QContiguousCache< T > Class Template Reference

The QContiguousCache class is a template class that provides a contiguous cache. More...

#include <qcontiguouscache.h>

Public Types
typedef const value_type *	const_pointer
typedef const value_type &	const_reference
typedef qptrdiff	difference_type
typedef value_type *	pointer
typedef value_type &	reference
typedef int	size_type
typedef T	value_type

Public Functions
void	append (const T &value)
	Inserts value at the end of the cache. More...
bool	areIndexesValid () const
	Returns whether the indexes for items stored in the cache are valid. More...
const T &	at (int pos) const
	Returns the item at index position i in the cache. More...
int	available () const
	Returns the number of items that can be added to the cache before it becomes full. More...
int	capacity () const
	Returns the number of items the cache can store before it is full. More...
void	clear ()
	Removes all items from the cache. More...
bool	containsIndex (int pos) const
	Returns true if the cache's index range includes the given index i. More...
int	count () const
	Same as size(). More...
void	detach ()
const T &	first () const
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. More...
T &	first ()
	Returns a reference to the first item in the cache. More...
int	firstIndex () const
	Returns the first valid index in the cache. More...
void	insert (int pos, const T &value)
	Inserts the value at the index position i. More...
bool	isDetached () const
bool	isEmpty () const
	Returns true if no items are stored within the cache. More...
bool	isFull () const
	Returns true if the number of items stored within the cache is equal to the capacity of the cache. More...
const T &	last () const
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. More...
T &	last ()
	Returns a reference to the last item in the cache. More...
int	lastIndex () const
	Returns the last valid index in the cache. More...
void	normalizeIndexes ()
	Moves the first index and last index of the cache such that they point to valid indexes. More...
bool	operator!= (const QContiguousCache< T > &other) const
	Returns true if other is not equal to this cache; otherwise returns false. More...
QContiguousCache< T > &	operator= (const QContiguousCache< T > &other)
	Assigns other to this cache and returns a reference to this cache. More...
bool	operator== (const QContiguousCache< T > &other) const
	Returns true if other is equal to this cache; otherwise returns false. More...
T &	operator[] (int i)
	Returns the item at index position i as a modifiable reference. More...
const T &	operator[] (int i) const
	Same as at(i). More...
void	prepend (const T &value)
	Inserts value at the start of the cache. More...
	QContiguousCache (int capacity=0)
	Constructs a cache with the given capacity. More...
	QContiguousCache (const QContiguousCache< T > &v)
	Constructs a copy of other. More...
void	removeFirst ()
	Removes the first item from the cache. More...
void	removeLast ()
	Removes the last item from the cache. More...
void	setCapacity (int size)
	Sets the capacity of the cache to the given size. More...
void	setSharable (bool sharable)
int	size () const
	Returns the number of items contained within the cache. More...
void	swap (QContiguousCache< T > &other)
	Swaps cache other with this cache. More...
T	takeFirst ()
	Removes the first item in the cache and returns it. More...
T	takeLast ()
	Removes the last item in the cache and returns it. More...
	~QContiguousCache ()
	Destroys the cache. More...

Private Types
typedef QContiguousCacheTypedData< T >	Data

Private Functions
int	alignOfTypedData () const
void	detach_helper ()
void	free (Data *x)
QContiguousCacheData *	malloc (int aalloc)
int	sizeOfTypedData ()

Properties
union {
QContiguousCacheData *   d
QContiguousCacheTypedData< T > *   p
};

Detailed Description

template<typename T>
class QContiguousCache< T >

The QContiguousCache class is a template class that provides a contiguous cache.

Note

This class or function is reentrant.

Since

4.6

The QContiguousCache class provides an efficient way of caching items for display in a user interface view. Unlike QCache, it adds a restriction that elements within the cache are contiguous. This has the advantage of matching how user interface views most commonly request data, as a set of rows localized around the current scrolled position. This restriction allows the cache to consume less memory and processor cycles than QCache. The QContiguousCache class also can provide an upper bound on memory usage via setCapacity().

