<\/p>\n
I just spent the best part of two hours attempting figure out an interactive REPL for Scala, a la the Groovy Console<\/b>, but a very basic version. My progress has not been lightning fast. Why?<\/p>\n I really do not understand why this code is not working at all. It is a Swing application to programmatically invokes Scala NSC REPL. I have two JEditorPanes in set horizontally in a JSplitPane. The upper editor pane is a reserved for text entry. The lower editor pane is not editable is reserved for capturing the output of the Scala.<\/p>\n To fire the REPL interactively in the upper pane, hold the CTRL key and pressed the RETURN\/ENTER key. Invoking the REPL works fine. However it is the update to the lower pane that causes concern. I can see the interactive REPL returning a result, yet the JEditorPane is not being updated. Is this a Swing Scala bug? Or does Java Swing bug?<\/p>\n I suspected the cause was a Swing multithreading problem hence I used SwingUtilites.invokeLater to make sure the update was on the Event Dispatch Thread, however to no avail. JComponent.repaint() nada, JComponent.validate() nada. What gives?<\/p>\n Oh yes in case you are wondering, JavaFX 2.0 early access does not yet have a multi-line equivalent of JTextComponent. <\/p>\n I will be very interested in finding out what is wrong with this picture? If you know the answer, then a pint of Staropramen is on me. Thanks<\/p>\n","protected":false},"excerpt":{"rendered":" I just spent the best part of two hours attempting figure out an interactive REPL for Scala, a la the Groovy Console, but a very basic version. My progress has not been lightning fast. Why? I really do not understand why this code is not working at all. It is a Swing application to […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[8,6,73],"tags":[],"_links":{"self":[{"href":"https:\/\/www.xenonique.co.uk\/blog\/wp-json\/wp\/v2\/posts\/258"}],"collection":[{"href":"https:\/\/www.xenonique.co.uk\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.xenonique.co.uk\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.xenonique.co.uk\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.xenonique.co.uk\/blog\/wp-json\/wp\/v2\/comments?post=258"}],"version-history":[{"count":8,"href":"https:\/\/www.xenonique.co.uk\/blog\/wp-json\/wp\/v2\/posts\/258\/revisions"}],"predecessor-version":[{"id":267,"href":"https:\/\/www.xenonique.co.uk\/blog\/wp-json\/wp\/v2\/posts\/258\/revisions\/267"}],"wp:attachment":[{"href":"https:\/\/www.xenonique.co.uk\/blog\/wp-json\/wp\/v2\/media?parent=258"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.xenonique.co.uk\/blog\/wp-json\/wp\/v2\/categories?post=258"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.xenonique.co.uk\/blog\/wp-json\/wp\/v2\/tags?post=258"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}\r\npackage swingrepl\r\n\r\nimport java.io._\r\nimport scala.swing._\r\nimport scala.swing.event._\r\n\r\nimport javax.swing.SwingUtilities\r\nimport scala.tools.nsc._\r\nimport scala.tools.nsc.interpreter._\r\n\r\n\/**\r\n * Swing version of the REPL\r\n * User: Peter\r\n * Date: 22\/03\/11\r\n * Time: 14:34\r\n *\/\r\nobject SwingRepl extends SimpleSwingApplication {\r\n\r\n def outputPane = new TextArea {\r\n editable = false\r\n text = "Text output"\r\n }\r\n\r\n def replInvoker = new ReplInvoker( outputPane )\r\n replInvoker.start()\r\n\r\n def inputPane: TextArea = new TextArea {\r\n text = "List(1,2,3,4,5) map ( n => n * n )"\r\n editable = true\r\n listenTo(keys)\r\n\r\n reactions += {\r\n case e: KeyPressed => {\r\n \/\/ println("keyCode =" +e.peer.getKeyCode+", keyChar = "+e.peer.getKeyChar)\r\n if ( e.peer.isControlDown && e.key == Key.Enter ) {\r\n replInvoker.interpret( text )\r\n }\r\n }\r\n\r\n case _ =>\r\n }\r\n }\r\n\r\n\r\n def scrollInputPane = new ScrollPane( inputPane )\r\n def scrollOutputPane = new ScrollPane( outputPane )\r\n\r\n def splitPane = new SplitPane( Orientation.Horizontal, scrollInputPane, scrollOutputPane ) {\r\n dividerLocation = 100\r\n }\r\n\r\n def top = new MainFrame {\r\n title = "Swing REPL"\r\n preferredSize = new Dimension(900, 900 )\r\n contents = splitPane\r\n }\r\n\r\n\r\n \/**\r\n * Programmatically launching the Scala REPL\r\n *\/\r\n class ReplInvoker( val outputPane: TextComponent ) {\r\n private val swriter = new StringWriter()\r\n private val pwriter = new PrintWriter( swriter ) {\r\n override def println( line: String ) {\r\n super.println( line )\r\n System.out.println("println line="+line)\r\n outputPane.text = swriter.toString()\r\n }\r\n override def print( line: String ) {\r\n super.print( line )\r\n System.out.println("print line="+line)\r\n System.out.println("swriter.toString="+swriter.toString )\r\n\r\n SwingUtilities.invokeLater( new Runnable() {\r\n override def run(): Unit = {\r\n outputPane.text = outputPane.text +"\\n"+ line +"\\n"\r\n outputPane.peer.validate()\r\n }\r\n })\r\n }\r\n }\r\n\r\n private val cmd = new InterpreterCommand(Nil, println )\r\n println("cmd="+cmd)\r\n private val settings = cmd.settings\r\n println("settings="+settings)\r\n\r\n settings.usejavacp.value = true\r\n\r\n private val interpreter = new Interpreter(settings, pwriter ) {\r\n override def reset() = { super.reset; unleash() }\r\n override def unleash() = { super.unleash; }\r\n }\r\n println("interpreter="+interpreter)\r\n private val completion = new Completion(interpreter)\r\n\r\n def start() {\r\n println("ReplInvoker.start")\r\n }\r\n\r\n def interpret(cmd: String): Unit = {\r\n println("replInvoker.interpret "+cmd )\r\n interpreter.interpret(cmd)\r\n }\r\n }\r\n}\r\n<\/pre>\n