public override void VisitSwitchStatement(SwitchStatementSyntax node)
{
if (!YieldChecker.HasSpecialStatement(node))
{
currentState.Add(node);
}
else
{
var nextState = GetNextState(node);
var switchState = currentState;
switchState.NextState = nextState;
var switchStatement = Cs.Switch(node.Expression);
foreach (var section in node.Sections.Select(x => x.WithStatements(SyntaxFactory.List(x.Statements.Select(BreakStatementStripper.StripStatements)))))
{
switchStatement = switchStatement.AddSections(Cs.Section(section.Labels, CaptureState(section, switchState.NextState, nextState)));
}
switchState.Statements.Add(switchStatement);
Close(switchState);
currentState = nextState;
}
}
public override void VisitTryStatement(TryStatementSyntax node)
{
if (!YieldChecker.HasSpecialStatement(node))
{
currentState.Add(YieldThisFixer.Fix(node));
}
else
{
if (node.Catches.Any())
{
throw new Exception("Yield statements cannot be contained inside try/catch blocks.");
}
var nextState = GetNextState(node);
MaybeCreateNewState();
var tryState = currentState;
tryState.NextState = nextState;
var exceptionName = SyntaxFactory.Identifier("$ex" + exceptionNameCounter++);
var finallyState = new State(this)
{
NextState = nextState, BreakState = nextState
};
foreach (var finallyStatement in node.Finally.Block.Statements)
{
finallyState.Add(finallyStatement);
}
finallyState.Add(Cs.If(Cs.This().Member(exceptionName).NotEqualTo(Cs.Null()), Cs.Throw(Cs.This().Member(exceptionName))));
Close(finallyState);
node = (TryStatementSyntax)HoistVariable(node, exceptionName, SyntaxFactory.ParseTypeName("System.Exception"));
tryState.NextState = finallyState;
tryState.Germ = yieldState =>
{
var gotoFinally = SyntaxFactory.Block(
Cs.Express(Cs.This().Member(exceptionName).Assign(SyntaxFactory.IdentifierName(exceptionName))),
ChangeState(finallyState),
GotoTop()
);
var statements = yieldState.Statements.ToArray();
yieldState.Statements.Clear();
yieldState.Statements.Add(Cs.Try().WithBlock(Cs.Block(statements)).WithCatches(SyntaxFactory.List(new[] {
SyntaxFactory.CatchClause(SyntaxFactory.CatchDeclaration(SyntaxFactory.ParseTypeName("System.Exception"), exceptionName), null, gotoFinally)
})));
};
node.Block.Accept(this);
if (!tryState.IsClosed)
{
CloseTo(tryState, finallyState);
}
currentState = nextState;
}
}
public override void VisitDoStatement(DoStatementSyntax node)
{
if (!YieldChecker.HasSpecialStatement(node))
{
currentState.Add(YieldThisFixer.Fix(node));
}
else
{
MaybeCreateNewState();
var nextState = GetNextState(node);
var conditionState = new State(this)
{
BreakState = nextState
};
var iterationState = currentState;
conditionState.Add(Cs.If(YieldThisFixer.Fix(node.Condition), ChangeState(iterationState), ChangeState(nextState)));
conditionState.Add(GotoTop());
SetClosed(conditionState);
iterationState.NextState = conditionState;
node.Statement.Accept(this);
if (currentState != nextState)
{
Close(currentState);
}
currentState = nextState;
}
}
public void GenerateStates()
{
var lastState = new State(this);
lastState.Statements.Add(Cs.Return(Cs.False()));
currentState = new State(this)
{
NextState = lastState
};
node.Accept(this);
// Post-process goto statements
if (labelStates.Any())
{
var gotoSubstituter = new GotoSubstituter(compilation, labelStates);
foreach (var state in states)
{
state.Statements = state.Statements.Select(x => (StatementSyntax)x.Accept(gotoSubstituter)).ToList();
}
}
if (!states.Last().Statements.Any())
{
states.Last().Statements.Add(Cs.Break());
}
}
public override void VisitLocalDeclarationStatement(LocalDeclarationStatementSyntax node)
{
var semanticModel = compilation.GetSemanticModel(node.SyntaxTree);
// Convert the variable declaration to an assignment expression statement
foreach (var variable in node.Declaration.Variables)
{
