Utilities/detail/ContainerRange.hpp

0001 // This file is part of the ACTS project.
0002 //
0003 // Copyright (C) 2016 CERN for the benefit of the ACTS project
0004 //
0005 // This Source Code Form is subject to the terms of the Mozilla Public
0006 // License, v. 2.0. If a copy of the MPL was not distributed with this
0007 // file, You can obtain one at https://mozilla.org/MPL/2.0/.
0008
0009 #pragma once
0010
0011 #include "Acts/Utilities/TypeTraits.hpp"
0012 #include "Acts/Utilities/detail/ContainerConcepts.hpp"
0013
0014 #include <stdexcept>
0015 #include <utility>
0016
0017 namespace Acts::detail {
0018
0019 template <typename Derived, typename DerivedReadOnly, typename Container,
0020           typename Index, bool ReadOnly>
0021 class ContainerRange {
0022  public:
0023   using container_type = const_if_t<ReadOnly, Container>;
0024   using index_type = Index;
0025   static constexpr bool read_only = ReadOnly;
0026   using index_range_type = std::pair<index_type, index_type>;
0027
0028   constexpr ContainerRange(container_type &container,
0029                            const index_range_type &range) noexcept
0030       : m_container(&container), m_range(range) {}
0031   template <bool OtherReadOnly>
0032   explicit constexpr ContainerRange(
0033       const ContainerRange<Derived, DerivedReadOnly, Container, Index,
0034                            OtherReadOnly> &other) noexcept
0035     requires(ReadOnly && !OtherReadOnly)
0036       : m_container(&other.container()), m_range(other.range()) {}
0037
0038   constexpr DerivedReadOnly asConst() const noexcept
0039     requires(!ReadOnly)
0040   {
0041     return {container(), range()};
0042   }
0043
0044   constexpr container_type &container() const noexcept { return *m_container; }
0045   constexpr const index_range_type &range() const noexcept { return m_range; }
0046
0047   constexpr std::size_t size() const noexcept {
0048     return m_range.second - m_range.first;
0049   }
0050   constexpr bool empty() const noexcept { return size() == 0; }
0051
0052   constexpr Derived subrange(index_type offset) const noexcept {
0053     assert(offset <= m_range.second - m_range.first &&
0054            "Subrange offset out of bounds");
0055     return {container(), {m_range.first + offset, m_range.second}};
0056   }
0057   constexpr Derived subrange(index_type offset,
0058                              index_type count) const noexcept {
0059     assert(offset <= m_range.second - m_range.first &&
0060            "Subrange offset out of bounds");
0061     assert(count <= m_range.second - m_range.first - offset &&
0062            "Subrange count out of bounds");
0063     return {container(),
0064             {m_range.first + offset, m_range.first + offset + count}};
0065   }
0066
0067   constexpr auto front() const noexcept { return container()[m_range.first]; }
0068   constexpr auto back() const noexcept {
0069     return container()[m_range.second - 1];
0070   }
0071
0072   constexpr auto begin() const noexcept {
0073     return container().begin() + m_range.first;
0074   }
0075   constexpr auto end() const noexcept {
0076     return container().begin() + m_range.second;
0077   }
0078
0079   constexpr auto operator[](Index index) const noexcept
0080     requires(ContainerHasArrayAccess<Container>)
0081   {
0082     assert(index < size() && "Index out of bounds");
0083     return (*m_container)[m_range.first + index];
0084   }
0085   constexpr auto at(Index index) const
0086     requires(ContainerHasAt<Container>)
0087   {
0088     if (index >= size()) {
0089       throw std::out_of_range("Index out of bounds");
0090     }
0091     return m_container->at(m_range.first + index);
0092   }
0093
0094  private:
0095   container_type *m_container{};
0096   index_range_type m_range{};
0097 };
0098
0099 }  // namespace Acts::detail