CODEWITHSUNDEEP
c#.netcode-generationroslyn
Alex Zhukovskiy
Alex Zhukovskiy

Reputation: 10015

How to get TypeSyntax from TypeDeclarationSyntax

I'm writing a simple Roslyn generator that generates an interface implementation so I want to get TypeSyntax from TypeDeclarationSyntax, because of following code:

// Our generator is applied to any class that our attribute is applied to.
var applyToInterface = (InterfaceDeclarationSyntax)applyTo;

// Trying to implement this interface
var clientClass = SyntaxFactory.ClassDeclaration(SyntaxFactory.Identifier(applyToInterface.Identifier.ValueText + "Client"))
    .WithModifiers(SyntaxTokenList.Create(SyntaxFactory.Token(SyntaxKind.PublicKeyword)))
    .WithBaseList(SyntaxFactory.SimpleBaseType(applyToInterface.???));

However, I don't see any way to create TypeSyntax except SyntaxFactory.ParseTypeName. But I don't want to get interface name and then convert it back to type, because of possible bugs (like + chars in generics instead of dot and so on).

What is the most convinient and recommended way to perform this operation? Currently I'm using

var clientClass = SyntaxFactory.ClassDeclaration(SyntaxFactory.Identifier(applyToInterface.Identifier.ValueText + "Client"))
    .WithModifiers(SyntaxTokenList.Create(SyntaxFactory.Token(SyntaxKind.PublicKeyword)))
    .AddBaseListTypes(SyntaxFactory.SimpleBaseType(SyntaxFactory.ParseTypeName(applyToInterface.Identifier.ValueText)));

But i'm not sure if it's correct always.

Upvotes: 3

Views: 1490

Answers (1)

johnny 5
johnny 5

Reputation: 21005

I believe the way you are doing it is correct, Due to Roslyn's lack of documentation I generally check their source to use internal examples to check my samples. I've found this sample from searching WithBaseList 

var implementedInterfaceTypeSyntax = extractedInterfaceSymbol.TypeParameters.Any()
            ? SyntaxFactory.GenericName(
                SyntaxFactory.Identifier(extractedInterfaceSymbol.Name),
                SyntaxFactory.TypeArgumentList(SyntaxFactory.SeparatedList(extractedInterfaceSymbol.TypeParameters.Select(p => SyntaxFactory.ParseTypeName(p.Name)))))
            : SyntaxFactory.ParseTypeName(extractedInterfaceSymbol.Name);

var baseList = typeDeclaration.BaseList ?? SyntaxFactory.BaseList();
var updatedBaseList = baseList.WithTypes(SyntaxFactory.SeparatedList(baseList.Types.Union(new[] { SyntaxFactory.SimpleBaseType(implementedInterfaceTypeSyntax) })));

In this instance they are using the symbol to generate the type.

Upvotes: 3

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