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Diffstat (limited to 'xpcom/ds/nsTArray.h')
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diff --git a/xpcom/ds/nsTArray.h b/xpcom/ds/nsTArray.h new file mode 100644 index 0000000000..f17624b721 --- /dev/null +++ b/xpcom/ds/nsTArray.h @@ -0,0 +1,3376 @@ +/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ +/* vim: set ts=8 sts=2 et sw=2 tw=80: */ +/* This Source Code Form is subject to the terms of the Mozilla Public + * License, v. 2.0. If a copy of the MPL was not distributed with this + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ + +#ifndef nsTArray_h__ +#define nsTArray_h__ + +#include <string.h> + +#include <algorithm> +#include <functional> +#include <initializer_list> +#include <iterator> +#include <new> +#include <ostream> +#include <type_traits> +#include <utility> + +#include "mozilla/Alignment.h" +#include "mozilla/ArrayIterator.h" +#include "mozilla/Assertions.h" +#include "mozilla/Attributes.h" +#include "mozilla/BinarySearch.h" +#include "mozilla/CheckedInt.h" +#include "mozilla/FunctionTypeTraits.h" +#include "mozilla/MathAlgorithms.h" +#include "mozilla/MemoryReporting.h" +#include "mozilla/NotNull.h" +#include "mozilla/Span.h" +#include "mozilla/fallible.h" +#include "mozilla/mozalloc.h" +#include "nsAlgorithm.h" +#include "nsDebug.h" +#include "nsISupports.h" +#include "nsRegionFwd.h" +#include "nsTArrayForwardDeclare.h" + +namespace JS { +template <class T> +class Heap; +} /* namespace JS */ + +class nsCycleCollectionTraversalCallback; +class nsRegion; + +namespace mozilla::a11y { +class BatchData; +} + +namespace mozilla { +namespace layers { +class Animation; +class FrameStats; +struct PropertyAnimationGroup; +struct TileClient; +} // namespace layers +} // namespace mozilla + +namespace mozilla { +struct SerializedStructuredCloneBuffer; +class SourceBufferTask; +} // namespace mozilla + +namespace mozilla::dom::binding_detail { +template <typename, typename> +class RecordEntry; +} + +namespace mozilla::dom::ipc { +class StructuredCloneData; +} // namespace mozilla::dom::ipc + +namespace mozilla::dom { +class ClonedMessageData; +class MessageData; +class MessagePortIdentifier; +struct MozPluginParameter; +template <typename T> +struct Nullable; +class OwningFileOrDirectory; +class OwningStringOrBooleanOrObject; +class OwningUTF8StringOrDouble; +class Pref; +class RefMessageData; +class ResponsiveImageCandidate; +class ServiceWorkerRegistrationData; +namespace indexedDB { +class SerializedStructuredCloneReadInfo; +class ObjectStoreCursorResponse; +class IndexCursorResponse; +} // namespace indexedDB +} // namespace mozilla::dom + +namespace mozilla::ipc { +class ContentSecurityPolicy; +template <class T> +class Endpoint; +} // namespace mozilla::ipc + +class JSStructuredCloneData; + +template <class T> +class RefPtr; + +// +// nsTArray<E> is a resizable array class, like std::vector. +// +// Unlike std::vector, which follows C++'s construction/destruction rules, +// By default, nsTArray assumes that instances of E can be relocated safely +// using memory utils (memcpy/memmove). +// +// The public classes defined in this header are +// +// nsTArray<E>, +// CopyableTArray<E>, +// FallibleTArray<E>, +// AutoTArray<E, N>, +// CopyableAutoTArray<E, N> +// +// nsTArray, CopyableTArray, AutoTArray and CopyableAutoTArray are infallible by +// default. To opt-in to fallible behaviour, use the `mozilla::fallible` +// parameter and check the return value. +// +// CopyableTArray and CopyableAutoTArray< are copy-constructible and +// copy-assignable. Use these only when syntactically necessary to avoid implcit +// unintentional copies. nsTArray/AutoTArray can be conveniently copied using +// the Clone() member function. Consider using std::move where possible. +// +// If you just want to declare the nsTArray types (e.g., if you're in a header +// file and don't need the full nsTArray definitions) consider including +// nsTArrayForwardDeclare.h instead of nsTArray.h. +// +// The template parameter E specifies the type of the elements and has the +// following requirements: +// +// E MUST be safely memmove()'able. +// E MUST define a copy-constructor. +// E MAY define operator< for sorting. +// E MAY define operator== for searching. +// +// (Note that the memmove requirement may be relaxed for certain types - see +// nsTArray_RelocationStrategy below.) +// +// There is a public type value_type defined as E within each array class, and +// we reference the type under this name below. +// +// For member functions taking a Comparator instance, Comparator must be either +// a functor with a tri-state comparison function with a signature compatible to +// +// /** @return negative iff a < b, 0 iff a == b, positive iff a > b */ +// int (const value_type& a, const value_type& b); +// +// or a class defining member functions with signatures compatible to: +// +// class Comparator { +// public: +// /** @return True if the elements are equals; false otherwise. */ +// bool Equals(const value_type& a, const value_type& b) const; +// +// /** @return True if (a < b); false otherwise. */ +// bool LessThan(const value_type& a, const value_type& b) const; +// }; +// +// The Equals member function is used for searching, and the LessThan member +// function is used for searching and sorting. Note that some member functions, +// e.g. Compare, are templates where a different type Item can be used for the +// element to compare to. In that case, the signatures must be compatible to +// allow those comparisons, but the details are not documented here. +// + +// +// nsTArrayFallibleResult and nsTArrayInfallibleResult types are proxy types +// which are used because you cannot use a templated type which is bound to +// void as an argument to a void function. In order to work around that, we +// encode either a void or a boolean inside these proxy objects, and pass them +// to the aforementioned function instead, and then use the type information to +// decide what to do in the function. +// +// Note that public nsTArray methods should never return a proxy type. Such +// types are only meant to be used in the internal nsTArray helper methods. +// Public methods returning non-proxy types cannot be called from other +// nsTArray members. +// +struct nsTArrayFallibleResult { + // Note: allows implicit conversions from and to bool + MOZ_IMPLICIT constexpr nsTArrayFallibleResult(bool aResult) + : mResult(aResult) {} + + MOZ_IMPLICIT constexpr operator bool() { return mResult; } + + private: + bool mResult; +}; + +struct nsTArrayInfallibleResult {}; + +// +// nsTArray*Allocators must all use the same |free()|, to allow swap()'ing +// between fallible and infallible variants. +// + +struct nsTArrayFallibleAllocatorBase { + typedef bool ResultType; + typedef nsTArrayFallibleResult ResultTypeProxy; + + static constexpr ResultType Result(ResultTypeProxy aResult) { + return aResult; + } + static constexpr bool Successful(ResultTypeProxy aResult) { return aResult; } + static constexpr ResultTypeProxy SuccessResult() { return true; } + static constexpr ResultTypeProxy FailureResult() { return false; } + static constexpr ResultType ConvertBoolToResultType(bool aValue) { + return aValue; + } +}; + +struct nsTArrayInfallibleAllocatorBase { + typedef void ResultType; + typedef nsTArrayInfallibleResult ResultTypeProxy; + + static constexpr ResultType Result(ResultTypeProxy aResult) {} + static constexpr bool Successful(ResultTypeProxy) { return true; } + static constexpr ResultTypeProxy SuccessResult() { return ResultTypeProxy(); } + + [[noreturn]] static ResultTypeProxy FailureResult() { + MOZ_CRASH("Infallible nsTArray should never fail"); + } + + template <typename T> + static constexpr ResultType ConvertBoolToResultType(T aValue) { + if (!aValue) { + MOZ_CRASH("infallible nsTArray should never convert false to ResultType"); + } + } + + template <typename T> + static constexpr ResultType ConvertBoolToResultType( + const mozilla::NotNull<T>& aValue) {} +}; + +struct nsTArrayFallibleAllocator : nsTArrayFallibleAllocatorBase { + static void* Malloc(size_t aSize) { return malloc(aSize); } + static void* Realloc(void* aPtr, size_t aSize) { + return realloc(aPtr, aSize); + } + + static void Free(void* aPtr) { free(aPtr); } + static void SizeTooBig(size_t) {} +}; + +struct nsTArrayInfallibleAllocator : nsTArrayInfallibleAllocatorBase { + static void* Malloc(size_t aSize) MOZ_NONNULL_RETURN { + return moz_xmalloc(aSize); + } + static void* Realloc(void* aPtr, size_t aSize) MOZ_NONNULL_RETURN { + return moz_xrealloc(aPtr, aSize); + } + + static void Free(void* aPtr) { free(aPtr); } + static void SizeTooBig(size_t aSize) { NS_ABORT_OOM(aSize); } +}; + +// nsTArray_base stores elements into the space allocated beyond +// sizeof(*this). This is done to minimize the size of the nsTArray +// object when it is empty. +struct nsTArrayHeader { + uint32_t mLength; + uint32_t mCapacity : 31; + uint32_t mIsAutoArray : 1; +}; + +extern "C" { +extern const nsTArrayHeader sEmptyTArrayHeader; +} + +namespace detail { +// nsTArray_CopyDisabler disables copy operations. +class nsTArray_CopyDisabler { + public: + nsTArray_CopyDisabler() = default; + + nsTArray_CopyDisabler(const nsTArray_CopyDisabler&) = delete; + nsTArray_CopyDisabler& operator=(const nsTArray_CopyDisabler&) = delete; +}; + +} // namespace detail + +// This class provides a SafeElementAt method to nsTArray<E*> which does +// not take a second default value parameter. +template <class E, class Derived> +struct nsTArray_SafeElementAtHelper : public ::detail::nsTArray_CopyDisabler { + typedef E* elem_type; + typedef size_t index_type; + + // No implementation is provided for these two methods, and that is on + // purpose, since we don't support these functions on non-pointer type + // instantiations. + elem_type& SafeElementAt(index_type aIndex); + const elem_type& SafeElementAt(index_type aIndex) const; +}; + +template <class E, class Derived> +struct nsTArray_SafeElementAtHelper<E*, Derived> + : public ::detail::nsTArray_CopyDisabler { + typedef E* elem_type; + // typedef const E* const_elem_type; XXX: see below + typedef size_t index_type; + + elem_type SafeElementAt(index_type aIndex) { + return static_cast<Derived*>(this)->SafeElementAt(aIndex, nullptr); + } + + // XXX: Probably should return const_elem_type, but callsites must be fixed. + // Also, the use of const_elem_type for nsTArray<xpcGCCallback> in + // xpcprivate.h causes build failures on Windows because xpcGCCallback is a + // function pointer and MSVC doesn't like qualifying it with |const|. + elem_type SafeElementAt(index_type aIndex) const { + return static_cast<const Derived*>(this)->SafeElementAt(aIndex, nullptr); + } +}; + +// E is a smart pointer type; the +// smart pointer can act as its element_type*. +template <class E, class Derived> +struct nsTArray_SafeElementAtSmartPtrHelper + : public ::detail::nsTArray_CopyDisabler { + typedef typename E::element_type* elem_type; + typedef const typename E::element_type* const_elem_type; + typedef size_t index_type; + + elem_type SafeElementAt(index_type aIndex) { + auto* derived = static_cast<Derived*>(this); + if (aIndex < derived->Length()) { + return derived->Elements()[aIndex]; + } + return nullptr; + } + + // XXX: Probably should return const_elem_type, but callsites must be fixed. + elem_type SafeElementAt(index_type aIndex) const { + auto* derived = static_cast<const Derived*>(this); + if (aIndex < derived->Length()) { + return derived->Elements()[aIndex]; + } + return nullptr; + } +}; + +template <class T> +class nsCOMPtr; + +template <class E, class Derived> +struct nsTArray_SafeElementAtHelper<nsCOMPtr<E>, Derived> + : public nsTArray_SafeElementAtSmartPtrHelper<nsCOMPtr<E>, Derived> {}; + +template <class E, class Derived> +struct nsTArray_SafeElementAtHelper<RefPtr<E>, Derived> + : public nsTArray_SafeElementAtSmartPtrHelper<RefPtr<E>, Derived> {}; + +namespace mozilla { +template <class T> +class OwningNonNull; +} // namespace mozilla + +template <class E, class Derived> +struct nsTArray_SafeElementAtHelper<mozilla::OwningNonNull<E>, Derived> + : public nsTArray_SafeElementAtSmartPtrHelper<mozilla::OwningNonNull<E>, + Derived> {}; + +// Servo bindings. +extern "C" void Gecko_EnsureTArrayCapacity(void* aArray, size_t aCapacity, + size_t aElementSize); +extern "C" void Gecko_ClearPODTArray(void* aArray, size_t aElementSize, + size_t aElementAlign); + +// +// This class serves as a base class for nsTArray. It shouldn't be used +// directly. It holds common implementation code that does not depend on the +// element type of the nsTArray. +// +template <class Alloc, class RelocationStrategy> +class nsTArray_base { + // Allow swapping elements with |nsTArray_base|s created using a + // different allocator. This is kosher because all allocators use + // the same free(). + template <class XAlloc, class XRelocationStrategy> + friend class nsTArray_base; + + // Needed for AppendElements from an array with a different allocator, which + // calls ShiftData. + template <class E, class XAlloc> + friend class nsTArray_Impl; + + friend void Gecko_EnsureTArrayCapacity(void* aArray, size_t aCapacity, + size_t aElemSize); + friend void Gecko_ClearPODTArray(void* aTArray, size_t aElementSize, + size_t aElementAlign); + + protected: + typedef nsTArrayHeader Header; + + public: + typedef size_t size_type; + typedef size_t index_type; + + // @return The number of elements in the array. + size_type Length() const { return mHdr->mLength; } + + // @return True if the array is empty or false otherwise. + bool IsEmpty() const { return Length() == 0; } + + // @return The number of elements that can fit in the array without forcing + // the array to be re-allocated. The length of an array is always less + // than or equal to its capacity. + size_type Capacity() const { return mHdr->mCapacity; } + +#ifdef DEBUG + void* DebugGetHeader() const { return mHdr; } +#endif + + protected: + nsTArray_base(); + + ~nsTArray_base(); + + nsTArray_base(const nsTArray_base&); + nsTArray_base& operator=(const nsTArray_base&); + + // Resize the storage if necessary to achieve the requested capacity. + // @param aCapacity The requested number of array elements. + // @param aElemSize The size of an array element. + // @return False if insufficient memory is available; true otherwise. + template <typename ActualAlloc> + typename ActualAlloc::ResultTypeProxy EnsureCapacity(size_type aCapacity, + size_type aElemSize) { + // Do this check here so that our callers can inline it. + if (aCapacity <= mHdr->mCapacity) { + return ActualAlloc::SuccessResult(); + } + return EnsureCapacityImpl<ActualAlloc>(aCapacity, aElemSize); + } + + // The rest of EnsureCapacity. Should only be called if aCapacity > + // mHdr->mCapacity. + template <typename ActualAlloc> + typename ActualAlloc::ResultTypeProxy