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/*
* Copyright 2011 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#ifndef SkTArray_DEFINED
#define SkTArray_DEFINED
#include "../private/SkTLogic.h"
#include "../private/SkTemplates.h"
#include "SkTypes.h"
#include <new>
#include <utility>
/** When MEM_MOVE is true T will be bit copied when moved.
When MEM_MOVE is false, T will be copy constructed / destructed.
In all cases T will be default-initialized on allocation,
and its destructor will be called from this object's destructor.
*/
template <typename T, bool MEM_MOVE = false> class SkTArray {
public:
/**
* Creates an empty array with no initial storage
*/
SkTArray() { this->init(); }
/**
* Creates an empty array that will preallocate space for reserveCount
* elements.
*/
explicit SkTArray(int reserveCount) { this->init(0, reserveCount); }
/**
* Copies one array to another. The new array will be heap allocated.
*/
explicit SkTArray(const SkTArray& that) {
this->init(that.fCount);
this->copy(that.fItemArray);
}
explicit SkTArray(SkTArray&& that) {
// TODO: If 'that' owns its memory why don't we just steal the pointer?
this->init(that.fCount);
that.move(fMemArray);
that.fCount = 0;
}
/**
* Creates a SkTArray by copying contents of a standard C array. The new
* array will be heap allocated. Be careful not to use this constructor
* when you really want the (void*, int) version.
*/
SkTArray(const T* array, int count) {
this->init(count);
this->copy(array);
}
SkTArray& operator=(const SkTArray& that) {
if (this == &that) {
return *this;
}
for (int i = 0; i < fCount; ++i) {
fItemArray[i].~T();
}
fCount = 0;
this->checkRealloc(that.count());
fCount = that.count();
this->copy(that.fItemArray);
return *this;
}
SkTArray& operator=(SkTArray&& that) {
if (this == &that) {
return *this;
}
for (int i = 0; i < fCount; ++i) {
fItemArray[i].~T();
}
fCount = 0;
this->checkRealloc(that.count());
fCount = that.count();
that.move(fMemArray);
that.fCount = 0;
return *this;
}
~SkTArray() {
for (int i = 0; i < fCount; ++i) {
fItemArray[i].~T();
}
if (fOwnMemory) {
sk_free(fMemArray);
}
}
/**
* Resets to count() == 0 and resets any reserve count.
*/
void reset() {
this->pop_back_n(fCount);
fReserved = false;
}
/**
* Resets to count() = n newly constructed T objects and resets any reserve count.
*/
void reset(int n) {
SkASSERT(n >= 0);
for (int i = 0; i < fCount; ++i) {
fItemArray[i].~T();
}
// Set fCount to 0 before calling checkRealloc so that no elements are moved.
fCount = 0;
this->checkRealloc(n);
fCount = n;
for (int i = 0; i < fCount; ++i) {
new (fItemArray + i) T;
}
fReserved = false;
}
/**
* Resets to a copy of a C array and resets any reserve count.
*/
void reset(const T* array, int count) {
for (int i = 0; i < fCount; ++i) {
fItemArray[i].~T();
}
fCount = 0;
this->checkRealloc(count);
fCount = count;
this->copy(array);
fReserved = false;
}
/**
* Ensures there is enough reserved space for n additional elements. The is guaranteed at least
* until the array size grows above n and subsequently shrinks below n, any version of reset()
* is called, or reserve() is called again.
*/
void reserve(int n) {
SkASSERT(n >= 0);
if (n > 0) {
this->checkRealloc(n);
fReserved = fOwnMemory;
} else {
fReserved = false;
}
}
void removeShuffle(int n) {
SkASSERT(n < fCount);
int newCount = fCount - 1;
fCount = newCount;
fItemArray[n].~T();
if (n != newCount) {
this->move(n, newCount);
}
}
/**
* Number of elements in the array.
*/
int count() const { return fCount; }
/**
* Is the array empty.
*/
bool empty() const { return !fCount; }
/**
* Adds 1 new default-initialized T value and returns it by reference. Note
* the reference only remains valid until the next call that adds or removes
* elements.
