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gecko-dev/xpcom/ds/nsTArray.h
Simon Giesecke f67e7d443b Bug 1617604 - Make fallible nsTArray::EmplaceBack callable. r=froydnj 
Differential Revision: https://phabricator.services.mozilla.com/D63862

--HG--
extra : moz-landing-system : lando
2020-02-24 17:53:37 +00:00

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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 <functional>
#include <initializer_list>
#include <new>
#include <ostream>
#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/DbgMacro.h"
#include "mozilla/FunctionTypeTraits.h"
#include "mozilla/MathAlgorithms.h"
#include "mozilla/MemoryReporting.h"
#include "mozilla/ReverseIterator.h"
#include "mozilla/Span.h"
#include "mozilla/TypeTraits.h"
#include "mozilla/fallible.h"
#include "mozilla/mozalloc.h"
#include "nsAlgorithm.h"
#include "nsCycleCollectionNoteChild.h"
#include "nsDebug.h"
#include "nsISupportsImpl.h"
#include "nsQuickSort.h"
#include "nsRegionFwd.h"
#include "nsTArrayForwardDeclare.h"
#include "nscore.h"
namespace JS {
template <class T>
class Heap;
} /* namespace JS */
class nsRegion;
namespace mozilla {
namespace layers {
struct TileClient;
struct RenderRootDisplayListData;
struct RenderRootUpdates;
} // namespace layers
} // namespace mozilla
namespace mozilla {
struct SerializedStructuredCloneBuffer;
class SourceBufferTask;
} // namespace mozilla
namespace mozilla {
namespace dom {
namespace ipc {
class StructuredCloneData;
} // namespace ipc
} // namespace dom
} // namespace mozilla
namespace mozilla {
namespace dom {
class ClonedMessageData;
class MessageData;
class RefMessageData;
namespace indexedDB {
struct StructuredCloneReadInfo;
class SerializedStructuredCloneReadInfo;
class ObjectStoreCursorResponse;
class IndexCursorResponse;
} // namespace indexedDB
} // namespace dom
} // namespace mozilla
class JSStructuredCloneData;
//
// nsTArray is a resizable array class, like std::vector.
//
// Unlike std::vector, which follows C++'s construction/destruction rules,
// nsTArray assumes that your "T" can be memmoved()'ed safely.
//
// The public classes defined in this header are
//
// nsTArray<T>,
// FallibleTArray<T>,
// AutoTArray<T, N>, and
//
// nsTArray and AutoTArray are infallible by default. To opt-in to fallible
// behaviour, use the `mozilla::fallible` parameter and check the return value.
//
// 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 (i.e., T in nsTArray<T>) specifies the type of the
// elements and has the following requirements:
//
// T MUST be safely memmove()'able.
// T MUST define a copy-constructor.
// T MAY define operator< for sorting.
// T MAY define operator== for searching.
//
// (Note that the memmove requirement may be relaxed for certain types - see
// nsTArray_CopyChooser below.)
//
// For methods taking a Comparator instance, the Comparator must be a class
// defining the following methods:
//
// class Comparator {
// public:
// /** @return True if the elements are equals; false otherwise. */
// bool Equals(const elem_type& a, const Item& b) const;
//
// /** @return True if (a < b); false otherwise. */
// bool LessThan(const elem_type& a, const Item& b) const;
// };
//
// The Equals method is used for searching, and the LessThan method is used for
// searching and sorting. The |Item| type above can be arbitrary, but must
// match the Item type passed to the sort or search function.
//
//
// 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 nsTArrayFallibleResult(bool aResult) : mResult(aResult) {}
MOZ_IMPLICIT 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 ResultType Result(ResultTypeProxy aResult) { return aResult; }
static bool Successful(ResultTypeProxy aResult) { return aResult; }
static ResultTypeProxy SuccessResult() { return true; }
static ResultTypeProxy FailureResult() { return false; }
static ResultType ConvertBoolToResultType(bool aValue) { return aValue; }
};
struct nsTArrayInfallibleAllocatorBase {
typedef void ResultType;
typedef nsTArrayInfallibleResult ResultTypeProxy;
static ResultType Result(ResultTypeProxy aResult) {}
static bool Successful(ResultTypeProxy) { return true; }
static ResultTypeProxy SuccessResult() { return ResultTypeProxy(); }
static ResultTypeProxy FailureResult() {
MOZ_CRASH("Infallible nsTArray should never fail");
return ResultTypeProxy();
}
static ResultType ConvertBoolToResultType(bool aValue) {
if (!aValue) {
MOZ_CRASH("infallible nsTArray should never convert false to ResultType");
}
}
};
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) { return moz_xmalloc(aSize); }
static void* Realloc(void* aPtr, size_t aSize) {
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 nsTArrayHeader sEmptyTArrayHeader;
}
// This class provides a SafeElementAt method to nsTArray<T*> which does
// not take a second default value parameter.
template <class E, class Derived>
struct nsTArray_SafeElementAtHelper {
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> {
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 the base type that the smart pointer is templated over; the
// smart pointer can act as E*.
template <class E, class Derived>
struct nsTArray_SafeElementAtSmartPtrHelper {
typedef E* elem_type;
typedef const E* 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<E, Derived> {};
template <class E, class Derived>
struct nsTArray_SafeElementAtHelper<RefPtr<E>, Derived>
: public nsTArray_SafeElementAtSmartPtrHelper<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<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);
MOZ_NORETURN MOZ_COLD void InvalidArrayIndex_CRASH(size_t aIndex,
size_t aLength);
//
// 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 Copy>
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 Allocator, class Copier>
friend class nsTArray_base;
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();
// 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);
// 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 (mHdr == EmptyHdr()) {
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, Copy>& aOther, size_type aElemSize,
size_t aElemAlign);
// This is an RAII class used in SwapArrayElements.