EnsureCapacityImpl(size_type aCapacity, + size_type aElemSize); + + // Extend the storage to accommodate aCount extra elements. + // @param aLength The current size of the array. + // @param aCount The number of elements to add. + // @param aElemSize The size of an array element. + // @return False if insufficient memory is available or the new length + // would overflow; true otherwise. + template <typename ActualAlloc> + typename ActualAlloc::ResultTypeProxy ExtendCapacity(size_type aLength, + size_type aCount, + size_type aElemSize); + + // Tries to resize the storage to the minimum required amount. If this fails, + // the array is left as-is. + // @param aElemSize The size of an array element. + // @param aElemAlign The alignment in bytes of an array element. + void ShrinkCapacity(size_type aElemSize, size_t aElemAlign); + + // Resizes the storage to 0. This may only be called when Length() is already + // 0. + // @param aElemSize The size of an array element. + // @param aElemAlign The alignment in bytes of an array element. + void ShrinkCapacityToZero(size_type aElemSize, size_t aElemAlign); + + // This method may be called to resize a "gap" in the array by shifting + // elements around. It updates mLength appropriately. If the resulting + // array has zero elements, then the array's memory is free'd. + // @param aStart The starting index of the gap. + // @param aOldLen The current length of the gap. + // @param aNewLen The desired length of the gap. + // @param aElemSize The size of an array element. + // @param aElemAlign The alignment in bytes of an array element. + template <typename ActualAlloc> + void ShiftData(index_type aStart, size_type aOldLen, size_type aNewLen, + size_type aElemSize, size_t aElemAlign); + + // This method may be called to swap elements from the end of the array to + // fill a "gap" in the array. If the resulting array has zero elements, then + // the array's memory is free'd. + // @param aStart The starting index of the gap. + // @param aCount The length of the gap. + // @param aElemSize The size of an array element. + // @param aElemAlign The alignment in bytes of an array element. + template <typename ActualAlloc> + void SwapFromEnd(index_type aStart, size_type aCount, size_type aElemSize, + size_t aElemAlign); + + // This method increments the length member of the array's header. + // Note that mHdr may actually be sEmptyTArrayHeader in the case where a + // zero-length array is inserted into our array. But then aNum should + // always be 0. + void IncrementLength(size_t aNum) { + if (HasEmptyHeader()) { + if (MOZ_UNLIKELY(aNum != 0)) { + // Writing a non-zero length to the empty header would be extremely bad. + MOZ_CRASH(); + } + } else { + mHdr->mLength += aNum; + } + } + + // This method inserts blank slots into the array. + // @param aIndex the place to insert the new elements. This must be no + // greater than the current length of the array. + // @param aCount the number of slots to insert + // @param aElementSize the size of an array element. + // @param aElemAlign the alignment in bytes of an array element. + template <typename ActualAlloc> + typename ActualAlloc::ResultTypeProxy InsertSlotsAt(index_type aIndex, + size_type aCount, + size_type aElementSize, + size_t aElemAlign); + + template <typename ActualAlloc, class Allocator> + typename ActualAlloc::ResultTypeProxy SwapArrayElements( + nsTArray_base<Allocator, RelocationStrategy>& aOther, size_type aElemSize, + size_t aElemAlign); + + template <class Allocator> + void MoveConstructNonAutoArray( + nsTArray_base<Allocator, RelocationStrategy>& aOther, size_type aElemSize, + size_t aElemAlign); + + template <class Allocator> + void MoveInit(nsTArray_base<Allocator, RelocationStrategy>& aOther, + size_type aElemSize, size_t aElemAlign); + + // This is an RAII class used in SwapArrayElements. + class IsAutoArrayRestorer { + public: + IsAutoArrayRestorer(nsTArray_base<Alloc, RelocationStrategy>& aArray, + size_t aElemAlign); + ~IsAutoArrayRestorer(); + + private: + nsTArray_base<Alloc, RelocationStrategy>& mArray; + size_t mElemAlign; + bool mIsAuto; + }; + + // Helper function for SwapArrayElements. Ensures that if the array + // is an AutoTArray that it doesn't use the built-in buffer. + template <typename ActualAlloc> + bool EnsureNotUsingAutoArrayBuffer(size_type aElemSize); + + // Returns true if this nsTArray is an AutoTArray with a built-in buffer. + bool IsAutoArray() const { return mHdr->mIsAutoArray; } + + // Returns a Header for the built-in buffer of this AutoTArray. + Header* GetAutoArrayBuffer(size_t aElemAlign) { + MOZ_ASSERT(IsAutoArray(), "Should be an auto array to call this"); + return GetAutoArrayBufferUnsafe(aElemAlign); + } + const Header* GetAutoArrayBuffer(size_t aElemAlign) const { + MOZ_ASSERT(IsAutoArray(), "Should be an auto array to call this"); + return GetAutoArrayBufferUnsafe(aElemAlign); + } + + // Returns a Header for the built-in buffer of this AutoTArray, but doesn't + // assert that we are an AutoTArray. + Header* GetAutoArrayBufferUnsafe(size_t aElemAlign) { + return const_cast<Header*>( + static_cast<const nsTArray_base<Alloc, RelocationStrategy>*>(this) + ->GetAutoArrayBufferUnsafe(aElemAlign)); + } + const Header* GetAutoArrayBufferUnsafe(size_t aElemAlign) const; + + // Returns true if this is an AutoTArray and it currently uses the + // built-in buffer to store its elements. + bool UsesAutoArrayBuffer() const; + + // The array's elements (prefixed with a Header). This pointer is never + // null. If the array is empty, then this will point to sEmptyTArrayHeader. + Header* mHdr; + + Header* Hdr() const MOZ_NONNULL_RETURN { return mHdr; } + Header** PtrToHdr() MOZ_NONNULL_RETURN { return &mHdr; } + static Header* EmptyHdr() MOZ_NONNULL_RETURN { + return const_cast<Header*>(&sEmptyTArrayHeader); + } + + [[nodiscard]] bool HasEmptyHeader() const { return mHdr == EmptyHdr(); } +}; + +namespace detail { + +// Used for argument checking in nsTArrayElementTraits::Emplace. +template <typename... T> +struct ChooseFirst; + +template <> +struct ChooseFirst<> { + // Choose a default type that is guaranteed to not match E* for any + // nsTArray<E>. + typedef void Type; +}; + +template <typename A, typename... Args> +struct ChooseFirst<A, Args...> { + typedef A Type; +}; + +} // namespace detail + +// +// This class defines convenience functions for element specific operations. +// Specialize this template if necessary. +// +template <class E> +class nsTArrayElementTraits { + public: + // Invoke the default constructor in place. + static inline void Construct(E* aE) { + // Do NOT call "E()"! That triggers C++ "default initialization" + // which zeroes out POD ("plain old data") types such as regular + // ints. We don't want that because it can be a performance issue + // and people don't expect it; nsTArray should work like a regular + // C/C++ array in this respect. + new (static_cast<void*>(aE)) E; + } + // Invoke the copy-constructor in place. + template <class A> + static inline void Construct(E* aE, A&& aArg) { + using E_NoCV = std::remove_cv_t<E>; + using A_NoCV = std::remove_cv_t<A>; + static_assert(!std::is_same_v<E_NoCV*, A_NoCV>, + "For safety, we disallow constructing nsTArray<E> elements " + "from E* pointers. See bug 960591."); + new (static_cast<void*>(aE)) E(std::forward<A>(aArg)); + } + // Construct in place. + template <class... Args> + static inline void Emplace(E* aE, Args&&... aArgs) { + using E_NoCV = std::remove_cv_t<E>; + using A_NoCV = + std::remove_cv_t<typename ::detail::ChooseFirst<Args...>::Type>; + static_assert(!std::is_same_v<E_NoCV*, A_NoCV>, + "For safety, we disallow constructing nsTArray<E> elements " + "from E* pointers. See bug 960591."); + new (static_cast<void*>(aE)) E(std::forward<Args>(aArgs)...); + } + // Invoke the destructor in place. + static inline void Destruct(E* aE) { aE->~E(); } +}; + +// The default comparator used by nsTArray +template <class A, class B> +class nsDefaultComparator { + public: + bool Equals(const A& aA, const B& aB) const { return aA == aB; } + bool LessThan(const A& aA, const B& aB) const { return aA < aB; } +}; + +template <bool IsTriviallyCopyConstructible, bool IsSameType> +struct AssignRangeAlgorithm { + template <class Item, class ElemType, class IndexType, class SizeType> + static void implementation(ElemType* aElements, IndexType aStart, + SizeType aCount, const Item* aValues) { + ElemType* iter = aElements + aStart; + ElemType* end = iter + aCount; + for (; iter != end; ++iter, ++aValues) { + nsTArrayElementTraits<ElemType>::Construct(iter, *aValues); + } + } +}; + +template <> +struct AssignRangeAlgorithm<true, true> { + template <class Item, class ElemType, class IndexType, class SizeType> + static void implementation(ElemType* aElements, IndexType aStart, + SizeType aCount, const Item* aValues) { + if (aValues) { + memcpy(aElements + aStart, aValues, aCount * sizeof(ElemType)); + } + } +}; + +// +// Normally elements are copied with memcpy and memmove, but for some element +// types that is problematic. The nsTArray_RelocationStrategy template class +// can be specialized to ensure that copying calls constructors and destructors +// instead, as is done below for JS::Heap<E> elements. +// + +// +// A class that defines how to copy elements using memcpy/memmove. +// +struct nsTArray_RelocateUsingMemutils { + const static bool allowRealloc = true; + + static void RelocateNonOverlappingRegionWithHeader(void* aDest, + const void* aSrc, + size_t aCount, + size_t aElemSize) { + memcpy(aDest, aSrc, sizeof(nsTArrayHeader) + aCount * aElemSize); + } + + static void RelocateOverlappingRegion(void* aDest, void* aSrc, size_t aCount, + size_t aElemSize) { + memmove(aDest, aSrc, aCount * aElemSize); + } + + static void RelocateNonOverlappingRegion(void* aDest, void* aSrc, + size_t aCount, size_t aElemSize) { + memcpy(aDest, aSrc, aCount * aElemSize); + } +}; + +// +// A template class that defines how to relocate elements using the type's move +// constructor and destructor appropriately. +// +template <class ElemType> +struct nsTArray_RelocateUsingMoveConstructor { + typedef nsTArrayElementTraits<ElemType> traits; + + const static bool allowRealloc = false; + + static void RelocateNonOverlappingRegionWithHeader(void* aDest, void* aSrc, + size_t aCount, + size_t aElemSize) { + nsTArrayHeader* destHeader = static_cast<nsTArrayHeader*>(aDest); + nsTArrayHeader* srcHeader = static_cast<nsTArrayHeader*>(aSrc); + *destHeader = *srcHeader; + RelocateNonOverlappingRegion( + static_cast<uint8_t*>(aDest) + sizeof(nsTArrayHeader), + static_cast<uint8_t*>(aSrc) + sizeof(nsTArrayHeader), aCount, + aElemSize); + } + + // RelocateNonOverlappingRegion and RelocateOverlappingRegion are defined by + // analogy with memmove and memcpy that are used for relocation of + // trivially-relocatable types through nsTArray_RelocateUsingMemutils. What + // they actually do is slightly different: RelocateOverlappingRegion checks to + // see which direction the movement needs to take place, whether from + // back-to-front of the range to be moved or from front-to-back. + // RelocateNonOverlappingRegion assumes that relocating front-to-back is + // always valid. They use RelocateRegionForward and RelocateRegionBackward, + // which are analogous to std::move and std::move_backward respectively, + // except they don't move-assign the destination from the source but + // move-construct the destination from the source and destroy the source. + static void RelocateOverlappingRegion(void* aDest, void* aSrc, size_t aCount, + size_t aElemSize) { + ElemType* destBegin = static_cast<ElemType*>(aDest); + ElemType* srcBegin = static_cast<ElemType*>(aSrc); + + // If destination and source are the same, this is a no-op. + // In practice, we don't do this. + if (destBegin == srcBegin) { + return; + } + + ElemType* srcEnd = srcBegin + aCount; + ElemType* destEnd = destBegin + aCount; + + // Figure out whether to relocate back-to-front or front-to-back. + if (srcEnd > destBegin && srcEnd < destEnd) { + RelocateRegionBackward(srcBegin, srcEnd, destEnd); + } else { + RelocateRegionForward(srcBegin, srcEnd, destBegin); + } + } + + static void RelocateNonOverlappingRegion(void* aDest, void* aSrc, + size_t aCount, size_t aElemSize) { + ElemType* destBegin = static_cast<ElemType*>(aDest); + ElemType* srcBegin = static_cast<ElemType*>(aSrc); + ElemType* srcEnd = srcBegin + aCount; +#ifdef DEBUG + ElemType* destEnd = destBegin + aCount; + MOZ_ASSERT(srcEnd <= destBegin || srcBegin >= destEnd); +#endif + RelocateRegionForward(srcBegin, srcEnd, destBegin); + } + + private: + static void RelocateRegionForward(ElemType* srcBegin, ElemType* srcEnd, + ElemType* destBegin) { + ElemType* srcElem = srcBegin; + ElemType* destElem = destBegin; + + while (srcElem != srcEnd) { + RelocateElement(srcElem, destElem); + ++destElem; + ++srcElem; + } + } + + static void RelocateRegionBackward(ElemType* srcBegin, ElemType* srcEnd, + ElemType* destEnd) { + ElemType* srcElem = srcEnd; + ElemType* destElem = destEnd; + while (srcElem != srcBegin) { + --destElem; + --srcElem; + RelocateElement(srcElem, destElem); + } + } + + static void RelocateElement(ElemType* srcElem, ElemType* destElem) { + traits::Construct(destElem, std::move(*srcElem)); + traits::Destruct(srcElem); + } +}; + +// +// The default behaviour is to use memcpy/memmove for everything. +// +template <class E> +struct MOZ_NEEDS_MEMMOVABLE_TYPE nsTArray_RelocationStrategy { + using Type = nsTArray_RelocateUsingMemutils; +}; + +// +// Some classes require constructors/destructors to be called, so they are +// specialized here. +// +#define MOZ_DECLARE_RELOCATE_USING_MOVE_CONSTRUCTOR(E) \ + template <> \ + struct nsTArray_RelocationStrategy<E> { \ + using Type = nsTArray_RelocateUsingMoveConstructor<E>; \ + }; + +#define MOZ_DECLARE_RELOCATE_USING_MOVE_CONSTRUCTOR_FOR_TEMPLATE(T) \ + template <typename S> \ + struct nsTArray_RelocationStrategy<T<S>> { \ + using Type = nsTArray_RelocateUsingMoveConstructor<T<S>>; \ + }; + +MOZ_DECLARE_RELOCATE_USING_MOVE_CONSTRUCTOR_FOR_TEMPLATE(JS::Heap) +MOZ_DECLARE_RELOCATE_USING_MOVE_CONSTRUCTOR_FOR_TEMPLATE(std::function) +MOZ_DECLARE_RELOCATE_USING_MOVE_CONSTRUCTOR_FOR_TEMPLATE(mozilla::ipc::Endpoint) + +MOZ_DECLARE_RELOCATE_USING_MOVE_CONSTRUCTOR(nsRegion) +MOZ_DECLARE_RELOCATE_USING_MOVE_CONSTRUCTOR(nsIntRegion) +MOZ_DECLARE_RELOCATE_USING_MOVE_CONSTRUCTOR(mozilla::layers::TileClient) +MOZ_DECLARE_RELOCATE_USING_MOVE_CONSTRUCTOR( + mozilla::SerializedStructuredCloneBuffer) +MOZ_DECLARE_RELOCATE_USING_MOVE_CONSTRUCTOR( + mozilla::dom::ipc::StructuredCloneData) +MOZ_DECLARE_RELOCATE_USING_MOVE_CONSTRUCTOR(mozilla::dom::ClonedMessageData) +MOZ_DECLARE_RELOCATE_USING_MOVE_CONSTRUCTOR( + mozilla::dom::indexedDB::ObjectStoreCursorResponse) +MOZ_DECLARE_RELOCATE_USING_MOVE_CONSTRUCTOR( + mozilla::dom::indexedDB::IndexCursorResponse) +MOZ_DECLARE_RELOCATE_USING_MOVE_CONSTRUCTOR( + mozilla::dom::indexedDB::SerializedStructuredCloneReadInfo); +MOZ_DECLARE_RELOCATE_USING_MOVE_CONSTRUCTOR(JSStructuredCloneData) +MOZ_DECLARE_RELOCATE_USING_MOVE_CONSTRUCTOR(mozilla::dom::MessageData) +MOZ_DECLARE_RELOCATE_USING_MOVE_CONSTRUCTOR(mozilla::dom::RefMessageData) +MOZ_DECLARE_RELOCATE_USING_MOVE_CONSTRUCTOR(mozilla::SourceBufferTask) + +// +// Base