com.trolltech.qt.xmlpatterns
Class QXmlName

java.lang.Object
  extended by com.trolltech.qt.internal.QSignalEmitterInternal
      extended by com.trolltech.qt.QSignalEmitter
          extended by com.trolltech.qt.QtJambiObject
              extended by com.trolltech.qt.xmlpatterns.QXmlName
All Implemented Interfaces:
QtJambiInterface, java.lang.Cloneable

public class QXmlName
extends QtJambiObject
implements java.lang.Cloneable

The QXmlName class represents the name of an XML node, in an efficient, namespace-aware way. QXmlName represents the name of an XML node in a way that is both efficient and safe for comparing names. Normally, an XML node represents an XML element or attribute, but QXmlName can also represent the names of other kinds of nodes, e.g., QAbstractXmlReceiver::processingInstruction() and QAbstractXmlReceiver::namespaceBinding().

The name of an XML node has three components: The namespace URI, the local name, and the prefix. To see what these refer to in XML, consider the following snippet.

<book xmlns:dc='http://purl.org/dc/elements/1.1'
      xmlns='http://example.com/MyDefault'>
    <dc:title>Mobey Dick</dc:title> ...
</book>
For the element named book, localName() returns book, namespaceUri() returns http://example.com/MyDefault, and prefix() returns an empty string. For the element named title, localName() returns title, namespaceUri() returns http://purl.org/dc/elements/1.1, and prefix() returns dc.

To ensure that operations with QXmlName are efficient, e.g., copying names and comparing them, each instance of QXmlName is associated with a name pool, which must be specified at QXmlName construction time. The three components of the QXmlName, i.e., the namespace URI, the local name, and the prefix, are stored in the name pool mapped to identifiers so they can be shared. For this reason, the only way to create a valid instance of QXmlName is to use the class constructor, where the name pool, local name, namespace URI, and prefix must all be specified.

Note that QXmlName's default constructor constructs a null instance. It is typically used for allocating unused entries in collections of QXmlName.

A side effect of associating each instance of QXmlName with a name pool is that each instance of QXmlName is tied to the QXmlNamePool with which it was created. However, the QXmlName class does not keep track of the name pool, so all the accessor functions, e.g., namespaceUri(), prefix(), localName(), and toClarkName() require that the correct name pool be passed to them. Failure to provide the correct name pool to these accessor functions results in undefined behavior.

Note that a name pool is not an XML namespace. One name pool can represent instances of QXmlName from different XML namespaces, and the instances of QXmlName from one XML namespace can be distributed over multiple name pools.

Comparing QXmlNames

To determine what a QXmlName refers to, the namespace URI and the local name are used. The prefix is not used because the prefix is simply a shorthand name for use in place of the normally much longer namespace URI. Nor is the prefix used in name comparisons. For example, the following two element nodes represent the same element and compare equal.
<svg xmlns="http://www.w3.org/2000/svg"/>
<x:svg xmlns:x="http://www.w3.org/2000/svg"/>
Although the second name has the prefix x, the two names compare equal as instances of QXmlName, because the prefix is not used in the comparison.

A local name can never be an empty string, although the prefix and namespace URI can. If the prefix is not empty, the namespace URI cannot be empty. Local names and prefixes must be valid NCNames, e.g., abc.def or abc123.

QXmlName represents what is sometimes called an expanded QName, or simply a QName.

See also:


Nested Class Summary
 
Nested classes/interfaces inherited from class com.trolltech.qt.QSignalEmitter
QSignalEmitter.AbstractSignal, QSignalEmitter.PrivateSignal0, QSignalEmitter.PrivateSignal1, QSignalEmitter.PrivateSignal2, QSignalEmitter.PrivateSignal3, QSignalEmitter.PrivateSignal4, QSignalEmitter.PrivateSignal5, QSignalEmitter.PrivateSignal6, QSignalEmitter.PrivateSignal7, QSignalEmitter.PrivateSignal8, QSignalEmitter.PrivateSignal9, QSignalEmitter.Signal0, QSignalEmitter.Signal1, QSignalEmitter.Signal2, QSignalEmitter.Signal3, QSignalEmitter.Signal4, QSignalEmitter.Signal5, QSignalEmitter.Signal6, QSignalEmitter.Signal7, QSignalEmitter.Signal8, QSignalEmitter.Signal9
 
Nested classes/interfaces inherited from class com.trolltech.qt.internal.QSignalEmitterInternal
com.trolltech.qt.internal.QSignalEmitterInternal.AbstractSignalInternal
 
Field Summary
 
Fields inherited from class com.trolltech.qt.internal.QSignalEmitterInternal
currentSender
 
Constructor Summary
QXmlName()
          Constructs an uninitialized QXmlName.
QXmlName(QXmlNamePool namePool, java.lang.String localName)
          Equivalent to calling QXmlName(namePool, localName, null, null)
QXmlName(QXmlNamePool namePool, java.lang.String localName, java.lang.String namespaceURI)
          Equivalent to calling QXmlName(namePool, localName, namespaceURI, null);
QXmlName(QXmlNamePool namePool, java.lang.String localName, java.lang.String namespaceURI, java.lang.String prefix)
          Constructs a QXmlName instance that inserts localName, namespaceURI and prefix into namePool if they aren't already there.
 
