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/*
* Copyright (C) 2008 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.
* 3. Neither the name of Apple Inc. ("Apple") nor the names of
* its contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY APPLE 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 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
#include <wtf/Noncopyable.h>
#include <wtf/Vector.h>
namespace WTF {
DECLARE_ALLOCATOR_WITH_HEAP_IDENTIFIER(SegmentedVector);
// An iterator for SegmentedVector. It supports only the pre ++ operator
template <typename T, size_t SegmentSize = 8> class SegmentedVector;
template <typename T, size_t SegmentSize = 8> class SegmentedVectorIterator {
WTF_MAKE_FAST_ALLOCATED;
private:
friend class SegmentedVector<T, SegmentSize>;
public:
typedef SegmentedVectorIterator<T, SegmentSize> Iterator;
using iterator_category = std::forward_iterator_tag;
using value_type = T;
using difference_type = ptrdiff_t;
using pointer = const T*;
using reference = const T&;
~SegmentedVectorIterator() { }
T& operator*() const { return m_vector.at(m_index); }
T* operator->() const { return &m_vector.at(m_index); }
// Only prefix ++ operator supported
Iterator& operator++()
{
m_index++;
return *this;
}
bool operator==(const Iterator& other) const
{
return m_index == other.m_index && &m_vector == &other.m_vector;
}
bool operator!=(const Iterator& other) const
{
return m_index != other.m_index || &m_vector != &other.m_vector;
}
SegmentedVectorIterator& operator=(const SegmentedVectorIterator<T, SegmentSize>& other)
{
m_vector = other.m_vector;
m_index = other.m_index;
return *this;
}
private:
SegmentedVectorIterator(SegmentedVector<T, SegmentSize>& vector, size_t index)
: m_vector(vector)
, m_index(index)
{
}
SegmentedVector<T, SegmentSize>& m_vector;
size_t m_index;
};
// SegmentedVector is just like Vector, but it doesn't move the values
// stored in its buffer when it grows. Therefore, it is safe to keep
// pointers into a SegmentedVector. The default tuning values are
// optimized for segmented vectors that get large; you may want to use
// SegmentedVector<thingy, 1> if you don't expect a lot of entries.
template <typename T, size_t SegmentSize>
class SegmentedVector final {
friend class SegmentedVectorIterator<T, SegmentSize>;
WTF_MAKE_NONCOPYABLE(SegmentedVector);
WTF_MAKE_FAST_ALLOCATED;
public:
using Iterator = SegmentedVectorIterator<T, SegmentSize>;
using value_type = T;
using iterator = Iterator;
SegmentedVector() = default;
~SegmentedVector()
{
deleteAllSegments();
}
size_t size() const { return m_size; }
bool isEmpty() const { return !size(); }
T& at(size_t index)
{
ASSERT_WITH_SECURITY_IMPLICATION(index < m_size);
return segmentFor(index)->entries[subscriptFor(index)];
}
const T& at(size_t index) const
{
return const_cast<SegmentedVector<T, SegmentSize>*>(this)->at(index);
}
T& operator[](size_t index)
{
return at(index);
}
const T& operator[](size_t index) const
{
return at(index);
}
T& first()
{
ASSERT_WITH_SECURITY_IMPLICATION(!isEmpty());
return at(0);
}
const T& first() const
{
ASSERT_WITH_SECURITY_IMPLICATION(!isEmpty());
return at(0);
}
T& last()
{
ASSERT_WITH_SECURITY_IMPLICATION(!isEmpty());
return at(size() - 1);
}
const T& last() const
{
ASSERT_WITH_SECURITY_IMPLICATION(!isEmpty());
return at(size() - 1);
}
T takeLast()
{
ASSERT_WITH_SECURITY_IMPLICATION(!isEmpty());
T result = WTFMove(last());
--m_size;
return result;
}
template<typename... Args>
void append(Args&&... args)
{
++m_size;
if (!segmentExistsFor(m_size - 1))
allocateSegment();
new (NotNull, &last()) T(std::forward<Args>(args)...);
}
template<typename... Args>
T& alloc(Args&&... args)
{
append(std::forward<Args>(args)...);
return last();
}
void removeLast()
{
last().~T();
--m_size;
}
void grow(size_t size)
{
ASSERT(size > m_size);
ensureSegmentsFor(size);
size_t oldSize = m_size;
m_size = size;
for (size_t i = oldSize; i < m_size; ++i)
new (NotNull, &at(i)) T();
}
void clear()
{
deleteAllSegments();
m_segments.clear();
m_size = 0;
}
Iterator begin()
{
return Iterator(*this, 0);
}
Iterator end()
{
return Iterator(*this, m_size);
}
void shrinkToFit()
{
m_segments.shrinkToFit();
}
private:
struct Segment {
#if COMPILER(MSVC)
#pragma warning(push)
#pragma warning(disable: 4200)
#endif
T entries[0];
#if COMPILER(MSVC)
#pragma warning(pop)
#endif
};
void deleteAllSegments()
{
for (size_t i = 0; i < m_size; ++i)
at(i).~T();
for (size_t i = 0; i < m_segments.size(); ++i)
SegmentedVectorMalloc::free(m_segments[i]);
}
bool segmentExistsFor(size_t index)
{
return index / SegmentSize < m_segments.size();
}
Segment* segmentFor(size_t index)
{
return m_segments[index / SegmentSize];
}
size_t subscriptFor(size_t index)
{
return index % SegmentSize;
}
void ensureSegmentsFor(size_t size)
{
size_t segmentCount = (m_size + SegmentSize - 1) / SegmentSize;
size_t neededSegmentCount = (size + SegmentSize - 1) / SegmentSize;
for (size_t i = segmentCount ? segmentCount - 1 : 0; i < neededSegmentCount; ++i)
ensureSegment(i);
}
void ensureSegment(size_t segmentIndex)
{
ASSERT_WITH_SECURITY_IMPLICATION(segmentIndex <= m_segments.size());
if (segmentIndex == m_segments.size())
allocateSegment();
}
void allocateSegment()
{
m_segments.append(static_cast<Segment*>(SegmentedVectorMalloc::malloc(sizeof(T) * SegmentSize)));
}
size_t m_size { 0 };
Vector<Segment*> m_segments;
};
} // namespace WTF
using WTF::SegmentedVector;