class for nsTArray_Impl that is templated on element type and derived +// nsTArray_Impl class, to allow extra conversions to be added for specific +// types. +// +template <class E, class Derived> +struct nsTArray_TypedBase : public nsTArray_SafeElementAtHelper<E, Derived> {}; + +// +// Specialization of nsTArray_TypedBase for arrays containing JS::Heap<E> +// elements. +// +// These conversions are safe because JS::Heap<E> and E share the same +// representation, and since the result of the conversions are const references +// we won't miss any barriers. +// +// The static_cast is necessary to obtain the correct address for the derived +// class since we are a base class used in multiple inheritance. +// +template <class E, class Derived> +struct nsTArray_TypedBase<JS::Heap<E>, Derived> + : public nsTArray_SafeElementAtHelper<JS::Heap<E>, Derived> { + operator const nsTArray<E>&() { + static_assert(sizeof(E) == sizeof(JS::Heap<E>), + "JS::Heap<E> must be binary compatible with E."); + Derived* self = static_cast<Derived*>(this); + return *reinterpret_cast<nsTArray<E>*>(self); + } + + operator const FallibleTArray<E>&() { + Derived* self = static_cast<Derived*>(this); + return *reinterpret_cast<FallibleTArray<E>*>(self); + } +}; + +namespace detail { + +// These helpers allow us to differentiate between tri-state comparator +// functions and classes with LessThan() and Equal() methods. If an object, when +// called as a function with two instances of our element type, returns an int, +// we treat it as a tri-state comparator. +// +// T is the type of the comparator object we want to check. U is the array +// element type that we'll be comparing. +// +// V is never passed, and is only used to allow us to specialize on the return +// value of the comparator function. +template <typename T, typename U, typename V = int> +struct IsCompareMethod : std::false_type {}; + +template <typename T, typename U> +struct IsCompareMethod< + T, U, decltype(std::declval<T>()(std::declval<U>(), std::declval<U>()))> + : std::true_type {}; + +// These two wrappers allow us to use either a tri-state comparator, or an +// object with Equals() and LessThan() methods interchangeably. They provide a +// tri-state Compare() method, and Equals() method, and a LessThan() method. +// +// Depending on the type of the underlying comparator, they either pass these +// through directly, or synthesize them from the methods available on the +// comparator. +// +// Callers should always use the most-specific of these methods that match their +// purpose. + +// Comparator wrapper for a tri-state comparator function +template <typename T, typename U, bool IsCompare = IsCompareMethod<T, U>::value> +struct CompareWrapper { +#ifdef _MSC_VER +# pragma warning(push) +# pragma warning(disable : 4180) /* Silence "qualifier applied to function \ + type has no meaning" warning */ +#endif + MOZ_IMPLICIT CompareWrapper(const T& aComparator) + : mComparator(aComparator) {} + + template <typename A, typename B> + int Compare(A& aLeft, B& aRight) const { + return mComparator(aLeft, aRight); + } + + template <typename A, typename B> + bool Equals(A& aLeft, B& aRight) const { + return Compare(aLeft, aRight) == 0; + } + + template <typename A, typename B> + bool LessThan(A& aLeft, B& aRight) const { + return Compare(aLeft, aRight) < 0; + } + + const T& mComparator; +#ifdef _MSC_VER +# pragma warning(pop) +#endif +}; + +// Comparator wrapper for a class with Equals() and LessThan() methods. +template <typename T, typename U> +struct CompareWrapper<T, U, false> { + MOZ_IMPLICIT CompareWrapper(const T& aComparator) + : mComparator(aComparator) {} + + template <typename A, typename B> + int Compare(A& aLeft, B& aRight) const { + if (LessThan(aLeft, aRight)) { + return -1; + } + if (Equals(aLeft, aRight)) { + return 0; + } + return 1; + } + + template <typename A, typename B> + bool Equals(A& aLeft, B& aRight) const { + return mComparator.Equals(aLeft, aRight); + } + + template <typename A, typename B> + bool LessThan(A& aLeft, B& aRight) const { + return mComparator.LessThan(aLeft, aRight); + } + + const T& mComparator; +}; + +} // namespace detail + +// +// nsTArray_Impl contains most of the guts supporting nsTArray, FallibleTArray, +// AutoTArray. +// +// The only situation in which you might need to use nsTArray_Impl in your code +// is if you're writing code which mutates a TArray which may or may not be +// infallible. +// +// Code which merely reads from a TArray which may or may not be infallible can +// simply cast the TArray to |const nsTArray&|; both fallible and infallible +// TArrays can be cast to |const nsTArray&|. +// +template <class E, class Alloc> +class nsTArray_Impl + : public nsTArray_base<Alloc, + typename nsTArray_RelocationStrategy<E>::Type>, + public nsTArray_TypedBase<E, nsTArray_Impl<E, Alloc>> { + private: + friend class nsTArray<E>; + + typedef nsTArrayFallibleAllocator FallibleAlloc; + typedef nsTArrayInfallibleAllocator InfallibleAlloc; + + public: + typedef typename nsTArray_RelocationStrategy<E>::Type relocation_type; + typedef nsTArray_base<Alloc, relocation_type> base_type; + typedef typename base_type::size_type size_type; + typedef typename base_type::index_type index_type; + typedef E value_type; + typedef nsTArray_Impl<E, Alloc> self_type; + typedef nsTArrayElementTraits<E> elem_traits; + typedef nsTArray_SafeElementAtHelper<E, self_type> safeelementat_helper_type; + typedef mozilla::ArrayIterator<value_type&, self_type> iterator; + typedef mozilla::ArrayIterator<const value_type&, self_type> const_iterator; + typedef std::reverse_iterator<iterator> reverse_iterator; + typedef std::reverse_iterator<const_iterator> const_reverse_iterator; + + using base_type::EmptyHdr; + using safeelementat_helper_type::SafeElementAt; + + // A special value that is used to indicate an invalid or unknown index + // into the array. + static const index_type NoIndex = index_type(-1); + + using base_type::Length; + + // + // Finalization method + // + + ~nsTArray_Impl() { + if (!base_type::IsEmpty()) { + ClearAndRetainStorage(); + } + // mHdr cleanup will be handled by base destructor + } + + // + // Initialization methods + // + + nsTArray_Impl() = default; + + // Initialize this array and pre-allocate some number of elements. + explicit nsTArray_Impl(size_type aCapacity) { SetCapacity(aCapacity); } + + // Initialize this array with an r-value. + // Allow different types of allocators, since the allocator doesn't matter. + template <typename Allocator> + explicit nsTArray_Impl(nsTArray_Impl<E, Allocator>&& aOther) noexcept { + // We cannot be a (Copyable)AutoTArray because that overrides this ctor. + MOZ_ASSERT(!this->IsAutoArray()); + + // This does not use SwapArrayElements because that's unnecessarily complex. + this->MoveConstructNonAutoArray(aOther, sizeof(value_type), + MOZ_ALIGNOF(value_type)); + } + + // The array's copy-constructor performs a 'deep' copy of the given array. + // @param aOther The array object to copy. + // + // It's very important that we declare this method as taking |const + // self_type&| as opposed to taking |const nsTArray_Impl<E, OtherAlloc>| for + // an arbitrary OtherAlloc. + // + // If we don't declare a constructor taking |const self_type&|, C++ generates + // a copy-constructor for this class which merely copies the object's + // members, which is obviously wrong. + // + // You can pass an nsTArray_Impl<E, OtherAlloc> to this method because + // nsTArray_Impl<E, X> can be cast to const nsTArray_Impl<E, Y>&. So the + // effect on the API is the same as if we'd declared this method as taking + // |const nsTArray_Impl<E, OtherAlloc>&|. + nsTArray_Impl(const nsTArray_Impl&) = default; + + // Allow converting to a const array with a different kind of allocator, + // Since the allocator doesn't matter for const arrays + template <typename Allocator> + [[nodiscard]] operator const nsTArray_Impl<E, Allocator>&() const& { + return *reinterpret_cast<const nsTArray_Impl<E, Allocator>*>(this); + } + // And we have to do this for our subclasses too + [[nodiscard]] operator const nsTArray<E>&() const& { + return *reinterpret_cast<const nsTArray<E>*>(this); + } + [[nodiscard]] operator const FallibleTArray<E>&() const& { + return *reinterpret_cast<const FallibleTArray<E>*>(this); + } + + // The array's assignment operator performs a 'deep' copy of the given + // array. It is optimized to reuse existing storage if possible. + // @param aOther The array object to copy. + nsTArray_Impl& operator=(const nsTArray_Impl&) = default; + + // The array's move assignment operator steals the underlying data from + // the other array. + // @param other The array object to move from. + self_type& operator=(self_type&& aOther) { + if (this != &aOther) { + Clear(); + this->MoveInit(aOther, sizeof(value_type), MOZ_ALIGNOF(value_type)); + } + return *this; + } + + // Return true if this array has the same length and the same + // elements as |aOther|. + template <typename Allocator> + [[nodiscard]] bool operator==( + const nsTArray_Impl<E, Allocator>& aOther) const { + size_type len = Length(); + if (len != aOther.Length()) { + return false; + } + + // XXX std::equal would be as fast or faster here + for (index_type i = 0; i < len; ++i) { + if (!(operator[](i) == aOther[i])) { + return false; + } + } + + return true; + } + + // Return true if this array does not have the same length and the same + // elements as |aOther|. + [[nodiscard]] bool operator!=(const self_type& aOther) const { + return !operator==(aOther); + } + + // If Alloc == FallibleAlloc, ReplaceElementsAt might fail, without a way to + // signal this to the caller, so we disallow copying via operator=. Callers + // should use ReplaceElementsAt with a fallible argument instead, and check + // the result. + template <typename Allocator, + typename = std::enable_if_t<std::is_same_v<Alloc, InfallibleAlloc>, + Allocator>> + self_type& operator=(const nsTArray_Impl<E, Allocator>& aOther) { + AssignInternal<InfallibleAlloc>(aOther.Elements(), aOther.Length()); + return *this; + } + + template <typename Allocator> + self_type& operator=(nsTArray_Impl<E, Allocator>&& aOther) { + Clear(); + this->MoveInit(aOther, sizeof(value_type), MOZ_ALIGNOF(value_type)); + return *this; + } + + // @return The amount of memory used by this nsTArray_Impl, excluding + // sizeof(*this). If you want to measure anything hanging off the array, you + // must iterate over the elements and measure them individually; hence the + // "Shallow" prefix. + [[nodiscard]] size_t ShallowSizeOfExcludingThis( + mozilla::MallocSizeOf aMallocSizeOf) const { + if (this->UsesAutoArrayBuffer() || this->HasEmptyHeader()) { + return 0; + } + return aMallocSizeOf(this->Hdr()); + } + + // @return The amount of memory used by this nsTArray_Impl, including + // sizeof(*this). If you want to measure anything hanging off the array, you + // must iterate over the elements and measure them individually; hence the + // "Shallow" prefix. + [[nodiscard]] size_t ShallowSizeOfIncludingThis( + mozilla::MallocSizeOf aMallocSizeOf) const { + return aMallocSizeOf(this) + ShallowSizeOfExcludingThis(aMallocSizeOf); + } + + // + // Accessor methods + // + + // This method provides direct access to the array elements. + // @return A pointer to the first element of the array. If the array is + // empty, then this pointer must not be dereferenced. + [[nodiscard]] value_type* Elements() MOZ_NONNULL_RETURN { + return reinterpret_cast<value_type*>(Hdr() + 1); + } + + // This method provides direct, readonly access to the array elements. + // @return A pointer to the first element of the array. If the array is + // empty, then this pointer must not be dereferenced. + [[nodiscard]] const value_type* Elements() const MOZ_NONNULL_RETURN { + return reinterpret_cast<const value_type*>(Hdr() + 1); + } + + // This method provides direct access to an element of the array. The given + // index must be within the array bounds. + // @param aIndex The index of an element in the array. + // @return A reference to the i'th element of the array. + [[nodiscard]] value_type& ElementAt(index_type aIndex) { + if (MOZ_UNLIKELY(aIndex >= Length())) { + mozilla::detail::InvalidArrayIndex_CRASH(aIndex, Length()); + } + return Elements()[aIndex]; + } + + // This method provides direct, readonly access to an element of the array + // The given index must be within the array bounds. + // @param aIndex The index of an element in the array. + // @return A const reference to the i'th element of the array. + [[nodiscard]] const value_type& ElementAt(index_type aIndex) const { + if (MOZ_UNLIKELY(aIndex >= Length())) { + mozilla::detail::InvalidArrayIndex_CRASH(aIndex, Length()); + } + return Elements()[aIndex]; + } + + // This method provides direct access to an element of the array in a bounds + // safe manner. If the requested index is out of bounds the provided default + // value is returned. + // @param aIndex The index of an element in the array. + // @param aDef The value to return if the index is out of bounds. + [[nodiscard]] value_type& SafeElementAt(index_type aIndex, value_type& aDef) { + return aIndex < Length() ? Elements()[aIndex] : aDef; + } + + // This method provides direct access to an element of the array in a bounds + // safe manner. If the requested index is out of bounds the provided default + // value is returned. + // @param aIndex The index of an element in the array. + // @param aDef The value to return if the index is out of bounds. + [[nodiscard]] const value_type& SafeElementAt(index_type aIndex, + const value_type& aDef) const { + return aIndex < Length() ? Elements()[aIndex] : aDef; + } + + // Shorthand for ElementAt(aIndex) + [[nodiscard]] value_type& operator[](index_type aIndex) { + return ElementAt(aIndex); + } + + // Shorthand for ElementAt(aIndex) + [[nodiscard]] const value_type& operator[](index_type aIndex) const { + return ElementAt(aIndex); + } + + // Shorthand for ElementAt(length - 1) + [[nodiscard]] value_type& LastElement() { return ElementAt(Length() - 1); } + + // Shorthand for ElementAt(length - 1) + [[nodiscard]] const value_type& LastElement() const { + return ElementAt(Length() - 1); + } + + // Shorthand for SafeElementAt(length - 1, def) + [[nodiscard]] value_type& SafeLastElement(value_type& aDef) { + return SafeElementAt(Length() - 1, aDef); + } + + // Shorthand for SafeElementAt(length - 1, def) + [[nodiscard]] const value_type& SafeLastElement( + const