package scala.tools.nsc.ast.parser;

import scala.tools.util.Position;
import scala.collection.mutable.ListBuffer;
import symtab.Flags;
import Tokens._;

abstract class Syntactic: ParserPhase {

  import global._;
  import posAssigner.atPos;

  class Parser(unit: CompilationUnit) {

    val in = new Scanner(unit);

    /** the markup parser
    val xmlp = new MarkupParser(unit, s, this, false);
     */

    /** The current nesting depths of while and do loops.
     */
    var loopNestingDepth = 0;

    /** this is the general parse method
     */
    def parse(): List[Tree] = {
      val ts = compilationUnit();
      accept(EOF);
      ts
    }

/////// ERROR HANDLING //////////////////////////////////////////////////////

    private def skip(): unit = {
      //System.out.println("<skipping> " + in.token2string(in.token));//DEBUG
      var nparens = 0;
      var nbraces = 0;
      while (true) {
	in.token match {
          case EOF =>
            return;
          case SEMI =>
            if (nparens == 0 && nbraces == 0) return;
          case RPAREN =>
            nparens = nparens - 1;
          case RBRACE =>
            if (nbraces == 0) return;
            nbraces = nbraces - 1;
          case LPAREN =>
            nparens = nparens + 1;
          case LBRACE =>
            nbraces = nbraces + 1;
          case _ =>
	}
	in.nextToken();
      }
    }

    def syntaxError(msg: String, skipIt: boolean): unit =
      syntaxError(in.pos, msg, skipIt);

    def syntaxError(pos: int, msg: String, skipIt: boolean): unit = {
      if (pos != in.errpos) {
	unit.error(pos, msg);
	in.errpos = pos;
      }
      if (skipIt) skip();
    }

    def accept(token: int): int = {
      val pos = in.pos;
      if (in.token != token)
	syntaxError(
	  if (Position.line(in.pos) > Position.line(in.lastpos)) in.lastpos
            else in.pos,
	  in.token2string(token) + " expected but " +
            in.token2string(in.token) + " found.", true);
      if (in.token == token) in.nextToken();
      pos
    }

    def errorTypeTree = GeneralTypeTree().setType(ErrorType).setPos(in.pos);
    def errorTermTree = Literal(null).setPos(in.pos);
    def errorPatternTree = Ident(nme.WILDCARD).setPos(in.pos);

/////// TOKEN CLASSES //////////////////////////////////////////////////////

    def isModifier: boolean = in.token match {
      case ABSTRACT | FINAL | SEALED | PRIVATE | PROTECTED | OVERRIDE => true
      case _ => false
    }

    def isLocalModifier: boolean = in.token match {
      case ABSTRACT | FINAL | SEALED => true
      case _ => false
    }

    def isDefIntro: boolean = in.token match {
      case VAL | VAR | DEF | TYPE | OBJECT |
           CASEOBJECT | CLASS | CASECLASS | TRAIT => true
      case _ => false
    }

    def isDclIntro: boolean = in.token match {
      case VAL | VAR | DEF | TYPE => true
      case _ => false
    }

    def isExprIntro: boolean = in.token match {
      case CHARLIT | INTLIT | LONGLIT | FLOATLIT | DOUBLELIT |
	   STRINGLIT | SYMBOLLIT | TRUE | FALSE | NULL | IDENTIFIER |
	   THIS | SUPER | IF | FOR | NEW | USCORE | TRY | WHILE |
	   DO | RETURN | THROW | LPAREN | LBRACE => true
      case _ => false
    }

/////// COMMENT AND ATTRIBUTE COLLECTION //////////////////////////////////////

    /** Join the comment associated with a definition
    */
    def joinComment(def trees: List[Tree]): List[Tree] = {
      val buf = in.docBuffer;
      if (buf != null) {
	in.docBuffer = null;
	trees map (t => DocDef(buf.toString(), t) setPos t.pos)
      } else trees
    }

/////// TREE CONSTRUCTION ////////////////////////////////////////////////////

    def fresh(): Name = unit.fresh.newName("x");

    /** Create a tree representing a packaging
    */
    def makePackaging(pkg: Tree, stats: List[Tree]): Tree =
      atPos(in.pos) {
	pkg match {
	  case Ident(name) =>
	    PackageDef(name, stats)
	  case Select(qual, name) =>
	    makePackaging(qual, List(PackageDef(name, stats)))
	}
      }

    /** Create tree representing binary operation expression or pattern.
    */
    def makeBinop(isExpr: boolean, left: Tree, op: Name, right: Tree): Tree = {
      if (isExpr) {
	if (isLeftAssoc(op)) {
	  Apply(Select(left, op.encode), List(right))
	} else {
	  val x: Name = fresh();
	  Block(
	    List(ValDef(0, x, EmptyTree, left)),
	    Apply(Select(right, op.encode), List(Ident(x))))
	}
      } else {
	Apply(Ident(op.encode.toTypeName), List(left, right))
      }
    }
    def makeAlternative(ts: List[Tree]): Tree = {
      def alternatives(t: Tree): List[Tree] = t match {
	case Alternative(ts) => ts
	case _ => List(t)
      }
      Alternative(for (val t <- ts; val a <- alternatives(t)) yield a)
    }

    def makeSequence(ts: List[Tree]): Tree = {
      def elements(t: Tree): List[Tree] = t match {
	case Sequence(ts) => ts
	case _ => List(t)
      }
      Sequence(for (val t <- ts; val e <- elements(t)) yield e)
    }

    def scalaDot(name: Name): Tree =
      Select(Ident(nme.scala), name);
    def scalaRuntimeDot(name: Name): Tree =
      Select(scalaDot(nme.runtime), name);
    def ScalaRunTimeDot(name: Name): Tree =
      Select(scalaRuntimeDot(nme.ScalaRunTime), name);
    def scalaBooleanDot(name: Name): Tree =
      Select(scalaDot(nme.Boolean), name);
    def scalaAnyRefConstr(): Tree =
      Apply(scalaDot(nme.AnyRef.toTypeName), List());
    def scalaObjectConstr(): Tree =
      Apply(scalaDot(nme.ScalaObject.toTypeName), List());
    def caseClassConstr(): Tree =
      Apply(scalaDot(nme.CaseClass.toTypeName), List());

    def makeWhile(lname: Name, cond: Tree, body: Tree): Tree = {
      val continu = Apply(Ident(lname), List());
      val rhs = If(cond, Block(List(body), continu), Literal(()));
      LabelDef(lname, Nil, rhs)
    }

    def makeDoWhile(lname: Name, body: Tree, cond: Tree): Tree = {
      val continu = Apply(Ident(lname), List());
      val rhs = Block(List(body), If(cond, continu, Literal(())));
      LabelDef(lname, Nil, rhs)
    }

    def makeBlock(stats: List[Tree]): Tree = {
      if (stats.isEmpty) Literal(())
      else if (!stats.last.isTerm) Block(stats, Literal(()));
      else if (stats.length == 1) stats(0)
      else Block(stats.init, stats.last)
    }

    /** Convert tree to formal parameter list
    */
    def convertToParams(t: Tree): List[ValDef] = t match {
      case Function(params, EmptyTree) =>
	params
      case Ident(_) | Typed(Ident(_), _) =>
	List(convertToParam(t));
      case Literal(x) if x == () => //todo: check with Literal(())
	Nil
      case _ =>
	syntaxError(t.pos, "malformed formal parameter list", false);
	Nil
    }

