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#include "qvector.h"

#include "qtools_p.h"

#include <string.h>

QT_BEGIN_NAMESPACE

static inline int alignmentThreshold()

{

    // malloc on 32-bit platforms should return pointers that are 8-byte aligned or more

    // while on 64-bit platforms they should be 16-byte aligned or more

    return 2 * sizeof(void*);

}

QVectorData QVectorData::shared_null = { Q_BASIC_ATOMIC_INITIALIZER(1), 0, 0, true, false, 0 };

QVectorData *QVectorData::malloc(int sizeofTypedData, int size, int sizeofT, QVectorData *init)

{

    QVectorData* p = (QVectorData *)qMalloc(sizeofTypedData + (size - 1) * sizeofT);

    Q_CHECK_PTR(p);

    ::memcpy(p, init, sizeofTypedData + (qMin(size, init->alloc) - 1) * sizeofT);

    return p;

}

QVectorData *QVectorData::allocate(int size, int alignment)

{

    return static_cast<QVectorData *>(alignment > alignmentThreshold() ? qMallocAligned(size, alignment) : qMalloc(size));

}

QVectorData *QVectorData::reallocate(QVectorData *x, int newsize, int oldsize, int alignment)

{

    if (alignment > alignmentThreshold())

        return static_cast<QVectorData *>(qReallocAligned(x, newsize, oldsize, alignment));

    return static_cast<QVectorData *>(qRealloc(x, newsize));

}

void QVectorData::free(QVectorData *x, int alignment)

{

    if (alignment > alignmentThreshold())

        qFreeAligned(x);

    else

        qFree(x);

}

int QVectorData::grow(int sizeofTypedData, int size, int sizeofT, bool excessive)

{

    if (excessive)

        return size + size / 2;

    return qAllocMore(size * sizeofT, sizeofTypedData - sizeofT) / sizeofT;

}

/*!

    \class QVector

    \brief The QVector class is a template class that provides a dynamic array.

    \ingroup tools

    \ingroup shared

    \reentrant

    QVector\<T\> is one of Qt's generic \l{container classes}. It

    stores its items in adjacent memory locations and provides fast

    index-based access.

    QList\<T\>, QLinkedList\<T\>, and QVarLengthArray\<T\> provide

    similar functionality. Here's an overview:

    \list

    \i For most purposes, QList is the right class to use. Operations

       like prepend() and insert() are usually faster than with

       QVector because of the way QList stores its items in memory

       (see \l{Algorithmic Complexity} for details),

       and its index-based API is more convenient than QLinkedList's

       iterator-based API. It also expands to less code in your

       executable.

    \i If you need a real linked list, with guarantees of \l{constant

       time} insertions in the middle of the list and iterators to

       items rather than indexes, use QLinkedList.

    \i If you want the items to occupy adjacent memory positions, or

       if your items are larger than a pointer and you want to avoid

       the overhead of allocating them on the heap individually at

       insertion time, then use QVector.

    \i If you want a low-level variable-size array, QVarLengthArray

       may be sufficient.

    \endlist

    Here's an example of a QVector that stores integers and a QVector

    that stores QString values:

    \snippet doc/src/snippets/code/src_corelib_tools_qvector.cpp 0

    QVector stores a vector (or array) of items. Typically, vectors

    are created with an initial size. For example, the following code

    constructs a QVector with 200 elements:

    \snippet doc/src/snippets/code/src_corelib_tools_qvector.cpp 1

    The elements are automatically initialized with a

    \l{default-constructed value}. If you want to initialize the

    vector with a different value, pass that value as the second

    argument to the constructor:

    \snippet doc/src/snippets/code/src_corelib_tools_qvector.cpp 2

    You can also call fill() at any time to fill the vector with a

    value.

    QVector uses 0-based indexes, just like C++ arrays. To access the

    item at a particular index position, you can use operator[](). On

    non-const vectors, operator[]() returns a reference to the item

    that can be used on the left side of an assignment:

    \snippet doc/src/snippets/code/src_corelib_tools_qvector.cpp 3

    For read-only access, an alternative syntax is to use at():

    \snippet doc/src/snippets/code/src_corelib_tools_qvector.cpp 4

    at() can be faster than operator[](), because it never causes a

    \l{deep copy} to occur.

    Another way to access the data stored in a QVector is to call

    data(). The function returns a pointer to the first item in the

    vector. You can use the pointer to directly access and modify the

    elements stored in the vector. The pointer is also useful if you

    need to pass a QVector to a function that accepts a plain C++

    array.

