virtualx-engine/thirdparty/icu4c/common/cmemory.h

849 lines
28 KiB
C++

// © 2016 and later: Unicode, Inc. and others.
// License & terms of use: http://www.unicode.org/copyright.html
/*
******************************************************************************
*
* Copyright (C) 1997-2016, International Business Machines
* Corporation and others. All Rights Reserved.
*
******************************************************************************
*
* File CMEMORY.H
*
* Contains stdlib.h/string.h memory functions
*
* @author Bertrand A. Damiba
*
* Modification History:
*
* Date Name Description
* 6/20/98 Bertrand Created.
* 05/03/99 stephen Changed from functions to macros.
*
******************************************************************************
*/
#ifndef CMEMORY_H
#define CMEMORY_H
#include "unicode/utypes.h"
#include <stddef.h>
#include <string.h>
#include "unicode/localpointer.h"
#if U_DEBUG && defined(UPRV_MALLOC_COUNT)
#include <stdio.h>
#endif
#define uprv_memcpy(dst, src, size) U_STANDARD_CPP_NAMESPACE memcpy(dst, src, size)
#define uprv_memmove(dst, src, size) U_STANDARD_CPP_NAMESPACE memmove(dst, src, size)
/**
* \def UPRV_LENGTHOF
* Convenience macro to determine the length of a fixed array at compile-time.
* @param array A fixed length array
* @return The length of the array, in elements
* @internal
*/
#define UPRV_LENGTHOF(array) (int32_t)(sizeof(array)/sizeof((array)[0]))
#define uprv_memset(buffer, mark, size) U_STANDARD_CPP_NAMESPACE memset(buffer, mark, size)
#define uprv_memcmp(buffer1, buffer2, size) U_STANDARD_CPP_NAMESPACE memcmp(buffer1, buffer2,size)
#define uprv_memchr(ptr, value, num) U_STANDARD_CPP_NAMESPACE memchr(ptr, value, num)
U_CAPI void * U_EXPORT2
uprv_malloc(size_t s) U_MALLOC_ATTR U_ALLOC_SIZE_ATTR(1);
U_CAPI void * U_EXPORT2
uprv_realloc(void *mem, size_t size) U_ALLOC_SIZE_ATTR(2);
U_CAPI void U_EXPORT2
uprv_free(void *mem);
U_CAPI void * U_EXPORT2
uprv_calloc(size_t num, size_t size) U_MALLOC_ATTR U_ALLOC_SIZE_ATTR2(1,2);
/**
* Get the least significant bits of a pointer (a memory address).
* For example, with a mask of 3, the macro gets the 2 least significant bits,
* which will be 0 if the pointer is 32-bit (4-byte) aligned.
*
* uintptr_t is the most appropriate integer type to cast to.
*/
#define U_POINTER_MASK_LSB(ptr, mask) ((uintptr_t)(ptr) & (mask))
/**
* Create & return an instance of "type" in statically allocated storage.
* e.g.
* static std::mutex *myMutex = STATIC_NEW(std::mutex);
* To destroy an object created in this way, invoke the destructor explicitly, e.g.
* myMutex->~mutex();
* DO NOT use delete.
* DO NOT use with class UMutex, which has specific support for static instances.
*
* STATIC_NEW is intended for use when
* - We want a static (or global) object.
* - We don't want it to ever be destructed, or to explicitly control destruction,
* to avoid use-after-destruction problems.
* - We want to avoid an ordinary heap allocated object,
* to avoid the possibility of memory allocation failures, and
* to avoid memory leak reports, from valgrind, for example.
* This is defined as a macro rather than a template function because each invocation
* must define distinct static storage for the object being returned.
*/
#define STATIC_NEW(type) [] () { \
alignas(type) static char storage[sizeof(type)]; \
return new(storage) type();} ()
/**
* Heap clean up function, called from u_cleanup()
* Clears any user heap functions from u_setMemoryFunctions()
* Does NOT deallocate any remaining allocated memory.
