Add use-default-language option

src/main/java/org/edmcouncil/rdf_toolkit/runner/CommandLineArgumentsHandler.java

@@ -107,6 +107,7 @@ public RdfToolkitOptions handleArguments(String[] args)
     optionHandler.handleLineEnd();
     optionHandler.handleOmitXmlnsNamespace();
     optionHandler.handleSuppressNamedIndividuals();
+    optionHandler.handleUseDefaultLanguage();
 
     rdfToolkitOptions.setRunningMode(RUN_ON_FILE);
 

src/main/java/org/edmcouncil/rdf_toolkit/runner/OptionHandler.java

@@ -44,6 +44,7 @@
 import static org.edmcouncil.rdf_toolkit.runner.constant.CommandLineOption.TARGET_DIRECTORY_PATTERN;
 import static org.edmcouncil.rdf_toolkit.runner.constant.CommandLineOption.TARGET_FORMAT;
 import static org.edmcouncil.rdf_toolkit.runner.constant.CommandLineOption.TRAILING_COMMENT;
+import static org.edmcouncil.rdf_toolkit.runner.constant.CommandLineOption.USE_DEFAULT_LANGUAGE;
 import static org.edmcouncil.rdf_toolkit.runner.constant.CommandLineOption.USE_DTD_SUBSET;
 import static org.edmcouncil.rdf_toolkit.runner.constant.RunningMode.PRINT_USAGE_AND_EXIT;
 import static org.edmcouncil.rdf_toolkit.runner.constant.RunningMode.RUN_ON_DIRECTORY;
@@ -391,4 +392,12 @@ public void handleSuppressNamedIndividuals() {
     boolean suppressNamedIndividuals = commandLine.hasOption(SUPPRESS_NAMED_INDIVIDUALS.getShortOpt());
     rdfToolkitOptions.setSuppressNamedIndividuals(suppressNamedIndividuals);
   }
+
+  public void handleUseDefaultLanguage() {
+    String defaultLanguage = null;
+    if (commandLine.hasOption(USE_DEFAULT_LANGUAGE.getShortOpt())) {
+      defaultLanguage = commandLine.getOptionValue(USE_DEFAULT_LANGUAGE.getShortOpt());
+    }
+    rdfToolkitOptions.setDefaultLanguage(defaultLanguage);
+  }
 }

src/main/java/org/edmcouncil/rdf_toolkit/runner/RdfToolkitOptions.java

@@ -25,6 +25,7 @@
 package org.edmcouncil.rdf_toolkit.runner;
 
 import static org.edmcouncil.rdf_toolkit.util.Constants.BASE_IRI;
+import static org.edmcouncil.rdf_toolkit.util.Constants.USE_DEFAULT_LANGUAGE;
 import static org.edmcouncil.rdf_toolkit.util.Constants.INDENT;
 import static org.edmcouncil.rdf_toolkit.util.Constants.INLINE_BLANK_NODES;
 import static org.edmcouncil.rdf_toolkit.util.Constants.LEADING_COMMENTS;
@@ -77,6 +78,7 @@ public class RdfToolkitOptions {
   private String lineEnd;
   private boolean omitXmlnsNamespace;
   private boolean suppressNamedIndividuals;
+  private String defaultLanguage;
 
   public RdfToolkitOptions(String[] args) {
     this.args = args;
@@ -108,6 +110,7 @@ public Map<String, Object> getOptions() {
     options.put(LINE_END, getLineEnd());
     options.put(OMIT_XMLNS_NAMESPACE, getOmitXmlnsNamespace());
     options.put(SUPPRESS_NAMED_INDIVIDUALS, getSuppressNamedIndividuals());
+    options.put(USE_DEFAULT_LANGUAGE, getDefaultLanguage());
     return options;
   }
 
@@ -302,4 +305,12 @@ public boolean getSuppressNamedIndividuals() {
   public void setSuppressNamedIndividuals(boolean suppressNamedIndividuals) {
     this.suppressNamedIndividuals = suppressNamedIndividuals;
   }
+
+  public String getDefaultLanguage() {
+    return defaultLanguage;
+  }
+
+  public void setDefaultLanguage(String defaultLanguage) {
+    this.defaultLanguage = defaultLanguage;
+  }
 }

src/main/java/org/edmcouncil/rdf_toolkit/runner/constant/CommandLineOption.java

@@ -55,7 +55,8 @@ public enum CommandLineOption {
   INDENT("i", "indent", true, "sets the indent string.  Default is a single tab character"),
   LINE_END("ln", "line-end", true, "sets the end-line character(s); supported characters: \\n (LF), \\r (CR). Default is the LF character"),
   OMIT_XMLNS_NAMESPACE("oxn", "omit-xmlns-namespace", false, "omits xmlns namespace"),
-  SUPPRESS_NAMED_INDIVIDUALS("sni", "suppress-named-individuals", false, "suppresses all instances of owl:NamedIndividual");
+  SUPPRESS_NAMED_INDIVIDUALS("sni", "suppress-named-individuals", false, "suppresses all instances of owl:NamedIndividual"),
+  USE_DEFAULT_LANGUAGE("udl", "use-default-language", true, "uses default language when a string is untyped and untagged");
 
   private final String shortOpt;
   private final String longOpt;

src/main/java/org/edmcouncil/rdf_toolkit/util/Constants.java

@@ -43,6 +43,7 @@ public class Constants {
   public static final String LINE_END = "lineEnd";
   public static final String OMIT_XMLNS_NAMESPACE = "omitXmlnsNamespace";
   public static final String SUPPRESS_NAMED_INDIVIDUALS = "suppressNamedIndividuals";
+  public static final String USE_DEFAULT_LANGUAGE = "useDefaultLanguage";
 
