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/*
* Copyright (C) 2024 Apple Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
* THE POSSIBILITY OF SUCH DAMAGE.
*/
#pragma once
namespace WTF {
template<typename Iterator> class BoundsCheckedIterator {
public:
// We require the caller to ask for 'begin' or 'end', rather than passing
// us arbitrary 'it' and 'end' iterators, because that way we can prove by
// construction that we have the correct 'end'.
template<typename Collection>
static BoundsCheckedIterator begin(Collection&& collection)
{
return BoundsCheckedIterator(std::forward<Collection>(collection), std::begin(collection));
}
template<typename Collection>
static BoundsCheckedIterator end(Collection&& collection)
{
return BoundsCheckedIterator(std::forward<Collection>(collection), std::end(collection));
}
BoundsCheckedIterator& operator++()
{
WTF_ALLOW_UNSAFE_BUFFER_USAGE_BEGIN
RELEASE_ASSERT(m_iterator != m_end);
++m_iterator;
WTF_ALLOW_UNSAFE_BUFFER_USAGE_END
return *this;
}
auto&& operator*() const
{
RELEASE_ASSERT(m_iterator != m_end);
return *m_iterator;
}
bool operator==(const BoundsCheckedIterator& other) const
{
return m_iterator == other.m_iterator;
}
private:
template<typename Collection>
BoundsCheckedIterator(Collection&& collection, Iterator&& iterator)
: m_iterator(WTFMove(iterator))
, m_end(std::end(collection))
{
}
Iterator m_iterator;
Iterator m_end;
};
template<typename Collection> auto boundsCheckedBegin(Collection&& collection)
{
return BoundsCheckedIterator<decltype(std::begin(collection))>::begin(std::forward<Collection>(collection));
}
template<typename Collection> auto boundsCheckedEnd(Collection&& collection)
{
return BoundsCheckedIterator<decltype(std::end(collection))>::end(std::forward<Collection>(collection));
}
template<typename Iterator> class IndexedRangeIterator {
public:
IndexedRangeIterator(Iterator&& iterator)
: m_iterator(WTFMove(iterator))
{
}
IndexedRangeIterator& operator++()
{
++m_index;
++m_iterator;
return *this;
}
auto operator*()
{
return std::pair<size_t, decltype(*m_iterator)> { m_index, *m_iterator };
}
bool operator==(const IndexedRangeIterator& other) const
{
return m_iterator == other.m_iterator;
}
private:
size_t m_index { 0 };
Iterator m_iterator;
};
template<typename Iterator>
class IndexedRange {
public:
template<typename Collection>
IndexedRange(Collection&& collection)
: m_begin(boundsCheckedBegin(std::forward<Collection>(collection)))
, m_end(boundsCheckedEnd(std::forward<Collection>(collection)))
{
// Prevent use after destruction of a returned temporary.
static_assert(std::ranges::borrowed_range<Collection>);
}
auto begin() { return m_begin; }
auto end() { return m_end; }
private:
Iterator m_begin;
Iterator m_end;
};
// Usage: for (auto [ index, value ] : indexedRange(collection)) { ... }
template<typename Collection> auto indexedRange(Collection&& collection)
{
using Iterator = IndexedRangeIterator<decltype(boundsCheckedBegin(std::forward<Collection>(collection)))>;
return IndexedRange<Iterator>(std::forward<Collection>(collection));
}
} // namespace WTF
using WTF::indexedRange;
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