*/
U_CFUNC UBool
cmemory_cleanup(void);
/**
* A function called by <TT>uhash_remove</TT>,
* <TT>uhash_close</TT>, or <TT>uhash_put</TT> to delete
* an existing key or value.
* @param obj A key or value stored in a hashtable
* @see uprv_deleteUObject
*/
typedef void U_CALLCONV UObjectDeleter(void* obj);
/**
* Deleter for UObject instances.
* Works for all subclasses of UObject because it has a virtual destructor.
*/
U_CAPI void U_EXPORT2
uprv_deleteUObject(void *obj);
#ifdef __cplusplus
#include <utility>
#include "unicode/uobject.h"
U_NAMESPACE_BEGIN
/**
* "Smart pointer" class, deletes memory via uprv_free().
* For most methods see the LocalPointerBase base class.
* Adds operator[] for array item access.
*
* @see LocalPointerBase
*/
template<typename T>
class LocalMemory : public LocalPointerBase<T> {
public:
using LocalPointerBase<T>::operator*;
using LocalPointerBase<T>::operator->;
/**
* Constructor takes ownership.
* @param p simple pointer to an array of T items that is adopted
*/
explicit LocalMemory(T *p=NULL) : LocalPointerBase<T>(p) {}
/**
* Move constructor, leaves src with isNull().
* @param src source smart pointer
*/
LocalMemory(LocalMemory<T> &&src) U_NOEXCEPT : LocalPointerBase<T>(src.ptr) {
src.ptr=NULL;
}
/**
* Destructor deletes the memory it owns.
*/
~LocalMemory() {
uprv_free(LocalPointerBase<T>::ptr);
}
/**
* Move assignment operator, leaves src with isNull().
* The behavior is undefined if *this and src are the same object.
* @param src source smart pointer
* @return *this
*/
LocalMemory<T> &operator=(LocalMemory<T> &&src) U_NOEXCEPT {
uprv_free(LocalPointerBase<T>::ptr);
LocalPointerBase<T>::ptr=src.ptr;
src.ptr=NULL;
return *this;
}
/**
* Swap pointers.
* @param other other smart pointer
*/
void swap(LocalMemory<T> &other) U_NOEXCEPT {
T *temp=LocalPointerBase<T>::ptr;
LocalPointerBase<T>::ptr=other.ptr;
other.ptr=temp;
}
/**
* Non-member LocalMemory swap function.
* @param p1 will get p2's pointer
* @param p2 will get p1's pointer
*/
friend inline void swap(LocalMemory<T> &p1, LocalMemory<T> &p2) U_NOEXCEPT {
p1.swap(p2);
}
/**
* Deletes the array it owns,
* and adopts (takes ownership of) the one passed in.
* @param p simple pointer to an array of T items that is adopted
*/
void adoptInstead(T *p) {
uprv_free(LocalPointerBase<T>::ptr);
LocalPointerBase<T>::ptr=p;
}
/**
* Deletes the array it owns, allocates a new one and reset its bytes to 0.
* Returns the new array pointer.
* If the allocation fails, then the current array is unchanged and
* this method returns NULL.
* @param newCapacity must be >0
* @return the allocated array pointer, or NULL if the allocation failed
*/
inline T *allocateInsteadAndReset(int32_t newCapacity=1);
/**
* Deletes the array it owns and allocates a new one, copying length T items.
* Returns the new array pointer.
* If the allocation fails, then the current array is unchanged and
* this method returns NULL.
* @param newCapacity must be >0
* @param length number of T items to be copied from the old array to the new one;
* must be no more than the capacity of the old array,
* which the caller must track because the LocalMemory does not track it
* @return the allocated array pointer, or NULL if the allocation failed
*/
inline T *allocateInsteadAndCopy(int32_t newCapacity=1, int32_t length=0);
/**
* Array item access (writable).
* No index bounds check.
