/// <summary>
/// Rewrite an async method into a state machine type.
/// </summary>
internal static BoundStatement Rewrite(
BoundStatement body,
MethodSymbol method,
int methodOrdinal,
VariableSlotAllocator slotAllocatorOpt,
TypeCompilationState compilationState,
DiagnosticBag diagnostics,
out AsyncStateMachine stateMachineType)
{
if (!method.IsAsync)
{
stateMachineType = null;
return(body);
}
CSharpCompilation compilation = method.DeclaringCompilation;
bool isAsyncEnumerableOrEnumerator = method.IsIAsyncEnumerableReturningAsync(compilation) ||
method.IsIAsyncEnumeratorReturningAsync(compilation);
if (isAsyncEnumerableOrEnumerator && !method.IsIterator)
{
bool containsAwait = AwaitDetector.ContainsAwait(body);
diagnostics.Add(containsAwait ? ErrorCode.ERR_PossibleAsyncIteratorWithoutYield : ErrorCode.ERR_PossibleAsyncIteratorWithoutYieldOrAwait,
method.Locations[0], method.ReturnType);
stateMachineType = null;
return(body);
}
// The CLR doesn't support adding fields to structs, so in order to enable EnC in an async method we need to generate a class.
// For async-iterators, we also need to generate a class.
var typeKind = (compilationState.Compilation.Options.EnableEditAndContinue || method.IsIterator) ? TypeKind.Class : TypeKind.Struct;
var bodyWithAwaitLifted = AwaitExpressionSpiller.Rewrite(body, method, compilationState, diagnostics);
stateMachineType = new AsyncStateMachine(slotAllocatorOpt, compilationState, method, methodOrdinal, typeKind);
compilationState.ModuleBuilderOpt.CompilationState.SetStateMachineType(method, stateMachineType);
AsyncRewriter rewriter = isAsyncEnumerableOrEnumerator
? new AsyncIteratorRewriter(bodyWithAwaitLifted, method, methodOrdinal, stateMachineType, slotAllocatorOpt, compilationState, diagnostics)
: new AsyncRewriter(bodyWithAwaitLifted, method, methodOrdinal, stateMachineType, slotAllocatorOpt, compilationState, diagnostics);
if (!rewriter.VerifyPresenceOfRequiredAPIs())
{
return(body);
}
try
{
return(rewriter.Rewrite());
}
catch (SyntheticBoundNodeFactory.MissingPredefinedMember ex)
{
diagnostics.Add(ex.Diagnostic);
return(new BoundBadStatement(body.Syntax, ImmutableArray.Create <BoundNode>(body), hasErrors: true));
}
}
internal AsyncIteratorRewriter(
BoundStatement body,
MethodSymbol method,
int methodOrdinal,
AsyncStateMachine stateMachineType,
VariableSlotAllocator slotAllocatorOpt,
TypeCompilationState compilationState,
DiagnosticBag diagnostics)
: base(body, method, methodOrdinal, stateMachineType, slotAllocatorOpt, compilationState, diagnostics)
{
Debug.Assert(method.IteratorElementType != null);
_isEnumerable = method.IsIAsyncEnumerableReturningAsync(method.DeclaringCompilation);
}
internal AsyncIteratorRewriter(
BoundStatement body,
MethodSymbol method,
int methodOrdinal,
AsyncStateMachine stateMachineType,
VariableSlotAllocator slotAllocatorOpt,
TypeCompilationState compilationState,
DiagnosticBag diagnostics)
: base(body, method, methodOrdinal, stateMachineType, slotAllocatorOpt, compilationState, diagnostics)
{
Debug.Assert(!TypeSymbol.Equals(method.IteratorElementTypeWithAnnotations.Type, null, TypeCompareKind.ConsiderEverything2));
_isEnumerable = method.IsIAsyncEnumerableReturningAsync(method.DeclaringCompilation);
Debug.Assert(_isEnumerable != method.IsIAsyncEnumeratorReturningAsync(method.DeclaringCompilation));
}
internal readonly TypeSymbol IteratorElementType; // only for async-iterators
public AsyncStateMachine(VariableSlotAllocator variableAllocatorOpt, TypeCompilationState compilationState, MethodSymbol asyncMethod, int asyncMethodOrdinal, TypeKind typeKind)
: base(variableAllocatorOpt, compilationState, asyncMethod, asyncMethodOrdinal)
{
_typeKind = typeKind;
CSharpCompilation compilation = asyncMethod.DeclaringCompilation;
var interfaces = ArrayBuilder <NamedTypeSymbol> .GetInstance();
bool isIterator = asyncMethod.IsIterator;
if (isIterator)
{
var elementType = TypeMap.SubstituteType(asyncMethod.IteratorElementType).TypeSymbol;
this.IteratorElementType = elementType;
bool isEnumerable = asyncMethod.IsIAsyncEnumerableReturningAsync(compilation);
if (isEnumerable)
{
// IAsyncEnumerable<TResult>
interfaces.Add(compilation.GetWellKnownType(WellKnownType.System_Collections_Generic_IAsyncEnumerable_T).Construct(elementType));
}
// IAsyncEnumerator<TResult>
interfaces.Add(compilation.GetWellKnownType(WellKnownType.System_Collections_Generic_IAsyncEnumerator_T).Construct(elementType));
// IValueTaskSource<bool>
interfaces.Add(compilation.GetWellKnownType(WellKnownType.System_Threading_Tasks_Sources_IValueTaskSource_T).Construct(compilation.GetSpecialType(SpecialType.System_Boolean)));
// IStrongBox<ManualResetValueTaskSourceLogic<bool>>
interfaces.Add(compilation.GetWellKnownType(WellKnownType.System_Runtime_CompilerServices_IStrongBox_T).Construct(
compilation.GetWellKnownType(WellKnownType.System_Threading_Tasks_ManualResetValueTaskSourceLogic_T)
.Construct(compilation.GetSpecialType(SpecialType.System_Boolean))));
// IAsyncDisposable
interfaces.Add(compilation.GetWellKnownType(WellKnownType.System_IAsyncDisposable));
}
interfaces.Add(compilation.GetWellKnownType(WellKnownType.System_Runtime_CompilerServices_IAsyncStateMachine));
_interfaces = interfaces.ToImmutableAndFree();
_constructor = isIterator ? (MethodSymbol) new IteratorConstructor(this) : new AsyncConstructor(this);
}