class IsAutoArrayRestorer {
public:
IsAutoArrayRestorer(nsTArray_base<Alloc, Copy>& aArray, size_t aElemAlign);
~IsAutoArrayRestorer();
private:
nsTArray_base<Alloc, Copy>& 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, Copy>*>(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 { return mHdr; }
Header** PtrToHdr() { return &mHdr; }
static Header* EmptyHdr() { return &sEmptyTArrayHeader; }
};
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) {
typedef typename mozilla::RemoveCV<E>::Type E_NoCV;
typedef typename mozilla::RemoveCV<A>::Type A_NoCV;
static_assert(!mozilla::IsSame<E_NoCV*, A_NoCV>::value,
"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) {
typedef typename mozilla::RemoveCV<E>::Type E_NoCV;
typedef typename mozilla::RemoveCV<
typename ::detail::ChooseFirst<Args...>::Type>::Type A_NoCV;
static_assert(!mozilla::IsSame<E_NoCV*, A_NoCV>::value,
"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 IsPod, 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_CopyChooser 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_CopyWithMemutils {
const static bool allowRealloc = true;
static void MoveNonOverlappingRegionWithHeader(void* aDest, const void* aSrc,
size_t aCount,
size_t aElemSize) {
memcpy(aDest, aSrc, sizeof(nsTArrayHeader) + aCount * aElemSize);
}
static void MoveOverlappingRegion(void* aDest, void* aSrc, size_t aCount,
size_t aElemSize) {
memmove(aDest, aSrc, aCount * aElemSize);
}
static void MoveNonOverlappingRegion(void* aDest, void* aSrc, size_t aCount,
size_t aElemSize) {
memcpy(aDest, aSrc, aCount * aElemSize);
}
};
//
// A template class that defines how to copy elements calling their constructors
// and destructors appropriately.
//
template <class ElemType>
struct nsTArray_CopyWithConstructors {
typedef nsTArrayElementTraits<ElemType> traits;
const static bool allowRealloc = false;
static void MoveNonOverlappingRegionWithHeader(void* aDest, void* aSrc,
size_t aCount,
size_t aElemSize) {
nsTArrayHeader* destHeader = static_cast<nsTArrayHeader*>(aDest);
nsTArrayHeader* srcHeader = static_cast<nsTArrayHeader*>(aSrc);
*destHeader = *srcHeader;
MoveNonOverlappingRegion(
static_cast<uint8_t*>(aDest) + sizeof(nsTArrayHeader),
static_cast<uint8_t*>(aSrc) + sizeof(nsTArrayHeader), aCount,
aElemSize);
}
// These functions are defined by analogy with memmove and memcpy.
// What they actually do is slightly different: MoveOverlappingRegion
// 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. MoveNonOverlappingRegion assumes that moving
// front-to-back is always valid. So they're really more like
// std::move{_backward,} in that respect. We keep these names because
// we think they read slightly better, and MoveNonOverlappingRegion is
// only ever called on overlapping regions from MoveOverlappingRegion.
static void MoveOverlappingRegion(void* aDest, void* aSrc, size_t aCount,
size_t aElemSize) {
ElemType* destElem = static_cast<ElemType*>(aDest);
ElemType* srcElem = static_cast<ElemType*>(aSrc);
ElemType* destElemEnd = destElem + aCount;
ElemType* srcElemEnd = srcElem + aCount;
if (destElem == srcElem) {
return; // In practice, we don't do this.
}
// Figure out whether to copy back-to-front or front-to-back.
if (srcElemEnd > destElem && srcElemEnd < destElemEnd) {
while (destElemEnd != destElem) {
--destElemEnd;
--srcElemEnd;
traits::Construct(destElemEnd, std::move(*srcElemEnd));
traits::Destruct(srcElemEnd);
}
} else {
MoveNonOverlappingRegion(aDest, aSrc, aCount, aElemSize);
}
}
static void MoveNonOverlappingRegion(void* aDest, void* aSrc, size_t aCount,
size_t aElemSize) {
ElemType* destElem = static_cast<ElemType*>(aDest);
ElemType* srcElem = static_cast<ElemType*>(aSrc);
ElemType* destElemEnd = destElem + aCount;
#ifdef DEBUG
ElemType* srcElemEnd = srcElem + aCount;
MOZ_ASSERT(srcElemEnd <= destElem || srcElemEnd > destElemEnd);
#endif
while (destElem != destElemEnd) {
traits::Construct(destElem, std::move(*srcElem));
traits::Destruct(srcElem);
++destElem;
++srcElem;
}
}
};
//
// The default behaviour is to use memcpy/memmove for everything.
//
template <class E>
struct MOZ_NEEDS_MEMMOVABLE_TYPE nsTArray_CopyChooser {
using Type = nsTArray_CopyWithMemutils;
};
//
// Some classes require constructors/destructors to be called, so they are
// specialized here.
