at.newmedialab.ldpath.model.backend.AbstractBackend Maven / Gradle / Ivy
package at.newmedialab.ldpath.model.backend;
import java.math.BigDecimal;
import java.math.BigInteger;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;
import at.newmedialab.ldpath.api.backend.RDFBackend;
import at.newmedialab.ldpath.util.FormatUtils;
/**
* This provides an generic implementation of all **Value(Node node)
* methods other than {@link #stringValue(Object)}.
* This allows to implement {@link RDFBackend}s 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);
* }
*
* 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);
* }
* implements RDFBackend {
/**
* A clone of the DateFormat provided by {@link FormatUtils} to parse xsd:date
* values. This is necessary because {@link SimpleDateFormat} is not thread
* save and therefore we do not directly use a public static member.
*/
private SimpleDateFormat dateFormat = (SimpleDateFormat)FormatUtils.ISO8601FORMAT_DATE.clone();
/**
* A clone of the DateFormat provided by {@link FormatUtils} to parse xsd:time
* values. This is necessary because {@link SimpleDateFormat} is not thread
* save and therefore we do not directly use a public static member.
*/
private SimpleDateFormat timeFormat = (SimpleDateFormat)FormatUtils.ISO8601FORMAT_TIME.clone();
/**
* Parses the Double value of the parsed node based on its lexical form as
* returned by {@link #stringValue(Object)}.
* @return the double value
* @throws NumberFormatException if the lexical form can not be converted
* to a Double.
* @see at.newmedialab.ldpath.api.backend.RDFBackend#doubleValue(java.lang.Object)
*/
@Override
public Double doubleValue(Node node) {
return new Double(trimPlusSign(stringValue(node)));
}
/**
* Parses the Float value of the parsed node based on its lexical form as
* returned by {@link #stringValue(Object)}.
* @return the float value
* @throws NumberFormatException if the lexical form can not be converted
* to a Double.
* @see at.newmedialab.ldpath.api.backend.RDFBackend#floatValue(java.lang.Object)
*/
public Float floatValue(Node node) {
return new Float(trimPlusSign(stringValue(node)));
};
/**
* Parses the {@link BigDecimal#longValueExact() Long value} of the parsed
* node by using {@link #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.
* @return the long value
* @throws NumberFormatException if the lexical form can not be converted
* to an Long.
* @throws ArithmeticException if the lexical form can not be converted
* to a Long.
* @see at.newmedialab.ldpath.api.backend.RDFBackend#longValue(java.lang.Object)
*/
@Override
public Long longValue(Node node) {
return decimalValue(node).longValueExact();
}
/**
* Parses the {@link BigDecimal#intValueExact() Integer value} of the parsed
* node by using {@link #decimalValue(Object)}. This has the advantage, that
* decimal values that are also valid integer values - such as '1.0' are also
* correctly converted to {@link Integer}.
* @return the int value
* @throws NumberFormatException if the lexical form can not be converted
* to an Long.
* @throws ArithmeticException if the lexical form can not be converted
* to a Long.
* @see at.newmedialab.ldpath.api.backend.RDFBackend#intValue(java.lang.Object)
*/
@Override
public Integer intValue(Node node) {
return decimalValue(node).intValueExact();
};
/**
* Parses the {@link BigDecimal} value from the lexical form of the parsed
* node as returned by {@link RDFBackend#stringValue(Object)}. This
* trims loading '+' sings.
* @return the int value
* @throws NumberFormatException if the lexical form can not be converted
* to an Long.
* @throws ArithmeticException if the lexical form can not be converted
* to a Long.
* @see at.newmedialab.ldpath.api.backend.RDFBackend#decimalValue(java.lang.Object)
*/
public BigDecimal decimalValue(Node node) {
return new BigDecimal(trimPlusSign(stringValue(node)));
};
/**
* Parses the {@link BigDecimal#toBigIntegerExact() BugIneger value} of the parsed
* node by using {@link #decimalValue(Object)}. This has the advantage, that
* decimal values that are also valid integer values - such as '1.0' are also
* correctly converted to {@link BigInteger}.