    /** Convert tree to formal parameter
    */
    def convertToParam(tree: Tree): ValDef =
      atPos(tree.pos) {
	tree match {
	  case Ident(name) =>
	    ValDef(Flags.PARAM, name, EmptyTree, EmptyTree)
	  case Typed(Ident(name), tpe) =>
	    ValDef(Flags.PARAM, name, tpe, EmptyTree)
	  case _ =>
	    syntaxError(tree.pos, "not a legal formal parameter", false);
	    ValDef(Flags.PARAM, nme.ERROR, errorTypeTree, EmptyTree)
	}
      }

    /** Convert (qual)ident to type identifier
     */
    def convertToTypeId(tree: Tree): Tree = tree match {
      case Ident(name) =>
	Ident(name.toTypeName).setPos(tree.pos)
      case Select(qual, name) =>
	Select(qual, name.toTypeName).setPos(tree.pos)
      case _ =>
        System.out.println(tree);//debug
	syntaxError(tree.pos, "identifier expected", false);
	errorTypeTree
    }

    /** Complete unapplied constructor with `()' arguments
     */
    def applyConstr(t: Tree): Tree = t match {
      case Apply(_, _) => t
      case _ => Apply(t, List()) setPos t.pos
    }

    /** make closure from tree */
    def makeClosure(tree: Tree): Tree = {
      val pname = fresh();
      def insertParam(tree: Tree): Tree = tree match {
	case Ident(name) =>
	  Select(Ident(pname), name)
	case Select(qual, name) =>
	  Select(insertParam(qual), name)
	case Apply(fn, args) =>
	  Apply(insertParam(fn), args)
	case TypeApply(fn, args) =>
	  TypeApply(insertParam(fn), args)
	case _ =>
	  syntaxError(tree.pos, "cannot convert to closure", false);
	  errorTermTree
      }
      Function(
	List(ValDef(Flags.PARAM, pname, EmptyTree, EmptyTree)),
	insertParam(tree))
    }

/////// OPERAND/OPERATOR STACK /////////////////////////////////////////////////

    case class OpInfo(operand: Tree, operator: Name, pos: int);
    var opstack: List[OpInfo] = Nil;

    def precedence(operator: Name): int =
      if (operator eq nme.ERROR) -1
      else {
	val firstCh = operator(0);
	if (((firstCh >= 'A') && (firstCh <= 'Z')) ||
	    ((firstCh >= 'a') && (firstCh <= 'z')))
	  1
	else
	  firstCh match {
	    case '|'             => 2
	    case '^'             => 3
	    case '&'             => 4
	    case '<' | '>'       => 5
	    case '=' | '!'       => 6
	    case ':'             => 7
	    case '+' | '-'       => 8;
	    case '*' | '/' | '%' => 9;
	    case _               => 10;
	  }
      }

    def isLeftAssoc(operator: Name): boolean =
      operator.length > 0 && operator(operator.length - 1) != ':';

    def reduceStack(isExpr: boolean, base: List[OpInfo], top0: Tree, prec: int, leftAssoc: boolean): Tree = {
      var top = top0;
      if (opstack != base &&
	  precedence(opstack.head.operator) == prec &&
	  isLeftAssoc(opstack.head.operator) != leftAssoc) {
	syntaxError(
	  opstack.head.pos,
	  "left- and right-associative operators with same precedence may not be mixed",
	  false);
      }
      while (opstack != base &&
	     (prec < precedence(opstack.head.operator) ||
	      (leftAssoc && prec == precedence(opstack.head.operator)))) {
	top = atPos(opstack.head.pos) {
	  makeBinop(isExpr, opstack.head.operand, opstack.head.operator, top)
	}
	opstack = opstack.tail;
      }
      top
    }

/////// IDENTIFIERS AND LITERALS ////////////////////////////////////////////////////////////

    final val MINUS: Name = "-";
    final val PLUS : Name = "+";
    final val BANG : Name = "!";
    final val TILDE: Name = "~";
    final val STAR : Name = "*";
    final val BAR  : Name = "|";
    final val OPT  : Name = "?";
    final val LT   : Name = "<";

    def ident(): Name =
      if (in.token == IDENTIFIER) {
	val name = in.name.encode;
	in.nextToken();
	name
      } else {
	accept(IDENTIFIER);
	nme.ERROR
      }

    /** StableRef  ::= StableId
     *              |  [Ident `.'] this
     *  SimpleType ::=  StableRef [`.' type]
     */
    def stableRef(thisOK: boolean, typeOK: boolean): Tree = {
      var t: Tree = null;
      if (in.token == THIS) {
	t = atPos(in.skipToken()) { This(nme.EMPTY.toTypeName) }
	if (!thisOK || in.token == DOT)
	  t = atPos(accept(DOT)) { selectors(t, typeOK) }
      } else if (in.token == SUPER) {
	t = atPos(in.skipToken()) {
	  Super(nme.EMPTY.toTypeName, mixinQualifierOpt())
	}
	t = atPos(accept(DOT)) { Select(t, ident()) }
	if (in.token == DOT)
	  t = atPos(in.skipToken()) { selectors(t, typeOK) }
      } else {
	val i = atPos(in.pos) { Ident(ident()) }
	t = i;
	if (in.token == DOT) {
	  val pos = in.skipToken();
	  if (in.token == THIS) {
	    in.nextToken();
	    t = atPos(i.pos) { This(i.name.toTypeName) }
	    if (!thisOK || in.token == DOT)
	      t = atPos(accept(DOT)) { selectors(t, typeOK) }
	  } else if (in.token == SUPER) {
	    in.nextToken();
	    t = atPos(i.pos) { Super(i.name.toTypeName, mixinQualifierOpt()) }
	    t = atPos(accept(DOT)) { Select(t, ident())}
	    if (in.token == DOT)
	      t = atPos(in.skipToken()) { selectors(t, typeOK) }
	  } else {
	    t = atPos(pos) { selectors(t, typeOK) }
	  }
	}
      }
      t
    }

    def selectors(t: Tree, typeOK: boolean): Tree =
      if (typeOK && in.token == TYPE) {
	in.nextToken();
	SingletonTypeTree(t)
      } else {
	val t1 = Select(t, ident());
	if (in.token == DOT) atPos(in.skipToken()) { selectors(t1, typeOK) }
	else t1
      }

    /** MixinQualifier ::= `[' Id `]'
    */
    def mixinQualifierOpt(): Name =
      if (in.token == LBRACKET) {
	in.nextToken();
	val name = ident().toTypeName;
	accept(RBRACKET);
	name
      } else {
	nme.EMPTY.toTypeName
      }

    /** StableId ::= Id
    *            |  StableRef `.' Id
    *            |  [Id '.'] super [MixinQualifier] ` `.' Id
    */
    def stableId(): Tree =
      stableRef(false, false);

    /** QualId ::= Id {`.' Id}
    */
    def qualId(): Tree = {
      val id = atPos(in.pos) { Ident(ident()) }
      if (in.token == DOT) atPos(in.skipToken()) { selectors(id, false) }
      else id
    }