    If you want to find all occurrences of a particular value in a

    vector, use indexOf() or lastIndexOf(). The former searches

    forward starting from a given index position, the latter searches

    backward. Both return the index of the matching item if they found

    one; otherwise, they return -1. For example:

    \snippet doc/src/snippets/code/src_corelib_tools_qvector.cpp 5

    If you simply want to check whether a vector contains a

    particular value, use contains(). If you want to find out how

    many times a particular value occurs in the vector, use count().

    QVector provides these basic functions to add, move, and remove

    items: insert(), replace(), remove(), prepend(), append(). With

    the exception of append() and replace(), these functions can be slow

    (\l{linear time}) for large vectors, because they require moving many

    items in the vector by one position in memory. If you want a container

    class that provides fast insertion/removal in the middle, use

    QList or QLinkedList instead.

    Unlike plain C++ arrays, QVectors can be resized at any time by

    calling resize(). If the new size is larger than the old size,

    QVector might need to reallocate the whole vector. QVector tries

    to reduce the number of reallocations by preallocating up to twice

    as much memory as the actual data needs.

    If you know in advance approximately how many items the QVector

    will contain, you can call reserve(), asking QVector to

    preallocate a certain amount of memory. You can also call

    capacity() to find out how much memory QVector actually

    allocated.

    Note that using non-const operators and functions can cause

    QVector to do a deep copy of the data. This is due to \l{implicit sharing}.

    QVector's value type must be an \l{assignable data type}. This

    covers most data types that are commonly used, but the compiler

    won't let you, for example, store a QWidget as a value; instead,

    store a QWidget *. A few functions have additional requirements;

    for example, indexOf() and lastIndexOf() expect the value type to

    support \c operator==().  These requirements are documented on a

    per-function basis.

    Like the other container classes, QVector provides \l{Java-style

    iterators} (QVectorIterator and QMutableVectorIterator) and

    \l{STL-style iterators} (QVector::const_iterator and

    QVector::iterator). In practice, these are rarely used, because

    you can use indexes into the QVector.

    In addition to QVector, Qt also provides QVarLengthArray, a very

    low-level class with little functionality that is optimized for

    speed.

    QVector does \e not support inserting, prepending, appending or replacing

    with references to its own values. Doing so will cause your application to

    abort with an error message.

    \sa QVectorIterator, QMutableVectorIterator, QList, QLinkedList

*/

/*!

    \fn QVector<T> QVector::mid(int pos, int length = -1) const

    Returns a vector whose elements are copied from this vector,

    starting at position \a pos. If \a length is -1 (the default), all

    elements after \a pos are copied; otherwise \a length elements (or

    all remaining elements if there are less than \a length elements)

    are copied.

*/

/*! \fn QVector::QVector()

    Constructs an empty vector.

    \sa resize()

*/

/*! \fn QVector::QVector(int size)

    Constructs a vector with an initial size of \a size elements.

    The elements are initialized with a \l{default-constructed

    value}.

    \sa resize()

*/

/*! \fn QVector::QVector(int size, const T &value)

    Constructs a vector with an initial size of \a size elements.

    Each element is initialized with \a value.

    \sa resize(), fill()

*/

/*! \fn QVector::QVector(const QVector<T> &other)

    Constructs a copy of \a other.

    This operation takes \l{constant time}, because QVector is

    \l{implicitly shared}. This makes returning a QVector from a

    function very fast. If a shared instance is modified, it will be

    copied (copy-on-write), and that takes \l{linear time}.

    \sa operator=()

*/

/*! \fn QVector::~QVector()

    Destroys the vector.

*/

/*! \fn QVector<T> &QVector::operator=(const QVector<T> &other)

    Assigns \a other to this vector and returns a reference to this

    vector.

*/

/*! \fn bool QVector::operator==(const QVector<T> &other) const

    Returns true if \a other is equal to this vector; otherwise

    returns false.

    Two vectors are considered equal if they contain the same values

    in the same order.

    This function requires the value type to have an implementation

    of \c operator==().

    \sa operator!=()

*/

/*! \fn bool QVector::operator!=(const QVector<T> &other) const

    Returns true if \a other is not equal to this vector; otherwise

    returns false.

    Two vectors are considered equal if they contain the same values

    in the same order.

    This function requires the value type to have an implementation

    of \c operator==().

    \sa operator==()

*/

/*! \fn int QVector::size() const

    Returns the number of items in the vector.

    \sa isEmpty(), resize()

*/

/*! \fn bool QVector::isEmpty() const

    Returns true if the vector has size 0; otherwise returns false.

    \sa size(), resize()

*/

/*! \fn void QVector::resize(int size)

    Sets the size of the vector to \a size. If \a size is greater than the

    current size, elements are added to the end; the new elements are

    initialized with a \l{default-constructed value}. If \a size is less

    than the current size, elements are removed from the end.