if (variable.Initializer != null)
{
var assignment = SyntaxFactory.IdentifierName(variable.Identifier.ToString()).Assign(variable.Initializer.Value);
currentState.Add(Cs.Express(YieldThisFixer.Fix(assignment)));
}
// Hoist the variable into a field
var symbol = (ILocalSymbol)ModelExtensions.GetDeclaredSymbol(semanticModel, variable);
node = (LocalDeclarationStatementSyntax)HoistVariable(node, variable.Identifier, symbol.Type.ToTypeSyntax());
}
}
public override void VisitYieldStatement(YieldStatementSyntax node)
{
var nextState = GetNextState(node);
if (node.ReturnOrBreakKeyword.IsKind(SyntaxKind.BreakKeyword))
{
currentState.Add(ChangeState(nextState));
currentState.Add(Cs.Return(Cs.False()));
}
else
{
currentState.Add(ChangeState(nextState));
currentState.Add(Cs.Express(Cs.This().Member("Current").Assign(YieldThisFixer.Fix(node.Expression))));
currentState.Add(Cs.Return(Cs.True()));
}
SetClosed(currentState);
currentState = nextState;
}
public ClassDeclarationSyntax CreateEnumerator()
{
var members = new List <MemberDeclarationSyntax>();
FieldDeclarationSyntax thisField = null;
if (!method.IsStatic)
{
thisField = Cs.Field(method.ContainingType.ToTypeSyntax(), "$this");
members.Add(thisField);
}
var stateGenerator = new YieldStateGenerator(compilation, node);
stateGenerator.GenerateStates();
var states = stateGenerator.States;
var isStartedField = Cs.Field(Cs.Bool(), isStarted);
members.Add(isStartedField);
var stateField = Cs.Field(Cs.Int(), StateGenerator.state);
members.Add(stateField);
foreach (var parameter in node.ParameterList.Parameters)
{
var parameterField = Cs.Field(parameter.Type, parameter.Identifier);
members.Add(parameterField);
}
foreach (var variable in stateGenerator.HoistedVariables)
{
var variableField = Cs.Field(variable.Item2, variable.Item1);
members.Add(variableField);
}
var className = "YieldEnumerator$" + method.GetMemberName();
var constructorParameters = new List <ParameterSyntax>();
if (!method.IsStatic)
{
constructorParameters.Add(SyntaxFactory.Parameter(SyntaxFactory.Identifier("$this")).WithType(thisField.Declaration.Type));
}
constructorParameters.AddRange(node.ParameterList.Parameters.Select(x => SyntaxFactory.Parameter(x.Identifier).WithType(x.Type)));
var constructor = SyntaxFactory.ConstructorDeclaration(className)
.AddModifiers(Cs.Public())
.WithParameterList(constructorParameters.ToArray())
.WithBody(
SyntaxFactory.Block(
// Assign fields
constructorParameters.Select(x => Cs.Express(Cs.Assign(Cs.This().Member(x.Identifier), SyntaxFactory.IdentifierName(x.Identifier))))
)
.AddStatements(
Cs.Express(Cs.Assign(Cs.This().Member(StateGenerator.state), Cs.Integer(1)))
)
);
members.Add(constructor);
var elementType = ((INamedTypeSymbol)method.ReturnType).TypeArguments[0];
var ienumerable = SyntaxFactory.ParseTypeName("System.Collections.Generic.IEnumerable<" + elementType.ToDisplayString() + ">");
var ienumerator = SyntaxFactory.ParseTypeName("System.Collections.Generic.IEnumerator<" + elementType.ToDisplayString() + ">");
// Generate the GetEnumerator method, which looks something like:
// var $isStartedLocal = $isStarted;
// $isStarted = true;
// if ($isStartedLocal)
// return this.Clone().GetEnumerator();
// else
// return this;
var getEnumerator = SyntaxFactory.MethodDeclaration(ienumerator, "GetEnumerator")
.AddModifiers(Cs.Public(), Cs.Override())
.WithBody(Cs.Block(
Cs.Local(isStartedLocal, SyntaxFactory.IdentifierName(isStarted)),
Cs.Express(SyntaxFactory.IdentifierName(isStarted).Assign(Cs.True())),
Cs.If(
SyntaxFactory.IdentifierName(isStartedLocal),
Cs.Return(Cs.This().Member("Clone").Invoke().Member("GetEnumerator").Invoke()),
Cs.Return(Cs.This()))));
members.Add(getEnumerator);
// Generate the MoveNext method, which looks something like:
// $top:
// while (true)
// {
// switch (state)
// {
// case 0: ...
