Soprano::Node Class Reference

A Node represents one RDF resource. More...

#include <Soprano/Node>

List of all members.

Public Types
enum	Type { EmptyNode = 0, ResourceNode = 1, LiteralNode = 2, BlankNode = 3 }
Public Member Functions
Constructors
	Node (const Node &other)
SOPRANO_CONSTRUCTOR_DEPRECATED	Node (const LiteralValue &value, const QString &language)
	Node (const LiteralValue &value)
	Node (const QString &id)
	Node (const QUrl &uri)
	Node ()
	~Node ()
Literal nodes
QUrl	dataType () const
QString	language () const
LiteralValue	literal () const
Blank nodes
QString	identifier () const
Type information
bool	isBlank () const
bool	isEmpty () const
bool	isLiteral () const
bool	isResource () const
bool	isValid () const
Type	type () const
Operators
bool	matches (const Node &other) const
bool	operator!= (const Node &other) const
Node &	operator= (const LiteralValue &literal)
Node &	operator= (const QUrl &resource)
Node &	operator= (const Node &other)
bool	operator== (const LiteralValue &other) const
bool	operator== (const QUrl &uri) const
bool	operator== (const Node &other) const
Conversion
QString	toN3 () const
QString	toString () const
Resource nodes
QUrl	uri () const
Static Public Member Functions
static QString	blankToN3 (const QString &blank)
static Node	createBlankNode (const QString &id)
static Node	createEmptyNode ()
static SOPRANO_DEPRECATED Node	createLiteralNode (const LiteralValue &value, const QString &language)
static Node	createLiteralNode (const LiteralValue &value)
static Node	createResourceNode (const QUrl &uri)
static QString	literalToN3 (const LiteralValue &literal)
static QString	resourceToN3 (const QUrl &resource)
Related Functions
(Note that these are not member functions.)
SOPRANO_EXPORT QTextStream &	operator<< (QTextStream &s, const Soprano::Node &)
SOPRANO_EXPORT QDebug	operator<< (QDebug s, const Soprano::Node &)

---

Detailed Description

A Node represents one RDF resource.

Nodes are the cornerstone of RDF data in Soprano. Four Nodes form one Statement and a Model is essentially a set of Statements.

A Node can have one of four types: EmptyNode, ResourceNode, LiteralNode, and BlankNode. Resource nodes are identified through their URI (uri()), literal nodes have a LiteralValue (literal()), and blank nodes have a string identifier.

Empty nodes can be used as wildcards in methods such as Model::listStatements.

Author:

Daniele Galdi <daniele.galdi@gmail.com>
Sebastian Trueg <trueg@kde.org>

Definition at line 53 of file node.h.

---

Member Enumeration Documentation

enum Soprano::Node::Type

Enumerator:

EmptyNode	An empty node, can be used as a wildcard in commands like Model::listStatements.
ResourceNode	A resource node has a URI which can be accessed via uri().
LiteralNode	A literal node has a literal value and an optional language.
BlankNode	A blank node has an identifier string.

Definition at line 56 of file node.h.

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Constructor & Destructor Documentation

Soprano::Node::Node

(

)

Default costructor.

Creates an empty node.

See also:

createEmptyNode()

Soprano::Node::Node

(

const QUrl &

uri

)

Creates a resource node.

Parameters:

uri

The URI of the node. If empty the type will be ignored and an empty node will be created.

See also:

createResourceNode()

Soprano::Node::Node

(

const QString &

id

)

[explicit]

Creates a blank node.

Parameters:

id

An identifier for the blank node.

See also:

createBlankNode()

Soprano::Node::Node

(

const LiteralValue &

value

)

Creates a literal node.

Parameters:

value

The value of a node. If empty the node will become an empty node.

See also:

createLiteralNode()

Since:

2.3

SOPRANO_CONSTRUCTOR_DEPRECATED Soprano::Node::Node	(	const LiteralValue &	value,
		const QString &	language
	)

Creates a literal node.

Parameters:

	value	The value of a node. If empty the node will become an empty node.
	language	The language of the literal value.

See also:

createLiteralNode()

Deprecated:

Use Soprano::Node::Node( const LiteralValue& ) and Soprano::LiteralValue::createPlainLiteral( const QString&, const LanguageTag& )

Soprano::Node::Node

(

const Node &

other

)

Copy constructor.

Soprano::Node::~Node

(

)

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Member Function Documentation

static QString Soprano::Node::blankToN3

(

const QString &

blank

)

[static]

Format a blank node identifier as N3 string to be used in SPARQL queries.

Returns:

A string representing the blank identifier in N3 encoding or an empty string for invalid/empty ids.

Example:

 _:blankNode

See also:

toN3

Since:

2.3

static Node Soprano::Node::createBlankNode

(

const QString &

id

)

[static]

Convenience method to create a blank node.

Using this method instead of the constructor may result in better readable code.

If you need to create a new blank node which is not used in the model yet and, thus, has a unique identifier see Model::createBlankNode().

Parameters:

id

An identifier for the blank node.

Returns:

A blank node or an empty Node if the specified identifier was empty.

static Node Soprano::Node::createEmptyNode

(

)

[static]

Convenience method to create an empty node.

Using this method instead of the default constructor may result in better readable code.

Returns:

An empty Node.

static SOPRANO_DEPRECATED Node Soprano::Node::createLiteralNode	(	const LiteralValue &	value,
		const QString &	language
	)			[static]

Convenience method to create a literal node.

Using this method instead of the constructor may result in better readable code.

Parameters:

	value	The value of a node. If empty the node will become an empty node.
	language	The language of the literal value.

Returns:

A literal node or an empty node if the specified value was empty.

