private MethodDeclarationSyntax AddMethodBody(MethodDeclarationSyntax containingMethod, MetaField field, Func <ExpressionSyntax, InvocationExpressionSyntax> mutatingInvocationFactory)
{
var returnExpression = field.IsLocallyDefined
? (ExpressionSyntax)SyntaxFactory.InvocationExpression( // this.With(field: this.field.SomeOperation(someArgs))
Syntax.ThisDot(WithMethodName),
SyntaxFactory.ArgumentList(SyntaxFactory.SingletonSeparatedList(
SyntaxFactory.Argument(
SyntaxFactory.NameColon(field.Name),
NoneToken,
mutatingInvocationFactory(Syntax.ThisDot(field.NameAsField))))))
: SyntaxFactory.CastExpression( // (TemplateType)base.SameMethod(sameArgs)
GetFullyQualifiedSymbolName(this.generator.applyToSymbol),
SyntaxFactory.InvocationExpression(
Syntax.BaseDot(SyntaxFactory.IdentifierName(containingMethod.Identifier)),
SyntaxFactory.ArgumentList(
Syntax.JoinSyntaxNodes(
SyntaxKind.CommaToken,
containingMethod.ParameterList.Parameters.Select(p => SyntaxFactory.Argument(SyntaxFactory.IdentifierName(p.Identifier)))))));
return(containingMethod.WithBody(SyntaxFactory.Block(
SyntaxFactory.ReturnStatement(returnExpression))));
}