// case 1: ...
// }
// }
var moveNextBody = SyntaxFactory.LabeledStatement("$top", Cs.While(Cs.True(),
Cs.Switch(Cs.This().Member(StateGenerator.state), states.Select((x, i) =>
Cs.Section(Cs.Integer(i), x.Statements.ToArray())).ToArray())));
var moveNext = SyntaxFactory.MethodDeclaration(Cs.Bool(), "MoveNext")
.AddModifiers(Cs.Public(), Cs.Override())
.WithBody(SyntaxFactory.Block(moveNextBody));
members.Add(moveNext);
TypeSyntax classNameWithTypeArguments = SyntaxFactory.IdentifierName(className);
if (method.TypeParameters.Any())
{
classNameWithTypeArguments = SyntaxFactory.GenericName(
SyntaxFactory.Identifier(className),
SyntaxFactory.TypeArgumentList(SyntaxFactory.SeparatedList(
method.TypeParameters.Select(x => SyntaxFactory.ParseTypeName(x.Name)),
method.TypeParameters.Select(x => x).Skip(1).Select(_ => SyntaxFactory.Token(SyntaxKind.CommaToken)))
));
}
var cloneBody = Cs.Block(
Cs.Return(classNameWithTypeArguments.New(
constructorParameters.Select(x => SyntaxFactory.IdentifierName(x.Identifier)).ToArray()
))
);
var clone = SyntaxFactory.MethodDeclaration(ienumerable, "Clone")
.AddModifiers(Cs.Public())
.WithBody(SyntaxFactory.Block(cloneBody));
members.Add(clone);
var baseTypes = new[] { SyntaxFactory.ParseTypeName("System.YieldIterator<" + elementType.ToDisplayString() + ">") };
var result = SyntaxFactory.ClassDeclaration(className).WithBaseList(baseTypes).WithMembers(members.ToArray());
if (method.TypeParameters.Any())
{
result = result.WithTypeParameterList(node.TypeParameterList);
}
return(result);
}
public InvocationExpressionSyntax Object(AnonymousObjectCreationExpressionSyntax obj, bool compact = false)
{
var method = context.JsniType.GetMembers("object").OfType <IMethodSymbol>().Single();
return(method.Invoke(obj, compact ? Cs.True() : Cs.False()));
}
public ClassDeclarationSyntax CreateStateMachine()
{
var members = new List <MemberDeclarationSyntax>();
FieldDeclarationSyntax thisField = null;
if (!method.IsStatic)
{
thisField = Cs.Field(method.ContainingType.ToTypeSyntax(), "$this");
members.Add(thisField);
}
var stateGenerator = new AsyncStateGenerator(compilation, node);
stateGenerator.GenerateStates();
var states = stateGenerator.States;
var stateField = Cs.Field(Cs.Int(), state);
members.Add(stateField);
var builderField = Cs.Field(Context.Instance.AsyncVoidMethodBuilder.ToTypeSyntax(), builder);
members.Add(builderField);
foreach (var parameter in node.ParameterList.Parameters)
{
var parameterField = Cs.Field(parameter.Type, parameter.Identifier);
members.Add(parameterField);
}
foreach (var variable in stateGenerator.HoistedVariables)
{
var variableField = Cs.Field(variable.Item2, variable.Item1);
members.Add(variableField);
}
var className = "Async$" + method.GetMemberName();