* @param i array index
* @return reference to the array item
*/
T &operator[](ptrdiff_t i) const { return LocalPointerBase<T>::ptr[i]; }
};
template<typename T>
inline T *LocalMemory<T>::allocateInsteadAndReset(int32_t newCapacity) {
if(newCapacity>0) {
T *p=(T *)uprv_malloc(newCapacity*sizeof(T));
if(p!=NULL) {
uprv_memset(p, 0, newCapacity*sizeof(T));
uprv_free(LocalPointerBase<T>::ptr);
LocalPointerBase<T>::ptr=p;
}
return p;
} else {
return NULL;
}
}
template<typename T>
inline T *LocalMemory<T>::allocateInsteadAndCopy(int32_t newCapacity, int32_t length) {
if(newCapacity>0) {
T *p=(T *)uprv_malloc(newCapacity*sizeof(T));
if(p!=NULL) {
if(length>0) {
if(length>newCapacity) {
length=newCapacity;
}
uprv_memcpy(p, LocalPointerBase<T>::ptr, (size_t)length*sizeof(T));
}
uprv_free(LocalPointerBase<T>::ptr);
LocalPointerBase<T>::ptr=p;
}
return p;
} else {
return NULL;
}
}
/**
* Simple array/buffer management class using uprv_malloc() and uprv_free().
* Provides an internal array with fixed capacity. Can alias another array
* or allocate one.
*
* The array address is properly aligned for type T. It might not be properly
* aligned for types larger than T (or larger than the largest subtype of T).
*
* Unlike LocalMemory and LocalArray, this class never adopts
* (takes ownership of) another array.
*
* WARNING: MaybeStackArray only works with primitive (plain-old data) types.
* It does NOT know how to call a destructor! If you work with classes with
* destructors, consider:
*
* - LocalArray in localpointer.h if you know the length ahead of time
* - MaybeStackVector if you know the length at runtime
*/
template<typename T, int32_t stackCapacity>
class MaybeStackArray {
public:
// No heap allocation. Use only on the stack.
static void* U_EXPORT2 operator new(size_t) U_NOEXCEPT = delete;
static void* U_EXPORT2 operator new[](size_t) U_NOEXCEPT = delete;
#if U_HAVE_PLACEMENT_NEW
static void* U_EXPORT2 operator new(size_t, void*) U_NOEXCEPT = delete;
#endif
/**
* Default constructor initializes with internal T[stackCapacity] buffer.
*/
MaybeStackArray() : ptr(stackArray), capacity(stackCapacity), needToRelease(false) {}
/**
* Automatically allocates the heap array if the argument is larger than the stack capacity.
* Intended for use when an approximate capacity is known at compile time but the true
* capacity is not known until runtime.
*/
MaybeStackArray(int32_t newCapacity, UErrorCode status) : MaybeStackArray() {
if (U_FAILURE(status)) {
return;
}
if (capacity < newCapacity) {
if (resize(newCapacity) == nullptr) {
status = U_MEMORY_ALLOCATION_ERROR;
}
}
}
/**
* Destructor deletes the array (if owned).
*/
~MaybeStackArray() { releaseArray(); }
/**
* Move constructor: transfers ownership or copies the stack array.
*/
MaybeStackArray(MaybeStackArray<T, stackCapacity> &&src) U_NOEXCEPT;
/**
* Move assignment: transfers ownership or copies the stack array.
*/
MaybeStackArray<T, stackCapacity> &operator=(MaybeStackArray<T, stackCapacity> &&src) U_NOEXCEPT;
/**
* Returns the array capacity (number of T items).
* @return array capacity
*/
int32_t getCapacity() const { return capacity; }
/**
* Access without ownership change.
* @return the array pointer
*/
T *getAlias() const { return ptr; }
/**
* Returns the array limit. Simple convenience method.
* @return getAlias()+getCapacity()
*/
T *getArrayLimit() const { return getAlias()+capacity; }
// No "operator T *() const" because that can make
// expressions like mbs[index] ambiguous for some compilers.
/**
* Array item access (const).
* No index bounds check.
