Literals.java
/*******************************************************************************
* Copyright (c) 2015 Eclipse RDF4J contributors, Aduna, and others.
*
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Distribution License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/org/documents/edl-v10.php.
*
* SPDX-License-Identifier: BSD-3-Clause
*******************************************************************************/
package org.eclipse.rdf4j.model.util;
import java.math.BigDecimal;
import java.math.BigInteger;
import java.util.Date;
import java.util.IllformedLocaleException;
import java.util.Locale;
import javax.xml.datatype.Duration;
import javax.xml.datatype.XMLGregorianCalendar;
import org.eclipse.rdf4j.model.Literal;
import org.eclipse.rdf4j.model.Value;
import org.eclipse.rdf4j.model.ValueFactory;
import org.eclipse.rdf4j.model.base.CoreDatatype;
import org.eclipse.rdf4j.model.datatypes.XMLDatatypeUtil;
import org.eclipse.rdf4j.model.vocabulary.XSD;
/**
* Various utility methods related to {@link Literal}.
*
* @author Arjohn Kampman
* @author Peter Ansell
* @See {@link Values}
*/
public class Literals {
/**
* Gets the label of the supplied literal. The fallback value is returned in case the supplied literal is
* <var>null</var>.
*
* @param l The literal to get the label for.
* @param fallback The value to fall back to in case the supplied literal is <var>null</var>.
* @return Either the literal's label, or the fallback value.
*/
public static String getLabel(Literal l, String fallback) {
return l != null ? l.getLabel() : fallback;
}
/**
* Returns the result of {@link #getLabel(Literal, String) getLabel((Literal)v, fallback} in case the supplied value
* is a literal, returns the fallback value otherwise.
*/
public static String getLabel(Value v, String fallback) {
return v instanceof Literal ? getLabel((Literal) v, fallback) : fallback;
}
/**
* Gets the byte value of the supplied literal. The fallback value is returned in case {@link Literal#byteValue()}
* throws a {@link NumberFormatException}.
*
* @param l The literal to get the byte value for.
* @param fallback The value to fall back to in case no byte value could gotten from the literal.
* @return Either the literal's byte value, or the fallback value.
*/
public static byte getByteValue(Literal l, byte fallback) {
try {
return l.byteValue();
} catch (NumberFormatException e) {
return fallback;
}
}
/**
* Returns the result of {@link #getByteValue(Literal, byte) getByteValue((Literal)value, fallback)} in case the
* supplied value is a literal, returns the fallback value otherwise.
*/
public static byte getByteValue(Value v, byte fallback) {
if (v instanceof Literal) {
return getByteValue((Literal) v, fallback);
} else {
return fallback;
}
}
/**
* Gets the short value of the supplied literal. The fallback value is returned in case {@link Literal#shortValue()}
* throws a {@link NumberFormatException}.
*
* @param l The literal to get the short value for.
* @param fallback The value to fall back to in case no short value could gotten from the literal.
* @return Either the literal's short value, or the fallback value.
*/
public static short getShortValue(Literal l, short fallback) {
try {
return l.shortValue();
} catch (NumberFormatException e) {
return fallback;
}
}
/**
* Returns the result of {@link #getShortValue(Literal, short) getShortValue((Literal)value, fallback)} in case the
* supplied value is a literal, returns the fallback value otherwise.
*/
public static short getShortValue(Value v, short fallback) {
if (v instanceof Literal) {
return getShortValue((Literal) v, fallback);
} else {
return fallback;
}
}
/**
* Gets the int value of the supplied literal. The fallback value is returned in case {@link Literal#intValue()}
* throws a {@link NumberFormatException}.
*
* @param l The literal to get the int value for.
* @param fallback The value to fall back to in case no int value could gotten from the literal.
* @return Either the literal's int value, or the fallback value.
*/
public static int getIntValue(Literal l, int fallback) {
try {
return l.intValue();
} catch (NumberFormatException e) {
return fallback;
}
}
/**
* Returns the result of {@link #getIntValue(Literal, int) getIntValue((Literal)value, fallback)} in case the
* supplied value is a literal, returns the fallback value otherwise.
