Issue #712: Move isValidLanguageTag to Literals

Signed-off-by: James Leigh <james.leigh@ontotext.com>

Author: James Leigh

core/model/src/main/java/org/eclipse/rdf4j/model/datatypes/XMLDatatypeUtil.java

@@ -10,8 +10,6 @@
 import java.math.BigDecimal;
 import java.math.BigInteger;
 import java.net.URISyntaxException;
-import java.util.IllformedLocaleException;
-import java.util.Locale;
 import java.util.StringTokenizer;
 
 import javax.xml.datatype.DatatypeConfigurationException;
@@ -24,6 +22,7 @@
 import org.eclipse.rdf4j.common.net.ParsedIRI;
 import org.eclipse.rdf4j.common.text.ASCIIUtil;
 import org.eclipse.rdf4j.model.IRI;
+import org.eclipse.rdf4j.model.util.Literals;
 import org.eclipse.rdf4j.model.vocabulary.XMLSchema;
 
 /**
@@ -277,7 +276,7 @@ else if (datatype.equals(XMLSchema.ANYURI)) {
 			result = isValidAnyURI(value);
 		}
 		else if (datatype.equals(XMLSchema.LANGUAGE)) {
-			result = isValidLanguage(value);
+			result = Literals.isValidLanguageTag(value);
 		}
 
 		return result;
@@ -681,15 +680,6 @@ public static boolean isValidAnyURI(String value) {
 		}
 	}
 
-	public static boolean isValidLanguage(String value) {
-		try {
-			new Locale.Builder().setLanguageTag(value);
-			return true;
-		} catch (IllformedLocaleException e) {
-			return false;
-		}
-	}
-
 	private static boolean isPrefixStartChar(int c) {
 		return ASCIIUtil.isLetter(c) || c >= 0x00C0 && c <= 0x00D6 || c >= 0x00D8 && c <= 0x00F6
 				|| c >= 0x00F8 && c <= 0x02FF || c >= 0x0370 && c <= 0x037D || c >= 0x037F && c <= 0x1FFF

core/model/src/main/java/org/eclipse/rdf4j/model/impl/ValidatingValueFactory.java

@@ -24,6 +24,7 @@
 import org.eclipse.rdf4j.model.Value;
 import org.eclipse.rdf4j.model.ValueFactory;
 import org.eclipse.rdf4j.model.datatypes.XMLDatatypeUtil;
+import org.eclipse.rdf4j.model.util.Literals;
 import org.eclipse.rdf4j.model.util.URIUtil;
 
 /**
@@ -138,8 +139,8 @@ public Literal createLiteral(String label, IRI datatype) {
 	}
 
 	public Literal createLiteral(String label, String language) {
-		if (!XMLDatatypeUtil.isValidLanguage(language)) {
-			throw new IllegalArgumentException("Not a validate language tag");
+		if (!Literals.isValidLanguageTag(language)) {
+			throw new IllegalArgumentException("Not a validate language tag: " + language);
 		}
 		return delegate.createLiteral(label, language);
 	}

core/model/src/main/java/org/eclipse/rdf4j/model/util/Literals.java

@@ -15,8 +15,8 @@
 import java.util.Objects;
 import java.util.Optional;
 
-import javax.xml.datatype.XMLGregorianCalendar;
 import javax.xml.datatype.Duration;
+import javax.xml.datatype.XMLGregorianCalendar;
 
 import org.eclipse.rdf4j.model.Literal;
 import org.eclipse.rdf4j.model.Value;
@@ -600,6 +600,25 @@ public static String normalizeLanguageTag(String languageTag)
 		return new Locale.Builder().setLanguageTag(languageTag).build().toLanguageTag().intern();
 	}
 
+	/**
+	 * Checks if the given string is a <a href="https://tools.ietf.org/html/bcp47">BCP47</a> language tag
+	 * according to the rules defined by the JDK in the {@link Locale} API.
+	 *
+	 * @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;
+		}
+	}
+
 	protected Literals() {
 		// Protected default constructor to prevent instantiation
 	}