The simplest way of using a contiguous cache is to use the append() and prepend().

MyRecord record(int row) const
{
    Q_ASSERT(row >= 0 && row < count());

    while(row > cache.lastIndex())
        cache.append(slowFetchRecord(cache.lastIndex()+1));
    while(row < cache.firstIndex())
        cache.prepend(slowFetchRecord(cache.firstIndex()-1));

    return cache.at(row);
}

If the cache is full then the item at the opposite end of the cache from
where the new item is appended or prepended will be removed.

This usage can be further optimized by using the insert() function
in the case where the requested row is a long way from the currently cached
items. If there is a gap between where the new item is inserted and the currently
cached items then the existing cached items are first removed to retain
the contiguous nature of the cache. Hence it is important to take some care then
when using insert() in order to avoid unwanted clearing of the cache.

The range of valid indexes for the QContiguousCache class are from
0 to INT_MAX.  Calling prepend() such that the first index would become less
than 0 or append() such that the last index would become greater
than INT_MAX can result in the indexes of the cache being invalid.
When the cache indexes are invalid it is important to call
normalizeIndexes() before calling any of containsIndex(), firstIndex(),
lastIndex(), at() or \ref QContiguousCache::operator[]() "operator[]()".
Calling these functions when the cache has invalid indexes will result in
undefined behavior. The indexes can be checked by using areIndexesValid()

In most cases the indexes will not exceed 0 to INT_MAX, and
normalizeIndexes() will not need to be used.

See the <b>Contiguous Cache Example</b>{Contiguous Cache} example.

Definition at line 90 of file qcontiguouscache.h.

Typedefs

const_pointer

template<typename T>

QContiguousCache< T >::const_pointer

Warning

This function is not part of the public interface.

Definition at line 97 of file qcontiguouscache.h.

const_reference

template<typename T>

QContiguousCache< T >::const_reference

Warning

This function is not part of the public interface.

Definition at line 99 of file qcontiguouscache.h.

Data

template<typename T>

typedef QContiguousCacheTypedData<T> QContiguousCache< T >::Data

private

Definition at line 91 of file qcontiguouscache.h.

difference_type

template<typename T>

QContiguousCache< T >::difference_type

Warning

This function is not part of the public interface.

Definition at line 100 of file qcontiguouscache.h.

pointer

template<typename T>

QContiguousCache< T >::pointer

Warning

This function is not part of the public interface.

Definition at line 96 of file qcontiguouscache.h.

reference

template<typename T>

QContiguousCache< T >::reference

Warning

This function is not part of the public interface.

Definition at line 98 of file qcontiguouscache.h.

size_type

template<typename T>

QContiguousCache< T >::size_type

Warning

This function is not part of the public interface.

Definition at line 101 of file qcontiguouscache.h.

value_type

template<typename T>

QContiguousCache< T >::value_type

Warning

This function is not part of the public interface.

Definition at line 95 of file qcontiguouscache.h.

Constructors and Destructors

QContiguousCache() [1/2]

template<typename T >

QContiguousCache< T >::QContiguousCache ( int  capacity = 0 )

explicit

Constructs a cache with the given capacity.

See also

setCapacity()

Definition at line 293 of file qcontiguouscache.h.

{
    d = malloc(cap);
    d->ref = 1;
    d->alloc = cap;
    d->count = d->start = d->offset = 0;
    d->sharable = true;
}

QContiguousCache() [2/2]

template<typename T>

QContiguousCache< T >::QContiguousCache ( const QContiguousCache< T > &  other )

inline

Constructs a copy of other.

This operation takes constant time, because QContiguousCache is implicitly shared. This makes returning a QContiguousCache from a function very fast. If a shared instance is modified, it will be copied (copy-on-write), and that takes linear time.

See also

operator=()

Definition at line 104 of file qcontiguouscache.h.

: d(v.d) { d->ref.ref(); if (!d->sharable) detach_helper(); }

~QContiguousCache()

template<typename T>

QContiguousCache< T >::~QContiguousCache ( )

inline

Destroys the cache.

Definition at line 106 of file qcontiguouscache.h.