*/
public static int getIntValue(Value v, int fallback) {
if (v instanceof Literal) {
return getIntValue((Literal) v, fallback);
} else {
return fallback;
}
}
/**
* Gets the long value of the supplied literal. The fallback value is returned in case {@link Literal#longValue()}
* throws a {@link NumberFormatException}.
*
* @param l The literal to get the long value for.
* @param fallback The value to fall back to in case no long value could gotten from the literal.
* @return Either the literal's long value, or the fallback value.
*/
public static long getLongValue(Literal l, long fallback) {
try {
return l.longValue();
} catch (NumberFormatException e) {
return fallback;
}
}
/**
* Returns the result of {@link #getLongValue(Literal, long) getLongValue((Literal)value, fallback)} in case the
* supplied value is a literal, returns the fallback value otherwise.
*/
public static long getLongValue(Value v, long fallback) {
if (v instanceof Literal) {
return getLongValue((Literal) v, fallback);
} else {
return fallback;
}
}
/**
* Gets the integer value of the supplied literal. The fallback value is returned in case
* {@link Literal#integerValue()} throws a {@link NumberFormatException}.
*
* @param l The literal to get the integer value for.
* @param fallback The value to fall back to in case no integer value could gotten from the literal.
* @return Either the literal's integer value, or the fallback value.
*/
public static BigInteger getIntegerValue(Literal l, BigInteger fallback) {
try {
return l.integerValue();
} catch (NumberFormatException e) {
return fallback;
}
}
/**
* Returns the result of {@link #getIntegerValue(Literal, BigInteger) getIntegerValue((Literal)value, fallback)} in
* case the supplied value is a literal, returns the fallback value otherwise.
*/
public static BigInteger getIntegerValue(Value v, BigInteger fallback) {
if (v instanceof Literal) {
return getIntegerValue((Literal) v, fallback);
} else {
return fallback;
}
}
/**
* Gets the decimal value of the supplied literal. The fallback value is returned in case
* {@link Literal#decimalValue()} throws a {@link NumberFormatException}.
*
* @param l The literal to get the decimal value for.
* @param fallback The value to fall back to in case no decimal value could gotten from the literal.
* @return Either the literal's decimal value, or the fallback value.
*/
public static BigDecimal getDecimalValue(Literal l, BigDecimal fallback) {
try {
return l.decimalValue();
} catch (NumberFormatException e) {
return fallback;
}
}
/**
* Returns the result of {@link #getDecimalValue(Literal, BigDecimal) getDecimalValue((Literal)value, fallback)} in
* case the supplied value is a literal, returns the fallback value otherwise.
*/
public static BigDecimal getDecimalValue(Value v, BigDecimal fallback) {
if (v instanceof Literal) {
return getDecimalValue((Literal) v, fallback);
} else {
return fallback;
}
}
/**
* Gets the float value of the supplied literal. The fallback value is returned in case {@link Literal#floatValue()}
* throws a {@link NumberFormatException}.
*
* @param l The literal to get the float value for.
* @param fallback The value to fall back to in case no float value could gotten from the literal.
* @return Either the literal's float value, or the fallback value.
*/
public static float getFloatValue(Literal l, float fallback) {
try {
return l.floatValue();
} catch (NumberFormatException e) {
return fallback;
}
}
/**
* Returns the result of {@link #getFloatValue(Literal, float) getFloatValue((Literal)value, fallback)} in case the
* supplied value is a literal, returns the fallback value otherwise.
*/
public static float getFloatValue(Value v, float fallback) {
if (v instanceof Literal) {
return getFloatValue((Literal) v, fallback);
} else {
return fallback;
}
}
/**
* Gets the double value of the supplied literal. The fallback value is returned in case
* {@link Literal#doubleValue()} throws a {@link NumberFormatException}.
*
* @param l The literal to get the double value for.
