1// build -goexperiment arenas
2
3// Copyright 2023 The Go Authors. All rights reserved.
4// Use of this source code is governed by a BSD-style
5// license that can be found in the LICENSE file.
6
7package main
8
9import (
10	"arena"
11	"log"
12	"reflect"
13)
14
15func main() {
16	a := arena.NewArena()
17	defer a.Free()
18
19	const iValue = 10
20
21	i := arena.New[int](a)
22	*i = iValue
23
24	if *i != iValue {
25		// This test doesn't reasonably expect this to fail. It's more likely
26		// that *i crashes for some reason. Still, why not check it.
27		log.Fatalf("bad i value: got %d, want %d", *i, iValue)
28	}
29
30	const wantLen = 125
31	const wantCap = 1912
32
33	sl := arena.MakeSlice[*int](a, wantLen, wantCap)
34	if len(sl) != wantLen {
35		log.Fatalf("bad arena slice length: got %d, want %d", len(sl), wantLen)
36	}
37	if cap(sl) != wantCap {
38		log.Fatalf("bad arena slice capacity: got %d, want %d", cap(sl), wantCap)
39	}
40	sl = sl[:cap(sl)]
41	for j := range sl {
42		sl[j] = i
43	}
44	for j := range sl {
45		if *sl[j] != iValue {
46			// This test doesn't reasonably expect this to fail. It's more likely
47			// that sl[j] crashes for some reason. Still, why not check it.
48			log.Fatalf("bad sl[j] value: got %d, want %d", *sl[j], iValue)
49		}
50	}
51
52	t := reflect.TypeOf(int(0))
53	v := reflect.ArenaNew(a, t)
54	if want := reflect.PointerTo(t); v.Type() != want {
55		log.Fatalf("unexpected type for arena-allocated value: got %s, want %s", v.Type(), want)
56	}
57	i2 := v.Interface().(*int)
58	*i2 = iValue
59
60	if *i2 != iValue {
61		// This test doesn't reasonably expect this to fail. It's more likely
62		// that *i crashes for some reason. Still, why not check it.
63		log.Fatalf("bad i2 value: got %d, want %d", *i2, iValue)
64	}
65}
66