    /** SimpleExpr    ::= literal
    *                  | symbol [ArgumentExprs]
    *                  | null
    */
    def literal(isPattern: boolean, isNegated: boolean): Tree = {
      def litToTree() = atPos(in.pos) {
	Literal(
	  in.token match {
	    case CHARLIT =>
	      in.intVal.asInstanceOf[char]
	    case INTLIT =>
	      in.intVal(isNegated).asInstanceOf[int]
	    case LONGLIT =>
	      in.intVal(isNegated)
	    case FLOATLIT =>
	      in.floatVal(isNegated).asInstanceOf[float]
	    case DOUBLELIT =>
	      in.floatVal(isNegated)
	    case STRINGLIT | SYMBOLLIT =>
	      in.name.toString()
	    case TRUE =>
	      true
	    case FALSE =>
	      false
	    case NULL =>
	      null
	    case _ =>
	      syntaxError("illegal literal", true);
	      null
	  })
      }

      val isSymLit = in.token == SYMBOLLIT;
      val t = litToTree();
      val pos = in.skipToken();
      if (isSymLit) {
        atPos(pos) {
	  var symid = scalaDot(nme.Symbol);
	  if (isPattern) { symid = convertToTypeId(symid) }
	  Apply(symid, List(t))
        }
      } else {
	t
      }
    }

//////// TYPES ///////////////////////////////////////////////////////////////

    /** TypedOpt ::= [`:' Type]
    */
    def typedOpt(): Tree =
      if (in.token == COLON) { in.nextToken(); typ() }
      else EmptyTree;

    /** SimpleTypedOpt ::= [`:' SimpleType]
    */
    def simpleTypedOpt(): Tree =
      if (in.token == COLON) { in.nextToken(); simpleType() }
      else EmptyTree;

    /** Types ::= Type {`,' Type}
    */
    def types(): List[Tree] = {
      val ts = new ListBuffer[Tree] + typ();
      while (in.token == COMMA) {
	in.nextToken();
	ts + typ();
      }
      ts.toList
    }

    /** Type ::= Type1 `=>' Type
    *         | `(' [Types] `)' `=>' Type
    *         | Type1
    */
    def typ(): Tree = {
      val t =
	if (in.token == LPAREN) {
	  in.nextToken();
	  if (in.token == RPAREN) {
	    in.nextToken();
	    atPos(accept(ARROW)) { FunctionTypeTree(List(), typ()) }
	  } else {
	    val t0 = typ();
	    if (in.token == COMMA) {
	      in.nextToken();
	      val ts = new ListBuffer[Tree] + t0 ++ types();
	      accept(RPAREN);
	      atPos (accept(ARROW)) { FunctionTypeTree(ts.toList, typ()) }
	    } else {
	      accept(RPAREN); t0
	    }
	  }
	} else {
	  type1()
	}
      if (in.token == ARROW) atPos(in.skipToken()) {
	FunctionTypeTree(List(t), typ()) }
      else t
    }

    /** Type1 ::= SimpleType {with SimpleType} [Refinement]
     */
    def type1(): Tree = {
      val pos = in.pos;
      var t = simpleType();
      if (in.token == WITH) {
	val ts = new ListBuffer[Tree] + t;
	while (in.token == WITH) {
	  in.nextToken(); ts + simpleType()
	}
	t = atPos(pos) { IntersectionTypeTree(ts.toList) }
      }
      if (in.token == LBRACE)
	t = atPos(pos) { RefinementTypeTree(t, refinement()) }
      t
    }

    /** SimpleType ::= SimpleType TypeArgs
     *              | SimpleType `#' Id
     *              | StableId
     *              | StableRef `.' type
     *              | `(' Type `)'
     */
    def simpleType(): Tree = {
      val pos = in.pos;
      var t: Tree =
	if (in.token == LPAREN) {
	  in.nextToken();
	  val t = typ();
	  accept(RPAREN);
	  t
	} else {
          val r = stableRef(false, true);
          r match {
            case SingletonTypeTree(_) => r
            case _ => convertToTypeId(r);
          }
	}
      while (true) {
	if (in.token == HASH)
	  t = atPos(in.skipToken()) {
	    SelectFromTypeTree(t, ident().toTypeName)
	  }
	else if (in.token == LBRACKET)
	  t = atPos(pos) { AppliedTypeTree(t, typeArgs()) }
	else
	  return t
      }
      null; //dummy
    }

    /** TypeArgs ::= `[' Types `]'
     */
    def typeArgs(): List[Tree] = {
      accept(LBRACKET);
      val ts = types();
      accept(RBRACKET);
      ts
    }

//////// EXPRESSIONS ////////////////////////////////////////////////////////

    /** EqualsExpr ::= `=' Expr
     */
    def equalsExpr(): Tree = {
      accept(EQUALS);
      expr()
    }

    /** Exprs ::= Expr {`,' Expr} [ `:' `_' `*' ]
     */
    def exprs(): List[Tree] = {
      val ts = new ListBuffer[Tree] + expr(true, false);
      while (in.token == COMMA) {
	in.nextToken(); ts + expr(true, false)
      }
      ts.toList
    }

    /** Expr       ::= Bindings `=>' Expr
     *               | Expr1
     *  ResultExpr ::= Bindings `=>' Block
     *               | Expr1
     *  Expr1      ::= (' Expr `)' Expr [[`;'] else Expr]
     *               | try `{' block `}' [catch Expr] [finally Expr]
     *               | while `(' Expr `)' Expr
     *               | do Expr [`;'] while `(' Expr `)'
     *               | for `(' Enumerators `)' (do | yield) Expr
     *               | throw Expr
     *               | return [Expr]
     *               | [SimpleExpr `.'] Id `=' Expr
     *               | SimpleExpr ArgumentExprs `=' Expr
     *               | `.' SimpleExpr
     *               | PostfixExpr [`:' Type1]
     *  Bindings   ::= Id [`:' Type1]
     *               | `(' [Binding {`,' Binding}] `)'
     *  Binding    ::= Id [`:' Type]
     */

    def expr(): Tree =
      expr(false, false);

    def expr(isArgument: boolean, isInBlock: boolean): Tree = {
      if (in.token == IF) {
	val pos = in.skipToken();
	accept(LPAREN);
	val cond = expr();
	accept(RPAREN);
	val thenp = expr();
	val elsep =
	  if (in.token == ELSE) { in.nextToken(); expr() }
	  else EmptyTree;
	atPos(pos) { If(cond, thenp, elsep) }
      } else if (in.token == TRY) {
	atPos(in.skipToken()) {
	  accept(LBRACE);
	  val body = block();
	  accept(RBRACE);
	  val catcher =
	    if (in.token == CATCH) { in.nextToken(); expr() }
	    else EmptyTree;
	  val finalizer =
	    if (in.token == FINALLY) { in.nextToken(); expr() }
	    else EmptyTree;
	  Try(body, catcher, finalizer)
	}
      } else if (in.token == WHILE) {
	val lname: Name = "label$" + loopNestingDepth;
	loopNestingDepth = loopNestingDepth + 1;
	val pos = in.skipToken();
	accept(LPAREN);
	val cond = expr();
	accept(RPAREN);
	val body = expr();
	loopNestingDepth = loopNestingDepth - 1;
	atPos(pos) { makeWhile(lname, cond, body) }
      } else if (in.token == DO) {
	val lname: Name = "label$" + loopNestingDepth;
	loopNestingDepth = loopNestingDepth + 1;
	val pos = in.skipToken();
	val body = expr();
	if (in.token == SEMI) in.nextToken();
	accept(WHILE);
	accept(LPAREN);
	val cond = expr();
	accept(RPAREN);
	loopNestingDepth = loopNestingDepth - 1;
	atPos(pos) { makeDoWhile(lname, body, cond) }
      } else if (in.token == FOR) {
	atPos(in.skipToken()) {
	  accept(LPAREN);
	  val enums = enumerators();
	  accept(RPAREN);
	  if (in.token == YIELD) {
	    in.nextToken(); For(enums, expr(), true)
	  } else For(enums, expr(), false)
	}
      } else if (in.token == RETURN) {
	atPos(in.skipToken()) {
	  Return(if (isExprIntro) expr() else Literal(()))
	}
      } else if (in.token == THROW) {
	atPos(in.skipToken()) {
	  Throw(expr())
	}
      } else if (in.token == DOT) {
	atPos(in.skipToken()) {
	  if (in.token == IDENTIFIER) makeClosure(simpleExpr())
	  else { syntaxError("identifier expected", true); errorTermTree }
	}
      } else {
	var t = postfixExpr();
	if (in.token == EQUALS) {
	  t match {
	    case Ident(_) | Select(_, _) | Apply(_, _) =>
	      t = atPos(in.skipToken()) { Assign(t, expr()) }
	    case _ =>
	  }
	} else if (in.token == COLON) {
	  val pos = in.skipToken();
	  if (isArgument && in.token == USCORE) {
	    val pos1 = in.skipToken();
	    if (in.token == IDENTIFIER && in.name == nme.STAR) {
	      in.nextToken();
	      t = atPos(pos) {
		Typed(t, atPos(pos1) { Ident(nme.WILDCARD_STAR.toTypeName) })
	      }
	    } else {
	      syntaxError(in.pos, "`*' expected", true);
	    }
	  } else {
	    t = atPos(pos) { Typed(t, type1()) }
	  }
	}
	if (in.token == ARROW) {
	  t = atPos(in.skipToken()) {
	    Function(convertToParams(t), if (isInBlock) block() else expr())
	  }
	}
	t
      }
    }

