private MSAst.Expression AddFinally(MSAst.Expression /*!*/ body)
{
if (_finally != null)
{
MSAst.ParameterExpression tryThrows = Ast.Variable(typeof(Exception), "$tryThrows");
MSAst.ParameterExpression locException = Ast.Variable(typeof(Exception), "$localException");
MSAst.Expression @finally = _finally;
// lots is going on here. We need to consider:
// 1. Exceptions propagating out of try/except/finally. Here we need to save the line #
// from the exception block and not save the # from the finally block later.
// 2. Exceptions propagating out of the finally block. Here we need to report the line number
// from the finally block and leave the existing stack traces cleared.
// 3. Returning from the try block: Here we need to run the finally block and not update the
// line numbers.
body = AstUtils.Try( // we use a fault to know when we have an exception and when control leaves normally (via
// either a return or the body completing successfully).
AstUtils.Try(
Parent.AddDebugInfo(AstUtils.Empty(), new SourceSpan(Span.Start, GlobalParent.IndexToLocation(_headerIndex))),
Ast.Assign(tryThrows, AstUtils.Constant(null, typeof(Exception))),
body,
AstUtils.Empty()
).Catch(
locException,
Expression.Block(
Ast.Assign(tryThrows, locException),
Expression.Rethrow()
)
)
).FinallyWithJumps(
// if we had an exception save the line # that was last executing during the try
AstUtils.If(
Expression.NotEqual(tryThrows, Expression.Default(typeof(Exception))),
Parent.GetSaveLineNumberExpression(tryThrows, false)
),
// clear the frames incase thae finally throws, and allow line number
// updates to proceed
UpdateLineUpdated(false),
// run the finally code
@finally,
// if we took an exception in the try block we have saved the line number. Otherwise
// we have no line number saved and will need to continue saving them if
// other exceptions are thrown.
AstUtils.If(
Expression.NotEqual(tryThrows, Expression.Default(typeof(Exception))),
UpdateLineUpdated(true)
)
);
body = Ast.Block(new[] { tryThrows }, body);
}
return(body);
}
public override MSAst.Expression Reduce()
{
// allocated all variables here so they won't be shared w/ other
// locals allocated during the body or except blocks.
MSAst.ParameterExpression lineUpdated = null;
MSAst.ParameterExpression runElse = null;
if (_else != null || (_handlers != null && _handlers.Length > 0))
{
lineUpdated = Ast.Variable(typeof(bool), "$lineUpdated_try");
if (_else != null)
{
runElse = Ast.Variable(typeof(bool), "run_else");
}
}
// don't allocate locals below here...
MSAst.Expression body = _body;
MSAst.Expression @else = _else;
MSAst.Expression @catch, result;
MSAst.ParameterExpression exception;
if (_handlers != null && _handlers.Length > 0)
{
exception = Ast.Variable(typeof(Exception), "$exception");
@catch = TransformHandlers(exception);
}
else
{
exception = null;
@catch = null;
}
// We have else clause, must generate guard around it
if (@else != null)
{
Debug.Assert(@catch != null);
// run_else = true;
// try {
// try_body
// } catch ( ... ) {
// run_else = false;
// catch_body
// }
// if (run_else) {
// else_body
// }
result =
Ast.Block(
Ast.Assign(runElse, AstUtils.Constant(true)),
// save existing line updated, we could choose to do this only for nested exception handlers.
PushLineUpdated(false, lineUpdated),
AstUtils.Try(
Parent.AddDebugInfo(AstUtils.Empty(), new SourceSpan(Span.Start, _header)),
body
).Catch(exception,
Ast.Assign(runElse, AstUtils.Constant(false)),
@catch,
// restore existing line updated after exception handler completes
PopLineUpdated(lineUpdated),
Ast.Assign(exception, Ast.Constant(null, typeof(Exception))),
AstUtils.Default(body.Type)
),
AstUtils.IfThen(runElse,
@else
),
AstUtils.Empty()
);
}
else if (@catch != null) // no "else" clause
// try {
// <try body>
// } catch (Exception e) {
// ... catch handling ...
// }
//
{
result =
AstUtils.Try(
GlobalParent.AddDebugInfo(AstUtils.Empty(), new SourceSpan(Span.Start, _header)),
// save existing line updated
PushLineUpdated(false, lineUpdated),
body
).Catch(exception,
@catch,
// restore existing line updated after exception handler completes
PopLineUpdated(lineUpdated),
Ast.Call(AstMethods.ExceptionHandled, Parent.LocalContext),
Ast.Assign(exception, Ast.Constant(null, typeof(Exception))),
AstUtils.Default(body.Type)
);
}
else
{
result = body;
}
return(Ast.Block(
GetVariables(lineUpdated, runElse),
AddFinally(result)
));
}
private MSAst.Expression AddFinally(MSAst.Expression /*!*/ body, MSAst.ParameterExpression nestedException)
{
if (_finally != null)
{
Debug.Assert(nestedException != null);
MSAst.ParameterExpression nestedFrames = Ast.Variable(typeof(List <DynamicStackFrame>), "$nestedFrames");
MSAst.Expression @finally = _finally;
// lots is going on here. We need to consider:
// 1. Exceptions propagating out of try/except/finally. Here we need to save the line #
// from the exception block and not save the # from the finally block later.
