package callback import ( "errors" "github.com/nspcc-dev/neo-go/pkg/core/interop" "github.com/nspcc-dev/neo-go/pkg/core/interop/interopnames" "github.com/nspcc-dev/neo-go/pkg/vm" "github.com/nspcc-dev/neo-go/pkg/vm/stackitem" ) // Callback is an interface for arbitrary callbacks. type Callback interface { // ArgCount returns expected number of arguments. ArgCount() int // LoadContext loads context and arguments on stack. LoadContext(*vm.VM, []stackitem.Item) } // Invoke invokes provided callback. func Invoke(ic *interop.Context) error { cb := ic.VM.Estack().Pop().Interop().Value().(Callback) args := ic.VM.Estack().Pop().Array() if cb.ArgCount() != len(args) { return errors.New("invalid argument count") } cb.LoadContext(ic.VM, args) switch t := cb.(type) { case *MethodCallback: id := interopnames.ToID([]byte(interopnames.SystemContractCall)) return ic.SyscallHandler(ic.VM, id) case *SyscallCallback: return ic.SyscallHandler(ic.VM, t.desc.ID) default: return nil } }