scala - lab3

class Pos private(val prog: String, val offs: Int, val line: Int, val col: Int) {
  def this(prog: String) = this(prog, 0, 1, 1)

  def ch = if (offs == prog.length) -1 else prog(offs)

  def inc = ch match {
    case '\n' => new Pos(prog, offs+1, line+1, 1)
    case -1   => this
    case _    => new Pos(prog, offs+1, line, col+1)
  }

  override def toString = "(" + line + ", " + col + ")"
}

object DomainTags extends Enumeration {
  type Tag = Value
  val WHITESPACE, IDENT, NUMBER, STRING_LIT, ERROR, END_OF_PROGRAM = Value
}
import DomainTags._

class Scanner {
  def scan(start: Pos, list: List[String]): (Tag, Pos, List[String]) =
    //sys.error("syntax error at " + start)
    (ERROR, start.inc, (start + "syntax error") :: list)
}

class Token(val start: Pos, scanner: Scanner, list: List[String]) {
  val (tag, follow, newlist) = start.ch match {
    case -1 => (END_OF_PROGRAM, start, list)
    case _  => scanner.scan(start, list)
  }

  def image = start.prog.substring(start.offs, follow.offs)

  def next = new Token(follow, scanner, newlist)

  def errList = list
}

trait Whitespaces extends Scanner {
  private def missWhitespace(pos: Pos): Pos = pos.ch match {
    case ' '  => missWhitespace(pos.inc)
    case '\t' => missWhitespace(pos.inc)
    case '\n' => missWhitespace(pos.inc)
    case _    => pos
  }

  override def scan(start: Pos, list: List[String]) = {
    val follow = missWhitespace(start)
    if (start != follow) (WHITESPACE, follow, list)
    else super.scan(start, list)
  }
}

trait Ident extends Scanner {
  private def findIdent(pos: Pos): Pos = {
    if (pos.ch == '_' || (pos.ch >= 'a' && pos.ch <= 'z') || (pos.ch >= 'A' && pos.ch <= 'Z') || (pos.ch >= '0' && pos.ch <= '9')) {
      findIdent(pos.inc)
    } else pos
  }

  override def scan(start: Pos, list: List[String]) = {
    if (start.ch == '_' || (start.ch >= 'a' && start.ch <= 'z') || (start.ch >= 'A' && start.ch <= 'Z')) {
      val follow = findIdent(start);
      if (start != follow) (IDENT, follow, list)
      else (ERROR, follow, (follow + "syntax error") :: list)//super.scan(start, list)  // переделать
    } else {
      super.scan(start, list)
    }
  }
}

trait StringLit extends Scanner {
  private def findStringLit(pos: Pos): Pos = {
    if ((pos.ch >= 'a' && pos.ch <= 'z') || (pos.ch >= 'A' && pos.ch <= 'Z')) {
      findStringLit(pos.inc)
    } else if (pos.ch == '\\') {
        if (pos.inc.ch == 'n' || pos.inc.ch == 't') {
          findStringLit(pos.inc)
        } else if (pos.inc.ch == '\"') {
          findStringLit(pos.inc.inc)
        } 
        else pos 
    } else pos
  }

  override def scan(start: Pos, list: List[String]) = {
    if (start.ch == '\"') {
      val follow = findStringLit(start.inc);
      if (start != follow) 
        if (follow.ch == '\"')
          (STRING_LIT, follow.inc, list)
        else (ERROR, follow, (follow + "symbol \" expected") :: list) //super.scan(start, list)  // синтаксическая ошибка
      else (ERROR, follow, (follow + "syntax error") :: list)//super.scan(start, list)
    } else {
      super.scan(start, list)
    }
  }
}

trait Number extends Scanner {
  private def step(pos: Pos): Pos = {
    if ((pos.ch >= '0' && pos.ch <= '9') || (pos.ch == '.' && pos.inc.ch != '.')) {
      step(pos.inc)
    } else pos
  }

  private def findNumber(pos: Pos): Pos = {
    if (pos.ch >= '0' && pos.ch <= '9') {
      if (pos.inc.ch >= '0' && pos.inc.ch <= '9') {
        if (pos.inc.inc.ch >= '0' && pos.inc.inc.ch <= '9') {
          if (pos.inc.inc.inc.ch == '.') {
            findNumber(pos.inc.inc.inc)
          } else if (pos.inc.inc.inc.ch >= '0' && pos.inc.inc.inc.ch <= '9') {
            step(pos)
          }
          else {
            pos.inc.inc
          }
        } else if (pos.inc.inc.ch == '.') {
          findNumber(pos.inc.inc)
        } else pos.inc
      } else if (pos.inc.ch == '.') {
          findNumber(pos.inc)
      } else pos
    } else if (pos.ch == '.') {
        if ((pos.inc.ch >= '0' && pos.inc.ch <= '9') && (pos.inc.inc.ch >= '0' && pos.inc.inc.ch <= '9') &&
          (pos.inc.inc.inc.ch >= '0' && pos.inc.inc.inc.ch <= '9')) {
          if (pos.inc.inc.inc.inc.ch >= '0' && pos.inc.inc.inc.inc.ch <= '9') {
            step(pos)
          } else findNumber(pos.inc.inc.inc)
        } else step(pos)
    } else pos
  }

  override def scan(start: Pos, list: List[String]) = {
    if (start.ch >= '0' && start.ch <= '9') {
      val follow = findNumber(start)
      if (follow.ch >= '0' && follow.ch <= '9') {
        (NUMBER, follow.inc, list)
      } else (ERROR, follow, (start + "syntax error") :: list)//super.scan(start, list) // syntax error
    } else {
      super.scan(start, list)
    }
  }
}

var t = new Token(
  new Pos("qwerty_qwerty  \"qwerty\\nqwerty\\t\\\"qwerty\" \n 1  10 100 1.000  10000  1.00  10000.0 " + 
    "1q \"jbj\\jfbfjb\"  "),
  new Scanner with Whitespaces with Ident with StringLit with Number,
  Nil
)

while (t.tag != END_OF_PROGRAM) {
  if (t.tag != ERROR) {
    println(t.tag.toString + " " + t.start + "-" + t.follow + ": " + t.image)
  }
  t = t.next
}

println(t.errList.reverse)