| public static Try ( ) : TryStatementBuilder | ||
| Результат | TryStatementBuilder | |
private MSAst.Expression AddModulePublishing(MSAst.Expression body)
{
if (_isModule)
{
PythonCompilerOptions pco = _compilerContext.Options as PythonCompilerOptions;
string moduleName = ModuleName;
if ((pco.Module & ModuleOptions.Initialize) != 0)
{
var tmp = Ast.Variable(typeof(object), "$originalModule");
// TODO: Should be try/fault
body = Ast.Block(
new[] { tmp },
AstUtils.Try(
Ast.Assign(tmp, Ast.Call(AstMethods.PublishModule, LocalContext, Ast.Constant(moduleName))),
body
).Catch(
typeof(Exception),
Ast.Call(AstMethods.RemoveModule, LocalContext, Ast.Constant(moduleName), tmp),
Ast.Rethrow(body.Type)
)
);
}
}
return(body);
}
/// <summary>
/// Takes current result and wraps it into try-filter(MethodUnwinder)-finally block that ensures correct "break" behavior for
/// Ruby method calls with a block given in arguments.
///
/// Sets up a RFC frame similarly to MethodDeclaration.
/// </summary>
public static void RuleControlFlowBuilder(MetaObjectBuilder /*!*/ metaBuilder, CallArguments /*!*/ args)
{
Debug.Assert(args.Signature.HasBlock);
if (metaBuilder.Error)
{
return;
}
// TODO (improvement):
// We don't special case null block here, although we could (we would need a test for that then).
// We could also statically know (via call-site flag) that the current method is not a proc-converter (passed by ref),
// which would make such calls faster.
var rfcVariable = metaBuilder.GetTemporary(typeof(RuntimeFlowControl), "#rfc");
var resultVariable = metaBuilder.GetTemporary(typeof(object), "#result");
MSA.ParameterExpression unwinder;
metaBuilder.Result = Ast.Block(
// initialize frame (RFC):
Ast.Assign(rfcVariable, Methods.CreateRfcForMethod.OpCall(AstUtils.Convert(args.GetBlockExpression(), typeof(Proc)))),
AstUtils.Try(
Ast.Assign(resultVariable, metaBuilder.Result)
).Filter(unwinder = Ast.Parameter(typeof(MethodUnwinder), "#unwinder"),
Ast.Equal(Ast.Field(unwinder, MethodUnwinder.TargetFrameField), rfcVariable),
// return unwinder.ReturnValue;
Ast.Assign(resultVariable, Ast.Field(unwinder, MethodUnwinder.ReturnValueField))
).Finally(
// we need to mark the RFC dead snce the block might escape and break later:
Methods.LeaveMethodFrame.OpCall(rfcVariable)
),
resultVariable
);
}
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 static MSA.Expression /*!*/ MakeUserMethodBody(AstGenerator gen, int lastLine,
MSA.Expression /*!*/ blockParameter, MSA.Expression /*!*/ rfcVariable,
MSA.ParameterExpression /*!*/ methodUnwinder, MSA.Expression /*!*/ bodyStatement, ResultOperation resultOperation,
int profileTickIndex, MSA.ParameterExpression stampVariable, MSA.LabelTarget returnLabel)
{
Assert.NotNull(blockParameter, rfcVariable, bodyStatement, methodUnwinder);
Debug.Assert(!resultOperation.IsIgnore, "return value should not be ignored");
Debug.Assert(returnLabel != null || resultOperation.Variable != null, "return label needed");
MSA.Expression resultExpression = Ast.Field(methodUnwinder, MethodUnwinder.ReturnValueField);
if (resultOperation.Variable != null)
{
resultExpression = Ast.Assign(resultOperation.Variable, resultExpression);
}
else
{
resultExpression = Ast.Return(returnLabel, resultExpression);
}
// TODO: move this to the caller:
MSA.Expression profileStart, profileEnd;
if (stampVariable != null)
{
profileStart = Ast.Assign(stampVariable, Methods.Stopwatch_GetTimestamp.OpCall());
profileEnd = Methods.UpdateProfileTicks.OpCall(Ast.Constant(profileTickIndex), stampVariable);
}
else
{
profileStart = profileEnd = Ast.Empty();
}
return(AstUtils.Try(
// initialize frame (RFC):
profileStart,
Ast.Assign(rfcVariable, Methods.CreateRfcForMethod.OpCall(AstUtils.Convert(blockParameter, typeof(Proc)))),
bodyStatement
).Filter(methodUnwinder, Ast.Equal(Ast.Field(methodUnwinder, MethodUnwinder.TargetFrameField), rfcVariable),
// return unwinder.ReturnValue;
resultExpression
).Finally(
Ast.Assign(Ast.Field(rfcVariable, RuntimeFlowControl.IsActiveMethodField), Ast.Constant(false)),
profileEnd,
gen != null && gen.TraceEnabled ? Methods.TraceMethodReturn.OpCall(
gen.CurrentScopeVariable,
Ast.Convert(Ast.Constant(gen.SourceUnit.Path), typeof(string)),
Ast.Constant(lastLine)
) : Ast.Empty()
));
}
/// <summary>
/// Takes current result and wraps it into try-filter(MethodUnwinder)-finally block that ensures correct "break" behavior for
/// library method calls with block given in bfcVariable (BlockParam).
