src/Pure/PIDE/document.scala

proper context for Syntax.parse_token;

/*  Title:      Pure/PIDE/document.scala
    Author:     Makarius

Document as collection of named nodes, each consisting of an editable
list of commands.
*/

package isabelle


import scala.collection.mutable
import scala.annotation.tailrec


object Document
{
  /* formal identifiers */

  type Version_ID = String
  type Command_ID = String
  type State_ID = String

  val NO_ID = ""



  /** named document nodes **/

  object Node
  {
    val empty: Node = new Node(Linear_Set())

    def command_starts(commands: Iterator[Command], offset: Int = 0): Iterator[(Command, Int)] =
    {
      var i = offset
      for (command <- commands) yield {
        val start = i
        i += command.length
        (command, start)
      }
    }
  }

  class Node(val commands: Linear_Set[Command])
  {
    /* command ranges */

    def command_starts: Iterator[(Command, Int)] =
      Node.command_starts(commands.iterator)

    def command_start(cmd: Command): Option[Int] =
      command_starts.find(_._1 == cmd).map(_._2)

    def command_range(i: Int): Iterator[(Command, Int)] =
      command_starts dropWhile { case (cmd, start) => start + cmd.length <= i }

    def command_range(i: Int, j: Int): Iterator[(Command, Int)] =
      command_range(i) takeWhile { case (_, start) => start < j }

    def command_at(i: Int): Option[(Command, Int)] =
    {
      val range = command_range(i)
      if (range.hasNext) Some(range.next) else None
    }

    def proper_command_at(i: Int): Option[Command] =
      command_at(i) match {
        case Some((command, _)) =>
          commands.reverse_iterator(command).find(cmd => !cmd.is_ignored)
        case None => None
      }
  }


  /* initial document */

  val init: Document =
  {
    val doc = new Document(NO_ID, Map().withDefaultValue(Node.empty), Map())
    doc.assign_states(Nil)
    doc
  }



  /** changes of plain text, eventually resulting in document edits **/

  type Node_Text_Edit = (String, List[Text_Edit])  // FIXME None: remove

  type Edit[C] =
   (String,  // node name
    Option[List[(Option[C], Option[C])]])  // None: remove, Some: insert/remove commands

  abstract class Snapshot
  {
    val document: Document
    val node: Document.Node
    val is_outdated: Boolean
    def convert(offset: Int): Int
    def revert(offset: Int): Int
  }

  object Change
  {
    val init = new Change(NO_ID, None, Nil, Future.value(Nil, Document.init))
  }

  class Change(
    val id: Version_ID,
    val parent: Option[Change],
    val edits: List[Node_Text_Edit],
    val result: Future[(List[Edit[Command]], Document)])
  {
    def ancestors: Iterator[Change] = new Iterator[Change]
    {
      private var state: Option[Change] = Some(Change.this)
      def hasNext = state.isDefined
      def next =
        state match {
          case Some(change) => state = change.parent; change
          case None => throw new NoSuchElementException("next on empty iterator")
        }
    }

    def join_document: Document = result.join._2
    def is_assigned: Boolean = result.is_finished && join_document.assignment.is_finished

    def snapshot(name: String, pending_edits: List[Text_Edit]): Snapshot =
    {
      val latest = Change.this
      val stable = latest.ancestors.find(_.is_assigned)
      require(stable.isDefined)

      val edits =
        (pending_edits /: latest.ancestors.takeWhile(_ != stable.get))((edits, change) =>
            (for ((a, eds) <- change.edits if a == name) yield eds).flatten ::: edits)
      lazy val reverse_edits = edits.reverse

      new Snapshot {
        val document = stable.get.join_document
        val node = document.nodes(name)
        val is_outdated = !(pending_edits.isEmpty && latest == stable.get)
        def convert(offset: Int): Int = (offset /: edits)((i, edit) => edit.convert(i))
        def revert(offset: Int): Int = (offset /: reverse_edits)((i, edit) => edit.revert(i))
      }
    }
  }



  /** editing **/

  def text_edits(session: Session, old_doc: Document, new_id: Version_ID,
      edits: List[Node_Text_Edit]): (List[Edit[Command]], Document) =
  {
    require(old_doc.assignment.is_finished)