* @see at.newmedialab.ldpath.api.backend.RDFBackend#integerValue(java.lang.Object)
*/
public java.math.BigInteger integerValue(Node node) {
return decimalValue(node).toBigIntegerExact();
};
/**
* Parses the boolean value from the {@link #stringValue(Object) lexical form}.
* Supports both '1' and {@link Boolean#parseBoolean(String)}.
* @return the boolean value
* @see at.newmedialab.ldpath.api.backend.RDFBackend#booleanValue(java.lang.Object)
*/
public Boolean booleanValue(Node node) {
String lexicalForm = stringValue(node);
if(lexicalForm.length() == 1){ //support '1' as true
return lexicalForm.charAt(0) == '1';
} else {
return Boolean.parseBoolean(lexicalForm);
}
};
/**
* Parses date vales based on the ISO8601 specification by using the
* {@link #stringValue(Object) lexical form} of the parsed node.
* @return the {@link Date} representing the parsed date.
* @throws IllegalArgumentException on any {@link ParseException} while
* parsing the {@link #stringValue(Object) lexical form} of the parsed
* node.
* @see at.newmedialab.ldpath.api.backend.RDFBackend#dateValue(java.lang.Object)
*/
public Date dateValue(Node node) {
String lexicalForm = stringValue(node);
try {
return parseDate(lexicalForm);
} catch (ParseException e) {
throw new IllegalArgumentException("could not parse ISO8601 date from '"+
lexicalForm+"'!",e);
}
};
/**
* Parses time value based on the ISO8601 specification by using the
* {@link #stringValue(Object) lexical form} of the parsed node.
* @return the {@link Date} representing the parsed date.
* @throws IllegalArgumentException on any {@link ParseException} while
* parsing the {@link #stringValue(Object) lexical form} of the parsed
* node.
* @see at.newmedialab.ldpath.api.backend.RDFBackend#timeValue(java.lang.Object)
*/
public Date timeValue(Node node) {
String lexicalForm = stringValue(node);
try {
return parseTime(lexicalForm);
} catch (ParseException e) {
throw new IllegalArgumentException("could not parse ISO8601 time from '"+
lexicalForm+"'!",e);
}
};
/**
* Parses dateTime value based on the {@link #stringValue(Object) lexical form}
* of the parsed node. For details about parsing see
* {@link FormatUtils#parseDate(String)}.
* @return the {@link Date} representing the parsed date.
* @throws IllegalArgumentException if the parsed node can not be converted
* to an {@link Date}.
* @see at.newmedialab.ldpath.api.backend.RDFBackend#dateTimeValue(java.lang.Object)
*/
public Date dateTimeValue(Node node) {
String lexicalForm = stringValue(node);
Date date = FormatUtils.parseDate(lexicalForm);
if(date == null){
throw new IllegalArgumentException("could not parse xsd:dateTime from '"+
lexicalForm+"'!");
} else {
return date;
}
};
@Override
public abstract String stringValue(Node node);
/**
* Removes the first character from the supplied string if this is a plus
* sign ('+'). Number strings with leading plus signs cannot be parsed by
* methods such as {@link Integer#parseInt(String)}.
* Taken from the Sesame XMLDatatypeUtil.
*/
private static String trimPlusSign(String s) {
return (s.length() > 0 && s.charAt(0) == '+') ? s.substring(1) : s;
}
/**
* Utility to parse xsd:date strings
* @param dateString
* @return
* @throws ParseException
*/
protected Date parseDate(String dateString) throws ParseException {
synchronized (dateFormat) {
return dateFormat.parse(dateString);
}
}
/**
* Utility to parse xsd:time strings
* @param timeString
* @return
* @throws ParseException
*/
protected Date parseTime(String timeString) throws ParseException {
synchronized (timeFormat) {
return timeFormat.parse(timeString);
}
}
}