value_type& aDef) const { + return SafeElementAt(Length() - 1, aDef); + } + + // Methods for range-based for loops. + [[nodiscard]] iterator begin() { return iterator(*this, 0); } + [[nodiscard]] const_iterator begin() const { + return const_iterator(*this, 0); + } + [[nodiscard]] const_iterator cbegin() const { return begin(); } + [[nodiscard]] iterator end() { return iterator(*this, Length()); } + [[nodiscard]] const_iterator end() const { + return const_iterator(*this, Length()); + } + [[nodiscard]] const_iterator cend() const { return end(); } + + // Methods for reverse iterating. + [[nodiscard]] reverse_iterator rbegin() { return reverse_iterator(end()); } + [[nodiscard]] const_reverse_iterator rbegin() const { + return const_reverse_iterator(end()); + } + [[nodiscard]] const_reverse_iterator crbegin() const { return rbegin(); } + [[nodiscard]] reverse_iterator rend() { return reverse_iterator(begin()); } + [[nodiscard]] const_reverse_iterator rend() const { + return const_reverse_iterator(begin()); + } + [[nodiscard]] const_reverse_iterator crend() const { return rend(); } + + // Span integration + + [[nodiscard]] operator mozilla::Span<value_type>() { + return mozilla::Span<value_type>(Elements(), Length()); + } + + [[nodiscard]] operator mozilla::Span<const value_type>() const { + return mozilla::Span<const value_type>(Elements(), Length()); + } + + // + // Search methods + // + + // This method searches for the first element in this array that is equal + // to the given element. + // @param aItem The item to search for. + // @param aComp The Comparator used to determine element equality. + // @return true if the element was found. + template <class Item, class Comparator> + [[nodiscard]] bool Contains(const Item& aItem, + const Comparator& aComp) const { + return ApplyIf( + aItem, 0, aComp, []() { return true; }, []() { return false; }); + } + + // Like Contains(), but assumes a sorted array. + template <class Item, class Comparator> + [[nodiscard]] bool ContainsSorted(const Item& aItem, + const Comparator& aComp) const { + return BinaryIndexOf(aItem, aComp) != NoIndex; + } + + // This method searches for the first element in this array that is equal + // to the given element. This method assumes that 'operator==' is defined + // for value_type. + // @param aItem The item to search for. + // @return true if the element was found. + template <class Item> + [[nodiscard]] bool Contains(const Item& aItem) const { + return Contains(aItem, nsDefaultComparator<value_type, Item>()); + } + + // Like Contains(), but assumes a sorted array. + template <class Item> + [[nodiscard]] bool ContainsSorted(const Item& aItem) const { + return BinaryIndexOf(aItem) != NoIndex; + } + + // This method searches for the offset of the first element in this + // array that is equal to the given element. + // @param aItem The item to search for. + // @param aStart The index to start from. + // @param aComp The Comparator used to determine element equality. + // @return The index of the found element or NoIndex if not found. + template <class Item, class Comparator> + [[nodiscard]] index_type IndexOf(const Item& aItem, index_type aStart, + const Comparator& aComp) const { + ::detail::CompareWrapper<Comparator, Item> comp(aComp); + + const value_type* iter = Elements() + aStart; + const value_type* iend = Elements() + Length(); + for (; iter != iend; ++iter) { + if (comp.Equals(*iter, aItem)) { + return index_type(iter - Elements()); + } + } + return NoIndex; + } + + // This method searches for the offset of the first element in this + // array that is equal to the given element. This method assumes + // that 'operator==' is defined for value_type. + // @param aItem The item to search for. + // @param aStart The index to start from. + // @return The index of the found element or NoIndex if not found. + template <class Item> + [[nodiscard]] index_type IndexOf(const Item& aItem, + index_type aStart = 0) const { + return IndexOf(aItem, aStart, nsDefaultComparator<value_type, Item>()); + } + + // This method searches for the offset of the last element in this + // array that is equal to the given element. + // @param aItem The item to search for. + // @param aStart The index to start from. If greater than or equal to the + // length of the array, then the entire array is searched. + // @param aComp The Comparator used to determine element equality. + // @return The index of the found element or NoIndex if not found. + template <class Item, class Comparator> + [[nodiscard]] index_type LastIndexOf(const Item& aItem, index_type aStart, + const Comparator& aComp) const { + ::detail::CompareWrapper<Comparator, Item> comp(aComp); + + size_type endOffset = aStart >= Length() ? Length() : aStart + 1; + const value_type* iend = Elements() - 1; + const value_type* iter = iend + endOffset; + for (; iter != iend; --iter) { + if (comp.Equals(*iter, aItem)) { + return index_type(iter - Elements()); + } + } + return NoIndex; + } + + // This method searches for the offset of the last element in this + // array that is equal to the given element. This method assumes + // that 'operator==' is defined for value_type. + // @param aItem The item to search for. + // @param aStart The index to start from. If greater than or equal to the + // length of the array, then the entire array is searched. + // @return The index of the found element or NoIndex if not found. + template <class Item> + [[nodiscard]] index_type LastIndexOf(const Item& aItem, + index_type aStart = NoIndex) const { + return LastIndexOf(aItem, aStart, nsDefaultComparator<value_type, Item>()); + } + + // This method searches for the offset for the element in this array + // that is equal to the given element. The array is assumed to be sorted. + // If there is more than one equivalent element, there is no guarantee + // on which one will be returned. + // @param aItem The item to search for. + // @param aComp The Comparator used. + // @return The index of the found element or NoIndex if not found. + template <class Item, class Comparator> + [[nodiscard]] index_type BinaryIndexOf(const Item& aItem, + const Comparator& aComp) const { + using mozilla::BinarySearchIf; + ::detail::CompareWrapper<Comparator, Item> comp(aComp); + + size_t index; + bool found = BinarySearchIf( + Elements(), 0, Length(), + // Note: We pass the Compare() args here in reverse order and negate the + // results for compatibility reasons. Some existing callers use Equals() + // functions with first arguments which match aElement but not aItem, or + // second arguments that match aItem but not aElement. To accommodate + // those callers, we preserve the argument order of the older version of + // this API. These callers, however, should be fixed, and this special + // case removed. + [&](const value_type& aElement) { + return -comp.Compare(aElement, aItem); + }, + &index); + return found ? index : NoIndex; + } + + // This method searches for the offset for the element in this array + // that is equal to the given element. The array is assumed to be sorted. + // This method assumes that 'operator==' and 'operator<' are defined. + // @param aItem The item to search for. + // @return The index of the found element or NoIndex if not found. + template <class Item> + [[nodiscard]] index_type BinaryIndexOf(const Item& aItem) const { + return BinaryIndexOf(aItem, nsDefaultComparator<value_type, Item>()); + } + + // + // Mutation methods + // + private: + template <typename ActualAlloc, class Item> + typename ActualAlloc::ResultType AssignInternal(const Item* aArray, + size_type aArrayLen); + + public: + template <class Allocator, typename ActualAlloc = Alloc> + [[nodiscard]] typename ActualAlloc::ResultType Assign( + const nsTArray_Impl<E, Allocator>& aOther) { + return AssignInternal<ActualAlloc>(aOther.Elements(), aOther.Length()); + } + + template <class Allocator> + [[nodiscard]] bool Assign(const nsTArray_Impl<E, Allocator>& aOther, + const mozilla::fallible_t&) { + return Assign<Allocator, FallibleAlloc>(aOther); + } + + template <class Allocator> + void Assign(nsTArray_Impl<E, Allocator>&& aOther) { + Clear(); + this->MoveInit(aOther, sizeof(value_type), MOZ_ALIGNOF(value_type)); + } + + // This method call the destructor on each element of the array, empties it, + // but does not shrink the array's capacity. + // See also SetLengthAndRetainStorage. + // Make sure to call Compact() if needed to avoid keeping a huge array + // around. + void ClearAndRetainStorage() { + if (this->HasEmptyHeader()) { + return; + } + + DestructRange(0, Length()); + base_type::mHdr->mLength = 0; + } + + // This method modifies the length of the array, but unlike SetLength + // it doesn't deallocate/reallocate the current internal storage. + // The new length MUST be shorter than or equal to the current capacity. + // If the new length is larger than the existing length of the array, + // then new elements will be constructed using value_type's default + // constructor. If shorter, elements will be destructed and removed. + // See also ClearAndRetainStorage. + // @param aNewLen The desired length of this array. + void SetLengthAndRetainStorage(size_type aNewLen) { + MOZ_ASSERT(aNewLen <= base_type::Capacity()); + size_type oldLen = Length(); + if (aNewLen > oldLen) { + /// XXX(Bug 1631367) SetLengthAndRetainStorage should be disabled for + /// FallibleTArray. + InsertElementsAtInternal<InfallibleAlloc>(oldLen, aNewLen - oldLen); + return; + } + if (aNewLen < oldLen) { + DestructRange(aNewLen, oldLen - aNewLen); + base_type::mHdr->mLength = aNewLen; + } + } + + // This method replaces a range of elements in this array. + // @param aStart The starting index of the elements to replace. + // @param aCount The number of elements to replace. This may be zero to + // insert elements without removing any existing elements. + // @param aArray The values to copy into this array. Must be non-null, + // and these elements must not already exist in the array + // being modified. + // @param aArrayLen The number of values to copy into this array. + // @return A pointer to the new elements in the array, or null if + // the operation failed due to insufficient memory. + private: + template <typename ActualAlloc, class Item> + value_type* ReplaceElementsAtInternal(index_type aStart, size_type aCount, + const Item* aArray, + size_type aArrayLen); + + public: + template <class Item> + [[nodiscard]] value_type* ReplaceElementsAt(index_type aStart, + size_type aCount, + const Item* aArray, + size_type aArrayLen, + const mozilla::fallible_t&) { + return ReplaceElementsAtInternal<FallibleAlloc>(aStart, aCount, aArray, + aArrayLen); + } + + // A variation on the ReplaceElementsAt method defined above. + template <class Item> + [[nodiscard]] value_type* ReplaceElementsAt(index_type aStart, + size_type aCount, + const nsTArray<Item>& aArray, + const mozilla::fallible_t&) { + return ReplaceElementsAtInternal<FallibleAlloc>(aStart, aCount, aArray); + } + + template <class Item> + [[nodiscard]] value_type* ReplaceElementsAt(index_type aStart, + size_type aCount, + mozilla::Span<Item> aSpan, + const mozilla::fallible_t&) { + return ReplaceElementsAtInternal<FallibleAlloc>(aStart, aCount, aSpan); + } + + // A variation on the ReplaceElementsAt method defined above. + template <class Item> + [[nodiscard]] value_type* ReplaceElementsAt(index_type aStart, + size_type aCount, + const Item& aItem, + const mozilla::fallible_t&) { + return ReplaceElementsAtInternal<FallibleAlloc>(aStart, aCount, aItem); + } + + // A variation on the ReplaceElementsAt method defined above. + template <class Item> + mozilla::NotNull<value_type*> ReplaceElementAt(index_type aIndex, + Item&& aItem) { + value_type* const elem = &ElementAt(aIndex); + elem_traits::Destruct(elem); + elem_traits::Construct(elem, std::forward<Item>(aItem)); + return mozilla::WrapNotNullUnchecked(elem); + } + + // InsertElementsAt is ReplaceElementsAt with 0 elements to replace. + // XXX Provide a proper documentation of InsertElementsAt. + template <class Item> + [[nodiscard]] value_type* InsertElementsAt(index_type aIndex, + const Item* aArray, + size_type aArrayLen, + const mozilla::fallible_t&) { + return ReplaceElementsAtInternal<FallibleAlloc>(aIndex, 0, aArray, + aArrayLen); + } + + template <class Item, class Allocator> + [[nodiscard]] value_type* InsertElementsAt( + index_type aIndex, const nsTArray_Impl<Item, Allocator>& aArray, + const mozilla::fallible_t&) { + return ReplaceElementsAtInternal<FallibleAlloc>( + aIndex, 0, aArray.Elements(), aArray.Length()); + } + + template <class Item> + [[nodiscard]] value_type* InsertElementsAt(index_type aIndex, + mozilla::Span<Item> aSpan, + const mozilla::fallible_t&) { + return ReplaceElementsAtInternal<FallibleAlloc>(aIndex, 0, aSpan.Elements(), + aSpan.Length()); + } + + private: + template <typename ActualAlloc> + value_type* InsertElementAtInternal(index_type aIndex); + + // Insert a new element without copy-constructing. This is useful to avoid + // temporaries. + // @return A pointer to the newly inserted element, or null on OOM. + public: + [[nodiscard]] value_type* InsertElementAt(index_type aIndex, + const mozilla::fallible_t&) { + return InsertElementAtInternal<FallibleAlloc>(aIndex); + } + + private: + template <typename ActualAlloc, class Item> + value_type* InsertElementAtInternal(index_type aIndex, Item&& aItem); + + // Insert a new element, move constructing if possible. + public: + template <class Item> + [[nodiscard]] value_type* InsertElementAt(index_type aIndex, Item&& aItem, + const mozilla::fallible_t&) { + return InsertElementAtInternal<FallibleAlloc>(aIndex, + std::forward<Item>(aItem)); + } + + // Reconstruct the element at the given index, and return a pointer to the + // reconstructed element. This will destroy the existing element and + // default-construct a new one, giving you a state much like what single-arg + // InsertElementAt(), or no-arg AppendElement() does, but without changing the + // length of the array. + // + // array[idx] = value_type() + // + // would accomplish the same thing as long as value_type has the appropriate + // moving operator=, but some types don't for various reasons. + mozilla::NotNull<value_type*> ReconstructElementAt(index_type aIndex) { + value_type* elem = &ElementAt(aIndex); + elem_traits::Destruct(elem); + elem_traits::Construct(elem); + return mozilla::WrapNotNullUnchecked(elem); + } + + // This method searches for the smallest index of an element that is strictly + // greater than |aItem|. If |aItem| is inserted at this index, the array will + // remain sorted and |aItem| would come after all elements that are equal to + // it. If |aItem| is greater than or equal to all elements in the array, the + // array length is returned. + // + // Note that consumers who want to know whether there are existing items equal + // to |aItem| in the array can just check that the return value here is > 0 + // and indexing into the previous slot gives something equal to |aItem|. + // + // + // @param aItem The item to search for. + // @param aComp The Comparator used. + // @return The index of greatest element <= to |aItem| + // @precondition The array is sorted + template <class Item, class Comparator> + [[nodiscard]] index_type IndexOfFirstElementGt( + const Item& aItem, const Comparator& aComp) const { + using mozilla::BinarySearchIf; + ::detail::CompareWrapper<Comparator, Item> comp(aComp); + + size_t index; + BinarySearchIf( + Elements(), 0, Length(), + [&](const value_type& aElement) { + return comp.Compare(aElement, aItem) <= 0 ? 