mirror of
https://github.com/golang/go
synced 2024-11-22 09:04:42 -07:00
e24977d231
The next CL will remove the -G flag, effectively hard-coding it to its current default (-G=3). Change-Id: Ib4743b529206928f9f1cca9fdb19989728327831 Reviewed-on: https://go-review.googlesource.com/c/go/+/388534 Reviewed-by: Keith Randall <khr@golang.org> Trust: Matthew Dempsky <mdempsky@google.com> Run-TryBot: Matthew Dempsky <mdempsky@google.com> TryBot-Result: Gopher Robot <gobot@golang.org>
68 lines
1.5 KiB
Go
68 lines
1.5 KiB
Go
// 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.
|
|
|
|
// Testing various generic uses of indexing, both for reads and writes.
|
|
|
|
package main
|
|
|
|
import "fmt"
|
|
|
|
// Can index an argument (read/write) constrained to be a slice or an array.
|
|
func Index1[T interface{ []int64 | [5]int64 }](x T) int64 {
|
|
x[2] = 5
|
|
return x[3]
|
|
}
|
|
|
|
// Can index an argument (read) constrained to be a byte array or a string.
|
|
func Index2[T interface{ []byte | string }](x T) byte {
|
|
return x[3]
|
|
}
|
|
|
|
// Can index an argument (write) constrained to be a byte array, but not a string.
|
|
func Index2a[T interface{ []byte }](x T) byte {
|
|
x[2] = 'b'
|
|
return x[3]
|
|
}
|
|
|
|
// Can index an argument (read/write) constrained to be a map. Maps can't
|
|
// be combined with any other type for indexing purposes.
|
|
func Index3[T interface{ map[int]int64 }](x T) int64 {
|
|
x[2] = 43
|
|
return x[3]
|
|
}
|
|
|
|
// But the type of the map keys or values can be parameterized.
|
|
func Index4[T any](x map[int]T) T {
|
|
var zero T
|
|
x[2] = zero
|
|
return x[3]
|
|
}
|
|
|
|
func test[T comparable](got, want T) {
|
|
if got != want {
|
|
panic(fmt.Sprintf("got %v, want %v", got, want))
|
|
}
|
|
}
|
|
|
|
func main() {
|
|
x := make([]int64, 4)
|
|
x[3] = 2
|
|
y := [5]int64{1, 2, 3, 4, 5}
|
|
z := "abcd"
|
|
w := make([]byte, 4)
|
|
w[3] = 5
|
|
v := make(map[int]int64)
|
|
v[3] = 18
|
|
|
|
test(Index1(x), int64(2))
|
|
test(Index1(y), int64(4))
|
|
test(Index2(z), byte(100))
|
|
test(Index2(w), byte(5))
|
|
test(Index2a(w), byte(5))
|
|
test(Index3(v), int64(18))
|
|
test(Index4(v), int64(18))
|
|
}
|