    /** PostfixExpr   ::= [`.'] InfixExpr [Id]
     *  InfixExpr     ::= PrefixExpr
     *                  | InfixExpr Id InfixExpr
     */
    def postfixExpr(): Tree = {
      val base = opstack;
      var top = prefixExpr();
      while (in.token == IDENTIFIER) {
	top = reduceStack(
	  true, base, top, precedence(in.name), isLeftAssoc(in.name));
	opstack = OpInfo(top, in.name, in.pos) :: opstack;
	ident();
	if (isExprIntro) {
	  top = prefixExpr();
	} else {
	  val topinfo = opstack.head;
	  opstack = opstack.tail;
	  return Select(
	    reduceStack(true, base, topinfo.operand, 0, true),
	    topinfo.operator.encode).setPos(topinfo.pos);
	}
      }
      reduceStack(true, base, top, 0, true)
    }

    /** PrefixExpr   ::= [`-' | `+' | `~' | `!'] SimpleExpr
    */
    def prefixExpr(): Tree =
      if (in.token == IDENTIFIER && in.name == MINUS) {
	val name = ident();
	in.token match {
	  case INTLIT | LONGLIT | FLOATLIT | DOUBLELIT => literal(false, true)
	  case _ => atPos(in.pos) { Select(simpleExpr(), name) }
	}
      } else if (in.token == IDENTIFIER && (in.name == PLUS || in.name == TILDE || in.name == BANG)) {
	val pos = in.pos;
	val name = ident();
	atPos(pos) { Select(simpleExpr(), name) }
      } else {
	simpleExpr()
      }

    /* SimpleExpr    ::= literal
     *                | xLiteral
     *                | StableRef
     *                | `(' [Expr] `)'
     *                | BlockExpr
     *                | new Template
     *                | SimpleExpr `.' Id
     *                | SimpleExpr TypeArgs
     *                | SimpleExpr ArgumentExprs
     */
    def simpleExpr(): Tree = {
      var t: Tree = _;
      in.token match {
	case CHARLIT | INTLIT | LONGLIT | FLOATLIT | DOUBLELIT | STRINGLIT |
	     SYMBOLLIT | TRUE | FALSE | NULL =>
	  t = literal(false, false);
	case IDENTIFIER | THIS | SUPER =>
	  t = /*if (s.xStartsXML) xmlp.xLiteral else*/ stableRef(true, false);
	case LPAREN =>
	  val pos = in.skipToken();
	  if (in.token == RPAREN) {
	    in.nextToken();
	    t = Literal(()).setPos(pos);
	  } else {
	    t = expr();
	    if (in.token == COMMA) {
	      val commapos = in.skipToken();
	      val ts = new ListBuffer[Tree] + t ++ exprs();
	      accept(RPAREN);
	      if (in.token == ARROW) {
		t = atPos(pos) {
		  Function(ts.toList map convertToParam, EmptyTree)
		}
	      } else {
		syntaxError(commapos, "`)' expected", false);
	      }
	    } else {
	      accept(RPAREN);
	    }
	  }
	case LBRACE =>
	  t = blockExpr()
	case NEW =>
	  t = atPos(in.skipToken()) {
	    val templ = template();
	    New(if (templ.parents.length == 1 && templ.body.isEmpty) templ.parents.head
	        else templ)
          }
	case _ =>
	  syntaxError("illegal start of simple expression", true);
	  t = errorTermTree
      }
      while (true) {
	in.token match {
	  case DOT =>
	    t = atPos(in.skipToken()) { Select(t, ident()) }
	  case LBRACKET =>
	    t match {
	      case Ident(_) | Select(_, _) =>
		t = atPos(in.pos) { TypeApply(t, typeArgs()) }
	      case _ =>
		return t;
	    }
	  case LPAREN | LBRACE =>
	    t = atPos(in.pos) { Apply(t, argumentExprs()) }
	  case _ =>
	    return t
	}
      }
      null;//dummy
    }

    /** ArgumentExprs ::= `(' [Exprs] `)'
      *                 | BlockExpr
     */
    def argumentExprs(): List[Tree] = {
      if (in.token == LBRACE) {
	List(blockExpr())
      } else {
	accept(LPAREN);
	val ts = if (in.token == RPAREN) List() else exprs();
	accept(RPAREN);
	ts
      }
    }

    /** BlockExpr ::= `{' CaseClause {CaseClause} `}'
     *              | `{' Block `}'
     */
    def blockExpr(): Tree = {
      val res =
	atPos(accept(LBRACE)) {
	  if (in.token == CASE) {
	    var stats: List[CaseDef] = List();
	    do {
	      stats = caseClause() :: stats;
	    } while (in.token == CASE);
	    Visitor(stats.reverse)
	  } else {
	    block()
	  }
	}
      accept(RBRACE);
      res
    }

    /** Block ::= BlockStatSeq
    */
    def block(): Tree = makeBlock(blockStatSeq(new ListBuffer[Tree]));

    /** caseClause : =>= case Pattern [if PostfixExpr] `=>' Block
     */
    def caseClause(): CaseDef =
      atPos(accept(CASE)) {
	val pat = pattern();
	val guard =
	  if (in.token == IF) { in.nextToken(); postfixExpr() }
	  else EmptyTree;
	CaseDef(pat, guard, atPos(accept(ARROW))(block()))
      }

    /** Enumerators ::= Generator {`;' Enumerator}
     *  Enumerator  ::= Generator
     *                | Expr
     */
    def enumerators(): List[Tree] = {
      val enums = new ListBuffer[Tree] + generator();
      while (in.token == SEMI) {
	in.nextToken();
	enums + (if (in.token == VAL) generator() else expr())
      }
      enums.toList
    }