1 : -1; + }, + &index); + return index; + } + + // A variation on the IndexOfFirstElementGt method defined above. + template <class Item> + [[nodiscard]] index_type IndexOfFirstElementGt(const Item& aItem) const { + return IndexOfFirstElementGt(aItem, + nsDefaultComparator<value_type, Item>()); + } + + private: + template <typename ActualAlloc, class Item, class Comparator> + value_type* InsertElementSortedInternal(Item&& aItem, + const Comparator& aComp) { + index_type index = IndexOfFirstElementGt<Item, Comparator>(aItem, aComp); + return InsertElementAtInternal<ActualAlloc>(index, + std::forward<Item>(aItem)); + } + + // Inserts |aItem| at such an index to guarantee that if the array + // was previously sorted, it will remain sorted after this + // insertion. + public: + template <class Item, class Comparator> + [[nodiscard]] value_type* InsertElementSorted(Item&& aItem, + const Comparator& aComp, + const mozilla::fallible_t&) { + return InsertElementSortedInternal<FallibleAlloc>(std::forward<Item>(aItem), + aComp); + } + + // A variation on the InsertElementSorted method defined above. + public: + template <class Item> + [[nodiscard]] value_type* InsertElementSorted(Item&& aItem, + const mozilla::fallible_t&) { + return InsertElementSortedInternal<FallibleAlloc>( + std::forward<Item>(aItem), nsDefaultComparator<value_type, Item>{}); + } + + private: + template <typename ActualAlloc, class Item> + value_type* AppendElementsInternal(const Item* aArray, size_type aArrayLen); + + // This method appends elements to the end of this array. + // @param aArray The elements to append to this array. + // @param aArrayLen The number of elements to append to this array. + // @return A pointer to the new elements in the array, or null if + // the operation failed due to insufficient memory. + public: + template <class Item> + [[nodiscard]] value_type* AppendElements(const Item* aArray, + size_type aArrayLen, + const mozilla::fallible_t&) { + return AppendElementsInternal<FallibleAlloc>(aArray, aArrayLen); + } + + template <class Item> + [[nodiscard]] value_type* AppendElements(mozilla::Span<Item> aSpan, + const mozilla::fallible_t&) { + return AppendElementsInternal<FallibleAlloc>(aSpan.Elements(), + aSpan.Length()); + } + + // A variation on the AppendElements method defined above. + template <class Item, class Allocator> + [[nodiscard]] value_type* AppendElements( + const nsTArray_Impl<Item, Allocator>& aArray, + const mozilla::fallible_t&) { + return AppendElementsInternal<FallibleAlloc>(aArray.Elements(), + aArray.Length()); + } + + private: + template <typename ActualAlloc, class Item, class Allocator> + value_type* AppendElementsInternal(nsTArray_Impl<Item, Allocator>&& aArray); + + // Move all elements from another array to the end of this array. + // @return A pointer to the newly appended elements, or null on OOM. + public: + template <class Item, class Allocator> + [[nodiscard]] value_type* AppendElements( + nsTArray_Impl<Item, Allocator>&& aArray, const mozilla::fallible_t&) { + return AppendElementsInternal<FallibleAlloc>(std::move(aArray)); + } + + // Append a new element, constructed in place from the provided arguments. + protected: + template <typename ActualAlloc, class... Args> + value_type* EmplaceBackInternal(Args&&... aItem); + + public: + template <class... Args> + [[nodiscard]] value_type* EmplaceBack(const mozilla::fallible_t&, + Args&&... aArgs) { + return EmplaceBackInternal<FallibleAlloc, Args...>( + std::forward<Args>(aArgs)...); + } + + private: + template <typename ActualAlloc, class Item> + value_type* AppendElementInternal(Item&& aItem); + + // Append a new element, move constructing if possible. + public: + template <class Item> + [[nodiscard]] value_type* AppendElement(Item&& aItem, + const mozilla::fallible_t&) { + return AppendElementInternal<FallibleAlloc>(std::forward<Item>(aItem)); + } + + private: + template <typename ActualAlloc> + value_type* AppendElementsInternal(size_type aCount) { + if (!ActualAlloc::Successful(this->template ExtendCapacity<ActualAlloc>( + Length(), aCount, sizeof(value_type)))) { + return nullptr; + } + value_type* elems = Elements() + Length(); + size_type i; + for (i = 0; i < aCount; ++i) { + elem_traits::Construct(elems + i); + } + this->IncrementLength(aCount); + return elems; + } + + // Append new elements without copy-constructing. This is useful to avoid + // temporaries. + // @return A pointer to the newly appended elements, or null on OOM. + public: + [[nodiscard]] value_type* AppendElements(size_type aCount, + const mozilla::fallible_t&) { + return AppendElementsInternal<FallibleAlloc>(aCount); + } + + private: + // Append a new element without copy-constructing. This is useful to avoid + // temporaries. + // @return A pointer to the newly appended element, or null on OOM. + public: + [[nodiscard]] value_type* AppendElement(const mozilla::fallible_t&) { + return AppendElements(1, mozilla::fallible); + } + + // This method removes a single element from this array, like + // std::vector::erase. + // @param pos to the element to remove + const_iterator RemoveElementAt(const_iterator pos) { + MOZ_ASSERT(pos.GetArray() == this); + + RemoveElementAt(pos.GetIndex()); + return pos; + } + + // This method removes a range of elements from this array, like + // std::vector::erase. + // @param first iterator to the first of elements to remove + // @param last iterator to the last of elements to remove + const_iterator RemoveElementsRange(const_iterator first, + const_iterator last) { + MOZ_ASSERT(first.GetArray() == this); + MOZ_ASSERT(last.GetArray() == this); + MOZ_ASSERT(last.GetIndex() >= first.GetIndex()); + + RemoveElementsAt(first.GetIndex(), last.GetIndex() - first.GetIndex()); + return first; + } + + // This method removes a range of elements from this array. + // @param aStart The starting index of the elements to remove. + // @param aCount The number of elements to remove. + void RemoveElementsAt(index_type aStart, size_type aCount); + + private: + // Remove a range of elements from this array, but do not check that + // the range is in bounds. + // @param aStart The starting index of the elements to remove. + // @param aCount The number of elements to remove. + void RemoveElementsAtUnsafe(index_type aStart, size_type aCount); + + public: + // Similar to the above, but it removes just one element. This does bounds + // checking only in debug builds. + void RemoveElementAtUnsafe(index_type aIndex) { + MOZ_ASSERT(aIndex < Length(), "Trying to remove an invalid element"); + RemoveElementsAtUnsafe(aIndex, 1); + } + + // A variation on the RemoveElementsAt method defined above. + void RemoveElementAt(index_type aIndex) { RemoveElementsAt(aIndex, 1); } + + // A variation on RemoveElementAt that removes the last element. + void RemoveLastElement() { RemoveLastElements(1); } + + // A variation on RemoveElementsAt that removes the last 'aCount' elements. + void RemoveLastElements(const size_type aCount) { + // This assertion is redundant, but produces a better error message than the + // release assertion within TruncateLength. + MOZ_ASSERT(aCount <= Length()); + TruncateLength(Length() - aCount); + } + + // Removes the last element of the array and returns a copy of it. + [[nodiscard]] value_type PopLastElement() { + // This function intentionally does not call ElementsAt and calls + // TruncateLengthUnsafe directly to avoid multiple release checks for + // non-emptiness. + // This debug assertion is redundant, but produces a better error message + // than the release assertion below. + MOZ_ASSERT(!base_type::IsEmpty()); + const size_type oldLen = Length(); + if (MOZ_UNLIKELY(0 == oldLen)) { + mozilla::detail::InvalidArrayIndex_CRASH(1, 0); + } + value_type elem = std::move(Elements()[oldLen - 1]); + TruncateLengthUnsafe(oldLen - 1); + return elem; + } + + // This method performs index-based removals from an array without preserving + // the order of the array. This is useful if you are using the array as a + // set-like data structure. + // + // These removals are efficient, as they move as few elements as possible. At + // most N elements, where N is the number of removed elements, will have to + // be relocated. + // + // ## Examples + // + // When removing an element from the end of the array, it can be removed in + // place, by destroying it and decrementing the length. + // + // [ 1, 2, 3 ] => [ 1, 2 ] + // ^ + // + // When removing any other single element, it is removed by swapping it with + // the last element, and then decrementing the length as before. + // + // [ 1, 2, 3, 4, 5, 6 ] => [ 1, 6, 3, 4, 5 ] + // ^ + // + // This method also supports efficiently removing a range of elements. If they + // are at the end, then they can all be removed like in the one element case. + // + // [ 1, 2, 3, 4, 5, 6 ] => [ 1, 2 ] + // ^--------^ + // + // If more elements are removed than exist after the removed section, the + // remaining elements will be shifted down like in a normal removal. + // + // [ 1, 2, 3, 4, 5, 6, 7, 8 ] => [ 1, 2, 7, 8 ] + // ^--------^ + // + // And if fewer elements are removed than exist after the removed section, + // elements will be moved from the end of the array to fill the vacated space. + // + // [ 1, 2, 3, 4, 5, 6, 7, 8 ] => [ 1, 7, 8, 4, 5, 6 ] + // ^--^ + // + // @param aStart The starting index of the elements to remove. @param aCount + // The number of elements to remove. + void UnorderedRemoveElementsAt(index_type aStart, size_type aCount); + + // A variation on the UnorderedRemoveElementsAt method defined above to remove + // a single element. This operation is sometimes called `SwapRemove`. + // + // This method is O(1), but does not preserve the order of the elements. + void UnorderedRemoveElementAt(index_type aIndex) { + UnorderedRemoveElementsAt(aIndex, 1); + } + + void Clear() { + ClearAndRetainStorage(); + base_type::ShrinkCapacityToZero(sizeof(value_type), + MOZ_ALIGNOF(value_type)); + } + + // This method removes elements based on the return value of the + // callback function aPredicate. If the function returns true for + // an element, the element is removed. aPredicate will be called + // for each element in order. It is not safe to access the array + // inside aPredicate. + // + // Returns the number of elements removed. + template <typename Predicate> + size_type RemoveElementsBy(Predicate aPredicate); + + // This helper function combines IndexOf with RemoveElementAt to "search + // and destroy" the first element that is equal to the given element. + // @param aItem The item to search for. + // @param aComp The Comparator used to determine element equality. + // @return true if the element was found + template <class Item, class Comparator> + bool RemoveElement(const Item& aItem, const Comparator& aComp) { + index_type i = IndexOf(aItem, 0, aComp); + if (i == NoIndex) { + return false; + } + + RemoveElementsAtUnsafe(i, 1); + return true; + } + + // A variation on the RemoveElement method defined above that assumes + // that 'operator==' is defined for value_type. + template <class Item> + bool RemoveElement(const Item& aItem) { + return RemoveElement(aItem, nsDefaultComparator<value_type, Item>()); + } + + // This helper function combines IndexOfFirstElementGt with + // RemoveElementAt to "search and destroy" the last element that + // is equal to the given element. + // @param aItem The item to search for. + // @param aComp The Comparator used to determine element equality. + // @return true if the element was found + template <class Item, class Comparator> + bool RemoveElementSorted(const Item& aItem, const Comparator& aComp) { + index_type index = IndexOfFirstElementGt(aItem, aComp); + if (index > 0 && aComp.Equals(ElementAt(index - 1), aItem)) { + RemoveElementsAtUnsafe(index - 1, 1); + return true; + } + return false; + } + + // A variation on the RemoveElementSorted method defined above. + template <class Item> + bool RemoveElementSorted(const Item& aItem) { + return RemoveElementSorted(aItem, nsDefaultComparator<value_type, Item>()); + } + + // This method causes the elements contained in this array and the given + // array to be swapped. + template <class Allocator> + void SwapElements(nsTArray_Impl<E, Allocator>& aOther) { + // The only case this might fail were if someone called this with a + // AutoTArray upcast to nsTArray_Impl, under the conditions mentioned in the + // overload for AutoTArray below. + this->template SwapArrayElements<InfallibleAlloc>( + aOther, sizeof(value_type), MOZ_ALIGNOF(value_type)); + } + + template <size_t N> + void SwapElements(AutoTArray<E, N>& aOther) { + // Allocation might fail if Alloc==FallibleAlloc and + // Allocator==InfallibleAlloc and aOther uses auto storage. Allow this for + // small inline sizes, and crash in the rare case of a small OOM error. + static_assert(!std::is_same_v<Alloc, FallibleAlloc> || + sizeof(E) * N <= 1024); + this->template SwapArrayElements<InfallibleAlloc>( + aOther, sizeof(value_type), MOZ_ALIGNOF(value_type)); + } + + template <class Allocator> + [[nodiscard]] auto SwapElements(nsTArray_Impl<E, Allocator>& aOther, + const mozilla::fallible_t&) { + // Allocation might fail if Alloc==FallibleAlloc and + // Allocator==InfallibleAlloc and aOther uses auto storage. + return FallibleAlloc::Result( + this->template SwapArrayElements<FallibleAlloc>( + aOther, sizeof(value_type), MOZ_ALIGNOF(value_type))); + } + + private: + // Used by ApplyIf functions to invoke a callable that takes either: + // - Nothing: F(void) + // - Index only: F(size_t) + // - Reference to element only: F(maybe-const value_type&) + // - Both index and reference: F(size_t, maybe-const value_type&) + // `value_type` must be const when called from const method. + template <typename T, typename Param0, typename Param1> + struct InvokeWithIndexAndOrReferenceHelper { + static constexpr bool valid = false; + }; + template <typename T> + struct InvokeWithIndexAndOrReferenceHelper<T, void, void> { + static constexpr bool valid = true; + template <typename F> + static auto Invoke(F&& f, size_t, T&) { + return f(); + } + }; + template <typename T> + struct InvokeWithIndexAndOrReferenceHelper<T, size_t, void> { + static