如何在Roslyn上获得扩展方法？

Question

I need to list all extension methods found on the file.

This is what I'm doing so far (looks like it's working):

var methods = nodes.OfType<MethodDeclarationSyntax>();    
var extensionMethods = methods.Where(m => 
        m.Modifiers.Any(t => t.Kind == SyntaxKind.StaticKeyword) 
        && m.ParameterList.Parameters.Any(p => 
            p.Modifiers.Any(pm => pm.Kind == SyntaxKind.ThisKeyword)));

Even though I couldn't test all cases it looks like this is working. But I was wondering if there was a more concise way to approach this solution.

Is there some sort of IsExtension or some SyntaxKind.ExtensionMethod? I took a look but could not find anything obvious, at least.

I'm using the latest Roslyn Sept/12

Answer 1

You're working at the syntactic level and at this level, there is no such thing as “extension method”. What you can do is to get semantic information (called Symbol ) for each method and there you will see whether it is an extension method. Something like:

SyntaxTree tree = …
var compilation = Compilation.Create("foo").AddSyntaxTrees(tree);
var model = compilation.GetSemanticModel(tree);

var methods = …
var extensionMethods =
   methods.Where(m => model.GetDeclaredSymbol(m).IsExtensionMethod);

This means your code actually needs to compile and you will also have to add any necessary references to the compilation.