Deprecated:

Use Soprano::Node::createLiteralNode( const LiteralValue& ) and Soprano::LiteralValue::createPlainLiteral( const QString&, const LanguageTag& )

static Node Soprano::Node::createLiteralNode

(

const LiteralValue &

value

)

[static]

Convenience method to create a literal node.

Using this method instead of the constructor may result in better readable code.

Parameters:

value

The value of a node. If empty the node will become an empty node.

Returns:

A literal node or an empty node if the specified value was empty.

Since:

2.3

static Node Soprano::Node::createResourceNode

(

const QUrl &

uri

)

[static]

Convenience method to create a resource node.

Using this method instead of the constructor may result in better readable code.

Parameters:

uri

The URI of the node. If empty the type will be ignored and an empty node will be created.

Returns:

A resource Node or an empty Node if the specified URI is empty.

QUrl Soprano::Node::dataType

(

)

const

Returns:

The datatype URI of a literal node, i.e. the XML schema type or an empty value if the node is not a LiteralNode.

See also:

LiteralValue::dataTypeUri

QString Soprano::Node::identifier

(

)

const

Retrieve a blank node's identifier.

Returns:

The node's identifier if it is a BlankNode, a null string otherwise.

bool Soprano::Node::isBlank

(

)

const

Returns:

true if the node is a BlankNode (anonymous).

bool Soprano::Node::isEmpty

(

)

const

Returns:

true if the node is empty.

bool Soprano::Node::isLiteral

(

)

const

Returns:

true if the node is a LiteralNode.

bool Soprano::Node::isResource

(

)

const

Returns:

true if the node is a ResourceNode.

bool Soprano::Node::isValid

(

)

const

Returns:

true if the node is a ResourceNode, LiteralNode or BlankNode.

QString Soprano::Node::language

(

)

const

Each literal value can have an associated language, thus each property can be stored for different languages.

An empty language refers to the default language.

Returns:

A string representing the language of the literal value or an empty string if the node is not a literal.

Deprecated:

Language exists on the Soprano::LiteralValue. Use Soprano::Node::literal() and Soprano::LiteralValue::language().

LiteralValue Soprano::Node::literal

(

)

const

Returns:

The literal value if the node is a LiteralNode. An null QString otherwise.

static QString Soprano::Node::literalToN3

(

const LiteralValue &

literal

)

[static]

Format a literal value as N3 string to be used in SPARQL queries.

Returns:

A string representing the literal in N3 encoding or an empty string for invalid literals.

Examples:

 "Hello World"^^<http://www.w3.org/2001/XMLSchema#string>
 "09-08-1977T17:42.234Z"^^<http://www.w3.org/2001/XMLSchema#dateTime>

See also:

toN3

Since:

2.3

bool Soprano::Node::matches

(

const Node &

other

)

const

Match this node against template node other.

The only difference to operator== is that empty nodes are matched as wildcards, i.e. they match any other node.

Be aware that the following is NOT always true since only other is treated a a wildcard:

 // NOT always true:
 a.matches(b) == b.matches(a)

Returns:

true if this node matches other, false if not.

See also:

Statement::matches

bool Soprano::Node::operator!=

(

const Node &

other

)

const

Comparision operator.

Returns:

true if this node and other differ.

Node& Soprano::Node::operator=

(

const LiteralValue &

literal

)

Assigns literal to this node and makes it a LiteralNode.

Node& Soprano::Node::operator=

(

const QUrl &

resource

)

Assigns resource to this node and makes it a ResourceNode.

Node& Soprano::Node::operator=

(

const Node &

other

)

bool Soprano::Node::operator==

(

const LiteralValue &

other

)

const

Comparision operator.

Returns:

true if this node is a LiteralNode and has literal value other.

bool Soprano::Node::operator==

(

const QUrl &

uri

)

const

Comparision operator.

Returns:

true if this node is a ResourceNode and has URI uri.

bool Soprano::Node::operator==

(

const Node &

other

)

const

Comparision operator.

Returns:

true if this node and other are equal.

static QString Soprano::Node::resourceToN3

(

const QUrl &

resource

)

[static]

Format a resource URI as N3 string to be used in SPARQL queries.

Returns:

A string representing the resource in N3 encoding or an empty string for invalid URIs.

Example:

 <http://soprano.sourceforce.net/>

See also:

toN3

Since:

2.3

QString Soprano::Node::toN3

(

)

const

Convert a Node into N3 notation to be used in SPARQL graph patterns.

Examples:

 <http://soprano.sourceforce.net/>
 "Hello World"^^<http://www.w3.org/2001/XMLSchema#string>
 "09-08-1977T17:42.234Z"^^<http://www.w3.org/2001/XMLSchema#dateTime>
 _:blankNode

Returns:

A string representing the node in N3 encoding or an empty string for invalid nodes.

See also:

toString()

Since:

2.2

QString Soprano::Node::toString

(

)

const

Converts the Node to a string.

Returns:

A String representation of the Node, suitable for storage, not really suitable for user readable strings.

See also:

LiteralValue::toString(), QUrl::toString(), toN3()

Type Soprano::Node::type

(

)

const

Returns:

The node type.

QUrl Soprano::Node::uri

(

)

const

Returns:

The URI if the node is a ResourceNode. An null QUrl otherwise.

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Friends And Related Function Documentation

SOPRANO_EXPORT QTextStream & operator<<	(	QTextStream &	s,
		const Soprano::Node &
	)			[related]

Default Soprano::Node stream operator.

The operator serializes the Node based on the N-Triples standard, except that it uses Unicode strings.

See also:

Soprano::Node::toN3()

SOPRANO_EXPORT QDebug operator<<	(	QDebug	s,
		const Soprano::Node &
	)			[related]

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

• node.h
• statement.h