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QXmlItem Class Reference
[QtXmlPatterns module]

The QXmlItem class represents an item in XQuery and XPath, which is either a node or an atomic value. More...

 #include <QXmlItem>

Note: All the functions in this class are reentrant.

This class was introduced in Qt 4.4.

• List of all members, including inherited members

Public Types

• typedef Iterator

Public Functions

• QXmlItem ()
• QXmlItem ( const QXmlItem & other )
• QXmlItem ( const QXmlNodeModelIndex & node )
• QXmlItem ( const QVariant & atomicValue )
• ~QXmlItem ()
• bool isAtomicValue () const
• bool isNode () const
• bool isNull () const
• QVariant toAtomicValue () const
• QXmlNodeModelIndex toNodeModelIndex () const
• QXmlItem & operator= ( const QXmlItem & other )

Detailed Description

The QXmlItem class represents an item in XQuery and XPath, which is either a node or an atomic value.

In XQuery, all expressions evaluate to a sequence of items, where each item is an atomic value or a XML node. For instance, this query:

 <aNode/>,
 xs:base64Binary("FFFF"),
 current-date(),
 3e3, (: A floating point value :)
 attribute {"name"} {()}

evaluate to a sequence of five items: an element, an atomic value which is binary data encoded in base64, a date, a float, and an attribute node.

QXmlItem is the class that represents XQuery items in the Qt API. It is always either a node or an item, which isNode() and isAtomicValue() tells. Atomic values are represented in Qt using QVariant, and a QXmlitem can be converted to one by calling toAtomicValue(). Similarly, nodes are represented with QXmlNodeModelIndex, and those can be retrieved by calling toNodeModelIndex().

A default constructed QXmlItem instance is neither a node or an atomic value, it is null, as isNull() tells.

QXmlItem instances will dangle if the model that QXmlNodeModelIndex instances refers to is deleted.

Member Type Documentation

typedef QXmlItem::Iterator

A QAbstractXmlForwardIterator over QXmlItem.

Member Function Documentation

QXmlItem::QXmlItem ()

Construct a null QXmlItem, which is neither a node nor an atomic value.

For a default constructed QXmlItem, isNull() returns true.

QXmlItem::QXmlItem ( const QXmlItem & other )

Constructs a QXmlItem instance that is a copy of other.

QXmlItem::QXmlItem ( const QXmlNodeModelIndex & node )

Constructs a QXmlItem instance that is a copy of node. This item will subsequently be a node.

See also QXmlItem::isNode().

QXmlItem::QXmlItem ( const QVariant & atomicValue )

Constructs a QXmlItem that is the atomic value atomicValue.

QXmlItem::~QXmlItem ()

Destructs this QXmlItem instance.

bool QXmlItem::isAtomicValue () const

Returns true if this item is an atomic value, otherwise false.

If this item is null, false is returned.

See also isNull() and isNode().

bool QXmlItem::isNode () const

Returns true if this item is a Node, otherwise false.

If this item is null, false is returned.

See also isNull() and isAtomicValue().

bool QXmlItem::isNull () const

Returns true if this QXmlItem instance do not represent an item.

QVariant QXmlItem::toAtomicValue () const

Considers this item an atomic value, and returns it in the form of a QVariant instance.

If this QXmlItem is not an atomic value, the return value is a default constructed QVariant.

See also isAtomicValue().

QXmlNodeModelIndex QXmlItem::toNodeModelIndex () const

Considers this item an node, and returns it in the form of a QXmlNodeModelIndex instance.

If this QXmlItem is not a node, the return value is undefined.

See also isNode().

QXmlItem & QXmlItem::operator= ( const QXmlItem & other )

Assigns other to this QXmlItem instance.