| public static If ( IfStatementTest tests, Expression @else ) : Expression | ||
| tests | IfStatementTest | |
| @else | Expression | |
| return | Expression | |
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);
}
internal override MSAst.Expression Transform(MSAst.Expression body)
{
return(GlobalParent.AddDebugInfoAndVoid(
AstUtils.If(
GlobalParent.Convert(typeof(bool), ConversionResultKind.ExplicitCast, _test),
body
),
Span
));
}
private void CreatePushFrameExpression()
{
_pushFrame = Ast.Block(
Ast.Assign(_framePushed, Ast.Constant(true)),
// Get thread
Ast.Assign(
_thread,
AstUtils.SimpleCallHelper(
typeof(RuntimeOps).GetMethod("GetCurrentThread"),
_debugContextExpression
)
),
_debugContext.ThreadFactory.CreatePushFrameExpression(_funcInfo, _debugMarker, _verifiedLocals, _variableInfos, _thread)
);
_conditionalPushFrame = AstUtils.If(
Ast.Equal(_framePushed, Ast.Constant(false)),
_pushFrame
);
}
/// <summary>
/// Transform multiple python except handlers for a try block into a single catch body.
/// </summary>
/// <param name="exception">The variable for the exception in the catch block.</param>
/// <returns>Null if there are no except handlers. Else the statement to go inside the catch handler</returns>
private MSAst.Expression TransformHandlers(MSAst.ParameterExpression exception)
{
Assert.NotEmpty(_handlers);
MSAst.ParameterExpression extracted = Ast.Variable(typeof(object), "$extracted");
var tests = new List <Microsoft.Scripting.Ast.IfStatementTest>(_handlers.Length);
MSAst.ParameterExpression converted = null;
MSAst.Expression catchAll = null;
for (int index = 0; index < _handlers.Length; index++)
{
TryStatementHandler tsh = _handlers[index];
if (tsh.Test != null)
{
Microsoft.Scripting.Ast.IfStatementTest ist;
// translating:
// except Test ...
//
// generate following AST for the Test (common part):
// CheckException(exception, Test)
MSAst.Expression test =
Ast.Call(
AstMethods.CheckException,
Parent.LocalContext,
extracted,
AstUtils.Convert(tsh.Test, typeof(object))
);
if (tsh.Target != null)
{
// translating:
// except Test, Target:
// <body>
// into:
// if ((converted = CheckException(exception, Test)) != null) {
// Target = converted;
// traceback-header
// <body>
// }
if (converted == null)
{
converted = Ast.Variable(typeof(object), "$converted");
}
ist = AstUtils.IfCondition(
Ast.NotEqual(
Ast.Assign(converted, test),
AstUtils.Constant(null)
),
Ast.Block(
tsh.Target.TransformSet(SourceSpan.None, converted, PythonOperationKind.None),
GlobalParent.AddDebugInfo(
GetTracebackHeader(
this,
exception,
tsh.Body
),
new SourceSpan(tsh.Start, tsh.Header)
),
AstUtils.Empty()
)
);
}
else
{
// translating:
// except Test:
// <body>
// into:
// if (CheckException(exception, Test) != null) {
// traceback-header
// <body>
// }
ist = AstUtils.IfCondition(
Ast.NotEqual(
test,
AstUtils.Constant(null)
),
GlobalParent.AddDebugInfo(
GetTracebackHeader(
this,
exception,
tsh.Body
),
new SourceSpan(tsh.Start, tsh.Header)
)
);
}
// Add the test to the if statement test cascade
tests.Add(ist);
}
else
{
Debug.Assert(index == _handlers.Length - 1);
Debug.Assert(catchAll == null);
// translating:
// except:
// <body>
// into:
// {
// traceback-header
// <body>
// }
catchAll = GlobalParent.AddDebugInfo(
GetTracebackHeader(this, exception, tsh.Body),
new SourceSpan(tsh.Start, tsh.Header)
);
}
}
MSAst.Expression body = null;
if (tests.Count > 0)
{
// rethrow the exception if we have no catch-all block
if (catchAll == null)
{
catchAll = Ast.Block(