   /**
    * Factory for generating literal values.

src/main/java/org/edmcouncil/rdf_toolkit/writer/IndentingWriter.java

@@ -33,6 +33,7 @@ public class IndentingWriter extends Writer {
   private String indentationString = "\t";
   private boolean indentationWritten = false;
   private String lineEnd;
+  private String defaultLanguage; // TODO remove
 
   public IndentingWriter(Writer out) {
     this.out = out;
@@ -70,6 +71,14 @@ public void setLineEnd(String lineEnd) {
     this.lineEnd = lineEnd;
   }
 
+  public String getDefaultLanguage() {
+    return this.defaultLanguage;
+  }
+
+  public void setDefaultLanguage(String defaultLanguage) {
+    this.defaultLanguage = defaultLanguage;
+  }
+
   public void writeEOL() throws IOException {
     this.write(getLineEnd());
     this.indentationWritten = false;

src/main/java/org/edmcouncil/rdf_toolkit/writer/SortedJsonLdWriter.java

@@ -28,7 +28,10 @@
 import static org.edmcouncil.rdf_toolkit.comparator.ComparisonUtils.isCollection;
 import static org.edmcouncil.rdf_toolkit.util.Constants.INDENT;
 import static org.edmcouncil.rdf_toolkit.util.Constants.LINE_END;
+import static org.edmcouncil.rdf_toolkit.util.Constants.xsString;
 
+import java.io.IOException;
+import java.util.Optional;
 import org.eclipse.rdf4j.model.BNode;
 import org.eclipse.rdf4j.model.IRI;
 import org.eclipse.rdf4j.model.Literal;
@@ -40,7 +43,6 @@
 import org.edmcouncil.rdf_toolkit.model.UnsortedTurtleObjectList;
 import org.edmcouncil.rdf_toolkit.model.UnsortedTurtlePredicateObjectMap;
 import org.edmcouncil.rdf_toolkit.util.Constants;
-import org.edmcouncil.rdf_toolkit.util.StringDataTypeOptions;
 import java.io.OutputStream;
 import java.io.OutputStreamWriter;
 import java.io.Writer;
@@ -624,58 +626,29 @@ protected void writeObject(Writer out, IRI iri, boolean isRdfType) throws Except
   protected void writeObject(Writer out, Literal literal) throws Exception {
     if (literal == null) {
       out.write("null<Literal>");
-    } else if (literal.getLanguage().isPresent() || ((overrideStringLanguage != null)
-        && (literal.getDatatype().stringValue().equals(Constants.xsString.stringValue())))) {
-      out.write("{");
-      if (out instanceof IndentingWriter) {
-        var indentingWriter = (IndentingWriter) out;
-        indentingWriter.writeEOL();
-        indentingWriter.increaseIndentation();
-      } else {
-        out.write("\n");
-      }
-
-      String lang = overrideStringLanguage == null ?
-          literal.getLanguage().orElse(overrideStringLanguage) :
-          overrideStringLanguage;
+      return;
+    }
 
-      out.write("\"@language\" : \"" + lang + "\",");
-      if (out instanceof IndentingWriter) {
-        var output = (IndentingWriter) out;
-        output.writeEOL();
-      } else {
-        out.write("\n");
-      }
+    IRI datatype = literal.getDatatype();
+    Optional<String> languageOptional = literal.getLanguage();
 
-      out.write("\"@value\" : \"" + escapeString(literal.stringValue()) + "\"");
+    if (overrideStringLanguage != null && (xsString.equals(datatype) || languageOptional.isPresent())) {
+      writeLanguage(literal, overrideStringLanguage);
+    } else if (languageOptional.isPresent()) {
+      writeLanguage(literal, languageOptional.get());
+    } else if (useDefaultLanguage != null && xsString.equals(datatype)) {
+      writeLanguage(literal, useDefaultLanguage);
+    } else if (datatype != null) {
+      out.write("{");
       if (out instanceof IndentingWriter) {
         var indentingWriter = (IndentingWriter) out;
         indentingWriter.writeEOL();
+        indentingWriter.increaseIndentation();
       } else {
         out.write("\n");
       }
 
