src/Pure/System/session.scala

some support for Session.File_Store;

/*  Title:      Pure/System/session.scala
    Author:     Makarius
    Options:    :folding=explicit:collapseFolds=1:

Isabelle session, potentially with running prover.
*/

package isabelle

import java.lang.System

import scala.actors.TIMEOUT
import scala.actors.Actor
import scala.actors.Actor._


object Session
{
  /* abstract file store */

  abstract class File_Store
  {
    def read(path: Path): String
  }


  /* events */

  case object Global_Settings
  case object Perspective
  case object Assignment
  case class Commands_Changed(set: Set[Command])

  sealed abstract class Phase
  case object Inactive extends Phase
  case object Startup extends Phase  // transient
  case object Failed extends Phase
  case object Ready extends Phase
  case object Shutdown extends Phase  // transient
}


class Session(val system: Isabelle_System, val file_store: Session.File_Store)
{
  /* real time parameters */  // FIXME properties or settings (!?)

  // user input (e.g. text edits, cursor movement)
  val input_delay = Time.seconds(0.3)

  // prover output (markup, common messages)
  val output_delay = Time.seconds(0.1)

  // GUI layout updates
  val update_delay = Time.seconds(0.5)


  /* pervasive event buses */

  val phase_changed = new Event_Bus[Session.Phase]
  val global_settings = new Event_Bus[Session.Global_Settings.type]
  val raw_messages = new Event_Bus[Isabelle_Process.Result]
  val commands_changed = new Event_Bus[Session.Commands_Changed]
  val perspective = new Event_Bus[Session.Perspective.type]
  val assignments = new Event_Bus[Session.Assignment.type]


  /* unique ids */

  private var id_count: Document.ID = 0
  def new_id(): Document.ID = synchronized {
    require(id_count > java.lang.Long.MIN_VALUE)
    id_count -= 1
    id_count
  }



  /** buffered command changes (delay_first discipline) **/

  private case object Stop

  private val (_, command_change_buffer) =
    Simple_Thread.actor("command_change_buffer", daemon = true)
  //{{{
  {
    var changed: Set[Command] = Set()
    var flush_time: Option[Long] = None

    def flush_timeout: Long =
      flush_time match {
        case None => 5000L
        case Some(time) => (time - System.currentTimeMillis()) max 0
      }

    def flush()
    {
      if (!changed.isEmpty) commands_changed.event(Session.Commands_Changed(changed))
      changed = Set()
      flush_time = None
    }

    def invoke()
    {
      val now = System.currentTimeMillis()
      flush_time match {
        case None => flush_time = Some(now + output_delay.ms)
        case Some(time) => if (now >= time) flush()
      }
    }

    var finished = false
    while (!finished) {
      receiveWithin(flush_timeout) {
        case command: Command => changed += command; invoke()
        case TIMEOUT => flush()
        case Stop => finished = true; reply(())
        case bad => System.err.println("command_change_buffer: ignoring bad message " + bad)
      }
    }
  }
  //}}}



  /** main protocol actor **/

  val thy_header = new Thy_Header(system.symbols)

  @volatile private var syntax = new Outer_Syntax(system.symbols)
  def current_syntax(): Outer_Syntax = syntax

  @volatile private var reverse_syslog = List[XML.Elem]()
  def syslog(): String = reverse_syslog.reverse.map(msg => XML.content(msg).mkString).mkString("\n")

  @volatile private var _phase: Session.Phase = Session.Inactive
  def phase = _phase
  private def phase_=(new_phase: Session.Phase)
  {
    _phase = new_phase
    phase_changed.event(new_phase)
  }
  def is_ready: Boolean = phase == Session.Ready

  private val global_state = new Volatile(Document.State.init)
  def current_state(): Document.State = global_state.peek()

  private case object Interrupt_Prover
  private case class Edit_Version(edits: List[Document.Edit_Text])
  private case class Start(timeout: Time, args: List[String])

  var verbose: Boolean = false

  private val (_, session_actor) = Simple_Thread.actor("session_actor", daemon = true)
  {
    var prover: Isabelle_Process with Isar_Document = null