// 2. Exceptions propagating out of the finally block. Here we need to report the line number
// from the finally block and leave the existing stack traces cleared.
// 3. Returning from the try block: Here we need to run the finally block and not update the
// line numbers.
body = AstUtils.Try( // we use a fault to know when we have an exception and when control leaves normally (via
// either a return or the body completing successfully).
AstUtils.Try(
Parent.AddDebugInfo(AstUtils.Empty(), new SourceSpan(Span.Start, _header)),
Ast.Assign(nestedException, AstUtils.Constant(false)),
body
).Fault(
// fault
Ast.Assign(nestedException, AstUtils.Constant(true))
)
).FinallyWithJumps(
// if we had an exception save the line # that was last executing during the try
AstUtils.If(
nestedException,
Parent.GetSaveLineNumberExpression(false)
),
// clear the frames incase thae finally throws, and allow line number
// updates to proceed
UpdateLineUpdated(false),
Ast.Assign(
nestedFrames,
Ast.Call(AstMethods.GetAndClearDynamicStackFrames)
),
// run the finally code
@finally,
// if the finally exits normally restore any previous exception info
Ast.Call(
AstMethods.SetDynamicStackFrames,
nestedFrames
),
// if we took an exception in the try block we have saved the line number. Otherwise
// we have no line number saved and will need to continue saving them if
// other exceptions are thrown.
AstUtils.If(
nestedException,
UpdateLineUpdated(true)
)
);
body = Ast.Block(new[] { nestedFrames }, body);
}
return(body);
}
public override MSAst.Expression Reduce()
{
// allocated all variables here so they won't be shared w/ other
// locals allocated during the body or except blocks.
MSAst.ParameterExpression?lineUpdated = null;
MSAst.ParameterExpression?runElse = null;
MSAst.ParameterExpression?previousExceptionContext = null;
Debug.Assert(Else is null || _handlers.Length > 0);
if (_handlers.Length > 0)
{
lineUpdated = Ast.Variable(typeof(bool), "$lineUpdated_try");
if (Else != null)
{
runElse = Ast.Variable(typeof(bool), "run_else");
}
}
// don't allocate locals below here...
MSAst.Expression body = Body;
MSAst.Expression? @else = Else;
MSAst.Expression? @catch;
MSAst.Expression result;
MSAst.ParameterExpression?exception;
if (_handlers.Length > 0)
{
previousExceptionContext = Ast.Variable(typeof(Exception), "$previousException");
exception = Ast.Variable(typeof(Exception), "$exception");
@catch = TransformHandlers(exception, previousExceptionContext);
}
else if (Finally != null)
{
exception = Ast.Variable(typeof(Exception), "$exception");
@catch = null;
}
else
{
exception = null;
@catch = null;
}
// We have else clause, must generate guard around it
if (@else != null)
{
Debug.Assert(runElse != null);
Debug.Assert(previousExceptionContext != null && exception != null && @catch != null);
// run_else = true;
// try {
// try_body
// } catch ( ... ) {
// run_else = false;
// catch_body
// }
// if (run_else) {
// else_body
// }
result =
Ast.Block(
Ast.Assign(runElse, AstUtils.Constant(true)),
// save existing line updated, we could choose to do this only for nested exception handlers.
PushLineUpdated(false, lineUpdated),
LightExceptions.RewriteExternal(
AstUtils.Try(
Parent.AddDebugInfo(AstUtils.Empty(), new SourceSpan(Span.Start, GlobalParent.IndexToLocation(HeaderIndex))),
Ast.Assign(previousExceptionContext, Ast.Call(AstMethods.SaveCurrentException)),
body,
AstUtils.Constant(null)
).Catch(exception,
Ast.Assign(runElse, AstUtils.Constant(false)),
@catch,
// restore existing line updated after exception handler completes
PopLineUpdated(lineUpdated),
Ast.Assign(exception, Ast.Constant(null, typeof(Exception))),
AstUtils.Constant(null)
)
),
AstUtils.IfThen(runElse,
@else
),
AstUtils.Empty()
);
}
else if (@catch != null) // no "else" clause
// try {
// <try body>
// } catch (Exception e) {
// ... catch handling ...
// }
//
{
Debug.Assert(previousExceptionContext != null && exception != null);
result =
LightExceptions.RewriteExternal(
AstUtils.Try(
GlobalParent.AddDebugInfo(AstUtils.Empty(), new SourceSpan(Span.Start, GlobalParent.IndexToLocation(HeaderIndex))),
// save existing line updated
PushLineUpdated(false, lineUpdated),
Ast.Assign(previousExceptionContext, Ast.Call(AstMethods.SaveCurrentException)),
body,
AstUtils.Constant(null)
).Catch(exception,
@catch,
// restore existing line updated after exception handler completes
PopLineUpdated(lineUpdated),
Ast.Assign(exception, Ast.Constant(null, typeof(Exception))),
AstUtils.Constant(null)
)
);
}
else
{
result = body;
}
return(Ast.Block(
GetVariables(lineUpdated, runElse, previousExceptionContext),
AddFinally(result),
AstUtils.Default(typeof(void))
));
}