/// <summary>
/// Generate the GetEnumerator() method for iterators and GetAsyncEnumerator() for async-iterators.
/// </summary>
protected SynthesizedImplementationMethod GenerateIteratorGetEnumerator(MethodSymbol getEnumeratorMethod, ref BoundExpression managedThreadId, int initialState)
{
// Produces:
// {StateMachineType} result;
// if (this.initialThreadId == {managedThreadId} && this.state == -2)
// {
// this.state = {initialState};
// extraReset
// result = this;
// }
// else
// {
// result = new {StateMachineType}({initialState});
// }
// result.parameter = this.parameterProxy; // copy all of the parameter proxies
// The implementation doesn't depend on the method body of the iterator method.
// Only on its parameters and staticness.
var getEnumerator = OpenMethodImplementation(
getEnumeratorMethod,
hasMethodBodyDependency: false);
var bodyBuilder = ArrayBuilder <BoundStatement> .GetInstance();
// {StateMachineType} result;
var resultVariable = F.SynthesizedLocal(stateMachineType, null);
// result = new {StateMachineType}({initialState})
BoundStatement makeIterator = F.Assignment(F.Local(resultVariable), F.New(stateMachineType.Constructor, F.Literal(initialState)));
var thisInitialized = F.GenerateLabel("thisInitialized");
if ((object)initialThreadIdField != null)
{
managedThreadId = MakeCurrentThreadId();
var thenBuilder = ArrayBuilder <BoundStatement> .GetInstance(4);
thenBuilder.Add(
// this.state = {initialState};
F.Assignment(F.Field(F.This(), stateField), F.Literal(initialState)));
thenBuilder.Add(
// result = this;
F.Assignment(F.Local(resultVariable), F.This()));
var extraReset = GetExtraResetForIteratorGetEnumerator();
if (extraReset != null)
{
thenBuilder.Add(extraReset);
}
thenBuilder.Add(
method.IsStatic || method.ThisParameter.Type.IsReferenceType ? // if this is a reference type, no need to copy it since it is not assignable
F.Goto(thisInitialized) : // goto thisInitialized
(BoundStatement)F.StatementList());
makeIterator = F.If(
// if (this.state == -2 && this.initialThreadId == Thread.CurrentThread.ManagedThreadId)
condition: F.LogicalAnd(
F.IntEqual(F.Field(F.This(), stateField), F.Literal(StateMachineStates.FinishedStateMachine)),
F.IntEqual(F.Field(F.This(), initialThreadIdField), managedThreadId)),
thenClause: F.Block(thenBuilder.ToImmutableAndFree()),
elseClauseOpt: makeIterator);
}
bodyBuilder.Add(makeIterator);
// Initialize all the parameter copies
var copySrc = initialParameters;
var copyDest = nonReusableLocalProxies;
if (!method.IsStatic)
{
// starting with "this"
CapturedSymbolReplacement proxy;
if (copyDest.TryGetValue(method.ThisParameter, out proxy))
{
bodyBuilder.Add(
F.Assignment(
proxy.Replacement(F.Syntax, stateMachineType => F.Local(resultVariable)),
copySrc[method.ThisParameter].Replacement(F.Syntax, stateMachineType => F.This())));
}
}
bodyBuilder.Add(F.Label(thisInitialized));
foreach (var parameter in method.Parameters)
{
CapturedSymbolReplacement proxy;
if (copyDest.TryGetValue(parameter, out proxy))
{
bodyBuilder.Add(
F.Assignment(
proxy.Replacement(F.Syntax, stateMachineType => F.Local(resultVariable)),
copySrc[parameter].Replacement(F.Syntax, stateMachineType => F.This())));
}
}
bodyBuilder.Add(F.Return(F.Local(resultVariable)));
F.CloseMethod(F.Block(ImmutableArray.Create(resultVariable), bodyBuilder.ToImmutableAndFree()));
return(getEnumerator);
}
/// <summary>
/// Generate the GetEnumerator() method for iterators and GetAsyncEnumerator() for async-iterators.
/// </summary>
protected SynthesizedImplementationMethod GenerateIteratorGetEnumerator(MethodSymbol getEnumeratorMethod, ref BoundExpression managedThreadId, int initialState)
{
// Produces:
// {StateMachineType} result;
// if (this.initialThreadId == {managedThreadId} && this.state == -2)
// {
// this.state = {initialState};
// extraReset
// result = this;
// }
// else
// {
// result = new {StateMachineType}({initialState});
// }
//
// // Initialize each parameter fields
// result.parameter = this.parameterProxy;
// OR
// if (token.Equals(default)) { result.parameter = this.parameterProxy; } else { result.parameter = token; } // for async-enumerable parameters marked with [EnumeratorCancellation]
// The implementation doesn't depend on the method body of the iterator method.