var constructorParameters = new List <ParameterSyntax>();
if (!method.IsStatic)
{
constructorParameters.Add(SyntaxFactory.Parameter(SyntaxFactory.Identifier("$this")).WithType(thisField.Declaration.Type));
}
constructorParameters.AddRange(node.ParameterList.Parameters.Select(x => SyntaxFactory.Parameter(x.Identifier).WithType(x.Type)));
var constructor = SyntaxFactory.ConstructorDeclaration(className)
.AddModifiers(Cs.Public())
.WithParameterList(constructorParameters.ToArray())
.WithBody(
SyntaxFactory.Block(
// Assign fields
constructorParameters.Select(x => Cs.Express(Cs.This().Member(x.Identifier).Assign(SyntaxFactory.IdentifierName(x.Identifier))))
)
.AddStatements(
Cs.Express(Cs.This().Member(state).Assign(Cs.Integer(-1))),
Cs.Express(Cs.This().Member(builder).Assign(builderField.Declaration.Type.New())),
Cs.Express(Cs.This().Member(builder).Member("Start").Invoke(Cs.This()))
)
);
members.Add(constructor);
// Generate the MoveNext method, which looks something like:
// $top:
// while (true)
// {
// switch (state)
// {
// case 0: ...
// case 1: ...
// }
// }
var moveNextBody = SyntaxFactory.LabeledStatement("$top", Cs.While(Cs.True(),
Cs.Switch(Cs.This().Member(state), states.Select((x, i) =>
Cs.Section(Cs.Integer(i), x.Statements.ToArray())).ToArray())));
var moveNext = SyntaxFactory.MethodDeclaration(Cs.Bool(), "MoveNext")
.AddModifiers(Cs.Public())
.WithBody(SyntaxFactory.Block(moveNextBody));
members.Add(moveNext);
var asyncStateMachine = SyntaxFactory.ParseTypeName("System.Runtime.CompilerServices.IAsyncStateMachine");
var baseTypes = new[] { asyncStateMachine };
var result = SyntaxFactory.ClassDeclaration(className).WithBaseList(baseTypes).WithMembers(members.ToArray());
if (method.TypeParameters.Any())
{
result = result.WithTypeParameterList(node.TypeParameterList);
}
return(result);
}
public override void VisitForEachStatement(ForEachStatementSyntax node)
{
if (!YieldChecker.HasSpecialStatement(node))
{
currentState.Add(YieldThisFixer.Fix(node));
}
else
{
// Convert the variable declaration in the for loop
var semanticModel = compilation.GetSemanticModel(node.SyntaxTree);
var symbol = (ILocalSymbol)ModelExtensions.GetDeclaredSymbol(semanticModel, node);
var targetType = ModelExtensions.GetTypeInfo(semanticModel, node.Expression);
// Hoist the variable into a field
node = (ForEachStatementSyntax)HoistVariable(node, node.Identifier, symbol.Type.ToTypeSyntax());
// Hoist the enumerator into a field
var enumerator = SyntaxFactory.Identifier(node.Identifier + "$enumerator");
var genericEnumeratorType = compilation.FindType("System.Collections.Generic.IEnumerable`1");
var elementType = targetType.ConvertedType.GetGenericArgument(genericEnumeratorType, 0);
var enumeratorType = elementType == null?