* @param i array index
* @return reference to the array item
*/
const T &operator[](ptrdiff_t i) const { return ptr[i]; }
/**
* Array item access (writable).
* No index bounds check.
* @param i array index
* @return reference to the array item
*/
T &operator[](ptrdiff_t i) { return ptr[i]; }
/**
* Deletes the array (if owned) and aliases another one, no transfer of ownership.
* If the arguments are illegal, then the current array is unchanged.
* @param otherArray must not be NULL
* @param otherCapacity must be >0
*/
void aliasInstead(T *otherArray, int32_t otherCapacity) {
if(otherArray!=NULL && otherCapacity>0) {
releaseArray();
ptr=otherArray;
capacity=otherCapacity;
needToRelease=false;
}
}
/**
* Deletes the array (if owned) and allocates a new one, copying length T items.
* Returns the new array pointer.
* If the allocation fails, then the current array is unchanged and
* this method returns NULL.
* @param newCapacity can be less than or greater than the current capacity;
* must be >0
* @param length number of T items to be copied from the old array to the new one
* @return the allocated array pointer, or NULL if the allocation failed
*/
inline T *resize(int32_t newCapacity, int32_t length=0);
/**
* Gives up ownership of the array if owned, or else clones it,
* copying length T items; resets itself to the internal stack array.
* Returns NULL if the allocation failed.
* @param length number of T items to copy when cloning,
* and capacity of the clone when cloning
* @param resultCapacity will be set to the returned array's capacity (output-only)
* @return the array pointer;
* caller becomes responsible for deleting the array
*/
inline T *orphanOrClone(int32_t length, int32_t &resultCapacity);
protected:
// Resizes the array to the size of src, then copies the contents of src.
void copyFrom(const MaybeStackArray &src, UErrorCode &status) {
if (U_FAILURE(status)) {
return;
}
if (this->resize(src.capacity, 0) == NULL) {
status = U_MEMORY_ALLOCATION_ERROR;
return;
}
uprv_memcpy(this->ptr, src.ptr, (size_t)capacity * sizeof(T));
}
private:
T *ptr;
int32_t capacity;
UBool needToRelease;
T stackArray[stackCapacity];
void releaseArray() {
if(needToRelease) {
uprv_free(ptr);
}
}
void resetToStackArray() {
ptr=stackArray;
capacity=stackCapacity;
needToRelease=false;
}
/* No comparison operators with other MaybeStackArray's. */
bool operator==(const MaybeStackArray & /*other*/) = delete;
bool operator!=(const MaybeStackArray & /*other*/) = delete;
/* No ownership transfer: No copy constructor, no assignment operator. */
MaybeStackArray(const MaybeStackArray & /*other*/) = delete;
void operator=(const MaybeStackArray & /*other*/) = delete;
};
template<typename T, int32_t stackCapacity>
icu::MaybeStackArray<T, stackCapacity>::MaybeStackArray(
MaybeStackArray <T, stackCapacity>&& src) U_NOEXCEPT
: ptr(src.ptr), capacity(src.capacity), needToRelease(src.needToRelease) {
if (src.ptr == src.stackArray) {
ptr = stackArray;
uprv_memcpy(stackArray, src.stackArray, sizeof(T) * src.capacity);
} else {
src.resetToStackArray(); // take ownership away from src
}
}
template<typename T, int32_t stackCapacity>
inline MaybeStackArray <T, stackCapacity>&
MaybeStackArray<T, stackCapacity>::operator=(MaybeStackArray <T, stackCapacity>&& src) U_NOEXCEPT {
releaseArray(); // in case this instance had its own memory allocated
capacity = src.capacity;
needToRelease = src.needToRelease;
if (src.ptr == src.stackArray) {
ptr = stackArray;