Parent.GetSaveLineNumberExpression(exception, true),
Ast.Throw(
Ast.Call(
typeof(ExceptionHelpers).GetMethod("UpdateForRethrow"),
exception
)
)
);
}
body = AstUtils.If(
tests.ToArray(),
catchAll
);
}
else
{
Debug.Assert(catchAll != null);
body = catchAll;
}
IList <MSAst.ParameterExpression> args;
if (converted != null)
{
args = new ReadOnlyCollectionBuilder <MSAst.ParameterExpression> {
converted, extracted
};
}
else
{
args = new ReadOnlyCollectionBuilder <MSAst.ParameterExpression> {
extracted
};
}
// Codegen becomes:
// extracted = PythonOps.SetCurrentException(exception)
// < dynamic exception analysis >
return(Ast.Block(
args,
Ast.Assign(
extracted,
Ast.Call(
AstMethods.SetCurrentException,
Parent.LocalContext,
exception
)
),
body,
Ast.Assign(extracted, Ast.Constant(null)),
AstUtils.Empty()
));
}
private MSAst.LambdaExpression CreateOuterLambda(Type lambdaType, MSAst.Expression debuggableBody)
{
List <MSAst.Expression> bodyExpressions = new List <MSAst.Expression>();
List <MSAst.Expression> tryExpressions = new List <MSAst.Expression>();
List <MSAst.Expression> finallyExpressions = new List <MSAst.Expression>();
Type returnType = lambdaType.GetMethod("Invoke").ReturnType;
MSAst.LabelTarget returnLabelTarget = Ast.Label(returnType);
// Init $funcInfo
tryExpressions.Add(
Ast.Assign(
_funcInfo,
Ast.Convert(_functionInfo, typeof(FunctionInfo))
)
);
// Init $traceLocations
// $TODO: only do this if we're in TracePoints mode
tryExpressions.Add(
Ast.Assign(
_traceLocations,
Ast.Call(typeof(RuntimeOps).GetMethod("GetTraceLocations"), _funcInfo)
)
);
// Init sourceFile locals
foreach (var entry in _sourceFilesMap)
{
tryExpressions.Add(
Ast.Assign(
entry.Value,
Ast.Constant(entry.Key, typeof(DebugSourceFile))
)
);
}
if (_noPushFrameOptimization)
{
tryExpressions.Add(_pushFrame);
}
tryExpressions.Add(Ast.Call(
typeof(RuntimeOps).GetMethod("OnFrameEnterTraceEvent"),
_thread
));
var frameExit = AstUtils.If(
Ast.Equal(
_debugMarkerLocationMap.Length > 0 ?
Ast.Property(_sourceFilesMap[_debugMarkerLocationMap[0].SourceFile], "Mode") :
_globalDebugMode,
AstUtils.Constant((int)DebugMode.FullyEnabled)
),
Ast.Call(
typeof(RuntimeOps).GetMethod("OnFrameExitTraceEvent"),
_thread,
_debugMarker,
_retVal != null ? (MSAst.Expression)Ast.Convert(_retVal, typeof(object)) : Ast.Constant(null)
)
);
// normal exit
tryExpressions.Add(
Ast.Block(
_retVal != null ? Ast.Assign(_retVal, debuggableBody) : debuggableBody,
Ast.Assign(_frameExitException, Ast.Constant(true)),
frameExit)
);
tryExpressions.Add(
_retVal != null ? (MSAst.Expression)Ast.Return(returnLabelTarget, _retVal) : Ast.Empty()
);
MSAst.Expression[] popFrame = new MSAst.Expression[] {
AstUtils.If(
// Fire thead-exit event if PopFrame returns true
Ast.AndAlso(
Ast.Equal(Ast.Call(typeof(RuntimeOps).GetMethod("PopFrame"), _thread), Ast.Constant(true)),
Ast.Equal(_globalDebugMode, AstUtils.Constant((int)DebugMode.FullyEnabled))
),
Ast.Call(
typeof(RuntimeOps).GetMethod("OnThreadExitEvent"),
_thread
)
)
};
if (_noPushFrameOptimization)
{
finallyExpressions.AddRange(popFrame);
}
else
{
finallyExpressions.Add(
AstUtils.If(
Ast.Equal(_framePushed, Ast.Constant(true)),
popFrame
)
);
}
MSAst.ParameterExpression caughtException;
// Run the function body
bodyExpressions.Add(Ast.TryCatchFinally(
Ast.TryCatch(
Ast.Block(
ArrayUtils.Append(tryExpressions.ToArray(), Ast.Default(returnType))
),
Ast.Catch(
caughtException = Ast.Variable(typeof(Exception), "$caughtException"),
Ast.Block(
// The expressions below will always throw.
