golang absdiff 代码
文件路径：/test/typeparam/absdiff.go
/ run
/ Copyright 2020 The Go Authors. All rights reserved.
/ Use of this source code is governed by a BSD-style
/ license that can be found in the LICENSE file.
package main
type Numeric interface {
~int | ~int8 | ~int16 | ~int32 | ~int64 |
~uint | ~uint8 | ~uint16 | ~uint32 | ~uint64 | ~uintptr |
~float32 | ~float64 |
~complex64 | ~complex128
}
/ numericAbs matches numeric types with an Abs method.
type numericAbs[T any] interface {
Numeric
Abs() T
}
/ AbsDifference computes the absolute value of the difference of
/ a and b, where the absolute value is determined by the Abs method.
func absDifference[T numericAbs[T]](a, b T) T {
d := a - b
return d.Abs()
}
/ orderedNumeric matches numeric types that support the < operator.
type orderedNumeric interface {
~int | ~int8 | ~int16 | ~int32 | ~int64 |
~uint | ~uint8 | ~uint16 | ~uint32 | ~uint64 | ~uintptr |
~float32 | ~float64
}
/ Complex matches the two complex types, which do not have a < operator.
type Complex interface {
~complex64 | ~complex128
}
/ For now, a lone type parameter is not permitted as RHS in a type declaration (issue #45639).
/ / orderedAbs is a helper type that defines an Abs method for
/ / ordered numeric types.
/ type orderedAbs[T orderedNumeric] T
/
/ func (a orderedAbs[T]) Abs() orderedAbs[T] {
/ if a < 0 {
/ return -a
/ }
/ return a
/ }
/
/ / complexAbs is a helper type that defines an Abs method for
/ / complex types.
/ type complexAbs[T Complex] T
/
/ func (a complexAbs[T]) Abs() complexAbs[T] {
/ r := float64(real(a))
/ i := float64(imag(a))
/ d := math.Sqrt(r*r + i*i)
/ return complexAbs[T](complex(d, 0))
/ }
/
/ / OrderedAbsDifference returns the absolute value of the difference
/ / between a and b, where a and b are of an ordered type.
/ func orderedAbsDifference[T orderedNumeric](a, b T) T {
/ return T(absDifference(orderedAbs[T](a), orderedAbs[T](b)))
/ }
/
/ / ComplexAbsDifference returns the absolute value of the difference
/ / between a and b, where a and b are of a complex type.
/ func complexAbsDifference[T Complex](a, b T) T {
/ return T(absDifference(complexAbs[T](a), complexAbs[T](b)))
/ }
func main() {
/ / For now, a lone type parameter is not permitted as RHS in a type declaration (issue #45639).
/ if got, want := orderedAbsDifference(1.0, -2.0), 3.0; got != want {
/ panic(fmt.Sprintf("got = %v, want = %v", got, want))
/ }
/ if got, want := orderedAbsDifference(-1.0, 2.0), 3.0; got != want {
/ panic(fmt.Sprintf("got = %v, want = %v", got, want))
/ }
/ if got, want := orderedAbsDifference(-20, 15), 35; got != want {
/ panic(fmt.Sprintf("got = %v, want = %v", got, want))
/ }
/
/ if got, want := complexAbsDifference(5.0+2.0i, 2.0-2.0i), 5+0i; got != want {
/ panic(fmt.Sprintf("got = %v, want = %v", got, want))
/ }
/ if got, want := complexAbsDifference(2.0-2.0i, 5.0+2.0i), 5+0i; got != want {
/ panic(fmt.Sprintf("got = %v, want = %v", got, want))
/ }
}