org.apache.marmotta.ldpath

Class LDPath<Node>

java.lang.Object

org.apache.marmotta.ldpath.LDPath<Node>

Type Parameters:

Node - the node type used by the backend

Author: Sebastian Schaffert

public class LDPath<Node>
extends Object

Main class providing query functionality for the different RDF backends.

Constructor Summary

Constructors

Constructor and Description
LDPath(RDFBackend<Node> backend) Initialise a new LDPath instance for querying the backend passed as argument with the default configuration.
LDPath(RDFBackend<Node> backend, Configuration<Node> config) Initialise a new LDPath instance for querying the backend passed as argument with a custom configuration for default functions, transformers and namespaces.

Method Summary

Methods

Modifier and Type	Method and Description
Configuration<Node>	getConfig() Return the configuration underlying this LDPath instance.
Set<SelectorFunction<Node>>	getFunctions() Return the collection of selector functions registered with this LDPath instance.
Map<String,NodeTransformer<?,Node>>	getTransformers()
Program<Node>	parseProgram(Reader program) Parse a program passed as argument and return it for further use.
Collection<Node>	pathQuery(Node context, String path, Map<String,String> namespaces) Execute a single path query starting from the given context node and return a collection of nodes resulting from the selection.
Collection<Node>	pathQuery(Node context, String path, Map<String,String> namespaces, Map<Node,List<Node>> paths) Execute a single path query starting from the given context node and return a collection of nodes resulting from the selection.
<T> Collection<T>	pathTransform(Node context, String path, Map<String,String> namespaces) Execute a single path query starting from the given context node and return a collection of nodes resulting from the selection.
Map<String,Collection<?>>	programQuery(Node context, Reader program) Evaluate a path program passed as argument starting from the given context node and return a mapping for each field in the program to the selected values.
void	registerFunction(SelectorFunction<Node> function) Register a selector function to be used in LDPath.
void	registerTransformer(String typeUri, NodeTransformer<?,Node> transformer) Register a result transformer for a type URI.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

LDPath

public LDPath(RDFBackend<Node> backend)

Initialise a new LDPath instance for querying the backend passed as argument with the default configuration.

Parameters:

backend -

LDPath

public LDPath(RDFBackend<Node> backend,
      Configuration<Node> config)

Initialise a new LDPath instance for querying the backend passed as argument with a custom configuration for default functions, transformers and namespaces.

Parameters:

backend -

config -

Method Detail

pathQuery

public Collection<Node> pathQuery(Node context,
                         String path,
                         Map<String,String> namespaces)
                           throws LDPathParseException

Execute a single path query starting from the given context node and return a collection of nodes resulting from the selection. Default namespaces (rdf, rdfs, skos, dc, foaf) are added automatically, further namespaces need to be passed as arguments.

Paths need to conform to the RdfPath Selector syntax described at the wiki. For example, the following selection would select the names of all friends:

foaf:knows / foaf:name

Note that since this method returns a collection of nodes, no transformations can be used.

Parameters:

context - the context node where to start the path query

path - the LDPath path specification

namespaces - an optional map mapping namespace prefixes to URIs (used for lookups of prefixes used in the path); can be null

Returns:

a collection of nodes

Throws:

LDPathParseException - when the path passed as argument is not valid

pathQuery

public Collection<Node> pathQuery(Node context,
                         String path,
                         Map<String,String> namespaces,
                         Map<Node,List<Node>> paths)
                           throws LDPathParseException

Execute a single path query starting from the given context node and return a collection of nodes resulting from the selection. In addition, the paths leading to the individual results are returned in the map passed as argument "paths".

Default namespaces (rdf, rdfs, skos, dc, foaf) are added automatically, further namespaces need to be passed as arguments.

Paths need to conform to the RdfPath Selector syntax described at the wiki. For example, the following selection would select the names of all friends:

foaf:knows / foaf:name

Note that since this method returns a collection of nodes, no transformations can be used.

Parameters:

context - the context node where to start the path query

path - the LDPath path specification

namespaces - an optional map mapping namespace prefixes to URIs (used for lookups of prefixes used in the path); can be null

Returns:

a collection of nodes

Throws:

LDPathParseException - when the path passed as argument is not valid

pathTransform

public <T> Collection<T> pathTransform(Node context,
                              String path,
                              Map<String,String> namespaces)
                            throws LDPathParseException

Execute a single path query starting from the given context node and return a collection of nodes resulting from the selection. Default namespaces (rdf, rdfs, skos, dc, foaf) are added automatically, further namespaces need to be passed as arguments.

Paths need to conform to the RdfPath Selector syntax described at the wiki. For example, the following selection would select the names of all friends:

foaf:knows / foaf:name

Note that since this method returns a collection of nodes, no transformations can be used.

Parameters:

context - the context node where to start the path query

path - the LDPath path specification

namespaces - an optional map mapping namespace prefixes to URIs (used for lookups of prefixes used in the path); can be null

Returns:

a collection of nodes

Throws:

LDPathParseException - when the path passed as argument is not valid

programQuery

public Map<String,Collection<?>> programQuery(Node context,
                                     Reader program)
                                       throws LDPathParseException

Evaluate a path program passed as argument starting from the given context node and return a mapping for each field in the program to the selected values.

Parameters:

context -

program -

Returns:

Throws:

LDPathParseException

parseProgram

public Program<Node> parseProgram(Reader program)
                           throws LDPathParseException

Parse a program passed as argument and return it for further use.

Parameters:

program - a reader containing the program in LDPath syntax

Returns:

the parsed program

Throws:

LDPathParseException

registerFunction

public void registerFunction(SelectorFunction<Node> function)

Register a selector function to be used in LDPath. Use this method in your own projects to register custom selector functions.

Parameters:

function -

getFunctions

public Set<SelectorFunction<Node>> getFunctions()

Return the collection of selector functions registered with this LDPath instance.

Returns:

registerTransformer

public void registerTransformer(String typeUri,
                       NodeTransformer<?,Node> transformer)

Register a result transformer for a type URI. Use this method in your own projects to register custom result transformers.

Parameters:

typeUri - a URI identifying the type for which to use this transformer; can be specified in path programs

transformer - instance of a node transformer

getTransformers

public Map<String,NodeTransformer<?,Node>> getTransformers()

getConfig

public Configuration<Node> getConfig()

Return the configuration underlying this LDPath instance.

Returns: