SBT command for extracting completions

sbt_complete.scala

package sbtcomplete

import sbt._
import complete.JLineCompletion
import Keys._

object SbtComplete {

  private val CompletionsCommand = "completions"
  private val CompletionsBrief = ("<arg>", "The string to complete.")
  private val CompletionsDetailed = "Displays completions for the specified string. The first (possibly empty) line denotes the common prefix of all results."

  private def completions = Command.single(CompletionsCommand, CompletionsBrief, CompletionsDetailed) { case (s: State, source) =>
    import JLineCompletion._

    lazy val completor = parserAsCompletor(s.combinedParser)

    val (insert, display) = completor(source, 0)
    val common = commonPrefix(insert)
    println(common)
    display.foreach(println)
    s
  }

  lazy val settings = Seq[Setting[_]](
    commands += completions
  )

}