SyntaxFactory.ParseTypeName("System.Collections.IEnumerator") :
SyntaxFactory.ParseTypeName("System.Collections.Generic.IEnumerator<" + elementType.ToDisplayString() + ">");
node = (ForEachStatementSyntax)HoistVariable(node, enumerator, enumeratorType);
currentState.Add(Cs.Express(SyntaxFactory.IdentifierName(enumerator).Assign(SyntaxFactory.InvocationExpression(SyntaxFactory.MemberAccessExpression(SyntaxKind.SimpleMemberAccessExpression, YieldThisFixer.Fix(node.Expression), SyntaxFactory.IdentifierName("GetEnumerator"))))));
// Mostly the same as while loop from here (key word, "mostly"; hence the lack of factoring here)
MaybeCreateNewState();
var nextState = GetNextState(node);
var iterationState = currentState;
iterationState.NextState = iterationState;
iterationState.BreakState = nextState;
var bodyBatch = new State(this, true)
{
NextState = iterationState.NextState
};
// Assign current item
bodyBatch.Add(Cs.Express(SyntaxFactory.IdentifierName(node.Identifier).Assign(SyntaxFactory.MemberAccessExpression(SyntaxKind.SimpleMemberAccessExpression,
SyntaxFactory.IdentifierName(enumerator), SyntaxFactory.IdentifierName("Current")))));
currentState = bodyBatch;
node.Statement.Accept(this);
var moveNext = SyntaxFactory.InvocationExpression(SyntaxFactory.MemberAccessExpression(SyntaxKind.SimpleMemberAccessExpression, SyntaxFactory.IdentifierName(enumerator), SyntaxFactory.IdentifierName("MoveNext")));
var forStatement = SyntaxFactory.WhileStatement(moveNext, SyntaxFactory.Block(bodyBatch.Statements));
iterationState.Statements.Add(forStatement);
CloseTo(iterationState, nextState);
if (currentState != nextState)
{
Close(currentState);
}
currentState = nextState;
}
}
public override void VisitForStatement(ForStatementSyntax node)
{
if (!YieldChecker.HasSpecialStatement(node))
{
currentState.Add(YieldThisFixer.Fix(node));
}
else
{
var semanticModel = compilation.GetSemanticModel(node.SyntaxTree);
// Convert the variable declarations in the for loop
if (node.Declaration != null)
{
foreach (var variable in node.Declaration.Variables.Where(x => x.Initializer != null))
{
var assignment = SyntaxFactory.IdentifierName(variable.Identifier.ToString()).Assign(variable.Initializer.Value);
currentState.Add(Cs.Express(assignment));
var symbol = (ILocalSymbol)ModelExtensions.GetDeclaredSymbol(semanticModel, variable);
// Hoist the variable into a field
node = (ForStatementSyntax)HoistVariable(node, variable.Identifier, SyntaxFactory.ParseTypeName(symbol.Type.GetFullName()));
}
}
foreach (var initializer in node.Initializers)
{
currentState.Add(Cs.Express(YieldThisFixer.Fix(initializer)));
}
MaybeCreateNewState();
var nextState = GetNextState(node);
var iterationState = currentState;
// postState determines where the flow goes after each iteration. If there are incrementors, it goes
// to a state that handles the incrementing, then goes back to the iteration state. Otherwise, the
// iteration state just points back to itself like the while loop.
State postState;
if (node.Incrementors.Any())
{
postState = new State(this);
postState.NextState = iterationState;
foreach (var incrementor in node.Incrementors)
{
postState.Add(Cs.Express(YieldThisFixer.Fix(incrementor)));
}
Close(postState);
}
else
{
postState = iterationState;
}
iterationState.NextState = nextState;
iterationState.BreakState = nextState;
var forStatement = SyntaxFactory.WhileStatement(node.Condition ?? Cs.True(), SyntaxFactory.Block(CaptureState(node.Statement, postState, nextState)));
iterationState.Statements.Add(forStatement);
Close(iterationState);
currentState = nextState;
}
}
public static StatementSyntax ChangeState(State newState)
{
return(Cs.Express(Cs.This().Member(state).Assign(Cs.Integer(newState.Index))));
}