mirror of
https://github.com/golang/go
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100 lines
2.8 KiB
Go
100 lines
2.8 KiB
Go
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// run -gcflags=-G=3
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// Copyright 2020 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package main
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import (
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"fmt"
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//"math"
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)
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type Numeric interface {
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type int, int8, int16, int32, int64,
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uint, uint8, uint16, uint32, uint64, uintptr,
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float32, float64,
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complex64, complex128
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}
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// numericAbs matches numeric types with an Abs method.
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type numericAbs[T any] interface {
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Numeric
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Abs() T
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}
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// AbsDifference computes the absolute value of the difference of
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// a and b, where the absolute value is determined by the Abs method.
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func absDifference[T numericAbs[T]](a, b T) T {
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d := a - b
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return d.Abs()
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}
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// orderedNumeric matches numeric types that support the < operator.
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type orderedNumeric interface {
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type int, int8, int16, int32, int64,
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uint, uint8, uint16, uint32, uint64, uintptr,
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float32, float64
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}
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// Complex matches the two complex types, which do not have a < operator.
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type Complex interface {
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type complex64, complex128
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}
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// orderedAbs is a helper type that defines an Abs method for
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// ordered numeric types.
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type orderedAbs[T orderedNumeric] T
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func (a orderedAbs[T]) Abs() orderedAbs[T] {
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// TODO(danscales): orderedAbs[T] conversion shouldn't be needed
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if a < orderedAbs[T](0) {
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return -a
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}
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return a
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}
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// complexAbs is a helper type that defines an Abs method for
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// complex types.
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// type complexAbs[T Complex] T
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// func (a complexAbs[T]) Abs() complexAbs[T] {
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// r := float64(real(a))
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// i := float64(imag(a))
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// d := math.Sqrt(r * r + i * i)
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// return complexAbs[T](complex(d, 0))
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// }
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// OrderedAbsDifference returns the absolute value of the difference
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// between a and b, where a and b are of an ordered type.
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func orderedAbsDifference[T orderedNumeric](a, b T) T {
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return T(absDifference(orderedAbs[T](a), orderedAbs[T](b)))
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}
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// ComplexAbsDifference returns the absolute value of the difference
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// between a and b, where a and b are of a complex type.
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// func complexAbsDifference[T Complex](a, b T) T {
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// return T(absDifference(complexAbs[T](a), complexAbs[T](b)))
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// }
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func main() {
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if got, want := orderedAbsDifference(1.0, -2.0), 3.0; got != want {
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panic(fmt.Sprintf("got = %v, want = %v", got, want))
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}
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if got, want := orderedAbsDifference(-1.0, 2.0), 3.0; got != want {
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panic(fmt.Sprintf("got = %v, want = %v", got, want))
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}
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if got, want := orderedAbsDifference(-20, 15), 35; got != want {
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panic(fmt.Sprintf("got = %v, want = %v", got, want))
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}
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// Still have to handle built-ins real/abs to make this work
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// if got, want := complexAbsDifference(5.0 + 2.0i, 2.0 - 2.0i), 5; got != want {
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// panic(fmt.Sprintf("got = %v, want = %v", got, want)
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// }
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// if got, want := complexAbsDifference(2.0 - 2.0i, 5.0 + 2.0i), 5; got != want {
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// panic(fmt.Sprintf("got = %v, want = %v", got, want)
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// }
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}
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