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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 { self: ICodes =>
import global.{Symbol, NoSymbol};
class ExceptionHandler(val method: IMethod, val label: String, val cls: Symbol) {
private var _startBlock: BasicBlock = _;
var finalizer: Finalizer = _;
/** Needed for the MSIL backend. */
var resultKind: TypeKind = _;
def setStartBlock(b: BasicBlock) = {
_startBlock = b;
b.exceptionHandlerHeader = true
}
def startBlock = _startBlock;
/** The list of blocks that are covered by this exception handler */
var covered: List[BasicBlock] = Nil;
def addCoveredBlock(b: BasicBlock): ExceptionHandler = {
covered = b :: covered;
this
}
/** Is `b' covered by this exception handler? */
def covers(b: BasicBlock): Boolean = covered.contains(b);
/** The body of this exception handler. May contain 'dead' blocks (which will not
* make it into generated code because linearizers may not include them) */
var blocks: List[BasicBlock] = Nil;
def addBlock(b: BasicBlock): Unit = blocks = b :: blocks;
override def toString() = "exh_" + label + "(" + cls.simpleName + ")";
/** A standard copy constructor */
def this(other: ExceptionHandler) = {
this(other.method, other.label, other.cls);
covered = other.covered;
setStartBlock(other.startBlock);
finalizer = other.finalizer;
}
def dup: ExceptionHandler = new ExceptionHandler(this);
}
class Finalizer(method: IMethod, label: String) extends ExceptionHandler(method, label, NoSymbol) {
override def toString() = "finalizer_" + label;
override def dup: Finalizer = new Finalizer(method, 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.");
}
}
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