59 lines
1.7 KiB
C++
59 lines
1.7 KiB
C++
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/*
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* This Source Code Form is subject to the terms of the Mozilla Public
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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 2021, Danny Robson <danny@nerdcruft.net>
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*/
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#pragma once
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#include <iterator>
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#include <type_traits>
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#include <utility>
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///////////////////////////////////////////////////////////////////////////////
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namespace cruft::iterator {
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/// An output iterator that calls placement new on a supplied pointer
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/// during assignment.
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///
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/// This simplifies usage of uninitialised arrays with STL algorithms.
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template <typename PointerT>
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struct placement_output {
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public:
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static_assert (std::is_pointer_v<PointerT>);
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using iterator_category = std::output_iterator_tag;
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using value_type = void;
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using difference_type = void;
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using pointer = void;
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using reference = void;
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placement_output (PointerT _cursor)
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: m_cursor (_cursor)
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{ ; }
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placement_output& operator++ () { ++m_cursor; return *this; }
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placement_output& operator * () { return *this; }
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placement_output& operator-> () { return this; }
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template <typename ValueT>
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placement_output&
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operator= (ValueT &&val)
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{
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new (m_cursor) bare_type (std::forward<ValueT> (val));
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return *this;
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}
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private:
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using bare_type = std::remove_pointer_t<PointerT>;
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PointerT m_cursor;
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};
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template <typename PointerT>
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placement_output (PointerT) -> placement_output<std::remove_reference_t<PointerT>>;
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}
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