Method Summary
 QXmlName clone()
           
static QXmlName fromClarkName(java.lang.String clarkName, QXmlNamePool namePool)
          Converts clarkName into a QXmlName, inserts into namePool, and returns it.
static boolean isNCName(java.lang.String candidate)
          Returns true if candidate is an NCName.
 boolean isNull()
          Returns true if this QXmlName is not initialized with a valid combination of namespace URI, local name, and prefix.
 java.lang.String localName(QXmlNamePool query)
          Returns the local name.
 java.lang.String namespaceUri(QXmlNamePool query)
          Returns the namespace URI.
 java.lang.String prefix(QXmlNamePool query)
          Returns the prefix.
 java.lang.String toClarkName(QXmlNamePool query)
          Returns this QXmlName formatted as a Clark Name.
 
Methods inherited from class com.trolltech.qt.QtJambiObject
dispose, disposed, equals, finalize, reassignNativeResources, tr, tr, tr
 
Methods inherited from class com.trolltech.qt.QSignalEmitter
blockSignals, disconnect, disconnect, signalsBlocked, signalSender, thread
 
Methods inherited from class com.trolltech.qt.internal.QSignalEmitterInternal
__qt_signalInitialization
 
Methods inherited from class java.lang.Object
getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 
Methods inherited from interface com.trolltech.qt.QtJambiInterface
disableGarbageCollection, nativeId, nativePointer, reenableGarbageCollection, setJavaOwnership
 

Constructor Detail

QXmlName

public QXmlName()
Constructs an uninitialized QXmlName. To build a valid QXmlName, you normally use the other constructor, which takes a name pool, namespace URI, local name, and prefix as parameters. But you can also use this constructor to build a null QXmlName and then assign an existing QXmlName to it.

See also:
isNull().


QXmlName

public QXmlName(QXmlNamePool namePool,
                java.lang.String localName,
                java.lang.String namespaceURI,
                java.lang.String prefix)
Constructs a QXmlName instance that inserts localName, namespaceURI and prefix into namePool if they aren't already there. The accessor functions namespaceUri(), prefix(), localName(), and toClarkName() must be passed the namePool used here, so the namePool must remain in scope while the accessor functions might be used. However, two instances can be compared with == or != and copied without the namePool. The user guarantees that the string components are valid for a QName. In particular, the local name, and the prefix (if present), must be valid NCNames The function isNCName() can be used to test validity of these names. The namespace URI should be an absolute URI. QUrl.isRelative() can be used to test whether the namespace URI is relative or absolute. Finally, providing a prefix is not valid when no namespace URI is provided. namePool is not copied. Nor is the reference to it retained in this instance. This constructor inserts the three strings into namePool.


QXmlName

public QXmlName(QXmlNamePool namePool,
                java.lang.String localName,
                java.lang.String namespaceURI)
Equivalent to calling QXmlName(namePool, localName, namespaceURI, null);


QXmlName

public QXmlName(QXmlNamePool namePool,
                java.lang.String localName)
Equivalent to calling QXmlName(namePool, localName, null, null)

Method Detail

isNull

public final boolean isNull()
Returns true if this QXmlName is not initialized with a valid combination of namespace URI, local name, and prefix.

A valid local name is always required. The prefix and namespace URI can be empty, but if the prefix is not empty, the namespace URI must not be empty. Local names and prefixes must be valid NCNames, e.g., abc.def or abc123.


localName

public final java.lang.String localName(QXmlNamePool query)
Returns the local name.

Note that for efficiency, the local name string is not stored in the QXmlName but in the QXmlNamePool that was passed to the constructor. Hence, that same namePool must be passed to this function, so it can be used for looking up the local name.


namespaceUri

public final java.lang.String namespaceUri(QXmlNamePool query)
Returns the namespace URI.

Note that for efficiency, the namespace URI string is not stored in the QXmlName but in the QXmlNamePool that was passed to the constructor. Hence, that same namePool must be passed to this function, so it can be used for looking up the namespace URI.


prefix

public final java.lang.String prefix(QXmlNamePool query)
Returns the prefix.

Note that for efficiency, the prefix string is not stored in the QXmlName but in the QXmlNamePool that was passed to the constructor. Hence, that same namePool must be passed to this function, so it can be used for looking up the prefix.


toClarkName

public final java.lang.String toClarkName(QXmlNamePool query)
Returns this QXmlName formatted as a Clark Name. For example, if the local name is html, the prefix is x, and the namespace URI is http://www.w3.org/1999/xhtml/, then the Clark Name returned is:
{http://www.w3.org/1999/xhtml/}x:html.
If the local name is MyWidget and the namespace is empty, the Clark Name returned is:
MyWidget
Note that for efficiency, the namespace URI, local name, and prefix strings are not stored in the QXmlName but in the QXmlNamePool that was passed to the constructor. Hence, that same namePool must be passed to this function, so it can be used for looking up the three string components.

This function can be useful for debugging.

See also:
fromClarkName().


fromClarkName

public static QXmlName fromClarkName(java.lang.String clarkName,
                                     QXmlNamePool namePool)
Converts clarkName into a QXmlName, inserts into namePool, and returns it.

A clark name is a way to present a full QName with only one string, where the namespace cannot contain braces. Here are a couple of examples:

Clark Name
Description
html The local name html, in no namespace
http://www.w3.org/1999/xhtmlhtml The local name html, in the XHTML namespace
http://www.w3.org/1999/xhtmlmy:html The local name html, in the XHTML namespace, with the prefix my
If the namespace contains braces, the returned value is either invalid or has undefined content.

If clarkName is an invalid name, a default constructed QXmlName is returned.

See also:
toClarkName().


isNCName

public static boolean isNCName(java.lang.String candidate)
Returns true if candidate is an NCName. An NCName is a string that can be used as a name in XML and XQuery, e.g., the prefix or local name in an element or attribute, or the name of a variable.

See also:


clone

public QXmlName clone()
Overrides:
clone in class java.lang.Object