src/cpp-common/bt2/borrowed-object-iterator.hpp

   1 /*
   2  * Copyright (c) 2022 Francis Deslauriers <francis.deslauriers@efficios.com>
   3  * Copyright (c) 2023 Philippe Proulx <pproulx@efficios.com>
   4  *
   5  * SPDX-License-Identifier: MIT
   6  */
   7
   8 #ifndef BABELTRACE_CPP_COMMON_BT2_BORROWED_OBJECT_ITERATOR_HPP
   9 #define BABELTRACE_CPP_COMMON_BT2_BORROWED_OBJECT_ITERATOR_HPP
  10
  11 #include <cstdint>
  12 #include <type_traits>
  13 #include <utility>
  14
  15 #include "common/assert.h"
  16
  17 #include "borrowed-object-proxy.hpp"
  18
  19 namespace bt2 {
  20
  21 /*
  22  * An iterator class to iterate an instance of a borrowed object
  23  * container of type `ContainerT`.
  24  *
  25  * `ContainerT` must implement:
  26  *
  27  *     // Returns the number of contained borrowed objects.
  28  *     std::uint64_t length() const noexcept;
  29  *
  30  *     // Returns the borrowed object at index `i`.
  31  *     SomeObject operator[](std::uint64_t i) const noexcept;
  32  */
  33 template <typename ContainerT>
  34 class BorrowedObjectIterator final
  35 {
  36     friend ContainerT;
  37
  38 public:
  39     using Object = typename std::remove_reference<
  40         decltype(std::declval<ContainerT>()[std::declval<std::uint64_t>()])>::type;
  41
  42 private:
  43     explicit BorrowedObjectIterator(const ContainerT container, const uint64_t idx) :
  44         _mContainer {container}, _mIdx {idx}
  45     {
  46     }
  47
  48 public:
  49     BorrowedObjectIterator& operator++() noexcept
  50     {
  51         ++_mIdx;
  52         return *this;
  53     }
  54
  55     BorrowedObjectIterator operator++(int) noexcept
  56     {
  57         const auto tmp = *this;
  58
  59         ++(*this);
  60         return tmp;
  61     }
  62
  63     bool operator==(const BorrowedObjectIterator& other) const noexcept
  64     {
  65         BT_ASSERT_DBG(_mContainer.isSame(other._mContainer));
  66         return _mIdx == other._mIdx;
  67     }
  68
  69     bool operator!=(const BorrowedObjectIterator& other) const noexcept
  70     {
  71         return !(*this == other);
  72     }
  73
  74     Object operator*() const noexcept
  75     {
  76         BT_ASSERT_DBG(_mIdx < _mContainer.length());
  77         return _mContainer[_mIdx];
  78     }
  79
  80     BorrowedObjectProxy<Object> operator->() const noexcept
  81     {
  82         return BorrowedObjectProxy<Object> {(**this).libObjPtr()};
  83     }
  84
  85 private:
  86     ContainerT _mContainer;
  87     std::uint64_t _mIdx;
  88 };
  89
  90 } /* namespace bt2 */
  91
  92 #endif /* BABELTRACE_CPP_COMMON_BT2_BORROWED_OBJECT_ITERATOR_HPP */