//
#define DECLARE_USE_COPY_CONSTRUCTORS(T) \
template <> \
struct nsTArray_CopyChooser<T> { \
using Type = nsTArray_CopyWithConstructors<T>; \
};
#define DECLARE_USE_COPY_CONSTRUCTORS_FOR_TEMPLATE(T) \
template <typename S> \
struct nsTArray_CopyChooser<T<S>> { \
using Type = nsTArray_CopyWithConstructors<T<S>>; \
};
DECLARE_USE_COPY_CONSTRUCTORS_FOR_TEMPLATE(JS::Heap)
DECLARE_USE_COPY_CONSTRUCTORS_FOR_TEMPLATE(std::function)
DECLARE_USE_COPY_CONSTRUCTORS(nsRegion)
DECLARE_USE_COPY_CONSTRUCTORS(nsIntRegion)
DECLARE_USE_COPY_CONSTRUCTORS(mozilla::layers::TileClient)
DECLARE_USE_COPY_CONSTRUCTORS(mozilla::layers::RenderRootDisplayListData)
DECLARE_USE_COPY_CONSTRUCTORS(mozilla::layers::RenderRootUpdates)
DECLARE_USE_COPY_CONSTRUCTORS(mozilla::SerializedStructuredCloneBuffer)
DECLARE_USE_COPY_CONSTRUCTORS(mozilla::dom::ipc::StructuredCloneData)
DECLARE_USE_COPY_CONSTRUCTORS(mozilla::dom::ClonedMessageData)
DECLARE_USE_COPY_CONSTRUCTORS(mozilla::dom::indexedDB::StructuredCloneReadInfo);
DECLARE_USE_COPY_CONSTRUCTORS(
mozilla::dom::indexedDB::ObjectStoreCursorResponse)
DECLARE_USE_COPY_CONSTRUCTORS(mozilla::dom::indexedDB::IndexCursorResponse)
DECLARE_USE_COPY_CONSTRUCTORS(
mozilla::dom::indexedDB::SerializedStructuredCloneReadInfo);
DECLARE_USE_COPY_CONSTRUCTORS(JSStructuredCloneData)
DECLARE_USE_COPY_CONSTRUCTORS(mozilla::dom::MessageData)
DECLARE_USE_COPY_CONSTRUCTORS(mozilla::dom::RefMessageData)
DECLARE_USE_COPY_CONSTRUCTORS(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 : mozilla::FalseType {};
template <typename T, typename U>
struct IsCompareMethod<T, U,
decltype(mozilla::DeclVal<T>()(mozilla::DeclVal<U>(),
mozilla::DeclVal<U>()))>
: mozilla::TrueType {};
// 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_CopyChooser<E>::Type>,
public nsTArray_TypedBase<E, nsTArray_Impl<E, Alloc>> {
private:
typedef nsTArrayFallibleAllocator FallibleAlloc;
typedef nsTArrayInfallibleAllocator InfallibleAlloc;
public:
typedef typename nsTArray_CopyChooser<E>::Type copy_type;
typedef nsTArray_base<Alloc, copy_type> base_type;
typedef typename base_type::size_type size_type;
typedef typename base_type::index_type index_type;
typedef E elem_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<elem_type&, nsTArray<E>> iterator;
typedef mozilla::ArrayIterator<const elem_type&, nsTArray<E>> const_iterator;
typedef mozilla::ReverseIterator<iterator> reverse_iterator;
typedef mozilla::ReverseIterator<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) {
SwapElements(aOther);
}
// 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>&|.
explicit nsTArray_Impl(const self_type& aOther) { AppendElements(aOther); }
explicit nsTArray_Impl(std::initializer_list<E> aIL) {
AppendElements(aIL.begin(), aIL.size());
}
// Allow converting to a const array with a different kind of allocator,
// Since the allocator doesn't matter for const arrays
template <typename Allocator>
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
operator const nsTArray<E>&() const {
return *reinterpret_cast<const nsTArray<E>*>(this);
}
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.
self_type& operator=(const self_type& aOther) {
if (this != &aOther) {
ReplaceElementsAt(0, Length(), aOther.Elements(), aOther.Length());
}
return *this;
}
// 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();
SwapElements(aOther);
}
return *this;
}
// Return true if this array has the same length and the same
// elements as |aOther|.
template <typename Allocator>
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|.
bool operator!=(const self_type& aOther) const { return !operator==(aOther); }
template <typename Allocator>
self_type& operator=(const nsTArray_Impl<E, Allocator>& aOther) {
ReplaceElementsAt(0, Length(), aOther.Elements(), aOther.Length());
return *this;
}
template <typename Allocator>
self_type& operator=(nsTArray_Impl<E, Allocator>&& aOther) {
Clear();
SwapElements(aOther);
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.
size_t ShallowSizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const {
if (this->UsesAutoArrayBuffer() || Hdr() == EmptyHdr()) {
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.
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.
elem_type* Elements() { return reinterpret_cast<elem_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.
const elem_type* Elements() const {
return reinterpret_cast<const elem_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.
elem_type& ElementAt(index_type aIndex) {
if (MOZ_UNLIKELY(aIndex >= Length())) {
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.
const elem_type& ElementAt(index_type aIndex) const {
if (MOZ_UNLIKELY(aIndex >= Length())) {
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.
elem_type& SafeElementAt(index_type aIndex, elem_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.
const elem_type& SafeElementAt(index_type aIndex,
const elem_type& aDef) const {
return aIndex < Length() ? Elements()[aIndex] : aDef;
}
// Shorthand for ElementAt(aIndex)
elem_type& operator[](index_type aIndex) { return ElementAt(aIndex); }
// Shorthand for ElementAt(aIndex)
const elem_type& operator[](index_type aIndex) const {
return ElementAt(aIndex);
}
// Shorthand for ElementAt(length - 1)
elem_type& LastElement() { return ElementAt(Length() - 1); }
// Shorthand for ElementAt(length - 1)
const elem_type& LastElement() const { return ElementAt(Length() - 1); }
// Shorthand for SafeElementAt(length - 1, def)
elem_type& SafeLastElement(elem_type& aDef) {
return SafeElementAt(Length() - 1, aDef);
}
// Shorthand for SafeElementAt(length - 1, def)
const elem_type& SafeLastElement(const elem_type& aDef) const {
return SafeElementAt(Length() - 1, aDef);
}
// Methods for range-based for loops.
iterator begin() { return iterator(*this, 0); }
const_iterator begin() const { return const_iterator(*this, 0); }
const_iterator cbegin() const { return begin(); }
iterator end() { return iterator(*this, Length()); }
const_iterator end() const { return const_iterator(*this, Length()); }
const_iterator cend() const { return end(); }
// Methods for reverse iterating.
reverse_iterator rbegin() { return reverse_iterator(end()); }
const_reverse_iterator rbegin() const {
return const_reverse_iterator(end());
}
const_reverse_iterator crbegin() const { return rbegin(); }
reverse_iterator rend() { return reverse_iterator(begin()); }
const_reverse_iterator rend() const {
return const_reverse_iterator(begin());
}
const_reverse_iterator crend() const { return rend(); }
// Span integration
operator mozilla::Span<elem_type>() {
return mozilla::Span<elem_type>(Elements(), Length());
}
operator mozilla::Span<const elem_type>() const {
return mozilla::Span<const elem_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>
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>
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 elem_type.
