protected override void SetupStateMachine()
{
_stateMachineClass.AddBaseType(TypeSystemServices.ValueTypeType);
_stateMachineClass.AddBaseType(TypeSystemServices.IAsyncStateMachineType);
_stateMachineClass.Modifiers |= TypeMemberModifiers.Final;
var ctr = TypeSystemServices.Map(typeof(AsyncStateMachineAttribute)).GetConstructors().Single();
_method.Method.Attributes.Add(
CodeBuilder.CreateAttribute(
ctr,
CodeBuilder.CreateTypeofExpression(_stateMachineClass.Entity)));
AsyncMethodBuilderMemberCollection.TryCreate(
TypeSystemServices,
_method.Method,
MethodGenArg(true),
out _asyncMethodBuilderMemberCollection);
_state = (IField)_stateMachineClass.AddInternalField(UniqueName("State"), TypeSystemServices.IntType).Entity;
_asyncMethodBuilderField = _stateMachineClass.AddInternalField(
UniqueName("Builder"),
_asyncMethodBuilderMemberCollection.BuilderType);
CreateSetStateMachine();
PreprocessMethod();
}
private void FixAsyncMethodBody(MethodInvocationExpression stateMachineConstructorInvocation)
{
var method = _method.Method;
// If the async method's result type is a type parameter of the method, then the AsyncTaskMethodBuilder<T>
// needs to use the method's type parameters inside the rewritten method body. All other methods generated
// during async rewriting are members of the synthesized state machine struct, and use the type parameters
// structs type parameters.
AsyncMethodBuilderMemberCollection methodScopeAsyncMethodBuilderMemberCollection;
if (!AsyncMethodBuilderMemberCollection.TryCreate(
TypeSystemServices,
method,
MethodGenArg(false),
out methodScopeAsyncMethodBuilderMemberCollection))
{
throw new NotImplementedException("Custom async patterns are not supported");
}
var bodyBuilder = new Block();
var builderVariable = CodeBuilder.DeclareTempLocal(method, methodScopeAsyncMethodBuilderMemberCollection.BuilderType);
var stateMachineType = stateMachineConstructorInvocation.ExpressionType;
var stateMachineVariable = CodeBuilder.DeclareLocal(
method,
UniqueName("async"),
stateMachineType);
bodyBuilder.Add(CodeBuilder.CreateAssignment(
CodeBuilder.CreateLocalReference(stateMachineVariable),
stateMachineConstructorInvocation));
// local.$builder = System.Runtime.CompilerServices.AsyncTaskMethodBuilder<typeArgs>.Create();
bodyBuilder.Add(
CodeBuilder.CreateAssignment(
CodeBuilder.CreateMemberReference(
CodeBuilder.CreateLocalReference(stateMachineVariable),
ExternalFieldEntity((IField)_asyncMethodBuilderField.Entity, stateMachineType)),
CodeBuilder.CreateMethodInvocation(methodScopeAsyncMethodBuilderMemberCollection.CreateBuilder)));
// local.$stateField = NotStartedStateMachine
bodyBuilder.Add(
CodeBuilder.CreateAssignment(
CodeBuilder.CreateMemberReference(
CodeBuilder.CreateLocalReference(stateMachineVariable),
ExternalFieldEntity(_state, stateMachineType)),
CodeBuilder.CreateIntegerLiteral(StateMachineStates.NotStartedStateMachine)));
bodyBuilder.Add(
CodeBuilder.CreateAssignment(
CodeBuilder.CreateLocalReference(builderVariable),
CodeBuilder.CreateMemberReference(
CodeBuilder.CreateLocalReference(stateMachineVariable),
ExternalFieldEntity((IField)_asyncMethodBuilderField.Entity, stateMachineType))));
// local.$builder.Start(ref local) -- binding to the method AsyncTaskMethodBuilder<typeArgs>.Start()
bodyBuilder.Add(
CodeBuilder.CreateMethodInvocation(
CodeBuilder.CreateLocalReference(builderVariable),
methodScopeAsyncMethodBuilderMemberCollection.Start.GenericInfo.ConstructMethod(stateMachineType),
CodeBuilder.CreateLocalReference(stateMachineVariable)));
var methodBuilderField = stateMachineType.ConstructedInfo == null
? (IField)_asyncMethodBuilderField.Entity
: stateMachineType.ConstructedInfo.Map((IField)_asyncMethodBuilderField.Entity);
bodyBuilder.Add(method.ReturnType.Entity == TypeSystemServices.VoidType
? new ReturnStatement()
: new ReturnStatement(
CodeBuilder.CreateMethodInvocation(
CodeBuilder.CreateMemberReference(
CodeBuilder.CreateLocalReference(stateMachineVariable),
methodBuilderField),
methodScopeAsyncMethodBuilderMemberCollection.Task.GetGetMethod())));
_method.Method.Body = bodyBuilder;
}