hash-consing on load, enabled per default

4 files changed, 51 insertions, 7 deletions

diff --git a/sources/scala/xml/Element.scala b/sources/scala/xml/Element.scala
index 04fb40bcb8..e4d24f1918 100644
--- a/sources/scala/xml/Element.scala
+++ b/sources/scala/xml/Element.scala
@@ -15,6 +15,8 @@ abstract class Element {
     def getAttribs:  Map[ String, String ]; // disabled
     def setAttribs( m:Map[ String, String ] ):Unit ;
 
+    override def hashCode() = Element.hashValue( getName, getAttribs, getChildren );
+
     def toXML: String = {
         "<" + getName + toXML_( getAttribs ) + ">"
         + toXML_( getChildren )
@@ -59,3 +61,14 @@ abstract class Element {
                 } // def toXML
 */
 } // abstract class
+
+object Element {
+  def hashValue( name:String, attribs:Map[ String, String ], children:Seq[ Element ] ) = {
+    name.hashCode() + attribs.hashCode() + children.hashCode()
+  }
+
+  def hashValue( name:String, attribs:java.util.Map, children:Seq[ Element ] ) = {
+    name.hashCode() + attribs.hashCode() + children.hashCode()
+  }
+
+}
diff --git a/sources/scala/xml/Generic.scala b/sources/scala/xml/Generic.scala
index d7d2a81445..22355cf226 100644
--- a/sources/scala/xml/Generic.scala
+++ b/sources/scala/xml/Generic.scala
@@ -25,15 +25,24 @@ object Generic {
 
     def   elementContainsText( name:java.lang.String ):boolean = true;
 
+    // default behaviour is hash-consing
+    val cache = new HashMap();
+
     def   createElement( elemName:String,
                          attribs :java.util.Map, // ignore attributes.
                          children:java.util.Iterator ):scala.Object = {
 
+          val el = Labelled( Symbol( elemName), iterToList[ Any ]( children ));
+	  val el_cache = cache.get( el as scala.All ) as scala.Object;
+	  if ( el_cache != null ) {
+	    System.err.println("[using cached elem!]");
+	    el_cache
+	  } else {
+	    cache.put( el as scala.All, el as scala.All );
+	    el
+	  }
 
 
-
-          Labelled( Symbol( elemName), iterToList[ Any ]( children ))
-
     }
 
     def createPCDATA( text:String ):scala.Object  = {
diff --git a/sources/scala/xml/PCDATA.scala b/sources/scala/xml/PCDATA.scala
index 120cbf4bf4..70d849f3bf 100644
--- a/sources/scala/xml/PCDATA.scala
+++ b/sources/scala/xml/PCDATA.scala
@@ -14,6 +14,7 @@ case class PCDATA( content:String ) extends Element  {
 
               override def toXML:String = content;
 
+              override def hashCode() = content.hashCode();
 	      override def toString() = "PCDATA("+content+")";
 
 } // PCDATA
diff --git a/sources/scala/xml/ScalaFactoryAdapter.scala b/sources/scala/xml/ScalaFactoryAdapter.scala
index 081e127e45..cb38c85860 100644
--- a/sources/scala/xml/ScalaFactoryAdapter.scala
+++ b/sources/scala/xml/ScalaFactoryAdapter.scala
@@ -46,16 +46,37 @@ abstract class ScalaFactoryAdapter
 
     val g: Map[ String, boolean ] ;
 
+    val compress: boolean ;
+
     def   elementContainsText( name:java.lang.String ):boolean =
          g.get( name ) ;
 
+    // if compress is set, used for hash-consing
+    val cache = new HashMap();
+
     def   createElement(elemName:String,
                         attribs:java.util.Map,
                         children:java.util.Iterator ):scala.Object = {
-          val c = f.get( elemName ); // constructor
-          val el = c( iterToList[Element]( children ) );
-          el.setAttribs( mapToMap[String,String]( attribs ) );
-	  el
+	  val _children = iterToList[Element]( children ); // 2do:optimize
+	  if( !compress ) {
+            val c = f.get( elemName ); // get constructor
+            val el = c( _children );
+            el.setAttribs( mapToMap[String,String]( attribs ) );
+	    el
+	  } else { // do hash-consing
+
+	    val h = Element.hashValue( elemName, attribs, _children );
+	    val el_cache = cache.get( h as scala.All ) as scala.Object;
+	    if ( el_cache != null ) {  // return cached elem
+	      el_cache
+	    } else {
+	      val c = f.get( elemName ); // get constructor
+              val el = c( _children );
+              el.setAttribs( mapToMap[String,String]( attribs ) );
+	      cache.put( h as scala.All, el as scala.All );
+	      el
+	    }
+	  }
     }
 
     def createPCDATA( text:String ):scala.Object  = {