// @param aItem The item to search for.
// @return true if the element was found.
template <class Item>
bool Contains(const Item& aItem) const {
return Contains(aItem, nsDefaultComparator<elem_type, Item>());
}
// Like Contains(), but assumes a sorted array.
template <class Item>
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>
index_type IndexOf(const Item& aItem, index_type aStart,
const Comparator& aComp) const {
::detail::CompareWrapper<Comparator, Item> comp(aComp);
const elem_type* iter = Elements() + aStart;
const elem_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 elem_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>
index_type IndexOf(const Item& aItem, index_type aStart = 0) const {
return IndexOf(aItem, aStart, nsDefaultComparator<elem_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>
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 elem_type* iend = Elements() - 1;
const elem_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 elem_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>
index_type LastIndexOf(const Item& aItem, index_type aStart = NoIndex) const {
return LastIndexOf(aItem, aStart, nsDefaultComparator<elem_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>
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 elem_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>
index_type BinaryIndexOf(const Item& aItem) const {
return BinaryIndexOf(aItem, nsDefaultComparator<elem_type, Item>());
}
//
// Mutation methods
//
template <class Allocator, typename ActualAlloc = Alloc>
typename ActualAlloc::ResultType Assign(
const nsTArray_Impl<E, Allocator>& aOther) {
return ActualAlloc::ConvertBoolToResultType(
!!ReplaceElementsAt<E, ActualAlloc>(0, Length(), aOther.Elements(),
aOther.Length()));
}
template <class Allocator>
MOZ_MUST_USE 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();
SwapElements(aOther);
}
// 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 (base_type::mHdr == EmptyHdr()) {
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 elem_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) {
InsertElementsAt(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.
protected:
template <class Item, typename ActualAlloc = Alloc>
elem_type* ReplaceElementsAt(index_type aStart, size_type aCount,
const Item* aArray, size_type aArrayLen);
public:
template <class Item>
MOZ_MUST_USE elem_type* ReplaceElementsAt(index_type aStart, size_type aCount,
const Item* aArray,
size_type aArrayLen,
const mozilla::fallible_t&) {
return ReplaceElementsAt<Item, FallibleAlloc>(aStart, aCount, aArray,
aArrayLen);
}
// A variation on the ReplaceElementsAt method defined above.
protected:
template <class Item, typename ActualAlloc = Alloc>
elem_type* ReplaceElementsAt(index_type aStart, size_type aCount,
const nsTArray<Item>& aArray) {
return ReplaceElementsAt<Item, ActualAlloc>(
aStart, aCount, aArray.Elements(), aArray.Length());
}
template <class Item, typename ActualAlloc = Alloc>
elem_type* ReplaceElementsAt(index_type aStart, size_type aCount,
mozilla::Span<const Item> aSpan) {
return ReplaceElementsAt<Item, ActualAlloc>(
aStart, aCount, aSpan.Elements(), aSpan.Length());
}
public:
template <class Item>
MOZ_MUST_USE elem_type* ReplaceElementsAt(index_type aStart, size_type aCount,
const nsTArray<Item>& aArray,
const mozilla::fallible_t&) {
return ReplaceElementsAt<Item, FallibleAlloc>(aStart, aCount, aArray);
}
template <class Item>
MOZ_MUST_USE elem_type* ReplaceElementsAt(index_type aStart, size_type aCount,
mozilla::Span<const Item> aSpan,
const mozilla::fallible_t&) {
return ReplaceElementsAt<Item, FallibleAlloc>(aStart, aCount, aSpan);
}
// A variation on the ReplaceElementsAt method defined above.
protected:
template <class Item, typename ActualAlloc = Alloc>
elem_type* ReplaceElementsAt(index_type aStart, size_type aCount,
const Item& aItem) {
return ReplaceElementsAt<Item, ActualAlloc>(aStart, aCount, &aItem, 1);
}
public:
template <class Item>
MOZ_MUST_USE elem_type* ReplaceElementsAt(index_type aStart, size_type aCount,
const Item& aItem,
const mozilla::fallible_t&) {
return ReplaceElementsAt<Item, FallibleAlloc>(aStart, aCount, aItem);
}
// A variation on the ReplaceElementsAt method defined above.
template <class Item>
elem_type* ReplaceElementAt(index_type aIndex, const Item& aItem) {
return ReplaceElementsAt(aIndex, 1, &aItem, 1);
}
// A variation on the ReplaceElementsAt method defined above.
protected:
template <class Item, typename ActualAlloc = Alloc>
elem_type* InsertElementsAt(index_type aIndex, const Item* aArray,
size_type aArrayLen) {
return ReplaceElementsAt<Item, ActualAlloc>(aIndex, 0, aArray, aArrayLen);
}
public:
template <class Item>
MOZ_MUST_USE elem_type* InsertElementsAt(index_type aIndex,
const Item* aArray,
size_type aArrayLen,
const mozilla::fallible_t&) {
return InsertElementsAt<Item, FallibleAlloc>(aIndex, aArray, aArrayLen);
}
// A variation on the ReplaceElementsAt method defined above.
protected:
template <class Item, class Allocator, typename ActualAlloc = Alloc>
elem_type* InsertElementsAt(index_type aIndex,
const nsTArray_Impl<Item, Allocator>& aArray) {
return ReplaceElementsAt<Item, ActualAlloc>(aIndex, 0, aArray.Elements(),
aArray.Length());
}
template <class Item, typename ActualAlloc = Alloc>
elem_type* InsertElementsAt(index_type aIndex,
mozilla::Span<const Item> aSpan) {
return ReplaceElementsAt<Item, ActualAlloc>(aIndex, 0, aSpan.Elements(),
aSpan.Length());
}
public:
template <class Item, class Allocator>
MOZ_MUST_USE elem_type* InsertElementsAt(
index_type aIndex, const nsTArray_Impl<Item, Allocator>& aArray,
const mozilla::fallible_t&) {
return InsertElementsAt<Item, Allocator, FallibleAlloc>(aIndex, aArray);
}
template <class Item>
MOZ_MUST_USE elem_type* InsertElementsAt(index_type aIndex,
mozilla::Span<const Item> aSpan,
const mozilla::fallible_t&) {
return InsertElementsAt<Item, FallibleAlloc>(aIndex, aSpan);
}
// 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.
