/*  Title:      Pure/Isar/outer_syntax.scala

    Author:     Makarius

Isabelle/Isar outer syntax.

*/

package isabelle

import scala.util.parsing.input.{Reader, CharSequenceReader}

import scala.collection.mutable

class Outer_Syntax

{

  protected val keywords: Map[String, String] = Map((";" -> Keyword.DIAG))

  protected val lexicon: Scan.Lexicon = Scan.Lexicon.empty

  lazy val completion: Completion = (new Completion).add_symbols // FIXME odd initialization

  def keyword_kind(name: String): Option[String] = keywords.get(name)

  def + (name: String, kind: String, replace: String): Outer_Syntax =

  {

    val new_keywords = keywords + (name -> kind)

    val new_lexicon = lexicon + name

    val new_completion = completion + (name, replace)

    new Outer_Syntax {

      override val lexicon = new_lexicon

      override val keywords = new_keywords

      override lazy val completion = new_completion

    }

  }

  def + (name: String, kind: String): Outer_Syntax = this + (name, kind, name)

  def + (name: String): Outer_Syntax = this + (name, Keyword.MINOR)

  def is_command(name: String): Boolean =

    keyword_kind(name) match {

      case Some(kind) => kind != Keyword.MINOR

      case None => false

    }

  def heading_level(name: String): Option[Int] =

    name match {

      // FIXME avoid hard-wired info!?

      case "header" => Some(1)

      case "chapter" => Some(2)

      case "section" | "sect" => Some(3)

      case "subsection" | "subsect" => Some(4)

      case "subsubsection" | "subsubsect" => Some(5)

      case _ =>

        keyword_kind(name) match {

          case Some(kind) if Keyword.theory(kind) => Some(6)

          case _ => None

        }

    }

  def heading_level(command: Command): Option[Int] =

    heading_level(command.name)

  /* tokenize */

  def scan(input: Reader[Char]): List[Token] =

  {

    import lexicon._

    parseAll(rep(token(is_command)), input) match {

      case Success(tokens, _) => tokens

      case _ => error("Unexpected failure of tokenizing input:\n" + input.source.toString)

    }

  }

  def scan(input: CharSequence): List[Token] =

    scan(new CharSequenceReader(input))

  def scan_context(input: CharSequence, context: Scan.Context): (List[Token], Scan.Context) =

  {

    import lexicon._

    var in: Reader[Char] = new CharSequenceReader(input)

    val toks = new mutable.ListBuffer[Token]

    var ctxt = context

    while (!in.atEnd) {

      parse(token_context(is_command, ctxt), in) match {

        case Success((x, c), rest) => { toks += x; ctxt = c; in = rest }

        case NoSuccess(_, rest) =>

          error("Unexpected failure of tokenizing input:\n" + rest.source.toString)

      }

    }

    (toks.toList, ctxt)

  }

}