some support for actual symbol recoding;

--- a/src/Tools/jEdit/src/jedit/IsabelleEncoding.scala	Thu Jun 25 23:03:09 2009 +0200
+++ b/src/Tools/jEdit/src/jedit/IsabelleEncoding.scala	Thu Jun 25 23:54:25 2009 +0200
@@ -8,25 +8,48 @@
 
 import org.gjt.sp.jedit.io.Encoding
 
-import java.nio.charset.{Charset, CodingErrorAction}
-import java.io.{InputStream, OutputStream, Reader, Writer, InputStreamReader, OutputStreamWriter}
+import java.nio.charset.{Charset, CharsetDecoder, CodingErrorAction}
+import java.io.{InputStream, OutputStream, Reader, Writer, InputStreamReader, OutputStreamWriter,
+  CharArrayReader, ByteArrayOutputStream}
+
+import scala.io.{Source, BufferedSource}
 
 
 class IsabelleEncoding extends Encoding
 {
   private val charset = Charset.forName(Isabelle_System.charset)
+  private val BUFSIZE = 32768
+
+  private def text_reader(in: InputStream, decoder: CharsetDecoder): Reader =
+  {
+    def source(): Source =
+      BufferedSource.fromInputStream(in, decoder, BUFSIZE, { () => source() })
+    val text = Source.fromInputStream(in, Isabelle_System.charset).mkString
+    val buffer = Isabelle.symbols.decode(text).toArray
+		new CharArrayReader(buffer)
+  }
 
 	override def getTextReader(in: InputStream): Reader =
-		new InputStreamReader(in, charset.newDecoder())
-
-	override def getTextWriter(out: OutputStream): Writer =
-		new OutputStreamWriter(out, charset.newEncoder())
+    text_reader(in, charset.newDecoder())
 
 	override def getPermissiveTextReader(in: InputStream): Reader =
 	{
 		val decoder = charset.newDecoder()
 		decoder.onMalformedInput(CodingErrorAction.REPLACE)
 		decoder.onUnmappableCharacter(CodingErrorAction.REPLACE)
-		new InputStreamReader(in, decoder)
+		text_reader(in, decoder)
 	}
+
+  override def getTextWriter(out: OutputStream): Writer =
+  {
+    val buffer = new ByteArrayOutputStream(BUFSIZE) {
+      override def flush()
+      {
+        val text = Isabelle.symbols.encode(toString(Isabelle_System.charset))
+        out.write(text.getBytes(Isabelle_System.charset))
+        out.flush()
+      }
+    }
+		new OutputStreamWriter(buffer, charset.newEncoder())
+  }
 }