{ if (!d) return; if (!d->ref.deref()) free(p); }

Functions

alignOfTypedData()

template<typename T>

int QContiguousCache< T >::alignOfTypedData ( ) const

inlineprivate

Definition at line 172 of file qcontiguouscache.h.

    {
#ifdef Q_ALIGNOF
        return qMax<int>(sizeof(void*), Q_ALIGNOF(Data));
#else
        return 0;
#endif
    }

append()

template<typename T >

void QContiguousCache< T >::append

(

const T &

value

)

Inserts value at the end of the cache.

If the cache is already full the item at the start of the cache will be removed.

See also

prepend(), insert(), isFull()

Definition at line 347 of file qcontiguouscache.h.

{
    if (!d->alloc)
        return;     // zero capacity
    detach();
    if (QTypeInfo<T>::isComplex) {
        if (d->count == d->alloc)
            (p->array + (d->start+d->count) % d->alloc)->~T();
        new (p->array + (d->start+d->count) % d->alloc) T(value);
    } else {
        p->array[(d->start+d->count) % d->alloc] = value;
    }

    if (d->count == d->alloc) {
        d->start++;
        d->start %= d->alloc;
        d->offset++;
    } else {
        d->count++;
    }
}

areIndexesValid()

template<typename T>

bool QContiguousCache< T >::areIndexesValid ( ) const

inline

Returns whether the indexes for items stored in the cache are valid.

Indexes can become invalid if items are appended after the index position INT_MAX or prepended before the index position 0. This is only expected to occur in very long lived circular buffer style usage of the contiguous cache. Indexes can be made valid again by calling normalizeIndexs().

See also

normalizeIndexes(), append(), prepend()

Definition at line 154 of file qcontiguouscache.h.

    { return d->offset >= 0 && d->offset < INT_MAX - d->count && (d->offset % d->alloc) == d->start; }

at()

template<typename T >

const T & QContiguousCache< T >::at ( int  i ) const

inline

Returns the item at index position i in the cache.

i must be a valid index position in the cache (i.e, firstIndex() <= i <= lastIndex()).

The indexes in the cache refer to the number of positions the item is from the first item appended into the cache. That is to say a cache with a capacity of 100, that has had 150 items appended will have a valid index range of 50 to 149. This allows inserting and retrieving items into the cache based on a theoretical infinite list

See also

firstIndex(), lastIndex(), insert(), operator[]()

Definition at line 425 of file qcontiguouscache.h.

Referenced by QContiguousCache< T >::operator==().

{ Q_ASSERT_X(pos >= d->offset && pos - d->offset < d->count, "QContiguousCache<T>::at", "index out of range"); return p->array[pos % d->alloc]; }

available()

template<typename T>

int QContiguousCache< T >::available ( ) const

inline

Returns the number of items that can be added to the cache before it becomes full.

See also

size(), capacity(), isFull()

Definition at line 127 of file qcontiguouscache.h.

{ return d->alloc - d->count; }

capacity()

template<typename T>

int QContiguousCache< T >::capacity ( ) const

inline

Returns the number of items the cache can store before it is full.

When a cache contains a number of items equal to its capacity, adding new items will cause items farthest from the added item to be removed.

See also

setCapacity(), size()

Definition at line 121 of file qcontiguouscache.h.

{return d->alloc; }

clear()

template<typename T >

void QContiguousCache< T >::clear

(

)

Removes all items from the cache.

The capacity is unchanged.

Definition at line 259 of file qcontiguouscache.h.

{
    if (d->ref == 1) {
        if (QTypeInfo<T>::isComplex) {
            int oldcount = d->count;
            T * i = p->array + d->start;
            T * e = p->array + d->alloc;
            while (oldcount--) {
                i->~T();
                i++;
                if (i == e)
                    i = p->array;
            }
        }
        d->count = d->start = d->offset = 0;
    } else {
        union { QContiguousCacheData *d; QContiguousCacheTypedData<T> *p; } x;
        x.d = malloc(d->alloc);
        x.d->ref = 1;
        x.d->alloc = d->alloc;
        x.d->count = x.d->start = x.d->offset = 0;
        x.d->sharable = true;
        if (!d->ref.deref()) free(p);
        d = x.d;
    }
}

containsIndex()

template<typename T>

bool QContiguousCache< T >::containsIndex ( int  i ) const

inline

Returns true if the cache's index range includes the given index i.