uprv_memcpy(stackArray, src.stackArray, sizeof(T) * src.capacity);
} else {
ptr = src.ptr;
src.resetToStackArray(); // take ownership away from src
}
return *this;
}
template<typename T, int32_t stackCapacity>
inline T *MaybeStackArray<T, stackCapacity>::resize(int32_t newCapacity, int32_t length) {
if(newCapacity>0) {
#if U_DEBUG && defined(UPRV_MALLOC_COUNT)
::fprintf(::stderr, "MaybeStackArray (resize) alloc %d * %lu\n", newCapacity, sizeof(T));
#endif
T *p=(T *)uprv_malloc(newCapacity*sizeof(T));
if(p!=NULL) {
if(length>0) {
if(length>capacity) {
length=capacity;
}
if(length>newCapacity) {
length=newCapacity;
}
uprv_memcpy(p, ptr, (size_t)length*sizeof(T));
}
releaseArray();
ptr=p;
capacity=newCapacity;
needToRelease=true;
}
return p;
} else {
return NULL;
}
}
template<typename T, int32_t stackCapacity>
inline T *MaybeStackArray<T, stackCapacity>::orphanOrClone(int32_t length, int32_t &resultCapacity) {
T *p;
if(needToRelease) {
p=ptr;
} else if(length<=0) {
return NULL;
} else {
if(length>capacity) {
length=capacity;
}
p=(T *)uprv_malloc(length*sizeof(T));
#if U_DEBUG && defined(UPRV_MALLOC_COUNT)
::fprintf(::stderr,"MaybeStacArray (orphan) alloc %d * %lu\n", length,sizeof(T));
#endif
if(p==NULL) {
return NULL;
}
uprv_memcpy(p, ptr, (size_t)length*sizeof(T));
}
resultCapacity=length;
resetToStackArray();
return p;
}
/**
* Variant of MaybeStackArray that allocates a header struct and an array
* in one contiguous memory block, using uprv_malloc() and uprv_free().
* Provides internal memory with fixed array capacity. Can alias another memory
* block or allocate one.
* The stackCapacity is the number of T items in the internal memory,
* not counting the H header.
* Unlike LocalMemory and LocalArray, this class never adopts
* (takes ownership of) another memory block.
*/
template<typename H, typename T, int32_t stackCapacity>
class MaybeStackHeaderAndArray {
public:
// No heap allocation. Use only on the stack.
static void* U_EXPORT2 operator new(size_t) U_NOEXCEPT = delete;
static void* U_EXPORT2 operator new[](size_t) U_NOEXCEPT = delete;
#if U_HAVE_PLACEMENT_NEW
static void* U_EXPORT2 operator new(size_t, void*) U_NOEXCEPT = delete;
#endif
/**
* Default constructor initializes with internal H+T[stackCapacity] buffer.
*/
MaybeStackHeaderAndArray() : ptr(&stackHeader), capacity(stackCapacity), needToRelease(false) {}
/**
* Destructor deletes the memory (if owned).
*/
~MaybeStackHeaderAndArray() { releaseMemory(); }
/**
* Returns the array capacity (number of T items).
* @return array capacity
*/
int32_t getCapacity() const { return capacity; }
/**
* Access without ownership change.
* @return the header pointer
*/
H *getAlias() const { return ptr; }
/**
* Returns the array start.
* @return array start, same address as getAlias()+1
*/
T *getArrayStart() const { return reinterpret_cast<T *>(getAlias()+1); }
/**
* Returns the array limit.
* @return array limit
*/
T *getArrayLimit() const { return getArrayStart()+capacity; }
/**
* Access without ownership change. Same as getAlias().
* A class instance can be used directly in expressions that take a T *.
* @return the header pointer
*/
operator H *() const { return ptr; }
/**
* Array item access (writable).
* No index bounds check.
* @param i array index
* @return reference to the array item
*/
T &operator[](ptrdiff_t i) { return getArrayStart()[i]; }
/**
* Deletes the memory block (if owned) and aliases another one, no transfer of ownership.
* If the arguments are illegal, then the current memory is unchanged.