constexpr bool valid = true; + template <typename F> + static auto Invoke(F&& f, size_t i, T&) { + return f(i); + } + }; + template <typename T> + struct InvokeWithIndexAndOrReferenceHelper<T, T&, void> { + static constexpr bool valid = true; + template <typename F> + static auto Invoke(F&& f, size_t, T& e) { + return f(e); + } + }; + template <typename T> + struct InvokeWithIndexAndOrReferenceHelper<T, const T&, void> { + static constexpr bool valid = true; + template <typename F> + static auto Invoke(F&& f, size_t, T& e) { + return f(e); + } + }; + template <typename T> + struct InvokeWithIndexAndOrReferenceHelper<T, size_t, T&> { + static constexpr bool valid = true; + template <typename F> + static auto Invoke(F&& f, size_t i, T& e) { + return f(i, e); + } + }; + template <typename T> + struct InvokeWithIndexAndOrReferenceHelper<T, size_t, const T&> { + static constexpr bool valid = true; + template <typename F> + static auto Invoke(F&& f, size_t i, T& e) { + return f(i, e); + } + }; + template <typename T, typename F> + static auto InvokeWithIndexAndOrReference(F&& f, size_t i, T& e) { + using Invoker = InvokeWithIndexAndOrReferenceHelper< + T, typename mozilla::FunctionTypeTraits<F>::template ParameterType<0>, + typename mozilla::FunctionTypeTraits<F>::template ParameterType<1>>; + static_assert(Invoker::valid, + "ApplyIf's Function parameters must match either: (void), " + "(size_t), (maybe-const value_type&), or " + "(size_t, maybe-const value_type&)"); + return Invoker::Invoke(std::forward<F>(f), i, e); + } + + public: + // 'Apply' family of methods. + // + // The advantages of using Apply methods with lambdas include: + // - Safety of accessing elements from within the call, when the array cannot + // have been modified between the iteration and the subsequent access. + // - Avoiding moot conversions: pointer->index during a search, followed by + // index->pointer after the search when accessing the element. + // - Embedding your code into the algorithm, giving the compiler more chances + // to optimize. + + // Search for the first element comparing equal to aItem with the given + // comparator (`==` by default). + // If such an element exists, return the result of evaluating either: + // - `aFunction()` + // - `aFunction(index_type)` + // - `aFunction(maybe-const? value_type&)` + // - `aFunction(index_type, maybe-const? value_type&)` + // (`aFunction` must have one of the above signatures with these exact types, + // including references; implicit conversions or generic types not allowed. + // If `this` array is const, the referenced `value_type` must be const too; + // otherwise it may be either const or non-const.) + // But if the element is not found, return the result of evaluating + // `aFunctionElse()`. + template <class Item, class Comparator, class Function, class FunctionElse> + auto ApplyIf(const Item& aItem, index_type aStart, const Comparator& aComp, + Function&& aFunction, FunctionElse&& aFunctionElse) const { + static_assert( + std::is_same_v< + typename mozilla::FunctionTypeTraits<Function>::ReturnType, + typename mozilla::FunctionTypeTraits<FunctionElse>::ReturnType>, + "ApplyIf's `Function` and `FunctionElse` must return the same type."); + + ::detail::CompareWrapper<Comparator, Item> comp(aComp); + + const value_type* const elements = Elements(); + const value_type* const iend = elements + Length(); + for (const value_type* iter = elements + aStart; iter != iend; ++iter) { + if (comp.Equals(*iter, aItem)) { + return InvokeWithIndexAndOrReference<const value_type>( + std::forward<Function>(aFunction), iter - elements, *iter); + } + } + return aFunctionElse(); + } + template <class Item, class Comparator, class Function, class FunctionElse> + auto ApplyIf(const Item& aItem, index_type aStart, const Comparator& aComp, + Function&& aFunction, FunctionElse&& aFunctionElse) { + static_assert( + std::is_same_v< + typename mozilla::FunctionTypeTraits<Function>::ReturnType, + typename mozilla::FunctionTypeTraits<FunctionElse>::ReturnType>, + "ApplyIf's `Function` and `FunctionElse` must return the same type."); + + ::detail::CompareWrapper<Comparator, Item> comp(aComp); + + value_type* const elements = Elements(); + value_type* const iend = elements + Length(); + for (value_type* iter = elements + aStart; iter != iend; ++iter) { + if (comp.Equals(*iter, aItem)) { + return InvokeWithIndexAndOrReference<value_type>( + std::forward<Function>(aFunction), iter - elements, *iter); + } + } + return aFunctionElse(); + } + template <class Item, class Function, class FunctionElse> + auto ApplyIf(const Item& aItem, index_type aStart, Function&& aFunction, + FunctionElse&& aFunctionElse) const { + return ApplyIf(aItem, aStart, nsDefaultComparator<value_type, Item>(), + std::forward<Function>(aFunction), + std::forward<FunctionElse>(aFunctionElse)); + } + template <class Item, class Function, class FunctionElse> + auto ApplyIf(const Item& aItem, index_type aStart, Function&& aFunction, + FunctionElse&& aFunctionElse) { + return ApplyIf(aItem, aStart, nsDefaultComparator<value_type, Item>(), + std::forward<Function>(aFunction), + std::forward<FunctionElse>(aFunctionElse)); + } + template <class Item, class Function, class FunctionElse> + auto ApplyIf(const Item& aItem, Function&& aFunction, + FunctionElse&& aFunctionElse) const { + return ApplyIf(aItem, 0, std::forward<Function>(aFunction), + std::forward<FunctionElse>(aFunctionElse)); + } + template <class Item, class Function, class FunctionElse> + auto ApplyIf(const Item& aItem, Function&& aFunction, + FunctionElse&& aFunctionElse) { + return ApplyIf(aItem, 0, std::forward<Function>(aFunction), + std::forward<FunctionElse>(aFunctionElse)); + } + + // + // Allocation + // + + // This method may increase the capacity of this array object to the + // specified amount. This method may be called in advance of several + // AppendElement operations to minimize heap re-allocations. This method + // will not reduce the number of elements in this array. + // @param aCapacity The desired capacity of this array. + // @return True if the operation succeeded; false if we ran out of memory + protected: + template <typename ActualAlloc = Alloc> + typename ActualAlloc::ResultType SetCapacity(size_type aCapacity) { + return ActualAlloc::Result(this->template EnsureCapacity<ActualAlloc>( + aCapacity, sizeof(value_type))); + } + + public: + [[nodiscard]] bool SetCapacity(size_type aCapacity, + const mozilla::fallible_t&) { + return SetCapacity<FallibleAlloc>(aCapacity); + } + + // This method modifies the length of the array. If the new length is + // larger than the existing length of the array, then new elements will be + // constructed using value_type's default constructor. Otherwise, this call + // removes elements from the array (see also RemoveElementsAt). + // @param aNewLen The desired length of this array. + // @return True if the operation succeeded; false otherwise. + // See also TruncateLength for a more efficient variant if the new length is + // guaranteed to be smaller than the old. + protected: + template <typename ActualAlloc = Alloc> + typename ActualAlloc::ResultType SetLength(size_type aNewLen) { + const size_type oldLen = Length(); + if (aNewLen > oldLen) { + return ActualAlloc::ConvertBoolToResultType( + InsertElementsAtInternal<ActualAlloc>(oldLen, aNewLen - oldLen) != + nullptr); + } + + TruncateLengthUnsafe(aNewLen); + return ActualAlloc::ConvertBoolToResultType(true); + } + + public: + [[nodiscard]] bool SetLength(size_type aNewLen, const mozilla::fallible_t&) { + return SetLength<FallibleAlloc>(aNewLen); + } + + // This method modifies the length of the array, but may only be + // called when the new length is shorter than the old. It can + // therefore be called when value_type has no default constructor, + // unlike SetLength. It removes elements from the array (see also + // RemoveElementsAt). + // @param aNewLen The desired length of this array. + void TruncateLength(size_type aNewLen) { + // This assertion is redundant, but produces a better error message than the + // release assertion below. + MOZ_ASSERT(aNewLen <= Length(), "caller should use SetLength instead"); + + if (MOZ_UNLIKELY(aNewLen > Length())) { + mozilla::detail::InvalidArrayIndex_CRASH(aNewLen, Length()); + } + + TruncateLengthUnsafe(aNewLen); + } + + private: + void TruncateLengthUnsafe(size_type aNewLen) { + const size_type oldLen = Length(); + if (oldLen) { + DestructRange(aNewLen, oldLen - aNewLen); + base_type::mHdr->mLength = aNewLen; + } + } + + // This method ensures that the array has length at least the given + // length. If the current length is shorter than the given length, + // then new elements will be constructed using value_type's default + // constructor. + // @param aMinLen The desired minimum length of this array. + // @return True if the operation succeeded; false otherwise. + protected: + template <typename ActualAlloc = Alloc> + typename ActualAlloc::ResultType EnsureLengthAtLeast(size_type aMinLen) { + size_type oldLen = Length(); + if (aMinLen > oldLen) { + return ActualAlloc::ConvertBoolToResultType( + !!InsertElementsAtInternal<ActualAlloc>(oldLen, aMinLen - oldLen)); + } + return ActualAlloc::ConvertBoolToResultType(true); + } + + public: + [[nodiscard]] bool EnsureLengthAtLeast(size_type aMinLen, + const mozilla::fallible_t&) { + return EnsureLengthAtLeast<FallibleAlloc>(aMinLen); + } + + // This method inserts elements into the array, constructing + // them using value_type's default constructor. + // @param aIndex the place to insert the new elements. This must be no + // greater than the current length of the array. + // @param aCount the number of elements to insert + private: + template <typename ActualAlloc> + value_type* InsertElementsAtInternal(index_type aIndex, size_type aCount) { + if (!ActualAlloc::Successful(this->template InsertSlotsAt<ActualAlloc>( + aIndex, aCount, sizeof(value_type), MOZ_ALIGNOF(value_type)))) { + return nullptr; + } + + // Initialize the extra array elements + value_type* iter = Elements() + aIndex; + value_type* iend = iter + aCount; + for (; iter != iend; ++iter) { + elem_traits::Construct(iter); + } + + return Elements() + aIndex; + } + + public: + [[nodiscard]] value_type* InsertElementsAt(index_type aIndex, + size_type aCount, + const mozilla::fallible_t&) { + return InsertElementsAtInternal<FallibleAlloc>(aIndex, aCount); + } + + // This method inserts elements into the array, constructing them + // value_type's copy constructor (or whatever one-arg constructor + // happens to match the Item type). + // @param aIndex the place to insert the new elements. This must be no + // greater than the current length of the array. + // @param aCount the number of elements to insert. + // @param aItem the value to use when constructing the new elements. + private: + template <typename ActualAlloc, class Item> + value_type* InsertElementsAtInternal(index_type aIndex, size_type aCount, + const Item& aItem); + + public: + template <class Item> + [[nodiscard]] value_type* InsertElementsAt(index_type aIndex, + size_type aCount, + const Item& aItem, + const mozilla::fallible_t&) { + return InsertElementsAt<Item, FallibleAlloc>(aIndex, aCount, aItem); + } + + // This method may be called to minimize the memory used by this array. + void Compact() { + ShrinkCapacity(sizeof(value_type), MOZ_ALIGNOF(value_type)); + } + + // + // Sorting + // + + // This method sorts the elements of the array. It uses the LessThan + // method defined on the given Comparator object to collate elements or + // it wraps a tri-state comparison lambda into such a comparator. + // It uses std::sort. It expects value_type to be move assignable and + // constructible and uses those always, regardless of the chosen + // nsTArray_RelocationStrategy. + // + // @param aComp The Comparator used to collate elements. + template <class Comparator> + void Sort(const Comparator& aComp) { + static_assert(std::is_move_assignable_v<value_type>); + static_assert(std::is_move_constructible_v<value_type>); + + ::detail::CompareWrapper<Comparator, value_type> comp(aComp); + std::sort(begin(), end(), [&comp](const auto& left, const auto& right) { + return comp.LessThan(left, right); + }); + } + + // A variation on the Sort method defined above that assumes that + // 'operator<' is defined for 'value_type'. + void Sort() { Sort(nsDefaultComparator<value_type, value_type>()); } + + // This method sorts the elements of the array in a stable way (i.e. not + // changing the relative order of elements considered equal by the + // Comparator). It uses the LessThan method defined on the given Comparator + // object to collate elements. + // It uses std::stable_sort. It expects value_type to be move assignable and + // constructible and uses those always, regardless of the chosen + // nsTArray_RelocationStrategy. + // + // @param aComp The Comparator used to collate elements. + template <class Comparator> + void StableSort(const Comparator& aComp) { + static_assert(std::is_move_assignable_v<value_type>); + static_assert(std::is_move_constructible_v<value_type>); + + const ::detail::CompareWrapper<Comparator, value_type> comp(aComp); + std::stable_sort(Elements(), Elements() + Length(), + [&comp](const auto& lhs, const auto& rhs) { + return comp.LessThan(lhs, rhs); + }); + } + + // A variation on the StableSort method defined above that assumes that + // 'operator<' is defined for 'value_type'. + void StableSort() { + StableSort(nsDefaultComparator<value_type, value_type>()); + } + + // This method reverses the array in place. + void Reverse() { + value_type* elements = Elements(); + const size_type len = Length(); + for (index_type i = 0, iend = len / 2; i < iend; ++i) { + std::swap(elements[i], elements[len - i - 1]); + } + } + + protected: + using base_type::Hdr; + using base_type::ShrinkCapacity; + + // This method invokes value_type's destructor on a range of elements. + // @param aStart The index of the first element to destroy. + // @param aCount The number of elements to destroy. + void DestructRange(index_type aStart, size_type aCount) { + value_type* iter = Elements() + aStart; + value_type* iend = iter + aCount; + for (; iter != iend; ++iter) { + elem_traits::Destruct(iter); + } + } + + // This method invokes value_type's copy-constructor on a range of elements. + // @param aStart The index of the first element to construct. + // @param aCount The number of elements to construct. + // @param aValues The array of elements to copy. + template <class Item> + void AssignRange(index_type aStart, size_type aCount, const Item* aValues) { + AssignRangeAlgorithm< + std::is_trivially_copy_constructible_v<Item>, + std::is_same_v<Item, value_type>>::implementation(Elements(), aStart, + aCount, aValues); + } +}; + +template <typename E, class Alloc> +template <typename ActualAlloc, class Item> +auto