/// </summary>
public static void RuleControlFlowBuilder(MetaObjectBuilder /*!*/ metaBuilder, CallArguments /*!*/ args)
{
if (metaBuilder.Error)
{
return;
}
var metaBlock = args.GetMetaBlock();
Debug.Assert(metaBlock != null, "RuleControlFlowBuilder should only be used if the signature has a block");
// We construct CF only for non-nil blocks thus we need a test for it:
if (metaBlock.Value == null)
{
metaBuilder.AddRestriction(Ast.Equal(metaBlock.Expression, AstUtils.Constant(null)));
return;
}
// don't need to test the exact type of the Proc since the code is subclass agnostic:
metaBuilder.AddRestriction(Ast.NotEqual(metaBlock.Expression, AstUtils.Constant(null)));
Expression bfcVariable = metaBuilder.BfcVariable;
Debug.Assert(bfcVariable != null);
// Method call with proc can invoke control flow that returns an arbitrary value from the call, so we need to type result to Object.
// Otherwise, the result could only be result of targetExpression unless its return type is void.
Expression resultVariable = metaBuilder.GetTemporary(typeof(object), "#result");
ParameterExpression unwinder;
metaBuilder.Result = Ast.Block(
Ast.Assign(bfcVariable, Methods.CreateBfcForLibraryMethod.OpCall(AstUtils.Convert(args.GetBlockExpression(), typeof(Proc)))),
AstUtils.Try(
Ast.Assign(resultVariable, AstUtils.Convert(metaBuilder.Result, typeof(object)))
).Filter(unwinder = Ast.Parameter(typeof(MethodUnwinder), "#unwinder"),
Methods.IsProcConverterTarget.OpCall(bfcVariable, unwinder),
Ast.Assign(resultVariable, Ast.Field(unwinder, MethodUnwinder.ReturnValueField)),
AstUtils.Default(typeof(object))
).Finally(
Methods.LeaveProcConverter.OpCall(bfcVariable)
),
resultVariable
);
}
/// <summary>
/// WithStatement is translated to the DLR AST equivalent to
/// the following Python code snippet (from with statement spec):
///
/// mgr = (EXPR)
/// exit = mgr.__exit__ # Not calling it yet
/// value = mgr.__enter__()
/// exc = True
/// try:
/// VAR = value # Only if "as VAR" is present
/// BLOCK
/// except:
/// # The exceptional case is handled here
/// exc = False
/// if not exit(*sys.exc_info()):
/// raise
/// # The exception is swallowed if exit() returns true
/// finally:
/// # The normal and non-local-goto cases are handled here
/// if exc:
/// exit(None, None, None)
///
/// </summary>
public override MSAst.Expression Reduce()
{
// Five statements in the result...