// If the exception needs to be cancelled then OnTraceEvent will throw ForceToGeneratorLoopException.
// If the exception is not being cancelled then we'll just rethrow at the end of the catch block.
AstUtils.If(
Ast.Not(
Ast.TypeIs(
caughtException,
typeof(ForceToGeneratorLoopException)
)
),
AstUtils.If(
Ast.NotEqual(_globalDebugMode, AstUtils.Constant((int)DebugMode.Disabled)),
_noPushFrameOptimization ? Ast.Empty() : _conditionalPushFrame,
Ast.Call(
typeof(RuntimeOps).GetMethod("OnTraceEventUnwind"),
_thread,
_debugMarker,
caughtException
)
),
// exception exit
AstUtils.If(
Ast.Not(_frameExitException),
frameExit
)
),
Ast.Rethrow(),
// Ensuring that the catch block is of the same type as the try block
Ast.Default(returnType)
)
)
),
Ast.Block(finallyExpressions),
Ast.Catch(
typeof(ForceToGeneratorLoopException),
Ast.TryFinally(
// Handle ForceToGeneratorLoopException
Ast.Block(
returnType != typeof(void) ? Ast.Block(
Ast.Assign(
_retValFromGeneratorLoop,
Ast.Call(
typeof(RuntimeOps).GetMethod("GeneratorLoopProc"),
_thread
)
),
AstUtils.If(
Ast.NotEqual(
_retValFromGeneratorLoop,
Ast.Constant(null)
),
Ast.Assign(_retVal, Ast.Convert(_retValFromGeneratorLoop, returnType)),
Ast.Return(
returnLabelTarget,
Ast.Convert(_retValFromGeneratorLoop, returnType)
)
).Else(
Ast.Assign(_retVal, Ast.Default(returnType)),
Ast.Return(
returnLabelTarget,
Ast.Default(returnType)
)
)
) :
Ast.Block(
Ast.Call(
typeof(RuntimeOps).GetMethod("GeneratorLoopProc"),
_thread
),
Ast.Return(returnLabelTarget)
)
,
// Ensuring that the catch block is of the same type as the try block
Ast.Default(returnType)
),
// Make sure that the debugMarker is up-to-date after the generator loop
Ast.Assign(
_debugMarker,
Ast.Call(
typeof(RuntimeOps).GetMethod("GetCurrentSequencePointForLeafGeneratorFrame"),
_thread
)
)
)
)
));
MSAst.Expression body = Ast.Block(bodyExpressions);
if (body.Type == typeof(void) && returnType != typeof(void))
{
body = Ast.Block(body, Ast.Default(returnType));
}
return(Ast.Lambda(
lambdaType,
Ast.Block(
_lambdaVars,
Ast.Label(returnLabelTarget, body)
),
_alias,
_lambdaParams));
}
protected override MSAst.Expression VisitTry(MSAst.TryExpression node)
{
MSAst.Expression b = Visit(node.Body);
ReadOnlyCollection <MSAst.CatchBlock> h = Visit(node.Handlers, VisitCatchBlock);
MSAst.Expression y = Visit(node.Finally);
MSAst.Expression f;
_insideConditionalBlock = true;
try {
f = Visit(node.Fault);
} finally {
_insideConditionalBlock = false;
}
node = Ast.MakeTry(node.Type, b, y, f, h);
List <MSAst.CatchBlock> newHandlers = null;
MSAst.Expression newFinally = null;
// If the TryStatement has any Catch blocks we need to insert the exception
// event as a first statement so that we can be notified of first-chance exceptions.
