src/compiler/scala/tools/nsc/backend/icode/ExceptionHandlers.scala


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/* NSC -- new scala compiler
 * Copyright 2005 LAMP/EPFL
 * @author  Martin Odersky
 */

// $Id$

package scala.tools.nsc.backend.icode;

import scala.collection.mutable.HashMap;
import scala.collection.mutable.HashSet;

/**
 * Exception handlers are pieces of code that `handle' exceptions on
 * the covered basic blocks. Since Scala's exception handling uses
 * pattern matching instead of just class names to identify handlers,
 * all our handlers will catch `Throwable' and rely on proper ordering
 * in the generated code to preserve nesting.
 */
trait ExceptionHandlers: ICodes {
  import global.{Symbol, NoSymbol};

  class ExceptionHandler(val method: IMethod, label: String, val cls: Symbol) {
    private var coveredBlocks: List[BasicBlock] = Nil;
    private var _startBlock: BasicBlock = _;
    var finalizer: Finalizer = _;

    def setStartBlock(b: BasicBlock) = _startBlock = b;
    def startBlock = _startBlock;

    def addBlock(b: BasicBlock): ExceptionHandler = {
      coveredBlocks = b :: coveredBlocks;
      this
    }

    def covered: List[BasicBlock] = coveredBlocks;

    override def toString() = "exh_" + label + "(" + cls.simpleName + ")";
  }

  class Finalizer(method: IMethod, label: String) extends ExceptionHandler(method, label, NoSymbol) {
    override def toString() = "finalizer_" + label;
  }

  object NoFinalizer extends Finalizer(null, "<no finalizer>") {
    override def startBlock: BasicBlock = error("NoFinalizer cannot have a start block.");
    override def setStartBlock(b: BasicBlock): Unit = error("NoFinalizer cannot have a start block.");
  }
}