    /** Generator ::= val Pattern1 `<-' Expr
     */
    def generator(): Tree =
      atPos(accept(VAL)) {
	PatDef(0, pattern1(false), { accept(LARROW); expr() })
      }

//////// PATTERNS ////////////////////////////////////////////////////////////

    /**   Patterns ::= SeqPattern { `,' SeqPattern }
     */
    def patterns(): List[Tree] = {
      val ts = new ListBuffer[Tree];
      ts + pattern(true);
      while (in.token == COMMA) {
	in.nextToken(); ts + pattern(true);
      }
      ts.toList
    }

    /**   Pattern  ::=  Pattern1 { `|' Pattern1 }
     *    SeqPattern ::= SeqPattern1 { `|' SeqPattern1 }
     */
    def pattern(seqOK: boolean): Tree = {
      val pos = in.pos;
      val t = pattern1(seqOK);
      if (in.token == IDENTIFIER && in.name == BAR) {
	val ts = new ListBuffer[Tree] + t;
	while (in.token == IDENTIFIER && in.name == BAR) {
          in.nextToken(); ts + pattern1(seqOK);
	}
	atPos(pos) { makeAlternative(ts.toList) }
      } else t
    }

    def pattern(): Tree = pattern(false);

    /**   Pattern1    ::= varid `:' Type1
     *                 |  `_' `:' Type1
     *                 |  Pattern2
     *    SeqPattern1 ::= varid `:' Type1
     *                 |  `_' `:' Type1
     *                 |  [SeqPattern2]
     */
    def pattern1(seqOK: boolean): Tree =
      if (seqOK && !isExprIntro) {
	atPos(in.pos) { Sequence(List()) }
      } else {
	val p = pattern2(seqOK);
	if (in.token == COLON && treeInfo.isVarPattern(p))
	  atPos(in.skipToken()) { Typed(p, type1()) }
	else p
      }

    /*   Pattern2    ::=  varid [ @ Pattern3 ]
     *                |   Pattern3
     *   SeqPattern2 ::=  varid [ @ SeqPattern3 ]
     *                |   SeqPattern3
     */
    def pattern2(seqOK: boolean): Tree = {
      val p = pattern3(seqOK);
      if (in.token == AT) {
	p match {
          case Ident(name) =>
	    if (name == nme.WILDCARD) {
	      in.nextToken(); pattern3(seqOK)
	    } else if (treeInfo.isVariableName(name)) {
	      atPos(in.skipToken()) { Bind(name, pattern3(seqOK)) }
	    } else {
	      p
	    }
          case _ =>
	    p
	}
      } else p
    }

    /*   Pattern3    ::= SimplePattern
     *                |  SimplePattern {Id SimplePattern}
     *   SeqPattern3 ::= SeqSimplePattern [ '*' | '?' | '+' ]
     *                |  SeqSimplePattern {Id SeqSimplePattern}
     */
    def pattern3(seqOK: boolean): Tree = {
      val base = opstack;
      var top = simplePattern(seqOK);
      if (seqOK && in.token == IDENTIFIER) {
	if (in.name == STAR) {    /*         p*  becomes  z@( |(p,z))       */
	  return atPos(in.skipToken()) {
            val zname = fresh();
            Bind(
	      zname,
	      makeAlternative(List(
		Sequence(List()), makeSequence(List(top, Ident(zname))))))
	  }
	} else if (in.name == PLUS) {    /*    p+   becomes   z@(p,(z| ))    */
          return atPos(in.skipToken()) {
	    val zname = fresh();
            Bind(
	      zname,
	      makeSequence(List(
		top, makeAlternative(List(Ident(zname), Sequence(List()))))))
	  }
	} else if (in.name == OPT) { /*    p?   becomes   (p| )            */
	  return atPos(in.skipToken()) {
	    makeAlternative(List(top, Sequence(List())))
	  }
	}
      }
      while (in.token == IDENTIFIER && in.name != BAR) {
	top = reduceStack(
          false, base, top, precedence(in.name), isLeftAssoc(in.name));
	opstack = OpInfo(top, in.name, in.pos) :: opstack;
	ident();
	top = simplePattern(seqOK)
      }
      reduceStack(false, base, top, 0, true)
    }

    /** SimplePattern    ::= varid
     *                    |  `_'
     *                    |  literal
     *                    |  `<' xLiteralPattern
     *                    |  StableId [ `(' Patterns `)' ]
     *                    |  `(' [Pattern] `)'
     *  SimpleSeqPattern ::= varid
     *                    |  `_'
     *                    |  literal
     *                    |  `<' xLiteralPattern
     *                    |  StableId [ `(' Patterns `)' ]
     *                    |  `(' Patterns `)'
     */
    def simplePattern(seqOK: boolean): Tree = in.token match {
      case IDENTIFIER | THIS =>
        var t = stableId();
	in.token match {
	  case INTLIT | LONGLIT | FLOATLIT | DOUBLELIT =>
	    t match {
	      case Ident(name) if name == nme.MINUS =>
		return literal(true, true);
	      case _ =>
	    }
	  case _ =>
	}
        if (in.token == LPAREN) {
	  atPos(in.skipToken()) {
	    val ps = if (in.token == RPAREN) List() else patterns();
	    accept(RPAREN);
	    Apply(convertToTypeId(t), ps)
	  }
        } else t
      case USCORE =>
	atPos(in.skipToken()) { Ident(nme.WILDCARD) }
      case CHARLIT | INTLIT | LONGLIT | FLOATLIT | DOUBLELIT | STRINGLIT | SYMBOLLIT | TRUE | FALSE | NULL =>
	literal(true, false)
      case LPAREN =>
	val pos = in.skipToken();
	val p =
	  if (seqOK) atPos(pos) { makeSequence(patterns()) }
	  else if (in.token != RPAREN) pattern(false);
	  else Literal(()).setPos(pos);
	accept(RPAREN);
	p
      case _ =>
	syntaxError("illegal start of simple pattern", true);
	errorPatternTree
    }

////////// MODIFIERS ////////////////////////////////////////////////////////////

    /** Modifiers ::= {Modifier}
     *  Modifier  ::= final
     *             | private
     *             | protected
     *             | override
     *             | abstract
     */
    def modifiers(): int = {
      def loop(mods: int): int = in.token match {
	case ABSTRACT =>
          loop(addMod(mods, Flags.ABSTRACT))
	case FINAL =>
          loop(addMod(mods, Flags.FINAL))
	case SEALED =>
          loop(addMod(mods, Flags.SEALED))
	case PRIVATE =>
          loop(addMod(mods, Flags.PRIVATE))
	case PROTECTED =>
          loop(addMod(mods, Flags.PROTECTED))
	case OVERRIDE =>
          loop(addMod(mods, Flags.OVERRIDE))
	case _ =>
          mods
      }
      loop(0);
    }

    /** LocalClassModifiers ::= {LocalClassModifier}
     *  LocalClassModifier  ::= final
     *                       | private
     */
    def localClassModifiers(): int = {
      def loop(mods: int): int = in.token match {
	case ABSTRACT =>
          loop(addMod(mods, Flags.ABSTRACT))
	case FINAL =>
          loop(addMod(mods, Flags.FINAL))
	case SEALED =>
          loop(addMod(mods, Flags.SEALED))
	case _ =>
          mods
      }
      loop(0)
    }

    private def addMod(mods: int, mod: int): int = {
      if ((mods & mod) != 0)
	syntaxError(in.pos, "repeated modifier", false);
      in.nextToken();
      mods | mod;
    }