*/
T& push_back() {
void* newT = this->push_back_raw(1);
return *new (newT) T;
}
/**
* Version of above that uses a copy constructor to initialize the new item
*/
T& push_back(const T& t) {
void* newT = this->push_back_raw(1);
return *new (newT) T(t);
}
/**
* Version of above that uses a move constructor to initialize the new item
*/
T& push_back(T&& t) {
void* newT = this->push_back_raw(1);
return *new (newT) T(std::move(t));
}
/**
* Construct a new T at the back of this array.
*/
template<class... Args> T& emplace_back(Args&&... args) {
void* newT = this->push_back_raw(1);
return *new (newT) T(std::forward<Args>(args)...);
}
/**
* Allocates n more default-initialized T values, and returns the address of
* the start of that new range. Note: this address is only valid until the
* next API call made on the array that might add or remove elements.
*/
T* push_back_n(int n) {
SkASSERT(n >= 0);
void* newTs = this->push_back_raw(n);
for (int i = 0; i < n; ++i) {
new (static_cast<char*>(newTs) + i * sizeof(T)) T;
}
return static_cast<T*>(newTs);
}
/**
* Version of above that uses a copy constructor to initialize all n items
* to the same T.
*/
T* push_back_n(int n, const T& t) {
SkASSERT(n >= 0);
void* newTs = this->push_back_raw(n);
for (int i = 0; i < n; ++i) {
new (static_cast<char*>(newTs) + i * sizeof(T)) T(t);
}
return static_cast<T*>(newTs);
}
/**
* Version of above that uses a copy constructor to initialize the n items
* to separate T values.
*/
T* push_back_n(int n, const T t[]) {
SkASSERT(n >= 0);
this->checkRealloc(n);
for (int i = 0; i < n; ++i) {
new (fItemArray + fCount + i) T(t[i]);
}
fCount += n;
return fItemArray + fCount - n;
}
/**
* Version of above that uses the move constructor to set n items.
*/
T* move_back_n(int n, T* t) {
SkASSERT(n >= 0);
this->checkRealloc(n);
for (int i = 0; i < n; ++i) {
new (fItemArray + fCount + i) T(std::move(t[i]));
}
fCount += n;
return fItemArray + fCount - n;
}
/**
* Removes the last element. Not safe to call when count() == 0.
*/
void pop_back() {
SkASSERT(fCount > 0);
--fCount;
fItemArray[fCount].~T();
this->checkRealloc(0);
}
/**
* Removes the last n elements. Not safe to call when count() < n.
*/
void pop_back_n(int n) {
SkASSERT(n >= 0);
SkASSERT(fCount >= n);
fCount -= n;
for (int i = 0; i < n; ++i) {
fItemArray[fCount + i].~T();
}
this->checkRealloc(0);
}
/**
* Pushes or pops from the back to resize. Pushes will be default
* initialized.
*/
void resize_back(int newCount) {
SkASSERT(newCount >= 0);
if (newCount > fCount) {
this->push_back_n(newCount - fCount);
} else if (newCount < fCount) {
this->pop_back_n(fCount - newCount);
}
}
/** Swaps the contents of this array with that array. Does a pointer swap if possible,
otherwise copies the T values. */
void swap(SkTArray* that) {
if (this == that) {
return;
}
if (fOwnMemory && that->fOwnMemory) {
SkTSwap(fItemArray, that->fItemArray);
SkTSwap(fCount, that->fCount);
SkTSwap(fAllocCount, that->fAllocCount);
} else {
// This could be more optimal...
SkTArray copy(std::move(*that));
*that = std::move(*this);
*this = std::move(copy);
}
}
T* begin() {
return fItemArray;
}
const T* begin() const {
return fItemArray;
}
T* end() {
return fItemArray ? fItemArray + fCount : NULL;
}
const T* end() const {
return fItemArray ? fItemArray + fCount : NULL;
}
/**
* Get the i^th element.
