KumaChan/standalone/ctn/pair.go

package ctn

import "reflect"


type Pair[A any, B any] func()(A,B)
func MakePair[A any, B any] (a A, b B) Pair[A,B] {
	return func() (A,B) {
		return a, b
	}
}
func ReflectMakePair(a reflect.Value, b reflect.Value) reflect.Value {
	return reflect.MakeFunc(ReflectTypePair(a.Type(), b.Type()), func([] reflect.Value) ([] reflect.Value) {
		return [] reflect.Value { a, b }
	})
}

func (p Pair[A,B]) First() A {
	var a, _ = p()
	return a
}
func (p Pair[A,B]) Second() B {
	var _, b = p()
	return b
}
func (p Pair[K,V]) Key() K {
	return p.First()
}
func (p Pair[K,V]) Value() V {
	return p.Second()
}
func ReflectPairUnpack(v reflect.Value) (reflect.Value, reflect.Value) {
	var ret = v.Call(nil)
	return ret[0], ret[1]
}

func ReflectTypePair(a reflect.Type, b reflect.Type) reflect.Type {
	return reflect.FuncOf (
		[] reflect.Type {},
		[] reflect.Type { a, b },
		false,
	)
}
func ReflectTypeMatchPair(t reflect.Type) (reflect.Type, reflect.Type, bool) {
	if !(t.Kind() == reflect.Func) { return nil, nil, false }
	if !(!(t.IsVariadic())) { return nil, nil, false }
	if !(t.NumIn() == 0) { return nil, nil, false }
	if !(t.NumOut() == 2) { return nil, nil, false }
	return t.Out(0), t.Out(1), true
}