//////// PARAMETERS //////////////////////////////////////////////////////////

    /** ParamClauses ::= {ParamClause}
     */
    def paramClauses(): List[List[ValDef]] = {
      val vds = new ListBuffer[List[ValDef]];
      while (in.token == LPAREN) vds + paramClause(false);
      vds.toList
    }

    /** ParamClauseOpt ::= [ParamClause]
     */
    def paramClauseOpt(ofClass: boolean): List[List[ValDef]] =
      if (in.token == LPAREN) List(paramClause(ofClass))
      else List();

    /** ParamClause ::= `(' [Param {`,' Param}] `)'
     *  ClassParamClause ::= `(' [ClassParam {`,' ClassParam}] `)'
     */
    def paramClause(ofClass: boolean): List[ValDef] = {
      accept(LPAREN);
      val params = new ListBuffer[ValDef];
      if (in.token != RPAREN) {
        params + param(ofClass);
        while (in.token == COMMA) {
          in.nextToken(); params + param(ofClass)
        }
      }
      accept(RPAREN);
      params.toList
    }

    /** Param ::= Id `:' ParamType
     *  ClassParam ::= [[modifiers] val] Param
     */
    def param(ofClass: boolean): ValDef = {
      atPos(in.pos) {
        var mods = if (ofClass) modifiers() | Flags.PARAM else Flags.PARAM;
        if (in.token == VAL) {
          in.nextToken(); mods = mods | Flags.PARAMACCESSOR;
        } else if (mods != Flags.PARAM) {
          accept(VAL);
        }
        val name = ident();
        accept(COLON);
        ValDef(mods, name, paramType(), EmptyTree)
      }
    }

    /** ParamType ::= Type | `=>' Type | Type `*'
     */
    def paramType(): Tree =
      if (in.token == ARROW)
        atPos(in.skipToken()) { FunctionTypeTree(List(), typ()) }
      else {
        val t = typ();
        if (in.token == IDENTIFIER && in.name == STAR) {
          in.nextToken();
          atPos(t.pos) {
            AppliedTypeTree(
              scalaDot(nme.REPEATED_PARAM_CLASS_NAME.toTypeName), List(t))
          }
        } else t
      }

    /** TypeParamClauseOpt ::= [`[' TypeParam {`,' TypeParam} `]']
     *  FunTypeParamClauseOpt ::= [`[' FunTypeParam {`,' FunTypeParam} `]']
     */
    def typeParamClauseOpt(ofClass: boolean): List[AbsTypeDef] = {
      val params = new ListBuffer[AbsTypeDef];
      if (in.token == LBRACKET) {
        in.nextToken();
        params + typeParam(ofClass);
        while (in.token == COMMA) {
          in.nextToken();
          params + typeParam(ofClass);
        }
        accept(RBRACKET);
      }
      params.toList
    }

    /** TypeParam    ::= [`+' | `-'] FunTypeParam
     *  FunTypeParam ::= Id TypeBounds
     */
    def typeParam(ofClass: boolean): AbsTypeDef = {
      var mods = Flags.PARAM;
      if (ofClass && in.token == IDENTIFIER) {
        if (in.name == PLUS) {
          in.nextToken();
          mods = mods | Flags.COVARIANT;
        } else if (in.name == MINUS) {
          in.nextToken();
          mods = mods | Flags.CONTRAVARIANT;
        }
      }
      atPos(in.pos) { typeBounds(mods, ident()) }
    }

    /** TypeBounds ::= [`>:' Type] [`<:' Type] [`<%' Type]
     */
    def typeBounds(mods: int, name: Name): AbsTypeDef = {
      def bound(tok: int, default: Name): Tree =
        if (in.token == tok) { in.nextToken(); typ() }
        else scalaDot(default.toTypeName);
      AbsTypeDef(mods, name.toTypeName,
                 bound(SUPERTYPE, nme.All),
                 bound(SUBTYPE, nme.Any),
                 bound(VIEWBOUND, nme.Any))
    }

//////// DEFS ////////////////////////////////////////////////////////////////

    /** Import  ::= import ImportExpr {`,' ImportExpr}
     */
    def importClause(): List[Tree] = {
      accept(IMPORT);
      val ts = new ListBuffer[Tree] + importExpr();
      while (in.token == COMMA) {
        in.nextToken(); ts + importExpr();
      }
      ts.toList
    }

    /**  ImportRef ::= StableId `.' (Id | `_' | ImportSelectors)
     */
    def importExpr(): Tree =
      atPos(in.pos) {
        var t: Tree = null;
        var pos = 0;
        if (in.token == THIS) {
          t = atPos(in.pos) { This(nme.EMPTY.toTypeName) }
          t = atPos(accept(DOT)) { Select(t, ident()) }
          pos = accept(DOT);
        } else {
          val i = atPos(in.pos) { Ident(ident()) }
          pos = accept(DOT);
          if (in.token == THIS) {
            in.nextToken();
            t = atPos(i.pos) { This(i.name.toTypeName) }
            t = atPos(accept(DOT)) { Select(t, ident()) }
            pos = accept(DOT);
          } else {
            t = i;
          }
        }
        def loop: Tree =
          if (in.token == USCORE) {
            in.nextToken();
            Import(t, List(nme.WILDCARD))
          } else if (in.token == LBRACE) {
            Import(t, importSelectors())
          } else {
            val name = ident();
            if (in.token == DOT) {
              t = atPos(pos) { Select(t, name) }
              pos = accept(DOT);
              loop
            } else {
              Import(t, List(name, name));
            }
          }
        loop
      }

    /** ImportSelectors ::= `{' {ImportSelector `,'} (ImportSelector | `_') `}'
     */
    def importSelectors(): List[Name] = {
      val names = new ListBuffer[Name];
      accept(LBRACE);
      var isLast = importSelector(names);
      while (!isLast && in.token == COMMA) {
        in.nextToken();
        isLast = importSelector(names);
      }
      accept(RBRACE);
      names.toList
    }

    /** ImportSelector ::= Id [`=>' Id | `=>' `_']
     */
    def importSelector(names: ListBuffer[Name]): boolean =
      if (in.token == USCORE) {
        in.nextToken(); names + nme.WILDCARD; true
      } else {
        val name = ident();
        names + name;
        if (in.token == ARROW) {
          in.nextToken();
          if (in.token == USCORE) {
            in.nextToken(); names + nme.WILDCARD;
          } else {
            names + ident()
          }
        } else {
          names + name
        }
        false
      }

    /** Def    ::= val PatDef
     *           | var VarDef
     *           | def FunDef
     *           | type TypeDef
     *           | TmplDef
     *  Dcl    ::= val ValDcl
     *           | var ValDcl
     *           | def FunDcl
     *           | type TypeDcl
     */
    def defOrDcl(mods: int): List[Tree] = {
      in.token match {
        case VAL =>
	  patDefOrDcl(mods);
        case VAR =>
          varDefOrDcl(mods);
        case DEF =>
          funDefOrDcl(mods);
        case TYPE =>
          in.nextToken();
          List(typeDefOrDcl(mods))
        case _ =>
          tmplDef(mods)
      }
    }

