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