protected:
template <typename ActualAlloc = Alloc>
elem_type* InsertElementAt(index_type aIndex);
public:
MOZ_MUST_USE
elem_type* InsertElementAt(index_type aIndex, const mozilla::fallible_t&) {
return InsertElementAt<FallibleAlloc>(aIndex);
}
// Insert a new element, move constructing if possible.
protected:
template <class Item, typename ActualAlloc = Alloc>
elem_type* InsertElementAt(index_type aIndex, Item&& aItem);
public:
template <class Item>
MOZ_MUST_USE elem_type* InsertElementAt(index_type aIndex, Item&& aItem,
const mozilla::fallible_t&) {
return InsertElementAt<Item, 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] = T()
//
// would accomplish the same thing as long as T has the appropriate moving
// operator=, but some types don't for various reasons.
elem_type* ReconstructElementAt(index_type aIndex) {
elem_type* elem = &ElementAt(aIndex);
elem_traits::Destruct(elem);
elem_traits::Construct(elem);
return 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>
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 elem_type& aElement) {
return comp.Compare(aElement, aItem) <= 0 ? 1 : -1;
},
&index);
return index;
}
// A variation on the IndexOfFirstElementGt method defined above.
template <class Item>
index_type IndexOfFirstElementGt(const Item& aItem) const {
return IndexOfFirstElementGt(aItem, nsDefaultComparator<elem_type, Item>());
}
// Inserts |aItem| at such an index to guarantee that if the array
// was previously sorted, it will remain sorted after this
// insertion.
protected:
template <class Item, class Comparator, typename ActualAlloc = Alloc>
elem_type* InsertElementSorted(Item&& aItem, const Comparator& aComp) {
index_type index = IndexOfFirstElementGt<Item, Comparator>(aItem, aComp);
return InsertElementAt<Item, ActualAlloc>(index, std::forward<Item>(aItem));
}
public:
template <class Item, class Comparator>
MOZ_MUST_USE elem_type* InsertElementSorted(Item&& aItem,
const Comparator& aComp,
const mozilla::fallible_t&) {
return InsertElementSorted<Item, Comparator, FallibleAlloc>(
std::forward<Item>(aItem), aComp);
}
// A variation on the InsertElementSorted method defined above.
protected:
template <class Item, typename ActualAlloc = Alloc>
elem_type* InsertElementSorted(Item&& aItem) {
nsDefaultComparator<elem_type, Item> comp;
return InsertElementSorted<Item, decltype(comp), ActualAlloc>(
std::forward<Item>(aItem), comp);
}
public:
template <class Item>
MOZ_MUST_USE elem_type* InsertElementSorted(Item&& aItem,
const mozilla::fallible_t&) {
return InsertElementSorted<Item, FallibleAlloc>(std::forward<Item>(aItem));
}
// 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.
protected:
template <class Item, typename ActualAlloc = Alloc>
elem_type* AppendElements(const Item* aArray, size_type aArrayLen);
template <class Item, typename ActualAlloc = Alloc>
elem_type* AppendElements(mozilla::Span<const Item> aSpan) {
return AppendElements<Item, FallibleAlloc>(aSpan.Elements(),
aSpan.Length());
}
template <class Item, size_t Length, typename ActualAlloc = Alloc>
elem_type* AppendElements(const mozilla::Array<Item, Length>& aArray) {
return AppendElements<Item, ActualAlloc>(&aArray[0], Length);
}
public:
template <class Item>
/* MOZ_MUST_USE */
elem_type* AppendElements(const Item* aArray, size_type aArrayLen,
const mozilla::fallible_t&) {
return AppendElements<Item, FallibleAlloc>(aArray, aArrayLen);
}
template <class Item>
/* MOZ_MUST_USE */
elem_type* AppendElements(mozilla::Span<const Item> aSpan,
const mozilla::fallible_t&) {
return AppendElements<Item, FallibleAlloc>(aSpan.Elements(),
aSpan.Length());
}
// A variation on the AppendElements method defined above.
protected:
template <class Item, class Allocator, typename ActualAlloc = Alloc>
elem_type* AppendElements(const nsTArray_Impl<Item, Allocator>& aArray) {
return AppendElements<Item, ActualAlloc>(aArray.Elements(),
aArray.Length());
}
public:
template <class Item, class Allocator>
/* MOZ_MUST_USE */
elem_type* AppendElements(const nsTArray_Impl<Item, Allocator>& aArray,
const mozilla::fallible_t&) {
return AppendElements<Item, Allocator, FallibleAlloc>(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.
protected:
template <class Item, class Allocator, typename ActualAlloc = Alloc>
elem_type* AppendElements(nsTArray_Impl<Item, Allocator>&& aArray);
public:
template <class Item, class Allocator, typename ActualAlloc = Alloc>
/* MOZ_MUST_USE */
elem_type* AppendElements(nsTArray_Impl<Item, Allocator>&& aArray,
const mozilla::fallible_t&) {
return AppendElements<Item, Allocator>(std::move(aArray));
}
// Append a new element, constructed in place from the provided arguments.
protected:
template <typename ActualAlloc, class... Args>
elem_type* EmplaceBackInternal(Args&&... aItem);
public:
template <class... Args>
MOZ_MUST_USE elem_type* EmplaceBack(const mozilla::fallible_t&,
Args&&... aArgs) {
return EmplaceBackInternal<FallibleAlloc, Args...>(
std::forward<Args>(aArgs)...);
}
// Append a new element, move constructing if possible.
protected:
template <class Item, typename ActualAlloc = Alloc>
elem_type* AppendElement(Item&& aItem);
public:
template <class Item>
/* MOZ_MUST_USE */
elem_type* AppendElement(Item&& aItem, const mozilla::fallible_t&) {
return AppendElement<Item, FallibleAlloc>(std::forward<Item>(aItem));
}
// Append new elements without copy-constructing. This is useful to avoid
// temporaries.