See also

firstIndex(), lastIndex()

Definition at line 140 of file qcontiguouscache.h.

{ return pos >= d->offset && pos - d->offset < d->count; }

count()

template<typename T>

int QContiguousCache< T >::count ( ) const

inline

Same as size().

Definition at line 122 of file qcontiguouscache.h.

{ return d->count; }

detach()

template<typename T>

void QContiguousCache< T >::detach ( )

inline

Warning

This function is not part of the public interface.

Definition at line 108 of file qcontiguouscache.h.

{ if (d->ref != 1) detach_helper(); }

detach_helper()

template<typename T >

void QContiguousCache< T >::detach_helper ( )

private

Definition at line 183 of file qcontiguouscache.h.

{
    union { QContiguousCacheData *d; QContiguousCacheTypedData<T> *p; } x;

    x.d = malloc(d->alloc);
    x.d->ref = 1;
    x.d->count = d->count;
    x.d->start = d->start;
    x.d->offset = d->offset;
    x.d->alloc = d->alloc;
    x.d->sharable = true;
    x.d->reserved = 0;

    T *dest = x.p->array + x.d->start;
    T *src = p->array + d->start;
    int oldcount = x.d->count;
    while (oldcount--) {
        if (QTypeInfo<T>::isComplex) {
            new (dest) T(*src);
        } else {
            *dest = *src;
        }
        dest++;
        if (dest == x.p->array + x.d->alloc)
            dest = x.p->array;
        src++;
        if (src == p->array + d->alloc)
            src = p->array;
    }

    if (!d->ref.deref())
        free(p);
    d = x.d;
}

first() [1/2]

template<typename T>

const T & QContiguousCache< T >::first ( ) const

inline

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Definition at line 144 of file qcontiguouscache.h.

{ Q_ASSERT(!isEmpty()); return p->array[d->start]; }

first() [2/2]

template<typename T>

T & QContiguousCache< T >::first ( )

inline

Returns a reference to the first item in the cache.

This function assumes that the cache isn't empty.

See also

last(), isEmpty()

Definition at line 146 of file qcontiguouscache.h.

{ Q_ASSERT(!isEmpty()); detach(); return p->array[d->start]; }

firstIndex()

template<typename T>

int QContiguousCache< T >::firstIndex ( ) const

inline

Returns the first valid index in the cache.

The index will be invalid if the cache is empty.

See also

capacity(), size(), lastIndex()

Definition at line 141 of file qcontiguouscache.h.

Referenced by operator<<().

{ return d->offset; }

free()

template<typename T >

void QContiguousCache< T >::free ( Data *  x )

private

Definition at line 331 of file qcontiguouscache.h.

{
    if (QTypeInfo<T>::isComplex) {
        int oldcount = d->count;
        T * i = p->array + d->start;
        T * e = p->array + d->alloc;
        while (oldcount--) {
            i->~T();
            i++;
            if (i == e)
                i = p->array;
        }
    }
    x->free(x);
}

insert()

template<typename T >

void QContiguousCache< T >::insert	(	int	i,
		const T &	value
	)

Inserts the value at the index position i.

If the cache already contains an item at i then that value is replaced. If i is either one more than lastIndex() or one less than firstIndex() it is the equivalent to an append() or a prepend().

If the given index i is not within the current range of the cache nor adjacent to the bounds of the cache's index range, the cache is first cleared before inserting the item. At this point the cache will have a size of 1. It is worthwhile taking effort to insert items in an order that starts adjacent to the current index range for the cache.

The range of valid indexes for the QContiguousCache class are from 0 to INT_MAX. Inserting outside of this range has undefined behavior.

