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262 lines
8.5 KiB
C++
262 lines
8.5 KiB
C++
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2; c-file-offsets: ((substatement-open . 0)) -*- */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef nsVoidArray_h___
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#define nsVoidArray_h___
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//#define DEBUG_VOIDARRAY 1
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#include "nsDebug.h"
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#include "mozilla/MemoryReporting.h"
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#include <stdint.h>
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// Comparator callback function for sorting array values.
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typedef int (* nsVoidArrayComparatorFunc)
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(const void* aElement1, const void* aElement2, void* aData);
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// Enumerator callback function. Return false to stop
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typedef bool (* nsVoidArrayEnumFunc)(void* aElement, void *aData);
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typedef bool (* nsVoidArrayEnumFuncConst)(const void* aElement, void *aData);
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// SizeOfExcludingThis callback function.
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typedef size_t (* nsVoidArraySizeOfElementIncludingThisFunc)(const void* aElement,
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mozilla::MallocSizeOf aMallocSizeOf,
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void *aData);
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/// A basic zero-based array of void*'s that manages its own memory
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class NS_COM_GLUE nsVoidArray {
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public:
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nsVoidArray();
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nsVoidArray(int32_t aCount); // initial count of aCount elements set to nullptr
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~nsVoidArray();
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nsVoidArray& operator=(const nsVoidArray& other);
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inline int32_t Count() const {
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return mImpl ? mImpl->mCount : 0;
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}
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// If the array grows, the newly created entries will all be null
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bool SetCount(int32_t aNewCount);
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// returns the max number that can be held without allocating
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inline int32_t GetArraySize() const {
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return mImpl ? mImpl->mSize : 0;
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}
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void* FastElementAt(int32_t aIndex) const
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{
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NS_ASSERTION(0 <= aIndex && aIndex < Count(), "nsVoidArray::FastElementAt: index out of range");
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return mImpl->mArray[aIndex];
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}
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// This both asserts and bounds-checks, because (1) we don't want
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// people to write bad code, but (2) we don't want to change it to
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// crashing for backwards compatibility. See bug 96108.
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void* ElementAt(int32_t aIndex) const
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{
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NS_ASSERTION(0 <= aIndex && aIndex < Count(), "nsVoidArray::ElementAt: index out of range");
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return SafeElementAt(aIndex);
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}
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// bounds-checked version
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void* SafeElementAt(int32_t aIndex) const
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{
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if (uint32_t(aIndex) >= uint32_t(Count())) // handles aIndex < 0 too
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{
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return nullptr;
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}
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// The bounds check ensures mImpl is non-null.
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return mImpl->mArray[aIndex];
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}
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void* operator[](int32_t aIndex) const { return ElementAt(aIndex); }
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int32_t IndexOf(void* aPossibleElement) const;
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bool InsertElementAt(void* aElement, int32_t aIndex);
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bool InsertElementsAt(const nsVoidArray &other, int32_t aIndex);
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bool ReplaceElementAt(void* aElement, int32_t aIndex);
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// useful for doing LRU arrays, sorting, etc
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bool MoveElement(int32_t aFrom, int32_t aTo);
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bool AppendElement(void* aElement) {
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return InsertElementAt(aElement, Count());
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}
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bool AppendElements(nsVoidArray& aElements) {
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return InsertElementsAt(aElements, Count());
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}
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bool RemoveElement(void* aElement);
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void RemoveElementsAt(int32_t aIndex, int32_t aCount);
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void RemoveElementAt(int32_t aIndex) { return RemoveElementsAt(aIndex,1); }
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void Clear();
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bool SizeTo(int32_t aMin);
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// Subtly different - Compact() tries to be smart about whether we
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// should reallocate the array; SizeTo() always reallocates.
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void Compact();
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void Sort(nsVoidArrayComparatorFunc aFunc, void* aData);
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bool EnumerateForwards(nsVoidArrayEnumFunc aFunc, void* aData);
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bool EnumerateForwards(nsVoidArrayEnumFuncConst aFunc, void* aData) const;
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bool EnumerateBackwards(nsVoidArrayEnumFunc aFunc, void* aData);
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// Measures the size of the array's element storage, and if
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// |aSizeOfElementIncludingThis| is non-nullptr, measures the size of things
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// pointed to by elements.
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size_t SizeOfExcludingThis(
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nsVoidArraySizeOfElementIncludingThisFunc aSizeOfElementIncludingThis,
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mozilla::MallocSizeOf aMallocSizeOf, void* aData = nullptr) const;
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protected:
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bool GrowArrayBy(int32_t aGrowBy);
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struct Impl {
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/**
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* The actual array size.
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*/
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int32_t mSize;
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/**
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* The number of elements in the array
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*/
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int32_t mCount;
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/**
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* Array data, padded out to the actual size of the array.