    /* unparsed dummy commands */

    def unparsed(source: String) =
      new Command(NO_ID, List(Token(Token.Kind.UNPARSED, source)))

    def is_unparsed(command: Command) = command.id == NO_ID


    /* phase 1: edit individual command source */

    @tailrec def edit_text(eds: List[Text_Edit],
        commands: Linear_Set[Command]): Linear_Set[Command] =
    {
      eds match {
        case e :: es =>
          Node.command_starts(commands.iterator).find {
            case (cmd, cmd_start) =>
              e.can_edit(cmd.source, cmd_start) ||
                e.is_insert && e.start == cmd_start + cmd.length
          } match {
            case Some((cmd, cmd_start)) if e.can_edit(cmd.source, cmd_start) =>
              val (rest, text) = e.edit(cmd.source, cmd_start)
              val new_commands = commands.insert_after(Some(cmd), unparsed(text)) - cmd
              edit_text(rest.toList ::: es, new_commands)

            case Some((cmd, cmd_start)) =>
              edit_text(es, commands.insert_after(Some(cmd), unparsed(e.text)))

            case None =>
              require(e.is_insert && e.start == 0)
              edit_text(es, commands.insert_after(None, unparsed(e.text)))
          }
        case Nil => commands
      }
    }


    /* phase 2: recover command spans */

    @tailrec def parse_spans(commands: Linear_Set[Command]): Linear_Set[Command] =
    {
      commands.iterator.find(is_unparsed) match {
        case Some(first_unparsed) =>
          val first =
            commands.reverse_iterator(first_unparsed).find(_.is_command) getOrElse commands.head
          val last =
            commands.iterator(first_unparsed).find(_.is_command) getOrElse commands.last
          val range =
            commands.iterator(first).takeWhile(_ != last).toList ::: List(last)

          val sources = range.flatMap(_.span.map(_.source))
          val spans0 = Thy_Syntax.parse_spans(session.current_syntax.scan(sources.mkString))

          val (before_edit, spans1) =
            if (!spans0.isEmpty && first.is_command && first.span == spans0.head)
              (Some(first), spans0.tail)
            else (commands.prev(first), spans0)

          val (after_edit, spans2) =
            if (!spans1.isEmpty && last.is_command && last.span == spans1.last)
              (Some(last), spans1.take(spans1.length - 1))
            else (commands.next(last), spans1)

          val inserted = spans2.map(span => new Command(session.create_id(), span))
          val new_commands =
            commands.delete_between(before_edit, after_edit).append_after(before_edit, inserted)
          parse_spans(new_commands)

        case None => commands
      }
    }


    /* phase 3: resulting document edits */

    {
      val doc_edits = new mutable.ListBuffer[Edit[Command]]
      var nodes = old_doc.nodes
      var former_states = old_doc.assignment.join

      for ((name, text_edits) <- edits) {
        val commands0 = nodes(name).commands
        val commands1 = edit_text(text_edits, commands0)
        val commands2 = parse_spans(commands1)   // FIXME somewhat slow

        val removed_commands = commands0.iterator.filter(!commands2.contains(_)).toList
        val inserted_commands = commands2.iterator.filter(!commands0.contains(_)).toList

        val cmd_edits =
          removed_commands.reverse.map(cmd => (commands0.prev(cmd), None)) :::
          inserted_commands.map(cmd => (commands2.prev(cmd), Some(cmd)))

        doc_edits += (name -> Some(cmd_edits))
        nodes += (name -> new Node(commands2))
        former_states --= removed_commands
      }
      (doc_edits.toList, new Document(new_id, nodes, former_states))
    }
  }
}


class Document(
    val id: Document.Version_ID,
    val nodes: Map[String, Document.Node],
    former_states: Map[Command, Command])  // FIXME !?
{
  /* command state assignment */

  val assignment = Future.promise[Map[Command, Command]]
  def await_assignment { assignment.join }

  @volatile private var tmp_states = former_states

  def assign_states(new_states: List[(Command, Command)])
  {
    assignment.fulfill(tmp_states ++ new_states)
    tmp_states = Map()
  }

  def current_state(cmd: Command): State =
  {
    require(assignment.is_finished)
    (assignment.join).get(cmd) match {
      case Some(cmd_state) => cmd_state.current_state
      case None => new State(cmd, Command.Status.UNDEFINED, 0, Nil, cmd.empty_markup)
    }
  }
}