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Diffstat (limited to 'test/typeparam/absdiff3.go')
-rw-r--r-- | test/typeparam/absdiff3.go | 98 |
1 files changed, 98 insertions, 0 deletions
diff --git a/test/typeparam/absdiff3.go b/test/typeparam/absdiff3.go new file mode 100644 index 0000000..c85cd1d --- /dev/null +++ b/test/typeparam/absdiff3.go @@ -0,0 +1,98 @@ +// run + +// Copyright 2022 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. + +// absdiff example using a function argument rather than attaching an +// Abs method to a structure containing base types. + +package main + +import ( + "fmt" + "math" +) + +type Numeric interface { + OrderedNumeric | Complex +} + +// absDifference computes the absolute value of the difference of +// a and b, where the absolute value is determined by the abs function. +func absDifference[T Numeric](a, b T, abs func(a T) T) T { + return abs(a - b) +} + +// OrderedNumeric matches numeric types that support the < operator. +type OrderedNumeric interface { + ~int | ~int8 | ~int16 | ~int32 | ~int64 | + ~uint | ~uint8 | ~uint16 | ~uint32 | ~uint64 | ~uintptr | + ~float32 | ~float64 +} + +func Abs[T OrderedNumeric](a T) T { + if a < 0 { + return -a + } + return a +} + +// Complex matches the two complex types, which do not have a < operator. +type Complex interface { + ~complex64 | ~complex128 +} + +func realimag(x any) (re, im float64) { + switch z := x.(type) { + case complex64: + re = float64(real(z)) + im = float64(imag(z)) + case complex128: + re = real(z) + im = imag(z) + default: + panic("unknown complex type") + } + return +} + +func ComplexAbs[T Complex](a T) T { + // TODO use direct conversion instead of realimag once #50937 is fixed + r, i := realimag(a) + // r := float64(real(a)) + // i := float64(imag(a)) + d := math.Sqrt(r*r + i*i) + return 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 absDifference(a, b, Abs[T]) +} + +// 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 absDifference(a, b, ComplexAbs[T]) +} + +func main() { + 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)) + } +} |