ttools: add entity declaration options to Formatter

Provide the option to declare some internal entities to the Formatter
class for it to use while parsing XML it's going to format.
I ended up not using this, but it might possibly come in useful at
a later date, so leave it in.

ttools/src/main/uk/ac/starlink/ttools/Formatter.java

@@ -3,13 +3,16 @@
 import java.io.ByteArrayInputStream;
 import java.io.IOException;
 import java.io.InputStream;
+import java.util.LinkedHashMap;
 import java.util.List;
+import java.util.Map;
 import java.util.StringTokenizer;
 import javax.xml.parsers.DocumentBuilder;
 import javax.xml.parsers.DocumentBuilderFactory;
 import javax.xml.parsers.ParserConfigurationException;
 import org.xml.sax.SAXException;
 import org.w3c.dom.Document;
+import org.w3c.dom.DocumentType;
 import org.w3c.dom.Element;
 import org.w3c.dom.Node;
 import org.w3c.dom.Text;
@@ -23,6 +26,7 @@
 public class Formatter {
 
     private final DocumentBuilder db_;
+    private final Map<String,String> entityMap_;
     private String manualName_ = "SUN/256";
 
     /**
@@ -35,6 +39,7 @@ public Formatter() {
         catch ( ParserConfigurationException e ) {
             throw new RuntimeException( e.getMessage(), e );
         }
+        entityMap_ = new LinkedHashMap<String,String>();
     }
 
     /**
@@ -67,6 +72,18 @@ public String getManualName() {
         return manualName_;
     }
 
+    /**
+     * Adds an internal entity declaration to this formatter. 
+     * Any entities added here are declared in the document declaration
+     * of XML parsed by the {@link #formatXML formatXML} method.
+     *
+     * @param  entName  internal entity name
+     * @param  entValue  entity value
+     */
+    public void addEntity( String entName, String entValue ) {
+        entityMap_.put( entName, entValue );
+    }
+
     /**
      * Returns a string which is a formatted version of a DOM.
      * The result is suitable for output on the terminal.
@@ -149,9 +166,12 @@ else if ( tag.equals( "ref" ) ) {
             else if ( child instanceof Text ) {
                 result.appendWords( ((Text) child).getData() );
             }
+            else if ( child instanceof DocumentType ) {
+            }
             else {
                 throw new IllegalArgumentException( "Can't serialize node " + 
-                                                    child.getClass() );
+                                                    child.getClass()
+                                                   .getName() );
             }
         }
     }
@@ -164,7 +184,23 @@ else if ( child instanceof Text ) {
      * @return  DOM
      */
     private Document readDOM( String xml ) throws SAXException {
-        String dxml = "<DOC>" + xml + "</DOC>";
+        StringBuffer sbuf = new StringBuffer()
+            .append( "<?xml version='1.0'?>" )
+            .append( "<!DOCTYPE doc [" );
+        for ( Map.Entry<String,String> entry : entityMap_.entrySet() ) {
+            sbuf.append( "<!ENTITY " )
+                .append( entry.getKey() )
+                .append( " " )
+                .append( "'" )
+                .append( entry.getValue() )
+                .append( "'" )
+                .append( ">" );
+        }
+        sbuf.append( "]>" )
+            .append( "<DOC>" )
+            .append( xml )
+            .append( "</DOC>" );
+        String dxml = sbuf.toString();
         try {
             InputStream in = new ByteArrayInputStream( dxml.getBytes() );
             Document doc = db_.parse( in );