* @param otherArray must not be NULL
* @param otherCapacity must be >0
*/
void aliasInstead(H *otherMemory, int32_t otherCapacity) {
if(otherMemory!=NULL && otherCapacity>0) {
releaseMemory();
ptr=otherMemory;
capacity=otherCapacity;
needToRelease=false;
}
}
/**
* Deletes the memory block (if owned) and allocates a new one,
* copying the header and length T array items.
* Returns the new header pointer.
* If the allocation fails, then the current memory is unchanged and
* this method returns NULL.
* @param newCapacity can be less than or greater than the current capacity;
* must be >0
* @param length number of T items to be copied from the old array to the new one
* @return the allocated pointer, or NULL if the allocation failed
*/
inline H *resize(int32_t newCapacity, int32_t length=0);
/**
* Gives up ownership of the memory if owned, or else clones it,
* copying the header and length T array items; resets itself to the internal memory.
* Returns NULL if the allocation failed.
* @param length number of T items to copy when cloning,
* and array capacity of the clone when cloning
* @param resultCapacity will be set to the returned array's capacity (output-only)
* @return the header pointer;
* caller becomes responsible for deleting the array
*/
inline H *orphanOrClone(int32_t length, int32_t &resultCapacity);
private:
H *ptr;
int32_t capacity;
UBool needToRelease;
// stackHeader must precede stackArray immediately.
H stackHeader;
T stackArray[stackCapacity];
void releaseMemory() {
if(needToRelease) {
uprv_free(ptr);
}
}
/* No comparison operators with other MaybeStackHeaderAndArray's. */
bool operator==(const MaybeStackHeaderAndArray & /*other*/) {return false;}
bool operator!=(const MaybeStackHeaderAndArray & /*other*/) {return true;}
/* No ownership transfer: No copy constructor, no assignment operator. */
MaybeStackHeaderAndArray(const MaybeStackHeaderAndArray & /*other*/) {}
void operator=(const MaybeStackHeaderAndArray & /*other*/) {}
};
template<typename H, typename T, int32_t stackCapacity>
inline H *MaybeStackHeaderAndArray<H, T, stackCapacity>::resize(int32_t newCapacity,
int32_t length) {
if(newCapacity>=0) {
#if U_DEBUG && defined(UPRV_MALLOC_COUNT)
::fprintf(::stderr,"MaybeStackHeaderAndArray alloc %d + %d * %ul\n", sizeof(H),newCapacity,sizeof(T));
#endif
H *p=(H *)uprv_malloc(sizeof(H)+newCapacity*sizeof(T));
if(p!=NULL) {
if(length<0) {
length=0;
} else if(length>0) {
if(length>capacity) {
length=capacity;
}
if(length>newCapacity) {
length=newCapacity;
}
}
uprv_memcpy(p, ptr, sizeof(H)+(size_t)length*sizeof(T));
releaseMemory();
ptr=p;
capacity=newCapacity;
needToRelease=true;
}
return p;
} else {
return NULL;
}
}
template<typename H, typename T, int32_t stackCapacity>
inline H *MaybeStackHeaderAndArray<H, T, stackCapacity>::orphanOrClone(int32_t length,
int32_t &resultCapacity) {
H *p;
if(needToRelease) {
p=ptr;
} else {
if(length<0) {
length=0;
} else if(length>capacity) {
length=capacity;
}
#if U_DEBUG && defined(UPRV_MALLOC_COUNT)
::fprintf(::stderr,"MaybeStackHeaderAndArray (orphan) alloc %ul + %d * %lu\n", sizeof(H),length,sizeof(T));
#endif
p=(H *)uprv_malloc(sizeof(H)+length*sizeof(T));
if(p==NULL) {
return NULL;
}
uprv_memcpy(p, ptr, sizeof(H)+(size_t)length*sizeof(T));
}
resultCapacity=length;
ptr=&stackHeader;
capacity=stackCapacity;
needToRelease=false;
return p;
}
/**
* A simple memory management class that creates new heap allocated objects (of
* any class that has a public constructor), keeps track of them and eventually
* deletes them all in its own destructor.
