JLine integration for tab completion combinators

util/complete/JLineCompletion.scala

@@ -0,0 +1,94 @@
+/* sbt -- Simple Build Tool
+ * Copyright 2011  Mark Harrah
+ */
+package sbt.parse
+
+	import jline.{CandidateListCompletionHandler,Completor,CompletionHandler,ConsoleReader}
+	import scala.annotation.tailrec
+	import collection.JavaConversions
+
+object JLineCompletion
+{
+	def installCustomCompletor(reader: ConsoleReader, parser: Parser[_]): Unit =
+		installCustomCompletor(parserAsCompletor(parser), reader)
+	def installCustomCompletor(reader: ConsoleReader)(complete: String => (Seq[String], Seq[String])): Unit =
+		installCustomCompletor(customCompletor(complete), reader)
+	def installCustomCompletor(complete: ConsoleReader => Boolean, reader: ConsoleReader): Unit =
+	{
+		reader.removeCompletor(DummyCompletor)
+		reader.addCompletor(DummyCompletor)
+		reader.setCompletionHandler(new CustomHandler(complete))
+	}
+
+	private[this] final class CustomHandler(completeImpl: ConsoleReader => Boolean) extends CompletionHandler
+	{
+		override def complete(reader: ConsoleReader, candidates: java.util.List[_], position: Int) = completeImpl(reader)
+	}
+	
+	// always provides dummy completions so that the custom completion handler gets called
+	//   (ConsoleReader doesn't call the handler if there aren't any completions)
+	//   the custom handler will then throw away the candidates and call the custom function
+	private[this] final object DummyCompletor extends Completor
+	{
+		override def complete(buffer: String, cursor: Int, candidates: java.util.List[_]): Int =
+		{
+			candidates.asInstanceOf[java.util.List[String]] add "dummy"
+			0
+		}
+	}
+
+	def parserAsCompletor(p: Parser[_]): ConsoleReader => Boolean =
+		customCompletor(str => convertCompletions(Parser.completions(p, str)))
+	def convertCompletions(c: Completions): (Seq[String], Seq[String]) =
+	{
+		( (Seq[String](), Seq[String]()) /: c.get) { case ( t @ (insert,display), comp) =>
+			if(comp.isEmpty) t else (insert :+ comp.append, insert :+ comp.display)
+		}
+	}
+	
+	def customCompletor(f: String => (Seq[String], Seq[String])): ConsoleReader => Boolean =
+		reader => {
+			val success = complete(beforeCursor(reader), f, reader, false)
+			reader.flushConsole()
+			success
+		}
+
+	def beforeCursor(reader: ConsoleReader): String =
+	{
+		val b = reader.getCursorBuffer
+		b.getBuffer.substring(0, b.cursor)
+	}
+
+	def complete(beforeCursor: String, completions: String => (Seq[String],Seq[String]), reader: ConsoleReader, inserted: Boolean): Boolean =
+	{
+		val (insert,display) = completions(beforeCursor)
+		if(insert.isEmpty)
+			inserted
+		else
+		{
+			lazy val common = commonPrefix(insert)
+			if(inserted || common.isEmpty)
+			{
+				showCompletions(display, reader)
+				reader.drawLine()
+				true
+			}
+			else
+			{
+				reader.getCursorBuffer.write(common)
+				reader.redrawLine()
+				complete(beforeCursor + common, completions, reader, true)
+			}
+		}
+	}
+	def showCompletions(cs: Seq[String], reader: ConsoleReader): Unit =
+		if(cs.isEmpty) () else CandidateListCompletionHandler.printCandidates(reader, JavaConversions.asJavaList(cs), true)
+
+	def commonPrefix(s: Seq[String]): String = if(s.isEmpty) "" else s reduceLeft commonPrefix
+	def commonPrefix(a: String, b: String): String =
+	{
+		val len = a.length min b.length
+		@tailrec def loop(i: Int): Int = if(i >= len) len else if(a(i) != b(i)) i else loop(i+1)
+		a.substring(0, loop(0))
+	}
+}

util/complete/src/test/scala/ParserTest.scala

@@ -3,6 +3,26 @@ package sbt.parse
 	import Parser._
 	import org.scalacheck._
 
+object JLineTest
+{
+	def main(args: Array[String])
+	{
+		import jline.{ConsoleReader,Terminal}
+		val reader = new ConsoleReader()
+		Terminal.getTerminal.disableEcho()
+
+		val parser = ParserExample.t
+		JLineCompletion.installCustomCompletor(reader, parser)
+		def loop() {
+			val line = reader.readLine("> ")
+			if(line ne null) {
+				println("Entered '" + line + "'")
+				loop()
+			}
+		}
+		loop()
+	}
+}
 object ParserTest extends Properties("Completing Parser")
 {
 	val wsc = charClass(_.isWhitespace)