    /* document changes */

    def handle_change(change: Document.Change)
    //{{{
    {
      val previous = change.previous.get_finished
      val (node_edits, version) = change.result.get_finished

      var former_assignment = global_state.peek().the_assignment(previous).get_finished
      for {
        (name, Some(cmd_edits)) <- node_edits
        (prev, None) <- cmd_edits
        removed <- previous.nodes(name).commands.get_after(prev)
      } former_assignment -= removed

      val id_edits =
        node_edits map {
          case (name, None) => (name, None)
          case (name, Some(cmd_edits)) =>
            val ids =
              cmd_edits map {
                case (c1, c2) =>
                  val id1 = c1.map(_.id)
                  val id2 =
                    c2 match {
                      case None => None
                      case Some(command) =>
                        if (global_state.peek().lookup_command(command.id).isEmpty) {
                          global_state.change(_.define_command(command))
                          prover.define_command(command.id, system.symbols.encode(command.source))
                        }
                        Some(command.id)
                    }
                  (id1, id2)
              }
            (name -> Some(ids))
        }
      global_state.change(_.define_version(version, former_assignment))
      prover.edit_version(previous.id, version.id, id_edits)
    }
    //}}}


    /* prover results */

    def bad_result(result: Isabelle_Process.Result)
    {
      if (verbose)
        System.err.println("Ignoring prover result: " + result.message.toString)
    }

    def handle_result(result: Isabelle_Process.Result)
    //{{{
    {
      result.properties match {
        case Position.Id(state_id) =>
          try {
            val st = global_state.change_yield(_.accumulate(state_id, result.message))
            command_change_buffer ! st.command
          }
          catch { case _: Document.State.Fail => bad_result(result) }
        case _ =>
          if (result.is_syslog) {
            reverse_syslog ::= result.message
            if (result.is_ready) {
              // FIXME move to ML side
              syntax += ("hence", Keyword.PRF_ASM_GOAL, "then have")
              syntax += ("thus", Keyword.PRF_ASM_GOAL, "then show")
              phase = Session.Ready
            }
            else if (result.is_exit && phase == Session.Startup) phase = Session.Failed
            else if (result.is_exit) phase = Session.Inactive
          }
          else if (result.is_stdout) { }
          else if (result.is_status) {
            result.body match {
              case List(Isar_Document.Assign(id, edits)) =>
                try {
                  val cmds: List[Command] = global_state.change_yield(_.assign(id, edits))
                  for (cmd <- cmds) command_change_buffer ! cmd
                  assignments.event(Session.Assignment)
                }
                catch { case _: Document.State.Fail => bad_result(result) }
              case List(Keyword.Command_Decl(name, kind)) => syntax += (name, kind)
              case List(Keyword.Keyword_Decl(name)) => syntax += name
              case _ => bad_result(result)
            }
          }
          else bad_result(result)
        }

      raw_messages.event(result)
    }
    //}}}


    /* main loop */

    var finished = false
    while (!finished) {
      receive {
        case Interrupt_Prover =>
          if (prover != null) prover.interrupt

        case Edit_Version(edits) if prover != null =>
          val previous = global_state.peek().history.tip.version
          val result = Future.fork { Thy_Syntax.text_edits(Session.this, previous.join, edits) }
          val change = global_state.change_yield(_.extend_history(previous, edits, result))

          val this_actor = self
          change.version.map(_ => {
            assignments.await { global_state.peek().is_assigned(previous.get_finished) }
            this_actor ! change })

          reply(())

        case change: Document.Change if prover != null => handle_change(change)

        case result: Isabelle_Process.Result => handle_result(result)

        case Start(timeout, args) if prover == null =>
          if (phase == Session.Inactive || phase == Session.Failed) {
            phase = Session.Startup
            prover = new Isabelle_Process(system, timeout, self, args:_*) with Isar_Document
          }

        case Stop =>
          if (phase == Session.Ready) {
            global_state.change(_ => Document.State.init)  // FIXME event bus!?
            phase = Session.Shutdown
            prover.terminate
            phase = Session.Inactive
          }
          finished = true
          reply(())

        case bad if prover != null =>
          System.err.println("session_actor: ignoring bad message " + bad)
      }
    }
  }



  /** main methods **/

  def start(timeout: Time, args: List[String]) { session_actor ! Start(timeout, args) }

  def stop() { command_change_buffer !? Stop; session_actor !? Stop }

  def interrupt() { session_actor ! Interrupt_Prover }

  def edit_version(edits: List[Document.Edit_Text]) { session_actor !? Edit_Version(edits) }

  def snapshot(name: String, pending_edits: List[Text.Edit]): Document.Snapshot =
    global_state.peek().snapshot(name, pending_edits)
}