if (node.Handlers != null && node.Handlers.Count > 0)
{
newHandlers = new List <MSAst.CatchBlock>();
foreach (var catchBlock in node.Handlers)
{
MSAst.ParameterExpression exceptionVar = catchBlock.Variable != null ? catchBlock.Variable : Ast.Parameter(catchBlock.Test, null);
MSAst.Expression debugMarker, thread;
if (_transformToGenerator)
{
debugMarker = Ast.Call(
typeof(RuntimeOps).GetMethod("GetCurrentSequencePointForGeneratorFrame"),
_frame
);
thread = Ast.Call(typeof(RuntimeOps).GetMethod("GetThread"), _frame);
}
else
{
debugMarker = _debugMarker;
thread = _thread;
}
MSAst.Expression exceptionEvent = Ast.Block(
// Rethrow ForceToGeneratorLoopException
AstUtils.If(
Ast.TypeIs(
exceptionVar,
typeof(ForceToGeneratorLoopException)
),
Ast.Throw(exceptionVar)
),
AstUtils.If(
Ast.Equal(_globalDebugMode, AstUtils.Constant((int)DebugMode.FullyEnabled)),
(_pushFrame != null) ? _pushFrame : Ast.Empty(),
Ast.Call(
typeof(RuntimeOps).GetMethod("OnTraceEvent"),
thread,
debugMarker,
exceptionVar
)
)
);
newHandlers.Add(Ast.MakeCatchBlock(
catchBlock.Test,
exceptionVar,
Ast.Block(
exceptionEvent,
catchBlock.Body
),
catchBlock.Filter
));
}
}
if (!_transformToGenerator && node.Finally != null)
{
// Prevent the user finally block from running if the frame is currently remapping to generator
newFinally = AstUtils.If(
Ast.Not(
Ast.Call(
typeof(RuntimeOps).GetMethod("IsCurrentLeafFrameRemappingToGenerator"),
_thread
)
),
node.Finally
);
}
if (newHandlers != null || newFinally != null)
{
node = Ast.MakeTry(
node.Type,
node.Body,
newFinally != null ? newFinally : node.Finally,
node.Fault,
newHandlers != null ? newHandlers : newHandlers
);
}
return(node);
}
private MSA.Expression /*!*/ TransformExceptionHandling(AstGenerator /*!*/ gen, ResultOperation resultOperation)
{
Assert.NotNull(gen);
MSA.Expression exceptionThrownVariable = gen.CurrentScope.DefineHiddenVariable("#exception-thrown", typeof(bool));
MSA.Expression exceptionRethrowVariable = gen.CurrentScope.DefineHiddenVariable("#exception-rethrow", typeof(bool));
MSA.Expression retryingVariable = gen.CurrentScope.DefineHiddenVariable("#retrying", typeof(bool));
MSA.Expression oldExceptionVariable = gen.CurrentScope.DefineHiddenVariable("#old-exception", typeof(Exception));
MSA.ParameterExpression unwinder, exceptionVariable;
MSA.Expression transformedBody;
MSA.Expression transformedEnsure;
MSA.Expression transformedElse;
if (_ensureStatements != null)
{
transformedEnsure = Ast.Block(
// ensure:
Ast.Assign(oldExceptionVariable, Methods.GetCurrentException.OpCall(gen.CurrentScopeVariable)),
gen.TransformStatements(_ensureStatements, ResultOperation.Ignore),
Methods.SetCurrentException.OpCall(gen.CurrentScopeVariable, oldExceptionVariable),
// rethrow:
AstUtils.IfThen(
Ast.AndAlso(
exceptionRethrowVariable,
Ast.NotEqual(oldExceptionVariable, AstUtils.Constant(null))
),
Ast.Throw(oldExceptionVariable)
)
);
}
else
{
// rethrow:
transformedEnsure = AstUtils.IfThen(
Ast.AndAlso(
exceptionRethrowVariable,
Ast.NotEqual(
Ast.Assign(oldExceptionVariable, Methods.GetCurrentException.OpCall(gen.CurrentScopeVariable)),
AstUtils.Constant(null, typeof(Exception)))
),
Ast.Throw(oldExceptionVariable)
);
}
if (_elseStatements != null)
{
transformedElse = gen.TransformStatements(_elseStatements, resultOperation);
}
else
{
transformedElse = AstUtils.Empty();
}
// body should do return, but else-clause is present => we cannot do return from the guarded statements:
