JensKrumsieck/ChemSharp

using Microsoft.CodeAnalysis;
using Microsoft.CodeAnalysis.CSharp.Syntax;

namespace ChemSharp.Molecules.Generator;

public static class InterfaceTools
{
    public static bool HasInterface(this ClassDeclarationSyntax syn, string interfaceName)
    {
        var basetypes = syn.BaseList!.Types.Select(s => s);
        return basetypes.Any(s => s.ToString() == interfaceName);
    }

    public static IEnumerable<ClassDeclarationSyntax> GetClassesImplementing(
        this GeneratorExecutionContext context, string interfaceName) =>
        context.Compilation.SyntaxTrees
               .SelectMany(tree => tree.GetRoot().DescendantNodes())
               .Where(x => x is ClassDeclarationSyntax)
               .Cast<ClassDeclarationSyntax>().Where(s => s.BaseList is not null)
               .Where(s => s.HasInterface(interfaceName));
}