1// Copyright 2020 The Go Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style
3// license that can be found in the LICENSE file.
4
5package cache
6
7import (
8	"io"
9
10	"golang.org/x/tools/internal/event/label"
11)
12
13var (
14	KeyCreateSession   = NewSessionKey("create_session", "A new session was added")
15	KeyUpdateSession   = NewSessionKey("update_session", "Updated information about a session")
16	KeyShutdownSession = NewSessionKey("shutdown_session", "A session was shut down")
17)
18
19// SessionKey represents an event label key that has a *Session value.
20type SessionKey struct {
21	name        string
22	description string
23}
24
25// NewSessionKey creates a new Key for *Session values.
26func NewSessionKey(name, description string) *SessionKey {
27	return &SessionKey{name: name, description: description}
28}
29
30func (k *SessionKey) Name() string        { return k.name }
31func (k *SessionKey) Description() string { return k.description }
32
33func (k *SessionKey) Format(w io.Writer, buf []byte, l label.Label) {
34	io.WriteString(w, k.From(l).ID())
35}
36
37// Of creates a new Label with this key and the supplied session.
38func (k *SessionKey) Of(v *Session) label.Label { return label.OfValue(k, v) }
39
40// Get can be used to get the session for the key from a label.Map.
41func (k *SessionKey) Get(lm label.Map) *Session {
42	if t := lm.Find(k); t.Valid() {
43		return k.From(t)
44	}
45	return nil
46}
47
48// From can be used to get the session value from a Label.
49func (k *SessionKey) From(t label.Label) *Session {
50	err, _ := t.UnpackValue().(*Session)
51	return err
52}
53