// Only on its parameters and staticness.
var getEnumerator = OpenMethodImplementation(
getEnumeratorMethod,
hasMethodBodyDependency: false);
var bodyBuilder = ArrayBuilder <BoundStatement> .GetInstance();
// {StateMachineType} result;
var resultVariable = F.SynthesizedLocal(stateMachineType, null);
// result = new {StateMachineType}({initialState})
BoundStatement makeIterator = F.Assignment(F.Local(resultVariable), F.New(stateMachineType.Constructor, F.Literal(initialState)));
var thisInitialized = F.GenerateLabel("thisInitialized");
if ((object)initialThreadIdField != null)
{
managedThreadId = MakeCurrentThreadId();
var thenBuilder = ArrayBuilder <BoundStatement> .GetInstance(4);
thenBuilder.Add(
// this.state = {initialState};
F.Assignment(F.Field(F.This(), stateField), F.Literal(initialState)));
thenBuilder.Add(
// result = this;
F.Assignment(F.Local(resultVariable), F.This()));
var extraReset = GetExtraResetForIteratorGetEnumerator();
if (extraReset != null)
{
thenBuilder.Add(extraReset);
}
if (method.IsStatic || method.ThisParameter.Type.IsReferenceType)
{
// if this is a reference type, no need to copy it since it is not assignable
thenBuilder.Add(
// goto thisInitialized;
F.Goto(thisInitialized));
}
makeIterator = F.If(
// if (this.state == -2 && this.initialThreadId == Thread.CurrentThread.ManagedThreadId)
condition: F.LogicalAnd(
F.IntEqual(F.Field(F.This(), stateField), F.Literal(StateMachineStates.FinishedStateMachine)),
F.IntEqual(F.Field(F.This(), initialThreadIdField), managedThreadId)),
thenClause: F.Block(thenBuilder.ToImmutableAndFree()),
elseClauseOpt: makeIterator);
}
bodyBuilder.Add(makeIterator);
// Initialize all the parameter copies
var copySrc = initialParameters;
var copyDest = nonReusableLocalProxies;
if (!method.IsStatic)
{
// starting with "this"
CapturedSymbolReplacement proxy;
if (copyDest.TryGetValue(method.ThisParameter, out proxy))
{
bodyBuilder.Add(
F.Assignment(
proxy.Replacement(F.Syntax, stateMachineType => F.Local(resultVariable)),
copySrc[method.ThisParameter].Replacement(F.Syntax, stateMachineType => F.This())));
}
}
bodyBuilder.Add(F.Label(thisInitialized));
foreach (var parameter in method.Parameters)
{
CapturedSymbolReplacement proxy;
if (copyDest.TryGetValue(parameter, out proxy))
{
// result.parameter = this.parameterProxy;
BoundExpression left = proxy.Replacement(F.Syntax, stateMachineType => F.Local(resultVariable));
BoundStatement copy = F.Assignment(
left,
copySrc[parameter].Replacement(F.Syntax, stateMachineType => F.This()));
if (this.method.IsAsync)
{
ParameterSymbol tokenParameter = getEnumeratorMethod.Parameters[0];
if (hasEnumeratorCancellationAttribute(parameter))
{
// For any async-enumerable parameter marked with [EnumeratorCancellation] attribute, conditionally copy GetAsyncEnumerator's cancellation token parameter instead
// if (token.Equals(default))
// result.parameter = this.parameterProxy;
// else
// result.parameter = token;
copy = F.If(
// if (token.Equals(default))
F.Call(F.Parameter(tokenParameter), WellKnownMember.System_Threading_CancellationToken__Equals, F.Default(tokenParameter.Type)),
// result.parameter = this.parameterProxy;
copy,
// result.parameter = token;
F.Assignment(left, F.Parameter(tokenParameter)));
}
}
bodyBuilder.Add(copy);
}
}
bodyBuilder.Add(F.Return(F.Local(resultVariable)));
F.CloseMethod(F.Block(ImmutableArray.Create(resultVariable), bodyBuilder.ToImmutableAndFree()));
return(getEnumerator);