    \sa size()

*/

/*! \fn int QVector::capacity() const

    Returns the maximum number of items that can be stored in the

    vector without forcing a reallocation.

    The sole purpose of this function is to provide a means of fine

    tuning QVector's memory usage. In general, you will rarely ever

    need to call this function. If you want to know how many items are

    in the vector, call size().

    \sa reserve(), squeeze()

*/

/*! \fn void QVector::reserve(int size)

    Attempts to allocate memory for at least \a size elements. If you

    know in advance how large the vector will be, you can call this

    function, and if you call resize() often you are likely to get

    better performance. If \a size is an underestimate, the worst

    that will happen is that the QVector will be a bit slower.

    The sole purpose of this function is to provide a means of fine

    tuning QVector's memory usage. In general, you will rarely ever

    need to call this function. If you want to change the size of the

    vector, call resize().

    \sa squeeze(), capacity()

*/

/*! \fn void QVector::squeeze()

    Releases any memory not required to store the items.

    The sole purpose of this function is to provide a means of fine

    tuning QVector's memory usage. In general, you will rarely ever

    need to call this function.

    \sa reserve(), capacity()

*/

/*! \fn void QVector::detach()

    \internal

*/

/*! \fn bool QVector::isDetached() const

    \internal

*/

/*! \fn void QVector::setSharable(bool sharable)

    \internal

*/

/*! \fn T *QVector::data()

    Returns a pointer to the data stored in the vector. The pointer

    can be used to access and modify the items in the vector.

    Example:

    \snippet doc/src/snippets/code/src_corelib_tools_qvector.cpp 6

    The pointer remains valid as long as the vector isn't

    reallocated.

    This function is mostly useful to pass a vector to a function

    that accepts a plain C++ array.

    \sa constData(), operator[]()

*/

/*! \fn const T *QVector::data() const

    \overload

*/

/*! \fn const T *QVector::constData() const

    Returns a const pointer to the data stored in the vector. The

    pointer can be used to access the items in the vector.

    The pointer remains valid as long as the vector isn't

    reallocated.

    This function is mostly useful to pass a vector to a function

    that accepts a plain C++ array.

    \sa data(), operator[]()

*/

/*! \fn void QVector::clear()

    Removes all the elements from the vector and releases the memory used by

    the vector.

*/

/*! \fn const T &QVector::at(int i) const

    Returns the item at index position \a i in the vector.

    \a i must be a valid index position in the vector (i.e., 0 <= \a

    i < size()).

    \sa value(), operator[]()

*/

/*! \fn T &QVector::operator[](int i)

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

    \a i must be a valid index position in the vector (i.e., 0 <= \a i

    < size()).

    Note that using non-const operators can cause QVector to do a deep

    copy.

    \sa at(), value()

*/

/*! \fn const T &QVector::operator[](int i) const

    \overload

    Same as at(\a i).

*/

/*! 

    \fn void QVector::append(const T &value)

    Inserts \a value at the end of the vector.

    Example:

    \snippet doc/src/snippets/code/src_corelib_tools_qvector.cpp 7

    This is the same as calling resize(size() + 1) and assigning \a

    value to the new last element in the vector.

    This operation is relatively fast, because QVector typically

    allocates more memory than necessary, so it can grow without

    reallocating the entire vector each time.

    \sa operator<<(), prepend(), insert()

*/

/*! \fn void QVector::prepend(const T &value)

    Inserts \a value at the beginning of the vector.

    Example:

    \snippet doc/src/snippets/code/src_corelib_tools_qvector.cpp 8

    This is the same as vector.insert(0, \a value).

    For large vectors, this operation can be slow (\l{linear time}),

    because it requires moving all the items in the vector by one

    position further in memory. If you want a container class that

    provides a fast prepend() function, use QList or QLinkedList

    instead.

    \sa append(), insert()

*/

/*! \fn void QVector::insert(int i, const T &value)

    Inserts \a value at index position \a i in the vector. If \a i is

    0, the value is prepended to the vector. If \a i is size(), the

    value is appended to the vector.

    Example:

    \snippet doc/src/snippets/code/src_corelib_tools_qvector.cpp 9

    For large vectors, this operation can be slow (\l{linear time}),

    because it requires moving all the items at indexes \a i and

    above by one position further in memory. If you want a container

    class that provides a fast insert() function, use QLinkedList

    instead.

    \sa append(), prepend(), remove()

*/

/*! \fn void QVector::insert(int i, int count, const T &value)

    \overload

    Inserts \a count copies of \a value at index position \a i in the

    vector.