    /** PatDef ::= Pattern2 {`,' Pattern2} [`:' Type] `=' Expr
     *  ValDcl ::= Id {`,' Id} `:' Type
     */
    def patDefOrDcl(mods: int): List[Tree] = {
      var newmods = mods;
      var lhs = new ListBuffer[Tree];
      do {
	in.nextToken();
	lhs + pattern2(false)
      } while (in.token == COMMA);
      val tp = typedOpt();
      val rhs =
	if (tp == EmptyTree || in.token == EQUALS) equalsExpr()
	else {
          newmods = newmods | Flags.DEFERRED;
          EmptyTree
        }
      for (val p <- lhs.toList) yield {
	atPos(p.pos) {
	  p match {
	    case Ident(name) =>
	      ValDef(mods, name, tp.duplicate, rhs.duplicate)
	    case _ =>
	      if (rhs == EmptyTree) {
		syntaxError(p.pos, "cannot defer pattern definition", false);
		errorPatternTree
	      } else {
		PatDef(
		  mods,
		  if (tp == EmptyTree) p else Typed(p, tp),
		  rhs.duplicate)
	      }
	  }
	}
      }
    }

    /** VarDef ::= Id {`,' Id} [`:' Type] `=' Expr
     *           | Id {`,' Id} `:' Type `=' `_'
     *  VarDcl ::= Id {`,' Id} `:' Type
     */
    def varDefOrDcl(mods: int): List[Tree] = {
      var newmods = mods | Flags.MUTABLE;
      val lhs = new ListBuffer[Pair[Int, Name]];
      do {
	lhs + Pair(in.skipToken(), ident())
      } while (in.token == COMMA);
      val tp = typedOpt();
      val rhs = if (tp == EmptyTree || in.token == EQUALS) {
	accept(EQUALS);
	if (tp != EmptyTree && in.token == USCORE) {
	  in.nextToken();
	  EmptyTree
	} else
	  expr();
      } else {
	newmods = newmods | Flags.DEFERRED;
	EmptyTree
      }
      lhs.toList map { case Pair(pos, name) =>
	ValDef(newmods, name, tp.duplicate, rhs.duplicate) setPos pos }
    }

    /** FunDef ::= FunSig {`,' FunSig} `:' Type `=' Expr
     *           | this ParamClause `=' ConstrExpr
     *  FunDcl ::= FunSig {`,' FunSig} `:' Type
     *  FunSig ::= id [FunTypeParamClause] ParamClauses
     */
    def funDefOrDcl(mods: int): List[Tree] = {
      in.nextToken();
      if (in.token == THIS)
        List(
          atPos(in.skipToken()) {
            val vparams = List(paramClause(false));
            accept(EQUALS);
      	    DefDef(
              mods, nme.CONSTRUCTOR, List(), vparams, EmptyTree, constrExpr())
          })
      else {
	var newmods = mods;
	val lhs = new ListBuffer[Tuple4[Int, Name, List[AbsTypeDef], List[List[ValDef]]]]
	  + Tuple4(
            in.pos, ident(), typeParamClauseOpt(false), paramClauses());
        while (in.token == COMMA)
	  lhs + Tuple4(
            in.skipToken(), ident(), typeParamClauseOpt(false), paramClauses());
	val restype = typedOpt();
	val rhs =
          if (restype == EmptyTree || in.token == EQUALS) equalsExpr();
          else {
	    newmods = newmods | Flags.DEFERRED;
	    EmptyTree
	  }
	for (val Tuple4(pos, name, tparams, vparams) <- lhs.toList) yield
          DefDef(newmods, name, tparams, vparams,
                 restype.duplicate, rhs.duplicate) setPos pos
      }
    }

    /** ConstrExpr      ::=  SelfInvocation
     *                    |  `{' SelfInvocation {`;' BlockStat} `}'
     *  SelfInvocation  ::= this ArgumentExpr
     */
    def constrExpr(): Tree =
      if (in.token == LBRACE) {
        atPos(in.skipToken()) {
          val statlist = new ListBuffer[Tree];
	  statlist + selfInvocation();
          val stats =
            if (in.token == SEMI) { in.nextToken(); blockStatSeq(statlist) }
            else statlist.toList;
          accept(RBRACE);
          makeBlock(stats)
        }
      } else selfInvocation();

    /** SelfInvocation  ::= this ArgumentExprs
     */
    def selfInvocation(): Tree =
      atPos(accept(THIS)) { Apply(Ident(nme.CONSTRUCTOR), argumentExprs()) }

    /** TypeDef ::= Id `=' Type
     *  TypeDcl ::= Id TypeBounds
     */
    def typeDefOrDcl(mods: int): Tree =
      atPos(in.pos) {
        val name = ident().toTypeName;
        in.token match {
          case LBRACKET =>
            val tparams = typeParamClauseOpt(true);
            accept(EQUALS);
            AliasTypeDef(mods, name, tparams, typ())
          case EQUALS =>
            in.nextToken();
            AliasTypeDef(mods, name, List(), typ())
          case SUPERTYPE | SUBTYPE | VIEWBOUND | SEMI | COMMA | RBRACE =>
            typeBounds(mods | Flags.DEFERRED, name)
          case _ =>
            syntaxError("`=', `>:', or `<:' expected", true);
            EmptyTree
        }
      }

      /**  TmplDef ::= ([case] class | trait) ClassDef
       *            | [case] object ObjectDef
       */
      def tmplDef(mods: int): List[Tree] = in.token match {
        case TRAIT =>
          classDef(mods | Flags.TRAIT | Flags.ABSTRACT);
        case CLASS =>
          classDef(mods);
        case CASECLASS =>
          classDef(mods | Flags.CASE);
        case OBJECT =>
          objectDef(mods);
        case CASEOBJECT =>
          objectDef(mods | Flags.CASE);
        case _ =>
          syntaxError("illegal start of definition", true);
	List()
      }

    /** ClassDef ::= ClassSig {`,' ClassSig} [`:' SimpleType] ClassTemplate
     *  ClassSig ::= Id [TypeParamClause] [ClassParamClause]
     */
    def classDef(mods: int): List[Tree] = {
      val lhs = new ListBuffer[Tuple4[Int, Name, List[AbsTypeDef], List[List[ValDef]]]];
      do {
        lhs + Tuple4(in.skipToken(),
	             ident().toTypeName,
		     typeParamClauseOpt(true),
		     paramClauseOpt(true))
      } while (in.token == COMMA);
      val thistpe = simpleTypedOpt();
      val template = classTemplate((mods & Flags.CASE) != 0);

      for (val Tuple4(pos, name, tparams, vparams) <- lhs.toList) yield
	ClassDef(mods, name, tparams, vparams, thistpe.duplicate,
                 template.duplicate.asInstanceOf[Template]) setPos pos
    }

    /** ObjectDef       ::= Id { , Id } [`:' SimpleType] ClassTemplate
     */
    def objectDef(mods: int): List[Tree] = {
      val lhs = new ListBuffer[Pair[Int, Name]];
      do {
	lhs + Pair(in.skipToken(), ident());
      } while (in.token == COMMA);
      val thistpe = simpleTypedOpt();
      val template = classTemplate((mods & Flags.CASE)!= 0);
      for (val Pair(pos, name) <- lhs.toList) yield
	ModuleDef(mods, name, thistpe.duplicate,
      		  template.duplicate.asInstanceOf[Template]) setPos pos
    }

    /** ClassTemplate ::= [`extends' Constr] {`with' Constr} [TemplateBody]
     */
    def classTemplate(isCaseClass:boolean): Template = {
      atPos(in.pos) {
	val parents = new ListBuffer[Tree];
	if (in.token == EXTENDS) {
          in.nextToken();
          parents + constr()
	} else {
          parents + scalaAnyRefConstr()
	}
	parents + scalaObjectConstr();
	if (isCaseClass) parents + caseClassConstr();
	if (in.token == WITH) {
	  in.nextToken();
	  template(parents)
	} else if (in.token == LBRACE) {
	  Template(parents.toList, templateBody())
	} else {
	  if (!(in.token == SEMI || in.token == COMMA || in.token == RBRACE))
            syntaxError("`extends' or `{' expected", true);
          Template(parents.toList, List())
	}
      }
    }

