public impl::skip_t<iterator_container<IterBase>>
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{
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public:
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using iterator_category = typename std::iterator_traits<IterBase>::iterator_category;
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using iterator = IterBase;
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iterator_container(IterBase begin, IterBase end): m_begin(std::move(begin)), m_end(std::move(end))
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{}
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template<typename Iter>
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iterator_container(Iter&& begin, Iter&& end): m_begin(std::forward<Iter>(begin)), m_end(std::forward<Iter>(end))
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{}
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auto rev() const
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{
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static_assert(meta::is_bidirectional_or_better_category_v<iterator_category>,
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".rev() must be used with bidirectional (or better) iterators!");
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return iterator_container<std::reverse_iterator<IterBase>>{std::reverse_iterator<IterBase>{end()},
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std::reverse_iterator<IterBase>{begin()}};
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}
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template<typename... Iter>
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auto zip(iterator_pair<Iter>... iterator_pairs) const
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{
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return zip_iterator_container(iterator_pair<decltype(begin())>{begin(), end()}, iterator_pairs...);
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}
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template<typename... Container>
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auto zip(Container& ... containers) const
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{
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return zip_iterator_container(iterator_pair<decltype(begin())>{begin(), end()},
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iterator_pair{containers.begin(), containers.end()}...);
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}
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template<typename... Container>
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auto zip(const Container& ... containers) const
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{
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return zip_iterator_container(iterator_pair<decltype(begin())>{begin(), end()},
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iterator_pair{containers.begin(), containers.end()}...);
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}
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auto enumerate() const
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{
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return enumerate_iterator_container{begin(), end(), static_cast<blt::size_t>(std::distance(begin(), end()))};
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}
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template<typename Func>
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auto map(Func func)
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{
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return iterator_container<blt::iterator::map_wrapper<IterBase, Func>>{
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blt::iterator::map_wrapper<IterBase, Func>{m_begin, func},
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blt::iterator::map_wrapper<IterBase, Func>{m_end, func}};
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}
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auto begin() const
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{
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return m_begin;
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}
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auto end() const
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{
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return m_end;
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}
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protected:
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IterBase m_begin;
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IterBase m_end;
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};
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}
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#endif //BLT_ITERATOR_ITER_COMMON
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