DtoGeneratorExtn1.cs

[Generator]
public class DtoGenerator : ISourceGenerator
{
    public void Execute(GeneratorExecutionContext context)
    {
        var targetTypeTracker = context.SyntaxContextReceiver as TargetTypeTracker;
        var codeBuilder = new StringBuilder();

        foreach (var typeNode in targetTypeTracker.TypesNeedingDtoGening)
        {
	    var generatedDtoClassName = $"{typeNode.Identifier.ValueText}Dto";
	    // emit code to create the DTO class with property getters and setters
	    // ...
	    // Start emitting mapping extension methods
	    codeBuilder.AppendLine($"\tpublic static class EntityExtensions{Guid.NewGuid().ToString().Replace("-", string.Empty)}");
	    codeBuilder.AppendLine("\t{");
	    codeBuilder.AppendLine($"\t\tpublic static {generatedDtoClassName} ToDto(this {typeNode.Identifier.ValueText} entity)");
	    codeBuilder.AppendLine("\t\t{");
	    codeBuilder.AppendLine($"\t\t\t\treturn new {generatedDtoClassName}");
	    codeBuilder.AppendLine($"\t\t\t\t{{");
	    
	    foreach (var pds in allProperties)
	    {
	    	var symbol = context.Compilation
                             .GetSemanticModel(pds.SyntaxTree)
                             .GetDeclaredSymbol(pds);
                var property = (symbol as IPropertySymbol);
		codeBuilder.AppendLine($"\t\t\t\t\t{property.Name} = entity.{property.Name},");
	    }

	    codeBuilder.AppendLine($"\t\t\t\t}};");
	    codeBuilder.AppendLine("\t\t}");
	    codeBuilder.AppendLine("\t}");
	    codeBuilder.AppendLine("}");
            context.AddSource(generatedDtoClassName,
                SourceText.From(codeBuilder.ToString(), Encoding.UTF8));
            codeBuilder.Clear();
        }
    }

    public void Initialize(GeneratorInitializationContext context) =>
        context.RegisterForSyntaxNotifications(() => new TargetTypeTracker());
}