*
* A typical use-case would be code like this:
*
* MemoryPool<MyType> pool;
*
* MyType* o1 = pool.create();
* if (o1 != nullptr) {
* foo(o1);
* }
*
* MyType* o2 = pool.create(1, 2, 3);
* if (o2 != nullptr) {
* bar(o2);
* }
*
* // MemoryPool will take care of deleting the MyType objects.
*
* It doesn't do anything more than that, and is intentionally kept minimalist.
*/
template<typename T, int32_t stackCapacity = 8>
class MemoryPool : public UMemory {
public:
MemoryPool() : fCount(0), fPool() {}
~MemoryPool() {
for (int32_t i = 0; i < fCount; ++i) {
delete fPool[i];
}
}
MemoryPool(const MemoryPool&) = delete;
MemoryPool& operator=(const MemoryPool&) = delete;
MemoryPool(MemoryPool&& other) U_NOEXCEPT : fCount(other.fCount),
fPool(std::move(other.fPool)) {
other.fCount = 0;
}
MemoryPool& operator=(MemoryPool&& other) U_NOEXCEPT {
fCount = other.fCount;
fPool = std::move(other.fPool);
other.fCount = 0;
return *this;
}
/**
* Creates a new object of typename T, by forwarding any and all arguments
* to the typename T constructor.
*
* @param args Arguments to be forwarded to the typename T constructor.
* @return A pointer to the newly created object, or nullptr on error.
*/
template<typename... Args>
T* create(Args&&... args) {
int32_t capacity = fPool.getCapacity();
if (fCount == capacity &&
fPool.resize(capacity == stackCapacity ? 4 * capacity : 2 * capacity,
capacity) == nullptr) {
return nullptr;
}
return fPool[fCount++] = new T(std::forward<Args>(args)...);
}
template <typename... Args>
T* createAndCheckErrorCode(UErrorCode &status, Args &&... args) {
if (U_FAILURE(status)) {
return nullptr;
}
T *pointer = this->create(args...);
if (U_SUCCESS(status) && pointer == nullptr) {
status = U_MEMORY_ALLOCATION_ERROR;
}
return pointer;
}
/**
* @return Number of elements that have been allocated.
*/
int32_t count() const {
return fCount;
}
protected:
int32_t fCount;
MaybeStackArray<T*, stackCapacity> fPool;
};
/**
* An internal Vector-like implementation based on MemoryPool.
*
* Heap-allocates each element and stores pointers.
*
* To append an item to the vector, use emplaceBack.
*
* MaybeStackVector<MyType> vector;
* MyType* element = vector.emplaceBack();
* if (!element) {
* status = U_MEMORY_ALLOCATION_ERROR;
* }
* // do stuff with element
*
* To loop over the vector, use a for loop with indices:
*
* for (int32_t i = 0; i < vector.length(); i++) {
* MyType* element = vector[i];
* }
*/
template<typename T, int32_t stackCapacity = 8>
class MaybeStackVector : protected MemoryPool<T, stackCapacity> {
public:
using MemoryPool<T, stackCapacity>::MemoryPool;
using MemoryPool<T, stackCapacity>::operator=;
template<typename... Args>
T* emplaceBack(Args&&... args) {
return this->create(args...);
}
template <typename... Args>
T *emplaceBackAndCheckErrorCode(UErrorCode &status, Args &&... args) {
return this->createAndCheckErrorCode(status, args...);
}
int32_t length() const {
return this->fCount;
}
T** getAlias() {
return this->fPool.getAlias();
}
const T *const *getAlias() const {
return this->fPool.getAlias();
}
/**
* Array item access (read-only).
* No index bounds check.
* @param i array index
* @return reference to the array item
*/
const T* operator[](ptrdiff_t i) const {
return this->fPool[i];
}
/**
* Array item access (writable).
* No index bounds check.
* @param i array index
* @return reference to the array item
*/
T* operator[](ptrdiff_t i) {
return this->fPool[i];
}
};
U_NAMESPACE_END
#endif /* __cplusplus */
#endif /* CMEMORY_H */