ReadOnlyCollectionBuilder <MSAst.Expression> statements = new ReadOnlyCollectionBuilder <MSAst.Expression>(6);
ReadOnlyCollectionBuilder <MSAst.ParameterExpression> variables = new ReadOnlyCollectionBuilder <MSAst.ParameterExpression>(6);
MSAst.ParameterExpression lineUpdated = Ast.Variable(typeof(bool), "$lineUpdated_with");
variables.Add(lineUpdated);
//******************************************************************
// 1. mgr = (EXPR)
//******************************************************************
MSAst.ParameterExpression manager = Ast.Variable(typeof(object), "with_manager");
variables.Add(manager);
statements.Add(
GlobalParent.AddDebugInfo(
Ast.Assign(
manager,
_contextManager
),
new SourceSpan(Start, _header)
)
);
//******************************************************************
// 2. exit = mgr.__exit__ # Not calling it yet
//******************************************************************
MSAst.ParameterExpression exit = Ast.Variable(typeof(object), "with_exit");
variables.Add(exit);
statements.Add(
MakeAssignment(
exit,
GlobalParent.Get(
"__exit__",
manager
)
)
);
//******************************************************************
// 3. value = mgr.__enter__()
//******************************************************************
MSAst.ParameterExpression value = Ast.Variable(typeof(object), "with_value");
variables.Add(value);
statements.Add(
GlobalParent.AddDebugInfoAndVoid(
MakeAssignment(
value,
Parent.Invoke(
new CallSignature(0),
Parent.LocalContext,
GlobalParent.Get(
"__enter__",
manager
)
)
),
new SourceSpan(Start, _header)
)
);
//******************************************************************
// 4. exc = True
//******************************************************************
MSAst.ParameterExpression exc = Ast.Variable(typeof(bool), "with_exc");
variables.Add(exc);
statements.Add(
MakeAssignment(
exc,
AstUtils.Constant(true)
)
);
//******************************************************************
// 5. The final try statement:
//
// try:
// VAR = value # Only if "as VAR" is present
// BLOCK
// except:
// # The exceptional case is handled here
// exc = False
// if not exit(*sys.exc_info()):
// raise
// # The exception is swallowed if exit() returns true
// finally:
// # The normal and non-local-goto cases are handled here
// if exc:
// exit(None, None, None)
//******************************************************************
MSAst.ParameterExpression exception;
MSAst.ParameterExpression nestedFrames = Ast.Variable(typeof(List <DynamicStackFrame>), "$nestedFrames");
variables.Add(nestedFrames);
statements.Add(
// try:
AstUtils.Try(
AstUtils.Try(// try statement body
PushLineUpdated(false, lineUpdated),
_var != null ?
(MSAst.Expression)Ast.Block(
// VAR = value
_var.TransformSet(SourceSpan.None, value, PythonOperationKind.None),
// BLOCK
_body,
AstUtils.Empty()
) :
// BLOCK
(MSAst.Expression)_body // except:, // try statement location
).Catch(exception = Ast.Variable(typeof(Exception), "exception"),
// Python specific exception handling code
TryStatement.GetTracebackHeader(
this,
exception,
GlobalParent.AddDebugInfoAndVoid(
Ast.Block(
// exc = False
MakeAssignment(
exc,
AstUtils.Constant(false)
),
Ast.Assign(
nestedFrames,
Ast.Call(AstMethods.GetAndClearDynamicStackFrames)
),
// if not exit(*sys.exc_info()):
// raise
AstUtils.IfThen(
GlobalParent.Convert(
typeof(bool),
ConversionResultKind.ExplicitCast,
GlobalParent.Operation(
typeof(bool),
PythonOperationKind.IsFalse,
MakeExitCall(exit, exception)
)
),
UpdateLineUpdated(true),
Ast.Call(
AstMethods.SetDynamicStackFrames,
nestedFrames
),
Ast.Throw(
Ast.Call(
AstMethods.MakeRethrowExceptionWorker,
exception
)
)
)
),
_body.Span
)
),
Ast.Call(
AstMethods.SetDynamicStackFrames,
nestedFrames
),
PopLineUpdated(lineUpdated),
Ast.Empty()
)
// finally:
).Finally(
// if exc:
// exit(None, None, None)
AstUtils.IfThen(
exc,
GlobalParent.AddDebugInfoAndVoid(
Ast.Block(
Ast.Dynamic(
GlobalParent.PyContext.Invoke(
new CallSignature(3) // signature doesn't include function
),
typeof(object),
new MSAst.Expression[] {
Parent.LocalContext,
exit,
AstUtils.Constant(null),
AstUtils.Constant(null),
AstUtils.Constant(null)
}
),
Ast.Empty()
),
_contextManager.Span
)
)
)
);
statements.Add(AstUtils.Empty());
return(Ast.Block(variables.ToReadOnlyCollection(), statements.ToReadOnlyCollection()));
}
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)
));
}
/// <summary>
/// Creates the LambdaExpression which implements the body of the function.
///
/// The functions signature is either "object Function(PythonFunction, ...)"
/// where there is one object parameter for each user defined parameter or
/// object Function(PythonFunction, object[]) for functions which take more
/// than PythonCallTargets.MaxArgs arguments.
