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+/* -*- 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 "nsQuickSort.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);
+
+ // 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 (Equals(aLeft, aRight)) {
+ return 0;
+ }
+ return LessThan(aLeft, aRight) ? -1 : 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:
+ // 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 function is meant to be used with the NS_QuickSort function. It
+ // maps the callback API expected by NS_QuickSort to the Comparator API
+ // used by nsTArray_Impl. See nsTArray_Impl::Sort.
+ template <class Comparator>
+ static int Compare(const void* aE1, const void* aE2, void* aData) {
+ const Comparator* c = reinterpret_cast<const Comparator*>(aData);
+ const value_type* a = static_cast<const value_type*>(aE1);
+ const value_type* b = static_cast<const value_type*>(aE2);
+ return c->Compare(*a, *b);
+ }
+
+ // This method sorts the elements of the array. It uses the LessThan
+ // method defined on the given Comparator object to collate elements.
+ // @param aComp The Comparator used to collate elements.
+ template <class Comparator>
+ void Sort(const Comparator& aComp) {
+ ::detail::CompareWrapper<Comparator, value_type> comp(aComp);
+
+ NS_QuickSort(Elements(), Length(), sizeof(value_type),
+ Compare<decltype(comp)>, &comp);
+ }
+
+ // 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.
+ // @param aComp The Comparator used to collate elements.
+ template <class Comparator>
+ void StableSort(const Comparator& aComp) {
+ 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);
+ });
+ }
+
+ // 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();
+ for (size_t i = 0; i < length; ++i) {
+ ImplCycleCollectionTraverse(aCallback, aField[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__