protected override Expression VisitTry(TryExpression node)
{
// Visit finally/fault block first
BlockInfo block = new BlockInfo {
InFinally = true
};
_blocks.Push(block);
Expression @finally = Visit(node.Finally);
Expression fault = Visit(node.Fault);
block.InFinally = false;
LabelTarget finallyEnd = block.FlowLabel;
if (finallyEnd != null)
{
if (@finally != null)
{
@finally = Expression.Label(finallyEnd, @finally);
}
if (fault != null)
{
fault = Expression.Label(finallyEnd, fault);
}
// Make a new target, which will be emitted after the try
block.FlowLabel = Expression.Label();
}
Expression @try = Visit(node.Body);
IList <CatchBlock> handlers = Visit(node.Handlers, VisitCatchBlock);
_blocks.Pop();
if (@try == node.Body &&
handlers == node.Handlers &&
@finally == node.Finally &&
fault == node.Fault)
{
return(node);
}
if (!block.HasFlow)
{
return(Expression.MakeTry(@try, @finally, fault, handlers));
}
// If there is a control flow in finally, emit outer:
// try {
// // try block body and all catch handling
// } catch (Exception all) {
// saved = all;
// } finally {
// finally_body
// if (saved != null) {
// throw saved;
// }
// }
//
// If we have a fault handler we turn this into the better:
// try {
// // try block body and all catch handling
// } catch (Exception all) {
// saved = all;
// fault_body
// throw saved
// }
if (handlers.Count > 0)
{
@try = Expression.MakeTry(@try, null, null, handlers);
}
var all = Expression.Variable(typeof(Exception), "$exception");
if (@finally != null)
{
handlers = new[] { Expression.Catch(all.Type, Expression.Empty()) };
@finally = Expression.Block(
@finally,
Expression.Condition(
Expression.NotEqual(all, Expression.Constant(null, all.Type)),
Expression.Throw(all),
Expression.Empty()
)
);
}
else
{
handlers = new[] {
Expression.Catch(
all.Type,
Expression.Block(fault, Expression.Throw(all))
)
};
fault = null;
}
// Emit flow control
return(Expression.Block(
new ParameterExpression[] { all },
Expression.MakeTry(@try, @finally, fault, handlers),
Expression.Label(block.FlowLabel),
MakeFlowControlSwitch(block)
));
}
