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);
}