adapter: add container transform adapter
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56
adapter.cpp
56
adapter.cpp
@ -9,47 +9,15 @@
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#include "adapter.hpp"
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//#include <vector>
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//#include <tuple>
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//#include <iostream>
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//
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//
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//using cruft::adapter::scalar;
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//
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//
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//void
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//foo (void) {
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// std::vector<std::tuple<int,int,int>> vals;
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//
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// using iterator_t = cruft::adapter::scalar<0, decltype(vals.begin ())>;
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//
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// static_assert (
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// std::is_same<
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// typename std::iterator_traits<
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// decltype(vals.begin ())
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// >::value_type,
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// std::tuple<int,int,int>
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// >::value
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// );
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//
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// static_assert (
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// std::is_same<
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// typename std::tuple_element<0, std::tuple<int,int,int>>::type,
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// int
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// >::value
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// );
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//
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// iterator_t end (vals.end ());
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//
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// //static_assert (
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// // std::is_same<
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// // typename iterator_t::reference,
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// // //decltype(*std::declval <scalar<0,std::tuple<int,int,int>>> ()),
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// // //typename scalar<0,decltype(vals.begin ())>::value_type,
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// // int&
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// // >::value
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// //);
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//
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// for (auto p = iterator_t (vals.begin ()), last = iterator_t (vals.end ()); p != last; ++p)
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// int b = *p;
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//}
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#include "concepts/named.hpp"
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#include <array>
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static std::array<int,5> v;
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static cruft::adapter::container::transform t (v, [](auto const&) { return false; });
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static_assert (
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std::is_same_v<
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typename std::iterator_traits<decltype(t)::iterator>::value_type,
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bool
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>
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);
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94
adapter.hpp
94
adapter.hpp
@ -3,14 +3,15 @@
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/.
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*
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* Copyright 2015-2019 Danny Robson <danny@nerdcruft.net>
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* Copyright 2015-2022 Danny Robson <danny@nerdcruft.net>
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*/
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#include "concepts/named.hpp"
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#include <cstddef>
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#include <iterator>
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#include <tuple>
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namespace cruft::adapter {
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namespace container {
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/// An identity proxy for a referenced container.
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@ -93,6 +94,95 @@ namespace cruft::adapter {
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private:
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T &m_target;
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};
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template <
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typename ContainerT,
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typename FunctionT
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>
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requires (
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std::is_invocable_v<
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FunctionT,
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typename std::iterator_traits<typename ContainerT::iterator>::value_type
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>
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)
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class transform {
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public:
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using value_type = std::invoke_result_t<
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FunctionT,
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typename std::iterator_traits<typename ContainerT::iterator>::value_type
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>;
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using pointer = void;
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using reference = void;
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using difference_type = typename std::iterator_traits<
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typename ContainerT::iterator
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>::difference_type;
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template <typename _ContainerT, typename _FunctionT>
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transform (_ContainerT &&_container, _FunctionT &&_function)
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: m_container (std::forward<_ContainerT> (_container))
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, m_function (std::forward< _FunctionT> (_function ))
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{ ; }
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auto begin (void) const { return iterator (m_container.begin (), m_function); }
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auto end (void) const { return iterator (m_container.end (), m_function); }
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class iterator {
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private:
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using underlying = typename ContainerT::iterator;
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public:
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// HACK: We really should be using the underlying iterator's
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// category. However it's a massive PITA to write this code
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// right now.
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using iterator_category = std::forward_iterator_tag; //typename std::iterator_traits<underlying>::iterator_category;
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using difference_type = typename std::iterator_traits<underlying>::difference_type;
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using value_type = transform::value_type;
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using pointer = void;
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using reference = void;
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iterator (
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typename ContainerT::iterator _cursor,
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FunctionT const &_function
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)
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: m_cursor (_cursor)
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, m_function (_function)
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{ ; }
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decltype(auto) operator* ()
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{
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return m_function (*m_cursor);
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}
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iterator& operator++ ()&
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{
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++m_cursor;
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return *this;
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}
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bool operator== (iterator const &rhs) const noexcept
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{
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return m_cursor == rhs.m_cursor;
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}
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private:
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typename ContainerT::iterator m_cursor;
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FunctionT const &m_function;
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};
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private:
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ContainerT m_container;
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FunctionT m_function;
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};
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template <typename ContainerT, typename FunctionT>
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transform (ContainerT, FunctionT) -> transform<
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std::remove_cvref_t<ContainerT>,
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std::remove_cvref_t< FunctionT>
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>;
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}
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@ -8,6 +8,12 @@
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#pragma once
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#include "../view.hpp"
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#include <algorithm>
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#include <utility>
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namespace cruft::iterator {
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///////////////////////////////////////////////////////////////////////////
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template <typename OutputIt, typename FunctionT>
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