// @return A pointer to the newly appended elements, or null on OOM.
protected:
template <typename ActualAlloc = Alloc>
elem_type* AppendElements(size_type aCount) {
if (!ActualAlloc::Successful(this->template ExtendCapacity<ActualAlloc>(
Length(), aCount, sizeof(elem_type)))) {
return nullptr;
}
elem_type* elems = Elements() + Length();
size_type i;
for (i = 0; i < aCount; ++i) {
elem_traits::Construct(elems + i);
}
this->IncrementLength(aCount);
return elems;
}
public:
/* MOZ_MUST_USE */
elem_type* AppendElements(size_type aCount, const mozilla::fallible_t&) {
return AppendElements<FallibleAlloc>(aCount);
}
// 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.
protected:
template <typename ActualAlloc = Alloc>
elem_type* AppendElement() {
return AppendElements<ActualAlloc>(1);
}
public:
/* MOZ_MUST_USE */
elem_type* AppendElement(const mozilla::fallible_t&) {
return AppendElement<FallibleAlloc>();
}
// 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 RemoveElementsAt(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 the RemoveElementAt that removes the last element.
void RemoveLastElement() { RemoveElementAt(Length() - 1); }
// Removes the last element of the array and returns a copy of it.
MOZ_MUST_USE
elem_type PopLastElement() {
elem_type elem = std::move(LastElement());
RemoveLastElement();
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();
Compact();
}
// 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.
template <typename Predicate>
void 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 elem_type.
template <class Item>
bool RemoveElement(const Item& aItem) {
return RemoveElement(aItem, nsDefaultComparator<elem_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<elem_type, Item>());
}
// This method causes the elements contained in this array and the given
// array to be swapped.
template <class Allocator>
typename Alloc::ResultType SwapElements(nsTArray_Impl<E, Allocator>& aOther) {
return Alloc::Result(this->template SwapArrayElements<Alloc>(
aOther, sizeof(elem_type), MOZ_ALIGNOF(elem_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 elem_type&)
// - Both index and reference: F(size_t, maybe-const elem_type&)
// `elem_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 elem_type&), or "
"(size_t, maybe-const elem_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? elem_type&)`
// - `aFunction(index_type, maybe-const? elem_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 `elem_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(
mozilla::IsSame<
typename mozilla::FunctionTypeTraits<Function>::ReturnType,
typename mozilla::FunctionTypeTraits<FunctionElse>::ReturnType>::
value,
"ApplyIf's `Function` and `FunctionElse` must return the same type.");
::detail::CompareWrapper<Comparator, Item> comp(aComp);
const elem_type* const elements = Elements();
const elem_type* const iend = elements + Length();
for (const elem_type* iter = elements + aStart; iter != iend; ++iter) {
if (comp.Equals(*iter, aItem)) {
return InvokeWithIndexAndOrReference<const elem_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(
mozilla::IsSame<
typename mozilla::FunctionTypeTraits<Function>::ReturnType,
typename mozilla::FunctionTypeTraits<FunctionElse>::ReturnType>::
value,
"ApplyIf's `Function` and `FunctionElse` must return the same type.");
::detail::CompareWrapper<Comparator, Item> comp(aComp);
elem_type* const elements = Elements();
elem_type* const iend = elements + Length();
for (elem_type* iter = elements + aStart; iter != iend; ++iter) {
if (comp.Equals(*iter, aItem)) {
return InvokeWithIndexAndOrReference<elem_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<elem_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<elem_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(elem_type)));
}
public:
MOZ_MUST_USE
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 elem_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 if the new length is guaranteed to be smaller than
// the old.
protected:
template <typename ActualAlloc = Alloc>
typename ActualAlloc::ResultType SetLength(size_type aNewLen) {
size_type oldLen = Length();
if (aNewLen > oldLen) {
return ActualAlloc::ConvertBoolToResultType(
InsertElementsAt<ActualAlloc>(oldLen, aNewLen - oldLen) != nullptr);
}
TruncateLength(aNewLen);
return ActualAlloc::ConvertBoolToResultType(true);
}
public:
MOZ_MUST_USE
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 elem_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) {
size_type oldLen = Length();
MOZ_ASSERT(aNewLen <= oldLen, "caller should use SetLength instead");
RemoveElementsAt(aNewLen, oldLen - 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 elem_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(
!!InsertElementsAt<ActualAlloc>(oldLen, aMinLen - oldLen));
}
return ActualAlloc::ConvertBoolToResultType(true);
}
public:
MOZ_MUST_USE
bool EnsureLengthAtLeast(size_type aMinLen, const mozilla::fallible_t&) {
return EnsureLengthAtLeast<FallibleAlloc>(aMinLen);
}
// This method inserts elements into the array, constructing
// them using elem_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
protected:
template <typename ActualAlloc = Alloc>
elem_type* InsertElementsAt(index_type aIndex, size_type aCount) {
if (!ActualAlloc::Successful(this->template InsertSlotsAt<ActualAlloc>(
aIndex, aCount, sizeof(elem_type), MOZ_ALIGNOF(elem_type)))) {
return nullptr;
}
// Initialize the extra array elements
elem_type* iter = Elements() + aIndex;
elem_type* iend = iter + aCount;
for (; iter != iend; ++iter) {
elem_traits::Construct(iter);
}
return Elements() + aIndex;
}
public:
MOZ_MUST_USE
elem_type* InsertElementsAt(index_type aIndex, size_type aCount,
const mozilla::fallible_t&) {
return InsertElementsAt<FallibleAlloc>(aIndex, aCount);
}
// This method inserts elements into the array, constructing them
// elem_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.