*/
T& operator[] (int i) {
SkASSERT(i < fCount);
SkASSERT(i >= 0);
return fItemArray[i];
}
const T& operator[] (int i) const {
SkASSERT(i < fCount);
SkASSERT(i >= 0);
return fItemArray[i];
}
/**
* equivalent to operator[](0)
*/
T& front() { SkASSERT(fCount > 0); return fItemArray[0];}
const T& front() const { SkASSERT(fCount > 0); return fItemArray[0];}
/**
* equivalent to operator[](count() - 1)
*/
T& back() { SkASSERT(fCount); return fItemArray[fCount - 1];}
const T& back() const { SkASSERT(fCount > 0); return fItemArray[fCount - 1];}
/**
* equivalent to operator[](count()-1-i)
*/
T& fromBack(int i) {
SkASSERT(i >= 0);
SkASSERT(i < fCount);
return fItemArray[fCount - i - 1];
}
const T& fromBack(int i) const {
SkASSERT(i >= 0);
SkASSERT(i < fCount);
return fItemArray[fCount - i - 1];
}
bool operator==(const SkTArray<T, MEM_MOVE>& right) const {
int leftCount = this->count();
if (leftCount != right.count()) {
return false;
}
for (int index = 0; index < leftCount; ++index) {
if (fItemArray[index] != right.fItemArray[index]) {
return false;
}
}
return true;
}
bool operator!=(const SkTArray<T, MEM_MOVE>& right) const {
return !(*this == right);
}
inline int allocCntForTest() const;
protected:
/**
* Creates an empty array that will use the passed storage block until it
* is insufficiently large to hold the entire array.
*/
template <int N>
SkTArray(SkAlignedSTStorage<N,T>* storage) {
this->initWithPreallocatedStorage(0, storage->get(), N);
}
/**
* Copy another array, using preallocated storage if preAllocCount >=
* array.count(). Otherwise storage will only be used when array shrinks
* to fit.
*/
template <int N>
SkTArray(const SkTArray& array, SkAlignedSTStorage<N,T>* storage) {
this->initWithPreallocatedStorage(array.fCount, storage->get(), N);
this->copy(array.fItemArray);
}
/**
* Move another array, using preallocated storage if preAllocCount >=
* array.count(). Otherwise storage will only be used when array shrinks
* to fit.
*/
template <int N>
SkTArray(SkTArray&& array, SkAlignedSTStorage<N,T>* storage) {
this->initWithPreallocatedStorage(array.fCount, storage->get(), N);
array.move(fMemArray);
array.fCount = 0;
}
/**
* Copy a C array, using preallocated storage if preAllocCount >=
* count. Otherwise storage will only be used when array shrinks
* to fit.
*/
template <int N>
SkTArray(const T* array, int count, SkAlignedSTStorage<N,T>* storage) {
this->initWithPreallocatedStorage(count, storage->get(), N);
this->copy(array);
}
private:
void init(int count = 0, int reserveCount = 0) {
SkASSERT(count >= 0);
SkASSERT(reserveCount >= 0);
fCount = count;
if (!count && !reserveCount) {
fAllocCount = 0;
fMemArray = nullptr;
fOwnMemory = false;
fReserved = false;
} else {
fAllocCount = SkTMax(count, SkTMax(kMinHeapAllocCount, reserveCount));
fMemArray = sk_malloc_throw(fAllocCount, sizeof(T));
fOwnMemory = true;
fReserved = reserveCount > 0;
}
}
void initWithPreallocatedStorage(int count, void* preallocStorage, int preallocCount) {
SkASSERT(count >= 0);
SkASSERT(preallocCount > 0);
SkASSERT(preallocStorage);
fCount = count;
fMemArray = nullptr;
fReserved = false;
if (count > preallocCount) {
fAllocCount = SkTMax(count, kMinHeapAllocCount);
fMemArray = sk_malloc_throw(fAllocCount, sizeof(T));
fOwnMemory = true;
} else {
fAllocCount = preallocCount;
fMemArray = preallocStorage;
fOwnMemory = false;
}
}
/** In the following move and copy methods, 'dst' is assumed to be uninitialized raw storage.
* In the following move methods, 'src' is destroyed leaving behind uninitialized raw storage.