See also

prepend(), append(), isFull(), firstIndex(), lastIndex()

Definition at line 394 of file qcontiguouscache.h.

{
    Q_ASSERT_X(pos >= 0 && pos < INT_MAX, "QContiguousCache<T>::insert", "index out of range");
    if (!d->alloc)
        return;     // zero capacity
    detach();
    if (containsIndex(pos)) {
        if (QTypeInfo<T>::isComplex) {
            (p->array + pos % d->alloc)->~T();
            new (p->array + pos % d->alloc) T(value);
        } else {
            p->array[pos % d->alloc] = value;
        }
    } else if (pos == d->offset-1)
        prepend(value);
    else if (pos == d->offset+d->count)
        append(value);
    else {
        // we don't leave gaps.
        clear();
        d->offset = pos;
        d->start = pos % d->alloc;
        d->count = 1;
        if (QTypeInfo<T>::isComplex)
            new (p->array + d->start) T(value);
        else
            p->array[d->start] = value;
    }
}

isDetached()

template<typename T>

bool QContiguousCache< T >::isDetached ( ) const

inline

Warning

This function is not part of the public interface.

Definition at line 109 of file qcontiguouscache.h.

{ return d->ref == 1; }

isEmpty()

template<typename T>

bool QContiguousCache< T >::isEmpty ( ) const

inline

Returns true if no items are stored within the cache.

See also

size(), capacity()

Definition at line 125 of file qcontiguouscache.h.

{ return d->count == 0; }

isFull()

template<typename T>

bool QContiguousCache< T >::isFull ( ) const

inline

Returns true if the number of items stored within the cache is equal to the capacity of the cache.

See also

size(), capacity()

Definition at line 126 of file qcontiguouscache.h.

{ return d->count == d->alloc; }

last() [1/2]

template<typename T>

const T & QContiguousCache< T >::last ( ) const

inline

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Definition at line 145 of file qcontiguouscache.h.

{ Q_ASSERT(!isEmpty()); return p->array[(d->start + d->count -1) % d->alloc]; }

last() [2/2]

template<typename T>

T & QContiguousCache< T >::last ( )

inline

Returns a reference to the last item in the cache.

This function assumes that the cache isn't empty.

See also

first(), isEmpty()

Definition at line 147 of file qcontiguouscache.h.

{ Q_ASSERT(!isEmpty()); detach(); return p->array[(d->start + d->count -1) % d->alloc]; }

lastIndex()

template<typename T>

int QContiguousCache< T >::lastIndex ( ) const

inline

Returns the last valid index in the cache.

The index will be invalid if the cache is empty.

See also

capacity(), size(), firstIndex()

Definition at line 142 of file qcontiguouscache.h.

Referenced by operator<<().

{ return d->offset + d->count - 1; }

malloc()

template<typename T >

QContiguousCacheData * QContiguousCache< T >::malloc ( int  aalloc )

inlineprivate

Definition at line 287 of file qcontiguouscache.h.

{
    return QContiguousCacheData::allocate(sizeOfTypedData() + (aalloc - 1) * sizeof(T), alignOfTypedData());
}

normalizeIndexes()

template<typename T>

void QContiguousCache< T >::normalizeIndexes ( )

inline

Moves the first index and last index of the cache such that they point to valid indexes.

The function does not modify the contents of the cache or the ordering of elements within the cache.

It is provided so that index overflows can be corrected when using the cache as a circular buffer.

QContiguousCache<int> cache(10);
cache.insert(INT_MAX, 1); // cache contains one value and has valid indexes, INT_MAX to INT_MAX
cache.append(2); // cache contains two values but does not have valid indexes.
cache.normalizeIndexes(); // cache has two values, 1 and 2.  New first index will be in the range of 0 to capacity().

See also

areIndexesValid(), append(), prepend()

Definition at line 157 of file qcontiguouscache.h.

{ d->offset = d->start; }

operator!=()

template<typename T>

bool QContiguousCache< T >::operator!= ( const QContiguousCache< T > &  other ) const

inline

Returns true if other is not equal to this cache; otherwise returns false.