nsTArray_Impl<E, Alloc>::AssignInternal(const Item* aArray, + size_type aArrayLen) -> + typename ActualAlloc::ResultType { + static_assert(std::is_same_v<ActualAlloc, InfallibleAlloc> || + std::is_same_v<ActualAlloc, FallibleAlloc>); + + if constexpr (std::is_same_v<ActualAlloc, InfallibleAlloc>) { + ClearAndRetainStorage(); + } + // Adjust memory allocation up-front to catch errors in the fallible case. + // We might relocate the elements to be destroyed unnecessarily. This could be + // optimized, but would make things more complicated. + if (!ActualAlloc::Successful(this->template EnsureCapacity<ActualAlloc>( + aArrayLen, sizeof(value_type)))) { + return ActualAlloc::ConvertBoolToResultType(false); + } + + MOZ_ASSERT_IF(this->HasEmptyHeader(), aArrayLen == 0); + if (!this->HasEmptyHeader()) { + if constexpr (std::is_same_v<ActualAlloc, FallibleAlloc>) { + ClearAndRetainStorage(); + } + AssignRange(0, aArrayLen, aArray); + base_type::mHdr->mLength = aArrayLen; + } + + return ActualAlloc::ConvertBoolToResultType(true); +} + +template <typename E, class Alloc> +template <typename ActualAlloc, class Item> +auto nsTArray_Impl<E, Alloc>::ReplaceElementsAtInternal(index_type aStart, + size_type aCount, + const Item* aArray, + size_type aArrayLen) + -> value_type* { + if (MOZ_UNLIKELY(aStart > Length())) { + mozilla::detail::InvalidArrayIndex_CRASH(aStart, Length()); + } + if (MOZ_UNLIKELY(aCount > Length() - aStart)) { + mozilla::detail::InvalidArrayIndex_CRASH(aStart + aCount, Length()); + } + + // Adjust memory allocation up-front to catch errors. + if (!ActualAlloc::Successful(this->template EnsureCapacity<ActualAlloc>( + Length() + aArrayLen - aCount, sizeof(value_type)))) { + return nullptr; + } + DestructRange(aStart, aCount); + this->template ShiftData<ActualAlloc>( + aStart, aCount, aArrayLen, sizeof(value_type), MOZ_ALIGNOF(value_type)); + AssignRange(aStart, aArrayLen, aArray); + return Elements() + aStart; +} + +template <typename E, class Alloc> +void nsTArray_Impl<E, Alloc>::RemoveElementsAt(index_type aStart, + size_type aCount) { + MOZ_ASSERT(aCount == 0 || aStart < Length(), "Invalid aStart index"); + + mozilla::CheckedInt<index_type> rangeEnd = aStart; + rangeEnd += aCount; + + if (MOZ_UNLIKELY(!rangeEnd.isValid() || rangeEnd.value() > Length())) { + mozilla::detail::InvalidArrayIndex_CRASH(aStart, Length()); + } + + RemoveElementsAtUnsafe(aStart, aCount); +} + +template <typename E, class Alloc> +void nsTArray_Impl<E, Alloc>::RemoveElementsAtUnsafe(index_type aStart, + size_type aCount) { + DestructRange(aStart, aCount); + this->template ShiftData<InfallibleAlloc>( + aStart, aCount, 0, sizeof(value_type), MOZ_ALIGNOF(value_type)); +} + +template <typename E, class Alloc> +void nsTArray_Impl<E, Alloc>::UnorderedRemoveElementsAt(index_type aStart, + size_type aCount) { + MOZ_ASSERT(aCount == 0 || aStart < Length(), "Invalid aStart index"); + + mozilla::CheckedInt<index_type> rangeEnd = aStart; + rangeEnd += aCount; + + if (MOZ_UNLIKELY(!rangeEnd.isValid() || rangeEnd.value() > Length())) { + mozilla::detail::InvalidArrayIndex_CRASH(aStart, Length()); + } + + // Destroy the elements which are being removed, and then swap elements in to + // replace them from the end. See the docs on the declaration of this + // function. + DestructRange(aStart, aCount); + this->template SwapFromEnd<InfallibleAlloc>( + aStart, aCount, sizeof(value_type), MOZ_ALIGNOF(value_type)); +} + +template <typename E, class Alloc> +template <typename Predicate> +auto nsTArray_Impl<E, Alloc>::RemoveElementsBy(Predicate aPredicate) + -> size_type { + if (this->HasEmptyHeader()) { + return 0; + } + + index_type j = 0; + const index_type len = Length(); + value_type* const elements = Elements(); + for (index_type i = 0; i < len; ++i) { + const bool result = aPredicate(elements[i]); + + // Check that the array has not been modified by the predicate. + MOZ_DIAGNOSTIC_ASSERT(len == base_type::mHdr->mLength && + elements == Elements()); + + if (result) { + elem_traits::Destruct(elements + i); + } else { + if (j < i) { + relocation_type::RelocateNonOverlappingRegion( + elements + j, elements + i, 1, sizeof(value_type)); + } + ++j; + } + } + + base_type::mHdr->mLength = j; + return len - j; +} + +template <typename E, class Alloc> +template <typename ActualAlloc, class Item> +auto nsTArray_Impl<E, Alloc>::InsertElementsAtInternal(index_type aIndex, + size_type aCount, + const Item& aItem) + -> value_type* { + if (!ActualAlloc::Successful(this->template InsertSlotsAt<ActualAlloc>( + aIndex, aCount, sizeof(value_type), MOZ_ALIGNOF(value_type)))) { + return nullptr; + } + + // Initialize the extra array elements + value_type* iter = Elements() + aIndex; + value_type* iend = iter + aCount; + for (; iter != iend; ++iter) { + elem_traits::Construct(iter, aItem); + } + + return Elements() + aIndex; +} + +template <typename E, class Alloc> +template <typename ActualAlloc> +auto nsTArray_Impl<E, Alloc>::InsertElementAtInternal(index_type aIndex) + -> value_type* { + if (MOZ_UNLIKELY(aIndex > Length())) { + mozilla::detail::InvalidArrayIndex_CRASH(aIndex, Length()); + } + + // Length() + 1 is guaranteed to not overflow, so EnsureCapacity is OK. + if (!ActualAlloc::Successful(this->template EnsureCapacity<ActualAlloc>( + Length() + 1, sizeof(value_type)))) { + return nullptr; + } + this->template ShiftData<ActualAlloc>(aIndex, 0, 1, sizeof(value_type), + MOZ_ALIGNOF(value_type)); + value_type* elem = Elements() + aIndex; + elem_traits::Construct(elem); + return elem; +} + +template <typename E, class Alloc> +template <typename ActualAlloc, class Item> +auto nsTArray_Impl<E, Alloc>::InsertElementAtInternal(index_type aIndex, + Item&& aItem) + -> value_type* { + if (MOZ_UNLIKELY(aIndex > Length())) { + mozilla::detail::InvalidArrayIndex_CRASH(aIndex, Length()); + } + + // Length() + 1 is guaranteed to not overflow, so EnsureCapacity is OK. + if (!ActualAlloc::Successful(this->template EnsureCapacity<ActualAlloc>( + Length() + 1, sizeof(value_type)))) { + return nullptr; + } + this->template ShiftData<ActualAlloc>(aIndex, 0, 1, sizeof(value_type), + MOZ_ALIGNOF(value_type)); + value_type* elem = Elements() + aIndex; + elem_traits::Construct(elem, std::forward<Item>(aItem)); + return elem; +} + +template <typename E, class Alloc> +template <typename ActualAlloc, class Item> +auto nsTArray_Impl<E, Alloc>::AppendElementsInternal(const Item* aArray, + size_type aArrayLen) + -> value_type* { + if (!ActualAlloc::Successful(this->template ExtendCapacity<ActualAlloc>( + Length(), aArrayLen, sizeof(value_type)))) { + return nullptr; + } + index_type len = Length(); + AssignRange(len, aArrayLen, aArray); + this->IncrementLength(aArrayLen); + return Elements() + len; +} + +template <typename E, class Alloc> +template <typename ActualAlloc, class Item, class Allocator> +auto nsTArray_Impl<E, Alloc>::AppendElementsInternal( + nsTArray_Impl<Item, Allocator>&& aArray) -> value_type* { + if constexpr (std::is_same_v<Alloc, Allocator>) { + MOZ_ASSERT(&aArray != this, "argument must be different aArray"); + } + if (Length() == 0) { + // XXX This might still be optimized. If aArray uses auto-storage but we + // won't, we might better retain our storage if it's sufficiently large. + this->ShrinkCapacityToZero(sizeof(value_type), MOZ_ALIGNOF(value_type)); + this->MoveInit(aArray, sizeof(value_type), MOZ_ALIGNOF(value_type)); + return Elements(); + } + + index_type len = Length(); + index_type otherLen = aArray.Length(); + if (!ActualAlloc::Successful(this->template ExtendCapacity<ActualAlloc>( + len, otherLen, sizeof(value_type)))) { + return nullptr; + } + relocation_type::RelocateNonOverlappingRegion( + Elements() + len, aArray.Elements(), otherLen, sizeof(value_type)); + this->IncrementLength(otherLen); + aArray.template ShiftData<ActualAlloc>(0, otherLen, 0, sizeof(value_type), + MOZ_ALIGNOF(value_type)); + return Elements() + len; +} + +template <typename E, class Alloc> +template <typename ActualAlloc, class Item> +auto nsTArray_Impl<E, Alloc>::AppendElementInternal(Item&& aItem) + -> value_type* { + // Length() + 1 is guaranteed to not overflow, so EnsureCapacity is OK. + if (!ActualAlloc::Successful(this->template EnsureCapacity<ActualAlloc>( + Length() + 1, sizeof(value_type)))) { + return nullptr; + } + value_type* elem = Elements() + Length(); + elem_traits::Construct(elem, std::forward<Item>(aItem)); + this->mHdr->mLength += 1; + return elem; +} + +template <typename E, class Alloc> +template <typename ActualAlloc, class... Args> +auto nsTArray_Impl<E, Alloc>::EmplaceBackInternal(Args&&... aArgs) + -> value_type* { + // Length() + 1 is guaranteed to not overflow, so EnsureCapacity is OK. + if (!ActualAlloc::Successful(this->template EnsureCapacity<ActualAlloc>( + Length() + 1, sizeof(value_type)))) { + return nullptr; + } + value_type* elem = Elements() + Length(); + elem_traits::Emplace(elem, std::forward<Args>(aArgs)...); + this->mHdr->mLength += 1; + return elem; +} + +template <typename E, typename Alloc> +inline void ImplCycleCollectionUnlink(nsTArray_Impl<E, Alloc>& aField) { + aField.Clear(); +} + +namespace detail { +// This is defined in the cpp file to avoid including +// nsCycleCollectionNoteChild.h in this header file. +void SetCycleCollectionArrayFlag(uint32_t& aFlags); +} // namespace detail + +template <typename E, typename Alloc> +inline void ImplCycleCollectionTraverse( + nsCycleCollectionTraversalCallback& aCallback, + nsTArray_Impl<E, Alloc>& aField, const char* aName, uint32_t aFlags = 0) { + ::detail::SetCycleCollectionArrayFlag(aFlags); + size_t length = aField.Length(); + E* elements = aField.Elements(); + for (size_t i = 0; i < length; ++i) { + ImplCycleCollectionTraverse(aCallback, elements[i], aName, aFlags); + } +} + +// +// nsTArray is an infallible vector class. See the comment at the top of this +// file for more details. +// +template <class E> +class nsTArray : public nsTArray_Impl<E, nsTArrayInfallibleAllocator> { + public: + using InfallibleAlloc = nsTArrayInfallibleAllocator; + using base_type = nsTArray_Impl<E, InfallibleAlloc>; + using self_type = nsTArray<E>; + using typename base_type::index_type; + using typename base_type::size_type; + using typename base_type::value_type; + + nsTArray() {} + explicit nsTArray(size_type aCapacity) : base_type(aCapacity) {} + MOZ_IMPLICIT nsTArray(std::initializer_list<E> aIL) { + AppendElements(aIL.begin(), aIL.size()); + } + + template <class Item> + nsTArray(const Item* aArray, size_type aArrayLen) { + AppendElements(aArray, aArrayLen); + } + + template <class Item> + explicit nsTArray(mozilla::Span<Item> aSpan) { + AppendElements(aSpan); + } + + template <class Allocator> + explicit nsTArray(const nsTArray_Impl<E, Allocator>& aOther) + : base_type(aOther) {} + template <class Allocator> + MOZ_IMPLICIT nsTArray(nsTArray_Impl<E, Allocator>&& aOther) + : base_type(std::move(aOther)) {} + + template <class Allocator> + self_type& operator=(const nsTArray_Impl<E, Allocator>& aOther) { + base_type::operator=(aOther); + return *this; + } + template <class Allocator> + self_type& operator=(nsTArray_Impl<E, Allocator>&& aOther) { + // This is quite complex, since we don't know if we are an AutoTArray. While + // AutoTArray overrides this operator=, this might be called on a nsTArray& + // bound to an AutoTArray. + base_type::operator=(std::move(aOther)); + return *this; + } + + using base_type::AppendElement; + using base_type::AppendElements; + using base_type::EmplaceBack; + using base_type::EnsureLengthAtLeast; + using base_type::InsertElementAt; + using base_type::InsertElementsAt; + using base_type::InsertElementSorted; + using base_type::ReplaceElementsAt; + using base_type::SetCapacity; + using base_type::SetLength; + + template <class Item> + mozilla::NotNull<value_type*> AppendElements(const Item* aArray, + size_type aArrayLen) { + return mozilla::WrapNotNullUnchecked( + this->template AppendElementsInternal<InfallibleAlloc>(aArray, + aArrayLen)); + } + + template <class Item> + mozilla::NotNull<value_type*> AppendElements(mozilla::Span<Item> aSpan) { + return mozilla::WrapNotNullUnchecked( + this->template AppendElementsInternal<InfallibleAlloc>(aSpan.Elements(), + aSpan.Length())); + } + + template <class Item, class Allocator> + mozilla::NotNull<value_type*> AppendElements( + const nsTArray_Impl<Item, Allocator>& aArray) { + return mozilla::WrapNotNullUnchecked( + this->template AppendElementsInternal<InfallibleAlloc>( + aArray.Elements(), aArray.Length())); + } + + template <class Item, class Allocator> + mozilla::NotNull<value_type*> AppendElements( + nsTArray_Impl<Item, Allocator>&& aArray) { + return mozilla::WrapNotNullUnchecked( + this->template AppendElementsInternal<InfallibleAlloc>( + std::move(aArray))); + } + + template <class Item> + mozilla::NotNull<value_type*> AppendElement(Item&& aItem) { + return mozilla::WrapNotNullUnchecked( + this->template AppendElementInternal<InfallibleAlloc>( + std::forward<Item>(aItem))); + } + + mozilla::NotNull<value_type*> AppendElements(size_type aCount) { + return mozilla::WrapNotNullUnchecked( + this->template AppendElementsInternal<InfallibleAlloc>(aCount)); + } + + mozilla::NotNull<value_type*> AppendElement() { + return mozilla::WrapNotNullUnchecked( + this->template AppendElementsInternal<InfallibleAlloc>(1)); + } + + self_type Clone() const { + self_type result; + result.Assign(*this); + return result; + } + + mozilla::NotNull<value_type*> InsertElementsAt(index_type aIndex, + size_type aCount) { + return mozilla::WrapNotNullUnchecked( + this->template InsertElementsAtInternal<InfallibleAlloc>(aIndex, + aCount)); + } + + template <class Item> + mozilla::NotNull<value_type*> InsertElementsAt(index_type aIndex, + size_type aCount, + const Item& aItem) { + return mozilla::WrapNotNullUnchecked( + this->template InsertElementsAtInternal<InfallibleAlloc>(aIndex, aCount, + aItem)); + } + + template <class Item> + mozilla::NotNull<value_type*> InsertElementsAt(index_type aIndex, + const Item* aArray, + size_type aArrayLen) { + return mozilla::WrapNotNullUnchecked( + this->template ReplaceElementsAtInternal<InfallibleAlloc>( + aIndex, 0, aArray, aArrayLen)); + } + + template <class Item, class Allocator> + mozilla::NotNull<value_type*> InsertElementsAt( + index_type aIndex, const nsTArray_Impl<Item, Allocator>& aArray) { + return mozilla::WrapNotNullUnchecked( + this->template ReplaceElementsAtInternal<InfallibleAlloc>( + aIndex, 0, aArray.Elements(), aArray.Length())); + } + + template <class Item> + mozilla::NotNull<value_type*> InsertElementsAt(index_type aIndex, + mozilla::Span<Item> aSpan) { + return mozilla::WrapNotNullUnchecked( + this->template ReplaceElementsAtInternal<InfallibleAlloc>( + aIndex, 0, aSpan.Elements(), aSpan.Length())); + } + + mozilla::NotNull<value_type*> InsertElementAt(index_type aIndex) { + return mozilla::WrapNotNullUnchecked( + this->template InsertElementAtInternal<InfallibleAlloc>(aIndex)); + } + + template <class Item> + mozilla::NotNull<value_type*> InsertElementAt(index_type aIndex, + Item&& aItem) { + return mozilla::WrapNotNullUnchecked( + this->template InsertElementAtInternal<InfallibleAlloc>( + aIndex, std::forward<Item>(aItem))); + } + + template <class Item> + mozilla::NotNull<value_type*> ReplaceElementsAt(index_type aStart, + size_type aCount, + const Item* aArray, + size_type aArrayLen) { + return mozilla::WrapNotNullUnchecked( + this->template ReplaceElementsAtInternal<InfallibleAlloc>( + aStart, aCount, aArray, aArrayLen)); + } + + template <class Item> + mozilla::NotNull<value_type*> ReplaceElementsAt( + index_type aStart, size_type aCount, const nsTArray<Item>& aArray) { + return ReplaceElementsAt(aStart, aCount, aArray.Elements(), + aArray.Length()); + } + + template <class Item> + mozilla::NotNull<value_type*> ReplaceElementsAt(index_type aStart, + size_type aCount, + mozilla::Span<Item> aSpan) { + return ReplaceElementsAt(aStart, aCount, aSpan.Elements(), aSpan.Length()); + } + + template <class Item> + mozilla::NotNull<value_type*> ReplaceElementsAt(index_type aStart, + size_type aCount, + const Item& aItem) { + return ReplaceElementsAt(aStart, aCount, &aItem, 1); + } + + template <class Item, class Comparator> + mozilla::NotNull<value_type*> InsertElementSorted(Item&& aItem, + const Comparator& aComp) { + return mozilla::WrapNotNullUnchecked( + this->template InsertElementSortedInternal<InfallibleAlloc>( + std::forward<Item>(aItem), aComp)); + } + + template <class Item> + mozilla::NotNull<value_type*> InsertElementSorted(Item&& aItem) { + return mozilla::WrapNotNullUnchecked( + this->template InsertElementSortedInternal<InfallibleAlloc>( + std::forward<Item>(aItem), + nsDefaultComparator<value_type, Item>{})); + } + + template <class... Args> + mozilla::NotNull<value_type*> EmplaceBack(Args&&... aArgs) { + return mozilla::WrapNotNullUnchecked( + this->template EmplaceBackInternal<InfallibleAlloc, Args...