-      if (out instanceof IndentingWriter) {
-        var indentingWriter = (IndentingWriter) out;
-        indentingWriter.decreaseIndentation();
-        out.write("}");
-      } else {
-        out.write("}");
-      }
-    } else if (literal.getDatatype() != null) {
-      boolean useExplicit = (stringDataTypeOption == StringDataTypeOptions.EXPLICIT)
-          || !(Constants.xsString.equals(literal.getDatatype())
-          || Constants.rdfLangString.equals(literal.getDatatype()));
-      if (useExplicit) {
-        out.write("{");
-        if (out instanceof IndentingWriter) {
-          var indentingWriter = (IndentingWriter) out;
-          indentingWriter.writeEOL();
-          indentingWriter.increaseIndentation();
-        } else {
-          out.write("\n");
-        }
-
+      if (shouldUseExplicitDatatypes(datatype)) {
         out.write("\"@type\" : \"");
         writeIri(out, literal.getDatatype());
         out.write("\",");
@@ -685,26 +658,59 @@ protected void writeObject(Writer out, Literal literal) throws Exception {
         } else {
           out.write("\n");
         }
+      }
 
-        out.write("\"@value\" : ");
-        writeString(out, literal.stringValue());
+      out.write("\"@value\" : ");
+      writeString(out, literal.stringValue());
 
-        if (out instanceof IndentingWriter) {
-          var indentingWriter = (IndentingWriter) out;
-          indentingWriter.decreaseIndentation();
-          indentingWriter.writeEOL();
-          out.write("}");
-        } else {
-          out.write("\n}");
-        }
+      if (out instanceof IndentingWriter) {
+        var indentingWriter = (IndentingWriter) out;
+        indentingWriter.decreaseIndentation();
+        indentingWriter.writeEOL();
+        out.write("}");
       } else {
-        writeString(out, literal.stringValue());
+        out.write("\n}");
       }
     } else {
       writeString(out, literal.stringValue());
     }
   }
 
+  private void writeLanguage(Literal literal, String lang) throws IOException {
+    out.write("{");
+    if (out instanceof IndentingWriter) {
+      var indentingWriter = (IndentingWriter) out;
+      indentingWriter.writeEOL();
+      indentingWriter.increaseIndentation();
+    } else {
+      out.write("\n");
+    }
+
+    out.write("\"@language\" : \"" + lang + "\",");
+    if (out instanceof IndentingWriter) {
+      var output = (IndentingWriter) out;
+      output.writeEOL();
+    } else {
+      out.write("\n");
+    }
+
+    out.write("\"@value\" : \"" + escapeString(literal.stringValue()) + "\"");
+    if (out instanceof IndentingWriter) {
+      var indentingWriter = (IndentingWriter) out;
+      indentingWriter.writeEOL();
+    } else {
+      out.write("\n");
+    }
+
+    if (out instanceof IndentingWriter) {
+      var indentingWriter = (IndentingWriter) out;
+      indentingWriter.decreaseIndentation();
+        out.write("}");
+    } else {
+      out.write("}");
+    }
+  }
+
   protected void writeString(Writer out, String str) throws Exception {
     // Note that JSON does not support multi-line strings, unlike Turtle
     if (str == null) {

src/main/java/org/edmcouncil/rdf_toolkit/writer/SortedRdfWriter.java

@@ -33,6 +33,7 @@
 import static org.edmcouncil.rdf_toolkit.util.Constants.STRING_DATA_TYPE_OPTION;
 import static org.edmcouncil.rdf_toolkit.util.Constants.SUPPRESS_NAMED_INDIVIDUALS;
 import static org.edmcouncil.rdf_toolkit.util.Constants.TRAILING_COMMENTS;
+import static org.edmcouncil.rdf_toolkit.util.Constants.USE_DEFAULT_LANGUAGE;
 import static org.edmcouncil.rdf_toolkit.util.Constants.USE_DTD_SUBSET;
 
 import org.eclipse.rdf4j.model.BNode;
@@ -207,6 +208,12 @@ public abstract class SortedRdfWriter extends AbstractRDFWriter {
    */
   protected boolean suppressNamedIndividuals = false;
 
+  /**
+   * If set, it's used to add a default language for literals with xsd:string datatype (explicit or implicit) and
+   * without language already specified. By default, <code>null</code>.
+   */
+  protected String useDefaultLanguage = null;
+
   /**
    * Output stream for this RDF writer.
    */
@@ -286,6 +293,9 @@ private void processOptions(Map<String, Object> options) {
     if (options.containsKey(SUPPRESS_NAMED_INDIVIDUALS)) {
       this.suppressNamedIndividuals = Boolean.parseBoolean(options.get(SUPPRESS_NAMED_INDIVIDUALS).toString());
     }
+    if (options.containsKey(USE_DEFAULT_LANGUAGE)) {
+      this.useDefaultLanguage = (String) options.get(USE_DEFAULT_LANGUAGE);
+    }
   }
 
   /**
@@ -720,4 +730,9 @@ protected abstract void writePredicateAndObjectValues(Writer out, IRI predicate,
       throws Exception;
 
   protected abstract void writeFooter(Writer out, String[] trailingComments) throws Exception;
+
+  protected boolean shouldUseExplicitDatatypes(IRI literalDatatype) {
+    return stringDataTypeOption == StringDataTypeOptions.EXPLICIT ||
+        !(Constants.xsString.equals(literalDatatype) || Constants.rdfLangString.equals(literalDatatype));
+  }
 }