////////// TEMPLATES ////////////////////////////////////////////////////////////
    /** Template  ::= Constr {`with' Constr} [TemplateBody]
     */
    def template(): Template = template(new ListBuffer[Tree]);

    def template(parents: ListBuffer[Tree]): Template = {
      parents + constr();
      while (in.token == WITH) {
	in.nextToken();
	parents + constr()
      }
      val stats = if (in.token == LBRACE) templateBody() else List();
      Template(parents.toList, stats)
    }

    /** Constr ::= StableId [TypeArgs] [`(' [Exprs] `)']
     */
    def constr(): Tree = {
      var t: Tree = convertToTypeId(stableId());
      if (in.token == LBRACKET)
        t = AppliedTypeTree(t, typeArgs()) setPos in.pos;
      if (in.token == LPAREN)
        t = Apply(t, argumentExprs()) setPos in.pos;
      applyConstr(t)
    }

    /** TemplateBody ::= `{' [TemplateStat {`;' TemplateStat}] `}'
     */
    def templateBody(): List[Tree] = {
      accept(LBRACE);
      var body = templateStatSeq();
      if (body.length == 0) body = List(EmptyTree);
      accept(RBRACE);
      body
    }

    /** Refinement ::= `{' [RefineStat {`;' RefineStat}] `}'
     */
    def refinement(): List[Tree] = {
      accept(LBRACE);
      val body = refineStatSeq();
      accept(RBRACE);
      body
    }

/////// STATSEQS //////////////////////////////////////////////////////////////

    /** Packaging ::= package QualId `{' TopStatSeq `}'
     */
    def packaging(): Tree = {
      atPos(accept(PACKAGE)) {
        val pkg = qualId();
        accept(LBRACE);
        val stats = topStatSeq();
        accept(RBRACE);
        makePackaging(pkg, stats)
      }
    }

    /** TopStatSeq ::= [TopStat {`;' TopStat}]
     *  TopStat ::= AttributeClauses Modifiers ClsDef
     *            | Packaging
     *            | Import
     *            |
     */
    def topStatSeq(): List[Tree] = {
      val stats = new ListBuffer[Tree];
      while (in.token != RBRACE && in.token != EOF) {
        if (in.token == PACKAGE) {
          stats + packaging()
        } else if (in.token == IMPORT) {
          stats ++ importClause()
        } else if (in.token == CLASS ||
                   in.token == CASECLASS ||
                   in.token == TRAIT ||
                   in.token == OBJECT ||
                   in.token == CASEOBJECT ||
                   in.token == LBRACKET ||
                   isModifier) {
          stats ++
            joinAttributes(attributeClauses(), joinComment(tmplDef(modifiers())))
        } else if (in.token != SEMI) {
          syntaxError("illegal start of class or object definition", true);
        }
        if (in.token != RBRACE && in.token != EOF) accept(SEMI);
      }
      stats.toList
    }

    /** TemplateStatSeq  ::= TemplateStat {`;' TemplateStat}
     *  TemplateStat     ::= Import
     *                     | AttributeClauses Modifiers Def
     *                     | AttributeClauses Modifiers Dcl
     *                     | Expr
     *                     |
     */
    def templateStatSeq(): List[Tree] = {
      val stats = new ListBuffer[Tree];
      while (in.token != RBRACE && in.token != EOF) {
        if (in.token == IMPORT) {
          stats ++ importClause()
        } else if (isExprIntro) {
          stats + expr()
        } else if (isDefIntro || isModifier || in.token == LBRACKET) {
          stats ++
            joinAttributes(attributeClauses(), joinComment(defOrDcl(modifiers())))
        } else if (in.token != SEMI) {
          syntaxError("illegal start of definition", true);
        }
        if (in.token != RBRACE) accept(SEMI);
      }
      stats.toList
    }

    /** AttributeClauses   ::= {AttributeClause}
     *  AttributeClause    ::= `[' Attribute {`,' Attribute} `]'
     *  Attribute          ::= Constr
     */
    def attributeClauses(): List[Tree] = {
      var attrs = new ListBuffer[Tree];
      while (in.token == LBRACKET) {
        in.nextToken();
        attrs + constr();
        while (in.token == COMMA) {
          in.nextToken();
          attrs + constr()
        }
        accept(RBRACKET);
      }
      attrs.toList
    }

    def joinAttributes(attrs: List[Tree], defs: List[Tree]): List[Tree] =
      defs map (defn =>
        (attrs :\ defn) ((attr, tree) => Attributed(attr, tree) setPos attr.pos));

    /** RefineStatSeq    ::= RefineStat {`;' RefineStat}
     *  RefineStat       ::= Dcl
     *                     | type TypeDef
     *                     |
     */
    def refineStatSeq(): List[Tree] = {
      val stats = new ListBuffer[Tree];
      while (in.token != RBRACE && in.token != EOF) {
        if (isDclIntro) {
          stats ++ joinComment(defOrDcl(0))
        } else if (in.token != SEMI) {
          syntaxError("illegal start of declaration", true);
        }
        if (in.token != RBRACE) accept(SEMI);
      }
      stats.toList
    }

    /** BlockStatSeq ::= { BlockStat `;' } [Expr]
     *  BlockStat    ::= Import
     *                 | Def
     *                 | LocalModifiers TmplDef
     *                 | Expr
     *                 |
     */
    def blockStatSeq(stats: ListBuffer[Tree]): List[Tree] = {
      while ((in.token != RBRACE) && (in.token != EOF) && (in.token != CASE)) {
        if (in.token == IMPORT) {
          stats ++ importClause();
          accept(SEMI);
        } else if (isExprIntro) {
          stats + expr(false, true);
          if (in.token != RBRACE && in.token != CASE) accept(SEMI);
        } else if (isDefIntro) {
          stats ++ defOrDcl(0);
          accept(SEMI);
          if (in.token == RBRACE || in.token == CASE) {
            stats + Literal(()).setPos(in.pos)
          }
        } else if (isLocalModifier) {
          stats ++ tmplDef(localClassModifiers());
          accept(SEMI);
          if (in.token == RBRACE || in.token == CASE) {
            stats + Literal(()).setPos(in.pos)
          }
        } else if (in.token == SEMI) {
          in.nextToken();
        } else {
          syntaxError("illegal start of statement", true);
        }
      }
      stats.toList
    }

    /** CompilationUnit ::= [ package QualId ( `;' | `{' TopStatSeq `}' ) ] TopStatSeq .
     */
    def compilationUnit(): List[Tree] = {
      if (in.token == PACKAGE) {
        val pos = in.skipToken();
        val pkg = qualId();
        if (in.token == SEMI) {
          in.nextToken();
          List(makePackaging(pkg, topStatSeq()) setPos pos);
        } else {
          val stats = new ListBuffer[Tree];
          accept(LBRACE);
          stats + atPos(pos) { makePackaging(pkg, topStatSeq()) }
          accept(RBRACE);
          stats ++ topStatSeq();
          stats.toList
        }
      } else {
        topStatSeq()
      }
    }
  }
}

//  LocalWords:  SOcos