* @param fallback The value to fall back to in case no double value could gotten from the literal.
* @return Either the literal's double value, or the fallback value.
*/
public static double getDoubleValue(Literal l, double fallback) {
try {
return l.doubleValue();
} catch (NumberFormatException e) {
return fallback;
}
}
/**
* Returns the result of {@link #getDoubleValue(Literal, double) getDoubleValue((Literal)value, fallback)} in case
* the supplied value is a literal, returns the fallback value otherwise.
*/
public static double getDoubleValue(Value v, double fallback) {
if (v instanceof Literal) {
return getDoubleValue((Literal) v, fallback);
} else {
return fallback;
}
}
/**
* Gets the boolean value of the supplied literal. The fallback value is returned in case
* {@link Literal#booleanValue()} throws a {@link NumberFormatException}.
*
* @param l The literal to get the boolean value for.
* @param fallback The value to fall back to in case no boolean value could gotten from the literal.
* @return Either the literal's boolean value, or the fallback value.
*/
public static boolean getBooleanValue(Literal l, boolean fallback) {
try {
return l.booleanValue();
} catch (IllegalArgumentException e) {
return fallback;
}
}
/**
* Returns the result of {@link #getBooleanValue(Literal, boolean) getBooleanValue((Literal)value, fallback)} in
* case the supplied value is a literal, returns the fallback value otherwise.
*/
public static boolean getBooleanValue(Value v, boolean fallback) {
if (v instanceof Literal) {
return getBooleanValue((Literal) v, fallback);
} else {
return fallback;
}
}
/**
* Gets the calendar value of the supplied literal. The fallback value is returned in case
* {@link Literal#calendarValue()} throws a {@link NumberFormatException}.
*
* @param l The literal to get the calendar value for.
* @param fallback The value to fall back to in case no calendar value could gotten from the literal.
* @return Either the literal's calendar value, or the fallback value.
*/
public static XMLGregorianCalendar getCalendarValue(Literal l, XMLGregorianCalendar fallback) {
try {
return l.calendarValue();
} catch (IllegalArgumentException e) {
return fallback;
}
}
/**
* Gets the {@link Duration} value of the supplied literal. The fallback value is returned in case
* {@link XMLDatatypeUtil#parseDuration(String)} throws an exception.
*
* @param l The literal to get the {@link Duration} value for.
* @param fallback The value to fall back to in case no Duration value could gotten from the literal.
* @return Either the literal's Duration value, or the fallback value.
*/
public static Duration getDurationValue(Literal l, Duration fallback) {
try {
return XMLDatatypeUtil.parseDuration(l.getLabel());
} catch (IllegalArgumentException | UnsupportedOperationException e) {
return fallback;
}
}
/**
* Returns the result of {@link #getCalendarValue(Literal, XMLGregorianCalendar) getCalendarValue((Literal)value,
* fallback)} in case the supplied value is a literal, returns the fallback value otherwise.
*/
public static XMLGregorianCalendar getCalendarValue(Value v, XMLGregorianCalendar fallback) {
if (v instanceof Literal) {
return getCalendarValue((Literal) v, fallback);
} else {
return fallback;
}
}
/**
* Creates a typed {@link Literal} out of the supplied object, mapping the runtime type of the object to the
* appropriate XML Schema type. If no mapping is available, the method returns a literal with the string
* representation of the supplied object as the value, and {@link XSD#STRING} as the datatype. Recognized types are
* {@link Boolean}, {@link Byte}, {@link Double}, {@link Float}, {@link Integer}, {@link Long}, {@link Short},
* {@link XMLGregorianCalendar } , and {@link Date}.
*
* @param valueFactory
* @param object an object to be converted to a typed literal.
* @return a typed literal representation of the supplied object.
* @throws NullPointerException If the object was null.
* @deprecated Use {@link Values#literal(Object)} instead.