/// </summary>
private LightLambdaExpression CreateFunctionLambda()
{
bool needsWrapperMethod = _parameters.Length > PythonCallTargets.MaxArgs;
Delegate originalDelegate;
Type delegateType = GetDelegateType(_parameters, needsWrapperMethod, out originalDelegate);
MSAst.ParameterExpression localContext = null;
ReadOnlyCollectionBuilder <MSAst.ParameterExpression> locals = new ReadOnlyCollectionBuilder <MSAst.ParameterExpression>();
if (NeedsLocalContext)
{
localContext = LocalCodeContextVariable;
locals.Add(localContext);
}
MSAst.ParameterExpression[] parameters = CreateParameters(needsWrapperMethod, locals);
List <MSAst.Expression> init = new List <MSAst.Expression>();
foreach (var param in _parameters)
{
IPythonVariableExpression pyVar = GetVariableExpression(param.PythonVariable) as IPythonVariableExpression;
if (pyVar != null)
{
var varInit = pyVar.Create();
if (varInit != null)
{
init.Add(varInit);
}
}
}
// Transform the parameters.
init.Add(Ast.ClearDebugInfo(GlobalParent.Document));
locals.Add(PythonAst._globalContext);
init.Add(Ast.Assign(PythonAst._globalContext, new GetGlobalContextExpression(_parentContext)));
GlobalParent.PrepareScope(locals, init);
// Create variables and references. Since references refer to
// parameters, do this after parameters have been created.
CreateFunctionVariables(locals, init);
// If the __class__ variable is used the a class method then we need to initialize it.
// This must be done before parameter initialization (in case one of the parameters is called __class__).
ClassDefinition parent = FindParentOfType <ClassDefinition>();
PythonVariable pVar;
if (parent != null && TryGetVariable("__class__", out pVar))
{
init.Add(
AssignValue(
GetVariableExpression(pVar),
Ast.Call(AstMethods.LookupName, parent.Parent.LocalContext, Ast.Constant(parent.Name))
)
);
}
// Initialize parameters - unpack tuples.
// Since tuples unpack into locals, this must be done after locals have been created.
InitializeParameters(init, needsWrapperMethod, parameters);
List <MSAst.Expression> statements = new List <MSAst.Expression>();
// add beginning sequence point
var start = GlobalParent.IndexToLocation(StartIndex);
statements.Add(GlobalParent.AddDebugInfo(
AstUtils.Empty(),
new SourceSpan(new SourceLocation(0, start.Line, start.Column), new SourceLocation(0, start.Line, Int32.MaxValue))));
// For generators, we need to do a check before the first statement for Generator.Throw() / Generator.Close().
// The exception traceback needs to come from the generator's method body, and so we must do the check and throw
// from inside the generator.
if (IsGenerator)
{
MSAst.Expression s1 = YieldExpression.CreateCheckThrowExpression(SourceSpan.None);
statements.Add(s1);
}
MSAst.ParameterExpression extracted = null;
if (!IsGenerator && _canSetSysExcInfo)
{
// need to allocate the exception here so we don't share w/ exceptions made & freed
// during the body.
extracted = Ast.Parameter(typeof(Exception), "$ex");
locals.Add(extracted);
}
if (_body.CanThrow && !(_body is SuiteStatement) && _body.StartIndex != -1)
{
statements.Add(UpdateLineNumber(GlobalParent.IndexToLocation(_body.StartIndex).Line));
}
statements.Add(Body);
MSAst.Expression body = Ast.Block(statements);
// If this function can modify sys.exc_info() (_canSetSysExcInfo), then it must restore the result on finish.
//
// Wrap in
// $temp = PythonOps.SaveCurrentException()
// <body>
// PythonOps.RestoreCurrentException($temp)
// Skip this if we're a generator. For generators, the try finally is handled by the PythonGenerator class
// before it's invoked. This is because the restoration must occur at every place the function returns from
// a yield point. That's different than the finally semantics in a generator.
if (extracted != null)
{
MSAst.Expression s = AstUtils.Try(
Ast.Assign(
extracted,
Ast.Call(AstMethods.SaveCurrentException)
),
body
).Finally(
Ast.Call(
AstMethods.RestoreCurrentException, extracted
)
);
body = s;
}
if (_body.CanThrow && GlobalParent.PyContext.PythonOptions.Frames)
{
body = AddFrame(LocalContext, Ast.Property(_functionParam, typeof(PythonFunction).GetProperty("__code__")), body);
locals.Add(FunctionStackVariable);
}
body = AddProfiling(body);
body = WrapScopeStatements(body, _body.CanThrow);
body = Ast.Block(body, AstUtils.Empty());
body = AddReturnTarget(body);
MSAst.Expression bodyStmt = body;
if (localContext != null)
{
var createLocal = CreateLocalContext(_parentContext);
init.Add(
Ast.Assign(
localContext,
createLocal
)
);
}
init.Add(bodyStmt);
bodyStmt = Ast.Block(init);
// wrap a scope if needed
bodyStmt = Ast.Block(locals.ToReadOnlyCollection(), bodyStmt);
return(AstUtils.LightLambda(
typeof(object),
delegateType,
AddDefaultReturn(bodyStmt, typeof(object)),
Name + "$" + Interlocked.Increment(ref _lambdaId),
parameters
));
}
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);
}
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))
));
}
