org.apache.marmotta.ldpath.model.backend

Class AbstractBackend<Node>

java.lang.Object

org.apache.marmotta.ldpath.model.backend.AbstractBackend<Node>

All Implemented Interfaces:

NodeBackend<Node>

public abstract class AbstractBackend<Node>
extends Object
implements NodeBackend<Node>

This provides an generic implementation of all **Value(Node node) methods other than stringValue(Object).

This allows to implement RDFBackends without dealing with the actual conversions needed for types literals not directly supported by a backend.

Backends however should implement - override default implementations provided by this class - **Value(Node node) methods with natively supported types to avoid unnecessary type conversions.

An Example for a RDFRepository<Object> that directly uses the the Java types for typed literals as nodes.

     public Double doubleValue(Object node) {
         //assume that this is typically only called on Double values
         try { 
             return (Double)node;
         } catch (ClassCastException e){
             //not a Double - call super to trigger parsing from
             //the lexical form.
             return super.doubleValue(node);
         }
 

Here an other possible implementation that does not assume that the node is of the requested type.

     public Double doubleValue(Object node) {
         if(node instanceof Double){
             return (Double)node;
         } else {
             //not a Double - call super to trigger parsing from
             //the lexical form.
             return super.doubleValue(node);
         }
 

It will depend on the use cases what of the two implementations performs better.

See Also:

NodeBackend.stringValue(java.lang.Object)

Constructor Summary

Constructors

Constructor and Description
AbstractBackend()

Method Summary

Methods

Modifier and Type	Method and Description
Boolean	booleanValue(Node node) Parses the boolean value from the lexical form.
Date	dateTimeValue(Node node) Parses dateTime value based on the lexical form of the parsed node.
Date	dateValue(Node node) Parses date vales based on the ISO8601 specification by using the lexical form of the parsed node.
BigDecimal	decimalValue(Node node) Parses the BigDecimal value from the lexical form of the parsed node as returned by NodeBackend.stringValue(Object).
Double	doubleValue(Node node) Parses the Double value of the parsed node based on its lexical form as returned by stringValue(Object).
Float	floatValue(Node node) Parses the Float value of the parsed node based on its lexical form as returned by stringValue(Object).
BigInteger	integerValue(Node node) Parses the BugIneger value of the parsed node by using decimalValue(Object).
Integer	intValue(Node node) Parses the Integer value of the parsed node by using decimalValue(Object).
Long	longValue(Node node) Parses the Long value of the parsed node by using decimalValue(Object).
protected Date	parseDate(String dateString) Utility to parse xsd:date strings
protected Date	parseTime(String timeString) Utility to parse xsd:time strings
abstract String	stringValue(Node node) Return the lexial representation of a node.
Date	timeValue(Node node) Parses time value based on the ISO8601 specification by using the lexical form of the parsed node.

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.marmotta.ldpath.api.backend.NodeBackend

createLiteral, createLiteral, createURI, getLiteralLanguage, getLiteralType, isBlank, isLiteral, isURI

Constructor Detail

AbstractBackend

public AbstractBackend()

Method Detail

doubleValue

public Double doubleValue(Node node)

Parses the Double value of the parsed node based on its lexical form as returned by stringValue(Object).

Specified by:

doubleValue in interface NodeBackend<Node>

Parameters:

node - the literal node for which to return the double value

Returns:

the double value

Throws:

NumberFormatException - if the lexical form can not be converted to a Double.

See Also:

NodeBackend.doubleValue(java.lang.Object)

floatValue

public Float floatValue(Node node)

Parses the Float value of the parsed node based on its lexical form as returned by stringValue(Object).

Specified by:

floatValue in interface NodeBackend<Node>

Parameters:

node - the literal node for which to return the float value

Returns:

the float value

Throws:

NumberFormatException - if the lexical form can not be converted to a Double.

See Also:

NodeBackend.floatValue(java.lang.Object)

longValue

public Long longValue(Node node)

Parses the Long value of the parsed node by using decimalValue(Object). This has the advantage, that decimal values that are also valid long values - such as '1.0' are also correctly converted to long.

