package node import ( "reflect" "go.uber.org/fx" ) // Option is a functional option which can be used with the New function to // change how the node is constructed // // Options are applied in sequence type Option func(*Settings) error // Options groups multiple options into one func Options(opts ...Option) Option { return func(s *Settings) error { for _, opt := range opts { if err := opt(s); err != nil { return err } } return nil } } // Error is a special option which returns an error when applied func Error(err error) Option { return func(_ *Settings) error { return err } } func ApplyIf(check func(s *Settings) bool, opts ...Option) Option { return func(s *Settings) error { if check(s) { return Options(opts...)(s) } return nil } } func If(b bool, opts ...Option) Option { return ApplyIf(func(s *Settings) bool { return b }, opts...) } // Override option changes constructor for a given type func Override(typ, constructor interface{}) Option { return func(s *Settings) error { if i, ok := typ.(invoke); ok { s.invokes[i] = fx.Invoke(constructor) return nil } if c, ok := typ.(special); ok { s.modules[c] = fx.Provide(constructor) return nil } ctor := as(constructor, typ) rt := reflect.TypeOf(typ).Elem() s.modules[rt] = fx.Provide(ctor) return nil } } func Unset(typ interface{}) Option { return func(s *Settings) error { if i, ok := typ.(invoke); ok { s.invokes[i] = nil return nil } if c, ok := typ.(special); ok { delete(s.modules, c) return nil } rt := reflect.TypeOf(typ).Elem() delete(s.modules, rt) return nil } } // From(*T) -> func(t T) T {return t} func From(typ interface{}) interface{} { rt := []reflect.Type{reflect.TypeOf(typ).Elem()} ft := reflect.FuncOf(rt, rt, false) return reflect.MakeFunc(ft, func(args []reflect.Value) (results []reflect.Value) { return args }).Interface() } // from go-ipfs // as casts input constructor to a given interface (if a value is given, it // wraps it into a constructor). // // Note: this method may look like a hack, and in fact it is one. // This is here only because https://github.com/uber-go/fx/issues/673 wasn't // released yet // // Note 2: when making changes here, make sure this method stays at // 100% coverage. This makes it less likely it will be terribly broken func as(in interface{}, as interface{}) interface{} { outType := reflect.TypeOf(as) if outType.Kind() != reflect.Ptr { panic("outType is not a pointer") } if reflect.TypeOf(in).Kind() != reflect.Func { ctype := reflect.FuncOf(nil, []reflect.Type{outType.Elem()}, false) return reflect.MakeFunc(ctype, func(args []reflect.Value) (results []reflect.Value) { out := reflect.New(outType.Elem()) out.Elem().Set(reflect.ValueOf(in)) return []reflect.Value{out.Elem()} }).Interface() } inType := reflect.TypeOf(in) ins := make([]reflect.Type, inType.NumIn()) outs := make([]reflect.Type, inType.NumOut()) for i := range ins { ins[i] = inType.In(i) } outs[0] = outType.Elem() for i := range outs[1:] { outs[i+1] = inType.Out(i + 1) } ctype := reflect.FuncOf(ins, outs, false) return reflect.MakeFunc(ctype, func(args []reflect.Value) (results []reflect.Value) { outs := reflect.ValueOf(in).Call(args) out := reflect.New(outType.Elem()) out.Elem().Set(outs[0]) outs[0] = out.Elem() return outs }).Interface() }