// (the value of the last expression in the body cannot be the last executed expression statement => we can ignore it):
transformedBody = gen.TransformStatements(_statements, (_elseStatements != null) ? ResultOperation.Ignore : resultOperation);
MSA.Expression enterRescue = null, leaveRescue = null;
var retryLabel = Ast.Label("retry");
// make rescue clause:
MSA.Expression transformedRescue;
if (_rescueClauses != null)
{
// outer-most EH blocks sets and clears runtime flag RuntimeFlowControl.InTryRescue:
if (gen.CurrentRescue == null)
{
enterRescue = Methods.EnterRescue.OpCall(gen.CurrentScopeVariable);
leaveRescue = Methods.LeaveRescue.OpCall(gen.CurrentScopeVariable);
}
else
{
enterRescue = leaveRescue = AstUtils.Empty();
}
gen.EnterRescueClause(retryingVariable, retryLabel);
var handlers = new IfStatementTest[_rescueClauses.Count];
for (int i = 0; i < handlers.Length; i++)
{
handlers[i] = _rescueClauses[i].Transform(gen, resultOperation);
}
transformedRescue =
AstUtils.Try(
enterRescue,
AstUtils.If(handlers, Ast.Assign(exceptionRethrowVariable, AstUtils.Constant(true)))
).Filter(unwinder = Ast.Parameter(typeof(EvalUnwinder), "#u"),
Ast.Equal(Ast.Field(unwinder, EvalUnwinder.ReasonField), AstUtils.Constant(BlockReturnReason.Retry)),
Ast.Block(
Ast.Assign(retryingVariable, AstUtils.Constant(true)),
Ast.Continue(retryLabel),
AstUtils.Empty()
)
);
gen.LeaveRescueClause();
}
else
{
transformedRescue = Ast.Assign(exceptionRethrowVariable, AstUtils.Constant(true));
}
if (_elseStatements != null)
{
transformedElse = AstUtils.Unless(exceptionThrownVariable, transformedElse);
}
var result = Ast.Block(
Ast.Label(retryLabel),
AstUtils.Try(
Ast.Assign(exceptionThrownVariable, AstUtils.Constant(false)),
Ast.Assign(exceptionRethrowVariable, AstUtils.Constant(false)),
Ast.Assign(retryingVariable, AstUtils.Constant(false)),
// save exception (old_$! is not used unless there is a rescue clause):
(_rescueClauses == null) ? (MSA.Expression)AstUtils.Empty() :
Ast.Assign(oldExceptionVariable, Methods.GetCurrentException.OpCall(gen.CurrentScopeVariable)),
AstUtils.Try(
Ast.Block(transformedBody, AstUtils.Empty())
).Filter(exceptionVariable = Ast.Parameter(typeof(Exception), "#e"),
Methods.CanRescue.OpCall(gen.CurrentScopeVariable, exceptionVariable),
Ast.Assign(exceptionThrownVariable, AstUtils.Constant(true)),
transformedRescue,
AstUtils.Empty()
).FinallyIf((_rescueClauses != null),
// restore previous exception if the current one has been handled:
AstUtils.Unless(exceptionRethrowVariable,
Methods.SetCurrentException.OpCall(gen.CurrentScopeVariable, oldExceptionVariable)
),
leaveRescue
),
// unless (exception_thrown) do <else-statements> end
transformedElse,
AstUtils.Empty()
).FilterIf((_rescueClauses != null || _elseStatements != null),
exceptionVariable = Ast.Parameter(typeof(Exception), "#e"),
Methods.CanRescue.OpCall(gen.CurrentScopeVariable, exceptionVariable),
Ast.Assign(exceptionRethrowVariable, AstUtils.Constant(true)),
AstUtils.Empty()
).FinallyWithJumps(
AstUtils.Unless(retryingVariable, transformedEnsure)
)
);
return(result);
}
private MSAst.Expression AddFinally(MSAst.Expression /*!*/ body, MSAst.ParameterExpression nestedException)
{
if (_finally != null)
{
Debug.Assert(nestedException != null);
MSAst.ParameterExpression nestedFrames = Ast.Variable(typeof(List <DynamicStackFrame>), "$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);
}