protected:
template <class Item, typename ActualAlloc = Alloc>
elem_type* InsertElementsAt(index_type aIndex, size_type aCount,
const Item& aItem);
public:
template <class Item>
MOZ_MUST_USE elem_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(elem_type), MOZ_ALIGNOF(elem_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 elem_type* a = static_cast<const elem_type*>(aE1);
const elem_type* b = static_cast<const elem_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, elem_type> comp(aComp);
NS_QuickSort(Elements(), Length(), sizeof(elem_type),
Compare<decltype(comp)>, &comp);
}
// A variation on the Sort method defined above that assumes that
// 'operator<' is defined for elem_type.
void Sort() { Sort(nsDefaultComparator<elem_type, elem_type>()); }
// This method reverses the array in place.
void Reverse() {
elem_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 elem_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) {
elem_type* iter = Elements() + aStart;
elem_type* iend = iter + aCount;
for (; iter != iend; ++iter) {
elem_traits::Destruct(iter);
}
}
// This method invokes elem_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<
mozilla::IsPod<Item>::value,
mozilla::IsSame<Item, elem_type>::value>::implementation(Elements(),
aStart, aCount,
aValues);
}
};
template <typename E, class Alloc>
template <class Item, typename ActualAlloc>
auto nsTArray_Impl<E, Alloc>::ReplaceElementsAt(index_type aStart,
size_type aCount,
const Item* aArray,
size_type aArrayLen)
-> elem_type* {
if (MOZ_UNLIKELY(aStart > Length())) {
InvalidArrayIndex_CRASH(aStart, Length());
}
// Adjust memory allocation up-front to catch errors.
if (!ActualAlloc::Successful(this->template EnsureCapacity<ActualAlloc>(
Length() + aArrayLen - aCount, sizeof(elem_type)))) {
return nullptr;
}
DestructRange(aStart, aCount);
this->template ShiftData<ActualAlloc>(
aStart, aCount, aArrayLen, sizeof(elem_type), MOZ_ALIGNOF(elem_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())) {
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(elem_type), MOZ_ALIGNOF(elem_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())) {
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(elem_type),
MOZ_ALIGNOF(elem_type));
}
template <typename E, class Alloc>
template <typename Predicate>
void nsTArray_Impl<E, Alloc>::RemoveElementsBy(Predicate aPredicate) {
if (base_type::mHdr == EmptyHdr()) {
return;
}
index_type j = 0;
index_type len = Length();
for (index_type i = 0; i < len; ++i) {
if (aPredicate(Elements()[i])) {
elem_traits::Destruct(Elements() + i);
} else {
if (j < i) {
copy_type::MoveNonOverlappingRegion(Elements() + j, Elements() + i, 1,
sizeof(elem_type));
}
++j;
}
}
base_type::mHdr->mLength = j;
}
template <typename E, class Alloc>
template <class Item, typename ActualAlloc>
auto nsTArray_Impl<E, Alloc>::InsertElementsAt(index_type aIndex,
size_type aCount,
const Item& aItem)
-> elem_type* {
if (!ActualAlloc::Successful(this->template InsertSlotsAt<ActualAlloc>(
aIndex, aCount, sizeof(elem_type), MOZ_ALIGNOF(elem_type)))) {
return nullptr;
}
// Initialize the extra array elements
elem_type* iter = Elements() + aIndex;
elem_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>::InsertElementAt(index_type aIndex) -> elem_type* {
if (MOZ_UNLIKELY(aIndex > Length())) {
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(elem_type)))) {
return nullptr;
}
this->template ShiftData<ActualAlloc>(aIndex, 0, 1, sizeof(elem_type),
MOZ_ALIGNOF(elem_type));
elem_type* elem = Elements() + aIndex;
elem_traits::Construct(elem);
return elem;
}
template <typename E, class Alloc>
template <class Item, typename ActualAlloc>
auto nsTArray_Impl<E, Alloc>::InsertElementAt(index_type aIndex, Item&& aItem)
-> elem_type* {
if (MOZ_UNLIKELY(aIndex > Length())) {
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(elem_type)))) {
return nullptr;
}
this->template ShiftData<ActualAlloc>(aIndex, 0, 1, sizeof(elem_type),
MOZ_ALIGNOF(elem_type));
elem_type* elem = Elements() + aIndex;
elem_traits::Construct(elem, std::forward<Item>(aItem));
return elem;
}
template <typename E, class Alloc>
template <class Item, typename ActualAlloc>
auto nsTArray_Impl<E, Alloc>::AppendElements(const Item* aArray,
size_type aArrayLen)
-> elem_type* {
if (!ActualAlloc::Successful(this->template ExtendCapacity<ActualAlloc>(
Length(), aArrayLen, sizeof(elem_type)))) {
return nullptr;
}
index_type len = Length();
AssignRange(len, aArrayLen, aArray);
this->IncrementLength(aArrayLen);
return Elements() + len;
}
template <typename E, class Alloc>
template <class Item, class Allocator, typename ActualAlloc>
auto nsTArray_Impl<E, Alloc>::AppendElements(
nsTArray_Impl<Item, Allocator>&& aArray) -> elem_type* {
MOZ_ASSERT(&aArray != this, "argument must be different aArray");
if (Length() == 0) {
SwapElements<ActualAlloc>(aArray);
return Elements();
}
index_type len = Length();
index_type otherLen = aArray.Length();
if (!Alloc::Successful(this->template ExtendCapacity<Alloc>(
len, otherLen, sizeof(elem_type)))) {
return nullptr;
}
copy_type::MoveNonOverlappingRegion(Elements() + len, aArray.Elements(),
otherLen, sizeof(elem_type));
this->IncrementLength(otherLen);
aArray.template ShiftData<Alloc>(0, otherLen, 0, sizeof(elem_type),
MOZ_ALIGNOF(elem_type));
return Elements() + len;
}
template <typename E, class Alloc>
template <class Item, typename ActualAlloc>
auto nsTArray_Impl<E, Alloc>::AppendElement(Item&& aItem) -> elem_type* {
// Length() + 1 is guaranteed to not overflow, so EnsureCapacity is OK.
