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67 lines
2.2 KiB
C++
67 lines
2.2 KiB
C++
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim:set ts=2 sw=2 sts=2 et cindent: */
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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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#ifndef AlignedTArray_h__
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#define AlignedTArray_h__
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#include "mozilla/Alignment.h"
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#include "nsTArray.h"
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/**
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* E: element type, must be a POD type.
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* N: N bytes alignment for the first element, defaults to 32
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*/
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template <typename E, int N = 32>
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class AlignedTArray : private nsTArray_Impl<E, nsTArrayInfallibleAllocator>
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{
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static_assert((N & (N-1)) == 0, "N must be power of 2");
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typedef nsTArray_Impl<E, nsTArrayInfallibleAllocator> base_type;
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public:
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typedef E elem_type;
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typedef typename base_type::size_type size_type;
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typedef typename base_type::index_type index_type;
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AlignedTArray() {}
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explicit AlignedTArray(size_type capacity) : base_type(capacity + sExtra) {}
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elem_type* Elements() { return getAligned(base_type::Elements()); }
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const elem_type* Elements() const { return getAligned(base_type::Elements()); }
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elem_type& operator[](index_type i) { return Elements()[i];}
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const elem_type& operator[](index_type i) const { return Elements()[i]; }
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void SetLength(size_type newLen)
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{
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base_type::SetLength(newLen + sExtra);
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}
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MOZ_WARN_UNUSED_RESULT
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bool SetLength(size_type newLen, const mozilla::fallible_t&)
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{
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return base_type::SetLength(newLen + sExtra, mozilla::fallible);
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}
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size_type Length() const {
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return base_type::Length() <= sExtra ? 0 : base_type::Length() - sExtra;
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}
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using base_type::ShallowSizeOfExcludingThis;
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using base_type::ShallowSizeOfIncludingThis;
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private:
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AlignedTArray(const AlignedTArray& other) = delete;
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void operator=(const AlignedTArray& other) = delete;
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static const size_type sPadding = N <= MOZ_ALIGNOF(E) ? 0 : N - MOZ_ALIGNOF(E);
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static const size_type sExtra = (sPadding + sizeof(E) - 1) / sizeof(E);
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template <typename U>
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static U* getAligned(U* p)
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{
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return reinterpret_cast<U*>(((uintptr_t)p + N - 1) & ~(N-1));
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}
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};
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#endif // AlignedTArray_h__
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