| // run |
| |
| // 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 main |
| |
| import ( |
| "fmt" |
| ) |
| |
| type Ordered interface { |
| ~int | ~int8 | ~int16 | ~int32 | ~int64 | |
| ~uint | ~uint8 | ~uint16 | ~uint32 | ~uint64 | ~uintptr | |
| ~float32 | ~float64 | |
| ~string |
| } |
| |
| // _List is a linked list of ordered values of type T. |
| type _List[T Ordered] struct { |
| next *_List[T] |
| val T |
| } |
| |
| func (l *_List[T]) Largest() T { |
| var max T |
| for p := l; p != nil; p = p.next { |
| if p.val > max { |
| max = p.val |
| } |
| } |
| return max |
| } |
| |
| type OrderedNum interface { |
| ~int | ~int8 | ~int16 | ~int32 | ~int64 | |
| ~uint | ~uint8 | ~uint16 | ~uint32 | ~uint64 | ~uintptr | |
| ~float32 | ~float64 |
| } |
| |
| // _ListNum is a linked _List of ordered numeric values of type T. |
| type _ListNum[T OrderedNum] struct { |
| next *_ListNum[T] |
| val T |
| } |
| |
| const Clip = 5 |
| |
| // clippedLargest returns the largest in the list of OrderNums, but a max of 5. |
| // Test use of untyped constant in an expression with a generically-typed parameter |
| func (l *_ListNum[T]) ClippedLargest() T { |
| var max T |
| for p := l; p != nil; p = p.next { |
| if p.val > max && p.val < Clip { |
| max = p.val |
| } |
| } |
| return max |
| } |
| |
| func main() { |
| i3 := &_List[int]{nil, 1} |
| i2 := &_List[int]{i3, 3} |
| i1 := &_List[int]{i2, 2} |
| if got, want := i1.Largest(), 3; got != want { |
| panic(fmt.Sprintf("got %d, want %d", got, want)) |
| } |
| |
| b3 := &_List[byte]{nil, byte(1)} |
| b2 := &_List[byte]{b3, byte(3)} |
| b1 := &_List[byte]{b2, byte(2)} |
| if got, want := b1.Largest(), byte(3); got != want { |
| panic(fmt.Sprintf("got %d, want %d", got, want)) |
| } |
| |
| f3 := &_List[float64]{nil, 13.5} |
| f2 := &_List[float64]{f3, 1.2} |
| f1 := &_List[float64]{f2, 4.5} |
| if got, want := f1.Largest(), 13.5; got != want { |
| panic(fmt.Sprintf("got %f, want %f", got, want)) |
| } |
| |
| s3 := &_List[string]{nil, "dd"} |
| s2 := &_List[string]{s3, "aa"} |
| s1 := &_List[string]{s2, "bb"} |
| if got, want := s1.Largest(), "dd"; got != want { |
| panic(fmt.Sprintf("got %s, want %s", got, want)) |
| } |
| |
| j3 := &_ListNum[int]{nil, 1} |
| j2 := &_ListNum[int]{j3, 32} |
| j1 := &_ListNum[int]{j2, 2} |
| if got, want := j1.ClippedLargest(), 2; got != want { |
| panic(fmt.Sprintf("got %d, want %d", got, want)) |
| } |
| g3 := &_ListNum[float64]{nil, 13.5} |
| g2 := &_ListNum[float64]{g3, 1.2} |
| g1 := &_ListNum[float64]{g2, 4.5} |
| if got, want := g1.ClippedLargest(), 4.5; got != want { |
| panic(fmt.Sprintf("got %f, want %f", got, want)) |
| } |
| } |