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*/
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void* mArray[1];
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};
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Impl* mImpl;
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#if DEBUG_VOIDARRAY
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int32_t mMaxCount;
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int32_t mMaxSize;
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bool mIsAuto;
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#endif
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// bit twiddlers
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void SetArray(Impl *newImpl, int32_t aSize, int32_t aCount);
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private:
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/// Copy constructors are not allowed
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nsVoidArray(const nsVoidArray& other);
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};
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//===================================================================
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// nsSmallVoidArray is not a general-purpose replacement for
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// ns(Auto)VoidArray because there is (some) extra CPU overhead for arrays
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// larger than 1 element, though not a lot. It is appropriate for
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// space-sensitive uses where sizes of 0 or 1 are moderately common or
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// more, and where we're NOT storing arbitrary integers or arbitrary
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// pointers.
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// NOTE: nsSmallVoidArray can ONLY be used for holding items that always
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// have the low bit as a 0 - i.e. element & 1 == 0. This happens to be
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// true for allocated and object pointers for all the architectures we run
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// on, but conceivably there might be some architectures/compilers for
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// which it is NOT true. We know this works for all existing architectures
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// because if it didn't then nsCheapVoidArray would have failed. Also note
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// that we will ASSERT if this assumption is violated in DEBUG builds.
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// XXX we're really re-implementing the whole nsVoidArray interface here -
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// some form of abstract class would be useful
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// I disagree on the abstraction here. If the point of this class is to be
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// as small as possible, and no one will ever derive from it, as I found
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// today, there should not be any virtualness to it to avoid the vtable
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// ptr overhead.
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class NS_COM_GLUE nsSmallVoidArray : private nsVoidArray
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{
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public:
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~nsSmallVoidArray();
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nsSmallVoidArray& operator=(nsSmallVoidArray& other);
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void* operator[](int32_t aIndex) const { return ElementAt(aIndex); }
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int32_t GetArraySize() const;
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int32_t Count() const;
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void* FastElementAt(int32_t aIndex) const;
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// This both asserts and bounds-checks, because (1) we don't want
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// people to write bad code, but (2) we don't want to change it to
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// crashing for backwards compatibility. See bug 96108.
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void* ElementAt(int32_t aIndex) const
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{
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NS_ASSERTION(0 <= aIndex && aIndex < Count(), "nsSmallVoidArray::ElementAt: index out of range");
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return SafeElementAt(aIndex);
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}
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void* SafeElementAt(int32_t aIndex) const {
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// let compiler inline; it may be able to remove these checks
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if (uint32_t(aIndex) >= uint32_t(Count())) // handles aIndex < 0 too
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{
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return nullptr;
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}
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return FastElementAt(aIndex);
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}
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int32_t IndexOf(void* aPossibleElement) const;
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bool InsertElementAt(void* aElement, int32_t aIndex);
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bool InsertElementsAt(const nsVoidArray &other, int32_t aIndex);
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bool ReplaceElementAt(void* aElement, int32_t aIndex);
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bool MoveElement(int32_t aFrom, int32_t aTo);
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bool AppendElement(void* aElement);
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bool AppendElements(nsVoidArray& aElements) {
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return InsertElementsAt(aElements, Count());
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}
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bool RemoveElement(void* aElement);
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void RemoveElementsAt(int32_t aIndex, int32_t aCount);
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void RemoveElementAt(int32_t aIndex);
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void Clear();
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bool SizeTo(int32_t aMin);
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void Compact();
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void Sort(nsVoidArrayComparatorFunc aFunc, void* aData);
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bool EnumerateForwards(nsVoidArrayEnumFunc aFunc, void* aData);
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bool EnumerateBackwards(nsVoidArrayEnumFunc aFunc, void* aData);
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private:
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bool HasSingle() const
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{
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return !!(reinterpret_cast<intptr_t>(mImpl) & 0x1);
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}
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void* GetSingle() const
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{
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NS_ASSERTION(HasSingle(), "wrong type");
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return reinterpret_cast<void*>
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(reinterpret_cast<intptr_t>(mImpl) & ~0x1);
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}
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void SetSingle(void *aChild)
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{
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NS_ASSERTION(HasSingle() || !mImpl, "overwriting array");
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mImpl = reinterpret_cast<Impl*>
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(reinterpret_cast<intptr_t>(aChild) | 0x1);
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}
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bool IsEmpty() const
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{
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// Note that this isn't the same as Count()==0
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return !mImpl;
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}
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const nsVoidArray* AsArray() const
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{
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NS_ASSERTION(!HasSingle(), "This is a single");
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return this;
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}
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nsVoidArray* AsArray()
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{
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NS_ASSERTION(!HasSingle(), "This is a single");
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return this;
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}
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bool EnsureArray();
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};
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#endif /* nsVoidArray_h___ */
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