src/Pure/PIDE/markup_tree.scala

more efficient Markup_Tree, based on branches sorted by quasi-order;
renamed markup_node.scala to markup_tree.scala and classes/objects accordingly;
Position.Range: produce actual Text.Range;
Symbol.Index.decode: convert 1-based Isabelle offsets here;
added static Command.range;
simplified Command.markup;
Document_Model.token_marker: flatten markup at most once;
tuned;

/*  Title:      Pure/PIDE/markup_tree.scala
    Author:     Fabian Immler, TU Munich
    Author:     Makarius

Markup trees over nested / non-overlapping text ranges.
*/

package isabelle


import javax.swing.tree.DefaultMutableTreeNode

import scala.collection.immutable.SortedMap
import scala.collection.mutable
import scala.annotation.tailrec


object Markup_Tree
{
  case class Node(val range: Text.Range, val info: Any)


  /* branches sorted by quasi-order -- overlapping intervals appear as equivalent */

  object Branches
  {
    type Entry = (Node, Markup_Tree)
    type T = SortedMap[Node, Entry]

    val empty = SortedMap.empty[Node, Entry](new scala.math.Ordering[Node]
      {
        def compare(x: Node, y: Node): Int = x.range compare y.range
      })
    def update(branches: T, entries: Entry*): T =
      branches ++ entries.map(e => (e._1 -> e))
    def make(entries: List[Entry]): T = update(empty, entries:_*)
  }

  val empty = new Markup_Tree(Branches.empty)
}


case class Markup_Tree(val branches: Markup_Tree.Branches.T)
{
  import Markup_Tree._

  def + (new_node: Node): Markup_Tree =
  {
    // FIXME tune overlapping == branches && rest.isEmpty
    val (overlapping, rest) =
    {
      val overlapping = new mutable.ListBuffer[Branches.Entry]
      var rest = branches
      while (rest.isDefinedAt(new_node)) {
        overlapping += rest(new_node)
        rest -= new_node
      }
      (overlapping.toList, rest)
    }
    overlapping match {
      case Nil =>
        new Markup_Tree(Branches.update(branches, new_node -> empty))

      case List((node, subtree))
        if node.range != new_node.range && (node.range contains new_node.range) =>
        new Markup_Tree(Branches.update(branches, node -> (subtree + new_node)))

      case _ if overlapping.forall(e => new_node.range contains e._1.range) =>
        val new_tree = new Markup_Tree(Branches.make(overlapping))
        new Markup_Tree(Branches.update(rest, new_node -> new_tree))

      case _ => // FIXME split markup!?
        System.err.println("Ignored overlapping markup: " + new_node); this
    }
  }

  // FIXME depth-first with result markup stack
  // FIXME projection to given range
  def flatten(parent: Node): List[Node] =
  {
    val result = new mutable.ListBuffer[Node]
    var offset = parent.range.start
    for ((_, (node, subtree)) <- branches.iterator) {
      if (offset < node.range.start)
        result += new Node(Text.Range(offset, node.range.start), parent.info)
      result ++= subtree.flatten(node)
      offset = node.range.stop
    }
    if (offset < parent.range.stop)
      result += new Node(Text.Range(offset, parent.range.stop), parent.info)
    result.toList
  }

  def filter(pred: Node => Boolean): Markup_Tree =
  {
    val bs = branches.toList.flatMap(entry => {
      val (_, (node, subtree)) = entry
      if (pred(node)) List((node, (node, subtree.filter(pred))))
      else subtree.filter(pred).branches.toList
    })
    new Markup_Tree(Branches.empty ++ bs)
  }

  def swing_tree(parent: DefaultMutableTreeNode)(swing_node: Node => DefaultMutableTreeNode)
  {
    for ((_, (node, subtree)) <- branches) {
      val current = swing_node(node)
      subtree.swing_tree(current)(swing_node)
      parent.add(current)
    }
  }
}