Two caches are considered equal if they contain the same values at the same indexes. This function requires the value type to implement the operator==().

See also

operator==()

Definition at line 119 of file qcontiguouscache.h.

{ return !(*this == other); }

operator=()

template<typename T >

QContiguousCache< T > & QContiguousCache< T >::operator=

(

const QContiguousCache< T > &

other

)

Assigns other to this cache and returns a reference to this cache.

Definition at line 303 of file qcontiguouscache.h.

{
    other.d->ref.ref();
    if (!d->ref.deref())
        free(d);
    d = other.d;
    if (!d->sharable)
        detach_helper();
    return *this;
}

operator==()

template<typename T >

bool QContiguousCache< T >::operator==

(

const QContiguousCache< T > &

other

)

const

Returns true if other is equal to this cache; otherwise returns false.

Two caches are considered equal if they contain the same values at the same indexes. This function requires the value type to implement the operator==().

See also

operator!=()

Definition at line 315 of file qcontiguouscache.h.

{
    if (other.d == d)
        return true;
    if (other.d->start != d->start
            || other.d->count != d->count
            || other.d->offset != d->offset
            || other.d->alloc != d->alloc)
        return false;
    for (int i = firstIndex(); i <= lastIndex(); ++i)
        if (!(at(i) == other.at(i)))
            return false;
    return true;
}

operator[]() [1/2]

template<typename T >

T & QContiguousCache< T >::operator[] ( int  i )

inline

Returns the item at index position i as a modifiable reference.

If the cache does not contain an item at the given index position i then it will first insert an empty item at that position.

In most cases it is better to use either at() or insert().

Note

This non-const overload of operator[] requires QContiguousCache to make a deep copy. Use at() for read-only access to a non-const QContiguousCache.

See also

insert(), at()

Definition at line 432 of file qcontiguouscache.h.

{
    detach();
    if (!containsIndex(pos))
        insert(pos, T());
    return p->array[pos % d->alloc];
}

operator[]() [2/2]

template<typename T >

const T & QContiguousCache< T >::operator[] ( int  i ) const

inline

Same as at(i).

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Definition at line 428 of file qcontiguouscache.h.

{ Q_ASSERT_X(pos >= d->offset && pos - d->offset < d->count, "QContiguousCache<T>::at", "index out of range"); return p->array[pos % d->alloc]; }

prepend()

template<typename T >

void QContiguousCache< T >::prepend

(

const T &

value

)

Inserts value at the start of the cache.

If the cache is already full the item at the end of the cache will be removed.

See also

append(), insert(), isFull()

Definition at line 370 of file qcontiguouscache.h.

{
    if (!d->alloc)
        return;     // zero capacity
    detach();
    if (d->start)
        d->start--;
    else
        d->start = d->alloc-1;
    d->offset--;

    if (d->count != d->alloc)
        d->count++;
    else
        if (d->count == d->alloc)
            (p->array + d->start)->~T();

    if (QTypeInfo<T>::isComplex)
        new (p->array + d->start) T(value);
    else
        p->array[d->start] = value;
}

removeFirst()

template<typename T >

void QContiguousCache< T >::removeFirst ( )

inline

Removes the first item from the cache.

This function assumes that the cache isn't empty.

See also

removeLast()

Definition at line 441 of file qcontiguouscache.h.

{
    Q_ASSERT(d->count > 0);
    detach();
    d->count--;
    if (QTypeInfo<T>::isComplex)
        (p->array + d->start)->~T();
    d->start = (d->start + 1) % d->alloc;
    d->offset++;
}

removeLast()

template<typename T >

void QContiguousCache< T >::removeLast ( )

inline

Removes the last item from the cache.

This function assumes that the cache isn't empty.

See also

removeFirst()

Definition at line 453 of file qcontiguouscache.h.

{
    Q_ASSERT(d->count > 0);
    detach();
    d->count--;
    if (QTypeInfo<T>::isComplex)
        (p->array + (d->start + d->count) % d->alloc)->~T();
}

setCapacity()

template<typename T >

void QContiguousCache< T >::setCapacity

(

int

size

)

Sets the capacity of the cache to the given size.