if (!ActualAlloc::Successful(this->template EnsureCapacity<ActualAlloc>(
Length() + 1, sizeof(elem_type)))) {
return nullptr;
}
elem_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)
-> elem_type* {
// Length() + 1 is guaranteed to not overflow, so EnsureCapacity is OK.
if (!ActualAlloc::Successful(this->template EnsureCapacity<ActualAlloc>(
Length() + 1, sizeof(elem_type)))) {
return nullptr;
}
elem_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();
}
template <typename E, typename Alloc>
inline void ImplCycleCollectionTraverse(
nsCycleCollectionTraversalCallback& aCallback,
nsTArray_Impl<E, Alloc>& aField, const char* aName, uint32_t aFlags = 0) {
aFlags |= CycleCollectionEdgeNameArrayFlag;
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:
typedef nsTArray_Impl<E, nsTArrayInfallibleAllocator> base_type;
typedef nsTArray<E> self_type;
typedef typename base_type::size_type size_type;
nsTArray() {}
explicit nsTArray(size_type aCapacity) : base_type(aCapacity) {}
explicit nsTArray(const nsTArray& aOther) : base_type(aOther) {}
MOZ_IMPLICIT nsTArray(nsTArray&& aOther) : base_type(std::move(aOther)) {}
MOZ_IMPLICIT nsTArray(std::initializer_list<E> aIL) : base_type(aIL) {}
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)) {}
self_type& operator=(const self_type& aOther) {
base_type::operator=(aOther);
return *this;
}
template <class Allocator>
self_type& operator=(const nsTArray_Impl<E, Allocator>& aOther) {
base_type::operator=(aOther);
return *this;
}
self_type& operator=(self_type&& aOther) {
base_type::operator=(std::move(aOther));
return *this;
}
template <class Allocator>
self_type& operator=(nsTArray_Impl<E, Allocator>&& aOther) {
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... Args>
typename base_type::elem_type* EmplaceBack(Args&&... aArgs) {
return this
->template EmplaceBackInternal<nsTArrayInfallibleAllocator, Args...>(
std::forward<Args>(aArgs)...);
}
};
//
// 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) {}
explicit FallibleTArray(const FallibleTArray<E>& aOther)
: base_type(aOther) {}
FallibleTArray(FallibleTArray<E>&& aOther) : base_type(std::move(aOther)) {}
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)) {}
self_type& operator=(const self_type& aOther) {
base_type::operator=(aOther);
return *this;
}
template <class Allocator>
self_type& operator=(const nsTArray_Impl<E, Allocator>& aOther) {
base_type::operator=(aOther);
return *this;
}
self_type& operator=(self_type&& aOther) {
base_type::operator=(std::move(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::elem_type elem_type;
AutoTArray() : mAlign() { Init(); }
AutoTArray(const self_type& aOther) : nsTArray<E>() {
Init();
this->AppendElements(aOther);
}
AutoTArray(self_type&& aOther) : nsTArray<E>() {
Init();
this->SwapElements(aOther);
}
explicit AutoTArray(const base_type& aOther) : mAlign() {
Init();
this->AppendElements(aOther);
}
explicit AutoTArray(base_type&& aOther) : mAlign() {
Init();
this->SwapElements(aOther);
}
template <typename Allocator>
explicit AutoTArray(nsTArray_Impl<elem_type, Allocator>&& aOther) {
Init();
this->SwapElements(aOther);
}
MOZ_IMPLICIT AutoTArray(std::initializer_list<E> aIL) : mAlign() {
Init();
this->AppendElements(aIL.begin(), aIL.size());
}
self_type& operator=(const self_type& aOther) {
base_type::operator=(aOther);
return *this;
}
self_type& operator=(self_type&& aOther) {
base_type::operator=(std::move(aOther));
return *this;
}
template <typename Allocator>
self_type& operator=(const nsTArray_Impl<elem_type, Allocator>& aOther) {
base_type::operator=(aOther);
return *this;
}
private:
// nsTArray_base casts itself as an nsAutoArrayBase in order to get a pointer
// to mAutoBuf.
template <class Allocator, class Copier>
friend class nsTArray_base;
void Init() {
static_assert(MOZ_ALIGNOF(elem_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(elem_type)) ==
reinterpret_cast<Header*>(&mAutoBuf),
"GetAutoArrayBuffer needs to be fixed");
}
// Declare mAutoBuf aligned to the maximum of the header's alignment and
// elem_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(elem_type)];
// Do the max operation inline to ensure that it is a compile-time constant.
mozilla::AlignedElem<(MOZ_ALIGNOF(Header) > MOZ_ALIGNOF(elem_type))
? MOZ_ALIGNOF(Header)
: MOZ_ALIGNOF(elem_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> {};
template <class E, size_t N>
struct nsTArray_CopyChooser<AutoTArray<E, N>> {
typedef nsTArray_CopyWithConstructors<AutoTArray<E, N>> Type;
};
// Span integration
namespace mozilla {
template <class ElementType, class TArrayAlloc>
Span<ElementType> MakeSpan(nsTArray_Impl<ElementType, TArrayAlloc>& aTArray) {
return aTArray;
}
template <class ElementType, class TArrayAlloc>
Span<const ElementType> MakeSpan(
const nsTArray_Impl<ElementType, TArrayAlloc>& aTArray) {
return aTArray;
}
template <typename T>
class nsTArrayBackInserter
: public std::iterator<std::output_iterator_tag, void, void, void, void> {
nsTArray<T>* mArray;
public:
explicit nsTArrayBackInserter(nsTArray<T>& aArray) : mArray{&aArray} {}
template <typename O>
nsTArrayBackInserter& operator=(O&& aValue) {
mArray->EmplaceBack(std::forward<O>(aValue));
return *this;
}
nsTArrayBackInserter& operator*() { return *this; }
void operator++() {}
};
template <typename T>
auto MakeBackInserter(nsTArray<T>& aArray) {
return nsTArrayBackInserter<T>{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::MakeSpan(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__
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