1//go:build go1.21
 2// +build go1.21
 3
 4/*
 5Copyright 2019 The logr Authors.
 6
 7Licensed under the Apache License, Version 2.0 (the "License");
 8you may not use this file except in compliance with the License.
 9You may obtain a copy of the License at
10
11    http://www.apache.org/licenses/LICENSE-2.0
12
13Unless required by applicable law or agreed to in writing, software
14distributed under the License is distributed on an "AS IS" BASIS,
15WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
16See the License for the specific language governing permissions and
17limitations under the License.
18*/
19
20package logr
21
22import (
23	"context"
24	"fmt"
25	"log/slog"
26)
27
28// FromContext returns a Logger from ctx or an error if no Logger is found.
29func FromContext(ctx context.Context) (Logger, error) {
30	v := ctx.Value(contextKey{})
31	if v == nil {
32		return Logger{}, notFoundError{}
33	}
34
35	switch v := v.(type) {
36	case Logger:
37		return v, nil
38	case *slog.Logger:
39		return FromSlogHandler(v.Handler()), nil
40	default:
41		// Not reached.
42		panic(fmt.Sprintf("unexpected value type for logr context key: %T", v))
43	}
44}
45
46// FromContextAsSlogLogger returns a slog.Logger from ctx or nil if no such Logger is found.
47func FromContextAsSlogLogger(ctx context.Context) *slog.Logger {
48	v := ctx.Value(contextKey{})
49	if v == nil {
50		return nil
51	}
52
53	switch v := v.(type) {
54	case Logger:
55		return slog.New(ToSlogHandler(v))
56	case *slog.Logger:
57		return v
58	default:
59		// Not reached.
60		panic(fmt.Sprintf("unexpected value type for logr context key: %T", v))
61	}
62}
63
64// FromContextOrDiscard returns a Logger from ctx.  If no Logger is found, this
65// returns a Logger that discards all log messages.
66func FromContextOrDiscard(ctx context.Context) Logger {
67	if logger, err := FromContext(ctx); err == nil {
68		return logger
69	}
70	return Discard()
71}
72
73// NewContext returns a new Context, derived from ctx, which carries the
74// provided Logger.
75func NewContext(ctx context.Context, logger Logger) context.Context {
76	return context.WithValue(ctx, contextKey{}, logger)
77}
78
79// NewContextWithSlogLogger returns a new Context, derived from ctx, which carries the
80// provided slog.Logger.
81func NewContextWithSlogLogger(ctx context.Context, logger *slog.Logger) context.Context {
82	return context.WithValue(ctx, contextKey{}, logger)
83}