| // Copyright 2021 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 a | |
| 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))) | |
| // } | |