105 lines
2.9 KiB
C++
105 lines
2.9 KiB
C++
/*
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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 2010-2018 Danny Robson <danny@nerdcruft.net>
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*/
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#pragma once
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namespace cruft::iterator {
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///////////////////////////////////////////////////////////////////////////
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/// Adapts a supplied iterator by dereferencing any operations that deal
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/// with the underlying value_type of the supplied iterator.
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template <typename IteratorT>
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struct dereference_adapter {
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//---------------------------------------------------------------------
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using difference_type = typename std::iterator_traits<IteratorT>::difference_type;
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using iterator_category = typename std::iterator_traits<IteratorT>::iterator_category;
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using value_type = std::remove_reference_t<
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decltype(
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*std::declval<
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typename std::iterator_traits<IteratorT>::value_type
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> ()
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)
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>;
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using pointer = value_type*;
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using reference = value_type&;
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//---------------------------------------------------------------------
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dereference_adapter (IteratorT _cursor)
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: m_cursor (_cursor)
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{ ; }
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//---------------------------------------------------------------------
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// Trivial conditional operations
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decltype(auto)
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operator== (dereference_adapter const &rhs) const
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{
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return m_cursor == rhs.m_cursor;
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}
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decltype(auto)
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operator!= (dereference_adapter const &rhs) const
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{
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return !(*this == rhs);
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}
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decltype(auto)
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operator<= (dereference_adapter const &rhs) const
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{
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return m_cursor <= rhs.m_cursor;
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}
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//---------------------------------------------------------------------
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// Iterator movement operations
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dereference_adapter&
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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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difference_type
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operator- (dereference_adapter const &rhs) const
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{
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return m_cursor - rhs.m_cursor;
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}
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auto
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operator+ (difference_type offset) const
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{
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return dereference_adapter { m_cursor + offset };
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}
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//---------------------------------------------------------------------
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// value_type operations
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decltype(auto)
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operator= (value_type const &rhs)
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{
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return **m_cursor = rhs;
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}
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decltype(auto) operator* () { return **m_cursor; }
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decltype(auto) operator-> () { return **m_cursor; }
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decltype(auto) operator* () const { return **m_cursor; }
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decltype(auto) operator-> () const { return **m_cursor; }
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private:
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IteratorT m_cursor;
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};
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}
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