*/
@Deprecated(since = "3.5.0")
public static Literal createLiteral(ValueFactory valueFactory, Object object) {
try {
return createLiteral(valueFactory, object, false);
} catch (LiteralUtilException e) {
// This should not happen by design
throw new IllegalStateException(e);
}
}
/**
* Creates a typed {@link Literal} out of the supplied object, mapping the runtime type of the object to the
* appropriate XML Schema type. If no mapping is available, the method throws a {@link LiteralUtilException}.
* Recognized types are {@link Boolean}, {@link Byte}, {@link Double}, {@link Float}, {@link Integer}, {@link Long},
* {@link Short}, {@link XMLGregorianCalendar } , and {@link Date}.
*
* @param valueFactory
* @param object an object to be converted to a typed literal.
* @return a typed literal representation of the supplied object.
* @throws LiteralUtilException If the literal could not be created.
* @throws NullPointerException If the object was null.
* @deprecated Use {@link Values#literal(Object, boolean)} instead.
*/
@Deprecated(since = "3.5.0")
public static Literal createLiteralOrFail(ValueFactory valueFactory, Object object) throws LiteralUtilException {
return createLiteral(valueFactory, object, true);
}
/**
* Creates a typed {@link Literal} out of the supplied object, mapping the runtime type of the object to the
* appropriate XML Schema type. If no mapping is available, the method throws an exception if the boolean parameter
* is true, or if it is false it returns a literal with the string representation of the supplied object as the
* value, and {@link XSD#STRING} as the datatype. Recognized types are {@link Boolean}, {@link Byte},
* {@link Double}, {@link Float}, {@link Integer}, {@link Long}, {@link Short}, {@link XMLGregorianCalendar } , and
* {@link Date}.
*
* @param valueFactory The {@link ValueFactory} to use when creating the result.
* @param object an object to be converted to a typed literal.
* @param throwExceptionOnFailure If true throws a {@link LiteralUtilException} when the object is not recognised.
* If false it returns a string typed literal based on the objects toString method.
* @return a typed literal representation of the supplied object.
* @throws LiteralUtilException If the literal could not be created.
* @throws NullPointerException If the object was null.
*/
private static Literal createLiteral(ValueFactory valueFactory, Object object, boolean throwExceptionOnFailure)
throws LiteralUtilException {
if (object == null) {
throw new NullPointerException("Cannot create a literal from a null");
}
if (object instanceof Boolean) {
return valueFactory.createLiteral((Boolean) object);
} else if (object instanceof Byte) {
return valueFactory.createLiteral((Byte) object);
} else if (object instanceof Double) {
return valueFactory.createLiteral((Double) object);
} else if (object instanceof Float) {
return valueFactory.createLiteral((Float) object);
} else if (object instanceof Integer) {
return valueFactory.createLiteral((Integer) object);
} else if (object instanceof Long) {
return valueFactory.createLiteral((Long) object);
} else if (object instanceof Short) {
return valueFactory.createLiteral((Short) object);
} else if (object instanceof XMLGregorianCalendar) {
return valueFactory.createLiteral((XMLGregorianCalendar) object);
} else if (object instanceof Date) {
return valueFactory.createLiteral((Date) object);
} else if (object instanceof String) {
return valueFactory.createLiteral(object.toString(), CoreDatatype.XSD.STRING);
} else {
if (throwExceptionOnFailure) {
throw new LiteralUtilException("Did not recognise object when creating literal");
}
return valueFactory.createLiteral(object.toString(), CoreDatatype.XSD.STRING);
}
}
/**
* Helper method for determining whether a literal could be created from an object using a {@link ValueFactory}.
*
* @param object an object to check for the possibility of being converted to a typed literal.
* @return True if a literal could be created from the given object, based solely on its type and the methods
* available on the {@link ValueFactory} interface and false otherwise. Returns false if the object is null.