Specified by:

longValue in interface NodeBackend<Node>

Parameters:

node - the literal node for which to return the long value

Returns:

the long value

Throws:

NumberFormatException - if the lexical form can not be converted to an Long.

ArithmeticException - if the lexical form can not be converted to a Long.

See Also:

NodeBackend.longValue(java.lang.Object)

intValue

public Integer intValue(Node node)

Parses the Integer value of the parsed node by using decimalValue(Object). This has the advantage, that decimal values that are also valid integer values - such as '1.0' are also correctly converted to Integer.

Specified by:

intValue in interface NodeBackend<Node>

Parameters:

node - the literal node for which to return the Integer (xsd:int) value

Returns:

the int value

Throws:

NumberFormatException - if the lexical form can not be converted to an Long.

ArithmeticException - if the lexical form can not be converted to a Long.

See Also:

NodeBackend.intValue(java.lang.Object)

decimalValue

public BigDecimal decimalValue(Node node)

Parses the BigDecimal value from the lexical form of the parsed node as returned by NodeBackend.stringValue(Object). This trims loading '+' sings.

Specified by:

decimalValue in interface NodeBackend<Node>

Parameters:

node - the literal node for which to return the xsd:decimal value

Returns:

the int value

Throws:

NumberFormatException - if the lexical form can not be converted to an Long.

ArithmeticException - if the lexical form can not be converted to a Long.

See Also:

NodeBackend.decimalValue(java.lang.Object)

integerValue

public BigInteger integerValue(Node node)

Parses the BugIneger value of the parsed node by using decimalValue(Object). This has the advantage, that decimal values that are also valid integer values - such as '1.0' are also correctly converted to BigInteger.

Specified by:

integerValue in interface NodeBackend<Node>

Parameters:

node - the literal node for which to return the xsd:integer value

Returns:

long value of the literal node

See Also:

NodeBackend.integerValue(java.lang.Object)

booleanValue

public Boolean booleanValue(Node node)

Parses the boolean value from the lexical form. Supports both '1' and Boolean.parseBoolean(String).

Specified by:

booleanValue in interface NodeBackend<Node>

Parameters:

node - the literal node for which to return the boolean value

Returns:

the boolean value

See Also:

NodeBackend.booleanValue(java.lang.Object)

dateValue

public Date dateValue(Node node)

Parses date vales based on the ISO8601 specification by using the lexical form of the parsed node.

Specified by:

dateValue in interface NodeBackend<Node>

Parameters:

node - the literal node for which to return the date value

Returns:

the Date representing the parsed date.

Throws:

IllegalArgumentException - on any ParseException while parsing the lexical form of the parsed node.

See Also:

NodeBackend.dateValue(java.lang.Object)

timeValue

public Date timeValue(Node node)

Parses time value based on the ISO8601 specification by using the lexical form of the parsed node.

Specified by:

timeValue in interface NodeBackend<Node>

Parameters:

node - the literal node for which to return the time value

Returns:

the Date representing the parsed date.

Throws:

IllegalArgumentException - on any ParseException while parsing the lexical form of the parsed node.

See Also:

NodeBackend.timeValue(java.lang.Object)

dateTimeValue

public Date dateTimeValue(Node node)

Parses dateTime value based on the lexical form of the parsed node. For details about parsing see FormatUtils.parseDate(String).

Specified by:

dateTimeValue in interface NodeBackend<Node>

Parameters:

node - the literal node for which to return the dateTime value

Returns:

the Date representing the parsed date.

Throws:

IllegalArgumentException - if the parsed node can not be converted to an Date.

See Also:

NodeBackend.dateTimeValue(java.lang.Object)

stringValue

public abstract String stringValue(Node node)

Description copied from interface: NodeBackend

Return the lexial representation of a node. For a literal, this will be the content, for a URI node it will be the URI itself, and for a blank node it will be the identifier of the node.

Specified by:

stringValue in interface NodeBackend<Node>

Returns:

parseDate

protected Date parseDate(String dateString)
                  throws ParseException

Utility to parse xsd:date strings

Parameters:

dateString -

Returns:

Throws:

ParseException

parseTime

protected Date parseTime(String timeString)
                  throws ParseException

Utility to parse xsd:time strings

Parameters:

timeString -

Returns:

Throws:

ParseException