*/
void copy(const T* src) {
// Some types may be trivially copyable, in which case we *could* use memcopy; but
// MEM_MOVE == true implies that the type is trivially movable, and not necessarily
// trivially copyable (think sk_sp<>). So short of adding another template arg, we
// must be conservative and use copy construction.
for (int i = 0; i < fCount; ++i) {
new (fItemArray + i) T(src[i]);
}
}
template <bool E = MEM_MOVE> SK_WHEN(E, void) move(int dst, int src) {
memcpy(&fItemArray[dst], &fItemArray[src], sizeof(T));
}
template <bool E = MEM_MOVE> SK_WHEN(E, void) move(void* dst) {
sk_careful_memcpy(dst, fMemArray, fCount * sizeof(T));
}
template <bool E = MEM_MOVE> SK_WHEN(!E, void) move(int dst, int src) {
new (&fItemArray[dst]) T(std::move(fItemArray[src]));
fItemArray[src].~T();
}
template <bool E = MEM_MOVE> SK_WHEN(!E, void) move(void* dst) {
for (int i = 0; i < fCount; ++i) {
new (static_cast<char*>(dst) + sizeof(T) * i) T(std::move(fItemArray[i]));
fItemArray[i].~T();
}
}
static constexpr int kMinHeapAllocCount = 8;
// Helper function that makes space for n objects, adjusts the count, but does not initialize
// the new objects.
void* push_back_raw(int n) {
this->checkRealloc(n);
void* ptr = fItemArray + fCount;
fCount += n;
return ptr;
}
void checkRealloc(int delta) {
SkASSERT(fCount >= 0);
SkASSERT(fAllocCount >= 0);
SkASSERT(-delta <= fCount);
int newCount = fCount + delta;
// We allow fAllocCount to be in the range [newCount, 3*newCount]. We also never shrink
// when we're currently using preallocated memory, would allocate less than
// kMinHeapAllocCount, or a reserve count was specified that has yet to be exceeded.
bool mustGrow = newCount > fAllocCount;
bool shouldShrink = fAllocCount > 3 * newCount && fOwnMemory && !fReserved;
if (!mustGrow && !shouldShrink) {
return;
}
// Whether we're growing or shrinking, we leave at least 50% extra space for future growth.
int newAllocCount = newCount + ((newCount + 1) >> 1);
// Align the new allocation count to kMinHeapAllocCount.
static_assert(SkIsPow2(kMinHeapAllocCount), "min alloc count not power of two.");
newAllocCount = (newAllocCount + (kMinHeapAllocCount - 1)) & ~(kMinHeapAllocCount - 1);
// At small sizes the old and new alloc count can both be kMinHeapAllocCount.
if (newAllocCount == fAllocCount) {
return;
}
fAllocCount = newAllocCount;
void* newMemArray = sk_malloc_throw(fAllocCount, sizeof(T));
this->move(newMemArray);
if (fOwnMemory) {
sk_free(fMemArray);
}
fMemArray = newMemArray;
fOwnMemory = true;
fReserved = false;
}
union {
T* fItemArray;
void* fMemArray;
};
int fCount;
int fAllocCount;
bool fOwnMemory : 1;
bool fReserved : 1;
};
template<typename T, bool MEM_MOVE> constexpr int SkTArray<T, MEM_MOVE>::kMinHeapAllocCount;
/**
* Subclass of SkTArray that contains a preallocated memory block for the array.
*/
template <int N, typename T, bool MEM_MOVE= false>
class SkSTArray : public SkTArray<T, MEM_MOVE> {
private:
typedef SkTArray<T, MEM_MOVE> INHERITED;
public:
SkSTArray() : INHERITED(&fStorage) {
}
SkSTArray(const SkSTArray& array)
: INHERITED(array, &fStorage) {
}
SkSTArray(SkSTArray&& array)
: INHERITED(std::move(array), &fStorage) {
}
explicit SkSTArray(const INHERITED& array)
: INHERITED(array, &fStorage) {
}
explicit SkSTArray(INHERITED&& array)
: INHERITED(std::move(array), &fStorage) {
}
explicit SkSTArray(int reserveCount)
: INHERITED(reserveCount) {
}
SkSTArray(const T* array, int count)
: INHERITED(array, count, &fStorage) {
}
SkSTArray& operator=(const SkSTArray& array) {
INHERITED::operator=(array);
return *this;
}
SkSTArray& operator=(SkSTArray&& array) {
INHERITED::operator=(std::move(array));
return *this;
}
SkSTArray& operator=(const INHERITED& array) {
INHERITED::operator=(array);
return *this;
}
SkSTArray& operator=(INHERITED&& array) {
INHERITED::operator=(std::move(array));
return *this;
}
private:
SkAlignedSTStorage<N,T> fStorage;
};
#endif