* @deprecated since 3.5.0
*/
@Deprecated
public static boolean canCreateLiteral(Object object) {
if (object == null) {
// Cannot create a literal from a null
// Avoid throwing a NullPointerException here to enable universal
// usage
// of this method
return false;
}
return object instanceof Boolean || object instanceof Byte || object instanceof Double
|| object instanceof Float
|| object instanceof Integer || object instanceof Long || object instanceof Short
|| object instanceof XMLGregorianCalendar || object instanceof Date || object instanceof String;
}
/**
* Helper method to determine whether a literal is a language literal, and not a typed literal.
*
* @param literal The literal to check
* @return True if the literal has a language tag attached to it and false otherwise.
*/
public static boolean isLanguageLiteral(Literal literal) {
return literal.getCoreDatatype() == CoreDatatype.RDF.LANGSTRING;
}
/**
* Normalizes the given <a href="https://tools.ietf.org/html/bcp47">BCP47</a> language tag according to the rules
* defined in <a href="https://www.rfc-editor.org/rfc/rfc5646.html#section-2.1.1">RFC 5646, section 2.1.1</a>:
* <p>
* <blockquote> All subtags, including extension and private use subtags, use lowercase letters with two exceptions:
* two-letter and four-letter subtags that neither appear at the start of the tag nor occur after singletons. Such
* two-letter subtags are all uppercase (as in the tags "en-CA-x-ca" or "sgn-BE-FR") and four- letter subtags are
* titlecase (as in the tag "az-Latn-x-latn"). </blockquote>
*
* @param languageTag An unnormalized, valid, language tag
* @return A normalized version of the given language tag
* @throws IllformedLocaleException If the given language tag is ill-formed according to the rules specified in
* BCP47 (RFC 5646).
*/
public static String normalizeLanguageTag(String languageTag) throws IllformedLocaleException {
// check if language tag is well-formed
new Locale.Builder().setLanguageTag(languageTag);
// all subtags are case-insensitive
String normalizedTag = languageTag.toLowerCase();
String[] subtags = normalizedTag.split("-");
for (int i = 1; i < subtags.length; i++) {
String subtag = subtags[i];
if (subtag.length() == 2) {
// exception 1: two-letter subtags not at the starte and not preceded by a singleton are upper case
if (subtags[i - 1].length() > 1 && subtag.matches("\\w\\w")) {
subtags[i] = subtag.toUpperCase();
}
} else if (subtag.length() == 4) {
// exception 2: four-letter subtags not at the start and not preceded by a singleton are title case
if (subtags[i - 1].length() > 1 && subtag.matches("\\w\\w\\w\\w")) {
subtags[i] = subtag.substring(0, 1).toUpperCase() + subtag.substring(1);
}
}
}
return String.join("-", subtags);
}
/**
* Checks if the given string is a well-formed <a href="https://tools.ietf.org/html/bcp47">BCP47</a> language tag
* according to the rules defined in <a href="https://www.rfc-editor.org/rfc/rfc5646.html#section-2.1.1">RFC 5646,
* section 2.1.1</a>.
*
* @param languageTag A language tag
* @return <code>true</code> if the given language tag is well-formed according to the rules specified in BCP47.
*/
public static boolean isValidLanguageTag(String languageTag) {
try {
new Locale.Builder().setLanguageTag(languageTag);
return true;
} catch (IllformedLocaleException e) {
return false;
}
}
/**
* Implements language range filtering for SPARQL langMatches
* (https://www.w3.org/TR/sparql11-query/#func-langMatches).
*
* @param langTag the tag to filter
* @param langRange the range to filter against
* @return true if langTag matches langRange
*/
public static boolean langMatches(String langTag, String langRange) {
boolean result = false;
if (langRange.equals("*")) {
result = !langTag.isEmpty();
} else if (langTag.length() == langRange.length()) {
result = langTag.equalsIgnoreCase(langRange);
} else if (langTag.length() > langRange.length()) {
// check if the range is a prefix of the tag
String prefix = langTag.substring(0, langRange.length());
result = prefix.equalsIgnoreCase(langRange) && langTag.charAt(langRange.length()) == '-';
}
return result;
}
protected Literals() {
// Protected default constructor to prevent instantiation
}
}