/*  Title:      Pure/library.scala

    Author:     Makarius

Basic library.

*/

package isabelle

import java.lang.System

import java.awt.Component

import javax.swing.JOptionPane

object Library

{

  /* separate */

  def separate[A](s: A, list: List[A]): List[A] =

    list match {

      case x :: xs if !xs.isEmpty => x :: s :: separate(s, xs)

      case _ => list

    }

  /* reverse CharSequence */

  class Reverse(text: CharSequence, start: Int, end: Int) extends CharSequence

  {

    require(0 <= start && start <= end && end <= text.length)

    def this(text: CharSequence) = this(text, 0, text.length)

    def length: Int = end - start

    def charAt(i: Int): Char = text.charAt(end - i - 1)

    def subSequence(i: Int, j: Int): CharSequence =

      if (0 <= i && i <= j && j <= length) new Reverse(text, end - j, end - i)

      else throw new IndexOutOfBoundsException

    override def toString: String =

    {

      val buf = new StringBuilder(length)

      for (i <- 0 until length)

        buf.append(charAt(i))

      buf.toString

    }

  }

  /* iterate over chunks (cf. space_explode/split_lines in ML) */

  def chunks(source: CharSequence, sep: Char = '\n') = new Iterator[CharSequence]

  {

    private val end = source.length

    private def next_chunk(i: Int): Option[(CharSequence, Int)] =

    {

      if (i < end) {

        var j = i; do j += 1 while (j < end && source.charAt(j) != sep)

        Some((source.subSequence(i + 1, j), j))

      }

      else None

    }

    private var state: Option[(CharSequence, Int)] = if (end == 0) None else next_chunk(-1)

    def hasNext(): Boolean = state.isDefined

    def next(): CharSequence =

      state match {

        case Some((s, i)) => { state = next_chunk(i); s }

        case None => throw new NoSuchElementException("next on empty iterator")

      }

  }

  /* simple dialogs */

  private def simple_dialog(kind: Int, default_title: String)

    (parent: Component, title: String, message: Any*)

  {

    Swing_Thread.now {

      JOptionPane.showMessageDialog(parent,

        message.toArray.asInstanceOf[Array[AnyRef]],

        if (title == null) default_title else title, kind)

    }

  }

  def dialog = simple_dialog(JOptionPane.PLAIN_MESSAGE, null) _

  def warning_dialog = simple_dialog(JOptionPane.WARNING_MESSAGE, "Warning") _

  def error_dialog = simple_dialog(JOptionPane.ERROR_MESSAGE, "Error") _

  /* timing */

  def timeit[A](message: String)(e: => A) =

  {

    val start = System.currentTimeMillis()

    val result = Exn.capture(e)

    val stop = System.currentTimeMillis()

    System.err.println(

      (if (message.isEmpty) "" else message + ": ") + (stop - start) + "ms elapsed time")

    Exn.release(result)

  }

}