A cache can hold a number of items equal to its capacity. When inserting, appending or prepending items to the cache, if the cache is already full then the item farthest from the added item will be removed.

If the given size is smaller than the current count of items in the cache then only the last size items from the cache will remain.

See also

capacity(), isFull()

Definition at line 219 of file qcontiguouscache.h.

{
    if (asize == d->alloc)
        return;
    detach();
    union { QContiguousCacheData *d; QContiguousCacheTypedData<T> *p; } x;
    x.d = malloc(asize);
    x.d->alloc = asize;
    x.d->count = qMin(d->count, asize);
    x.d->offset = d->offset + d->count - x.d->count;
    if(asize)
        x.d->start = x.d->offset % x.d->alloc;
    else
        x.d->start = 0;

    int oldcount = x.d->count;
    if(oldcount)
    {
        T *dest = x.p->array + (x.d->start + x.d->count-1) % x.d->alloc;
        T *src = p->array + (d->start + d->count-1) % d->alloc;
        while (oldcount--) {
            if (QTypeInfo<T>::isComplex) {
                new (dest) T(*src);
            } else {
                *dest = *src;
            }
            if (dest == x.p->array)
                dest = x.p->array + x.d->alloc;
            dest--;
            if (src == p->array)
                src = p->array + d->alloc;
            src--;
        }
    }
    /* free old */
    free(p);
    d = x.d;
}

setSharable()

template<typename T>

void QContiguousCache< T >::setSharable ( bool  sharable )

inline

Warning

This function is not part of the public interface.

Definition at line 110 of file qcontiguouscache.h.

{ if (!sharable) detach(); d->sharable = sharable; }

size()

template<typename T>

int QContiguousCache< T >::size ( ) const

inline

Returns the number of items contained within the cache.

See also

capacity()

Definition at line 123 of file qcontiguouscache.h.

{ return d->count; }

sizeOfTypedData()

template<typename T>

int QContiguousCache< T >::sizeOfTypedData ( )

inlineprivate

Definition at line 167 of file qcontiguouscache.h.

                          {
        // this is more or less the same as sizeof(Data), except that it doesn't
        // count the padding at the end
        return reinterpret_cast<const char *>(&(reinterpret_cast<const Data *>(this))->array[1]) - reinterpret_cast<const char *>(this);
    }

swap()

template<typename T>

void QContiguousCache< T >::swap ( QContiguousCache< T > &  other )

inline

Swaps cache other with this cache.

Since

4.8

This operation is very fast and never fails.

Definition at line 117 of file qcontiguouscache.h.

{ qSwap(d, other.d); }

takeFirst()

template<typename T >

T QContiguousCache< T >::takeFirst ( )

inline

Removes the first item in the cache and returns it.

This function assumes that the cache isn't empty.

If you don't use the return value, removeFirst() is more efficient.

See also

takeLast(), removeFirst()

Definition at line 463 of file qcontiguouscache.h.

{ T t = first(); removeFirst(); return t; }

takeLast()

template<typename T >

T QContiguousCache< T >::takeLast ( )

inline

Removes the last item in the cache and returns it.

This function assumes that the cache isn't empty.

If you don't use the return value, removeLast() is more efficient.

See also

takeFirst(), removeLast()

Definition at line 467 of file qcontiguouscache.h.

{ T t = last(); removeLast(); return t; }

Properties

@49

union { ... }

d

template<typename T>

QContiguousCacheData* QContiguousCache< T >::d

Definition at line 92 of file qcontiguouscache.h.

Referenced by QContiguousCache< T >::operator=(), QContiguousCache< T >::operator==(), QContiguousCache< T >::setSharable(), and QContiguousCache< T >::swap().

p

template<typename T>

QContiguousCacheTypedData<T>* QContiguousCache< T >::p

Definition at line 92 of file qcontiguouscache.h.

---

The documentation for this class was generated from the following files:

• /src/corelib/tools/qcontiguouscache.h
• /src/corelib/tools/qcontiguouscache.cpp