>( + std::forward<Args>(aArgs)...)); + } +}; + +template <class E> +class CopyableTArray : public nsTArray<E> { + public: + using nsTArray<E>::nsTArray; + + CopyableTArray(const CopyableTArray& aOther) : nsTArray<E>() { + this->Assign(aOther); + } + CopyableTArray& operator=(const CopyableTArray& aOther) { + if (this != &aOther) { + this->Assign(aOther); + } + return *this; + } + template <typename Allocator> + MOZ_IMPLICIT CopyableTArray(const nsTArray_Impl<E, Allocator>& aOther) { + this->Assign(aOther); + } + template <typename Allocator> + CopyableTArray& operator=(const nsTArray_Impl<E, Allocator>& aOther) { + if constexpr (std::is_same_v<Allocator, nsTArrayInfallibleAllocator>) { + if (this == &aOther) { + return *this; + } + } + this->Assign(aOther); + return *this; + } + template <typename Allocator> + MOZ_IMPLICIT CopyableTArray(nsTArray_Impl<E, Allocator>&& aOther) + : nsTArray<E>{std::move(aOther)} {} + template <typename Allocator> + CopyableTArray& operator=(nsTArray_Impl<E, Allocator>&& aOther) { + static_cast<nsTArray<E>&>(*this) = std::move(aOther); + return *this; + } + + CopyableTArray(CopyableTArray&&) = default; + CopyableTArray& operator=(CopyableTArray&&) = default; +}; + +// +// FallibleTArray is a fallible vector class. +// +template <class E> +class FallibleTArray : public nsTArray_Impl<E, nsTArrayFallibleAllocator> { + public: + typedef nsTArray_Impl<E, nsTArrayFallibleAllocator> base_type; + typedef FallibleTArray<E> self_type; + typedef typename base_type::size_type size_type; + + FallibleTArray() = default; + explicit FallibleTArray(size_type aCapacity) : base_type(aCapacity) {} + + template <class Allocator> + explicit FallibleTArray(const nsTArray_Impl<E, Allocator>& aOther) + : base_type(aOther) {} + template <class Allocator> + explicit FallibleTArray(nsTArray_Impl<E, Allocator>&& aOther) + : base_type(std::move(aOther)) {} + + template <class Allocator> + self_type& operator=(const nsTArray_Impl<E, Allocator>& aOther) { + base_type::operator=(aOther); + return *this; + } + template <class Allocator> + self_type& operator=(nsTArray_Impl<E, Allocator>&& aOther) { + base_type::operator=(std::move(aOther)); + return *this; + } +}; + +// +// AutoTArray<E, N> is like nsTArray<E>, but with N elements of inline storage. +// Storing more than N elements is fine, but it will cause a heap allocation. +// +template <class E, size_t N> +class MOZ_NON_MEMMOVABLE AutoTArray : public nsTArray<E> { + static_assert(N != 0, "AutoTArray<E, 0> should be specialized"); + + public: + typedef AutoTArray<E, N> self_type; + typedef nsTArray<E> base_type; + typedef typename base_type::Header Header; + typedef typename base_type::value_type value_type; + + AutoTArray() : mAlign() { Init(); } + + AutoTArray(self_type&& aOther) : nsTArray<E>() { + Init(); + this->MoveInit(aOther, sizeof(value_type), MOZ_ALIGNOF(value_type)); + } + + explicit AutoTArray(base_type&& aOther) : mAlign() { + Init(); + this->MoveInit(aOther, sizeof(value_type), MOZ_ALIGNOF(value_type)); + } + + template <typename Allocator> + explicit AutoTArray(nsTArray_Impl<value_type, Allocator>&& aOther) { + Init(); + this->MoveInit(aOther, sizeof(value_type), MOZ_ALIGNOF(value_type)); + } + + MOZ_IMPLICIT AutoTArray(std::initializer_list<E> aIL) : mAlign() { + Init(); + this->AppendElements(aIL.begin(), aIL.size()); + } + + self_type& operator=(self_type&& aOther) { + base_type::operator=(std::move(aOther)); + return *this; + } + + template <typename Allocator> + self_type& operator=(nsTArray_Impl<value_type, Allocator>&& aOther) { + base_type::operator=(std::move(aOther)); + return *this; + } + + // Intentionally hides nsTArray_Impl::Clone to make clones usually be + // AutoTArray as well. + self_type Clone() const { + self_type result; + result.Assign(*this); + return result; + } + + private: + // nsTArray_base casts itself as an nsAutoArrayBase in order to get a pointer + // to mAutoBuf. + template <class Allocator, class RelocationStrategy> + friend class nsTArray_base; + + void Init() { + static_assert(MOZ_ALIGNOF(value_type) <= 8, + "can't handle alignments greater than 8, " + "see nsTArray_base::UsesAutoArrayBuffer()"); + // Temporary work around for VS2012 RC compiler crash + Header** phdr = base_type::PtrToHdr(); + *phdr = reinterpret_cast<Header*>(&mAutoBuf); + (*phdr)->mLength = 0; + (*phdr)->mCapacity = N; + (*phdr)->mIsAutoArray = 1; + + MOZ_ASSERT(base_type::GetAutoArrayBuffer(MOZ_ALIGNOF(value_type)) == + reinterpret_cast<Header*>(&mAutoBuf), + "GetAutoArrayBuffer needs to be fixed"); + } + + // Declare mAutoBuf aligned to the maximum of the header's alignment and + // value_type's alignment. We need to use a union rather than + // MOZ_ALIGNED_DECL because GCC is picky about what goes into + // __attribute__((aligned(foo))). + union { + char mAutoBuf[sizeof(nsTArrayHeader) + N * sizeof(value_type)]; + // Do the max operation inline to ensure that it is a compile-time constant. + mozilla::AlignedElem<(MOZ_ALIGNOF(Header) > MOZ_ALIGNOF(value_type)) + ? MOZ_ALIGNOF(Header) + : MOZ_ALIGNOF(value_type)> + mAlign; + }; +}; + +// +// Specialization of AutoTArray<E, N> for the case where N == 0. +// AutoTArray<E, 0> behaves exactly like nsTArray<E>, but without this +// specialization, it stores a useless inline header. +// +// We do have many AutoTArray<E, 0> objects in memory: about 2,000 per tab as +// of May 2014. These are typically not explicitly AutoTArray<E, 0> but rather +// AutoTArray<E, N> for some value N depending on template parameters, in +// generic code. +// +// For that reason, we optimize this case with the below partial specialization, +// which ensures that AutoTArray<E, 0> is just like nsTArray<E>, without any +// inline header overhead. +// +template <class E> +class AutoTArray<E, 0> : public nsTArray<E> { + using nsTArray<E>::nsTArray; +}; + +template <class E, size_t N> +struct nsTArray_RelocationStrategy<AutoTArray<E, N>> { + using Type = nsTArray_RelocateUsingMoveConstructor<AutoTArray<E, N>>; +}; + +template <class E, size_t N> +class CopyableAutoTArray : public AutoTArray<E, N> { + public: + typedef CopyableAutoTArray<E, N> self_type; + using AutoTArray<E, N>::AutoTArray; + + CopyableAutoTArray(const CopyableAutoTArray& aOther) : AutoTArray<E, N>() { + this->Assign(aOther); + } + CopyableAutoTArray& operator=(const CopyableAutoTArray& aOther) { + if (this != &aOther) { + this->Assign(aOther); + } + return *this; + } + template <typename Allocator> + MOZ_IMPLICIT CopyableAutoTArray(const nsTArray_Impl<E, Allocator>& aOther) { + this->Assign(aOther); + } + template <typename Allocator> + CopyableAutoTArray& operator=(const nsTArray_Impl<E, Allocator>& aOther) { + if constexpr (std::is_same_v<Allocator, nsTArrayInfallibleAllocator>) { + if (this == &aOther) { + return *this; + } + } + this->Assign(aOther); + return *this; + } + template <typename Allocator> + MOZ_IMPLICIT CopyableAutoTArray(nsTArray_Impl<E, Allocator>&& aOther) + : AutoTArray<E, N>{std::move(aOther)} {} + template <typename Allocator> + CopyableAutoTArray& operator=(nsTArray_Impl<E, Allocator>&& aOther) { + static_cast<AutoTArray<E, N>&>(*this) = std::move(aOther); + return *this; + } + + // CopyableTArray exists for cases where an explicit Clone is not possible. + // These uses should not be mixed, so we delete Clone() here. + self_type Clone() const = delete; + + CopyableAutoTArray(CopyableAutoTArray&&) = default; + CopyableAutoTArray& operator=(CopyableAutoTArray&&) = default; +}; + +namespace mozilla { +template <typename E, typename ArrayT> +class nsTArrayBackInserter { + ArrayT* mArray; + + class Proxy { + ArrayT& mArray; + + public: + explicit Proxy(ArrayT& aArray) : mArray{aArray} {} + + template <typename E2> + void operator=(E2&& aValue) { + mArray.AppendElement(std::forward<E2>(aValue)); + } + }; + + public: + using iterator_category = std::output_iterator_tag; + using value_type = void; + using difference_type = void; + using pointer = void; + using reference = void; + explicit nsTArrayBackInserter(ArrayT& aArray) : mArray{&aArray} {} + + // Return a proxy so that nsTArrayBackInserter has the default special member + // functions, and the operator= template is defined in Proxy rather than this + // class (which otherwise breaks with recent MS STL versions). + // See also Bug 1331137, comment 11. + Proxy operator*() { return Proxy(*mArray); } + + nsTArrayBackInserter& operator++() { return *this; } + nsTArrayBackInserter& operator++(int) { return *this; } +}; +} // namespace mozilla + +template <typename E> +auto MakeBackInserter(nsTArray<E>& aArray) { + return mozilla::nsTArrayBackInserter<E, nsTArray<E>>{aArray}; +} + +// Span integration +namespace mozilla { +template <typename E, class Alloc> +Span(nsTArray_Impl<E, Alloc>&) -> Span<E>; + +template <typename E, class Alloc> +Span(const nsTArray_Impl<E, Alloc>&) -> Span<const E>; + +// Provides a view on a nsTArray through which the existing array elements can +// be accessed in a non-const way, but the array itself cannot be modified, so +// that references to elements are guaranteed to be stable. +template <typename E> +class nsTArrayView { + public: + using element_type = E; + using pointer = element_type*; + using reference = element_type&; + using index_type = typename Span<element_type>::index_type; + using size_type = typename Span<element_type>::index_type; + + explicit nsTArrayView(nsTArray<element_type> aArray) + : mArray(std::move(aArray)), mSpan(mArray) {} + + element_type& operator[](index_type aIndex) { return mSpan[aIndex]; } + + const element_type& operator[](index_type aIndex) const { + return mSpan[aIndex]; + } + + size_type Length() const { return mSpan.Length(); } + + auto begin() { return mSpan.begin(); } + auto end() { return mSpan.end(); } + auto begin() const { return mSpan.begin(); } + auto end() const { return mSpan.end(); } + auto cbegin() const { return mSpan.cbegin(); } + auto cend() const { return mSpan.cend(); } + + Span<element_type> AsSpan() { return mSpan; } + Span<const element_type> AsSpan() const { return mSpan; } + + private: + nsTArray<element_type> mArray; + const Span<element_type> mSpan; +}; + +template <typename Range, typename = std::enable_if_t<std::is_same_v< + typename std::iterator_traits< + typename Range::iterator>::iterator_category, + std::random_access_iterator_tag>>> +auto RangeSize(const Range& aRange) { + // See https://en.cppreference.com/w/cpp/iterator/begin, section 'User-defined + // overloads'. + using std::begin; + using std::end; + + return std::distance(begin(aRange), end(aRange)); +} + +/** + * Materialize a range as a nsTArray (or a compatible variant, like AutoTArray) + * of an explicitly specified type. The array value type must be implicitly + * convertible from the range's value type. + */ +template <typename Array, typename Range> +auto ToTArray(const Range& aRange) { + using std::begin; + using std::end; + + Array res; + res.SetCapacity(RangeSize(aRange)); + std::copy(begin(aRange), end(aRange), MakeBackInserter(res)); + return res; +} + +/** + * Materialize a range as a nsTArray of its (decayed) value type. + */ +template <typename Range> +auto ToArray(const Range& aRange) { + return ToTArray<nsTArray<std::decay_t< + typename std::iterator_traits<typename Range::iterator>::value_type>>>( + aRange); +} + +/** + * Appends all elements from a range to an array. + */ +template <typename Array, typename Range> +void AppendToArray(Array& aArray, const Range& aRange) { + using std::begin; + using std::end; + + aArray.SetCapacity(aArray.Length() + RangeSize(aRange)); + std::copy(begin(aRange), end(aRange), MakeBackInserter(aArray)); +} + +} // namespace mozilla + +// MOZ_DBG support + +template <class E, class Alloc> +std::ostream& operator<<(std::ostream& aOut, + const nsTArray_Impl<E, Alloc>& aTArray) { + return aOut << mozilla::Span(aTArray); +} + +// Assert that AutoTArray doesn't have any extra padding inside. +// +// It's important that the data stored in this auto array takes up a multiple of +// 8 bytes; e.g. AutoTArray<uint32_t, 1> wouldn't work. Since AutoTArray +// contains a pointer, its size must be a multiple of alignof(void*). (This is +// because any type may be placed into an array, and there's no padding between +// elements of an array.) The compiler pads the end of the structure to +// enforce this rule. +// +// If we used AutoTArray<uint32_t, 1> below, this assertion would fail on a +// 64-bit system, where the compiler inserts 4 bytes of padding at the end of +// the auto array to make its size a multiple of alignof(void*) == 8 bytes. + +static_assert(sizeof(AutoTArray<uint32_t, 2>) == + sizeof(void*) + sizeof(nsTArrayHeader) + sizeof(uint32_t) * 2, + "AutoTArray shouldn't contain any extra padding, " + "see the comment"); + +// Definitions of nsTArray_Impl methods +#include "nsTArray-inl.h" + +#endif // nsTArray_h__ |