1// Copyright 2012 Google Inc. All rights reserved.
2// Use of this source code is governed by the Apache 2.0
3// license that can be found in the LICENSE file.
4
5package appengine
6
7import (
8	"fmt"
9	"regexp"
10
11	"appengine_internal"
12	basepb "appengine_internal/base"
13	"appengine_internal/github.com/golang/protobuf/proto"
14)
15
16// Namespace returns a replacement context that operates within the given namespace.
17func Namespace(c Context, namespace string) (Context, error) {
18	if !validNamespace.MatchString(namespace) {
19		return nil, fmt.Errorf("appengine: namespace %q does not match /%s/", namespace, validNamespace)
20	}
21	return &namespacedContext{
22		Context:   c,
23		namespace: namespace,
24	}, nil
25}
26
27// validNamespace matches valid namespace names.
28var validNamespace = regexp.MustCompile(`^[0-9A-Za-z._-]{0,100}$`)
29
30// namespacedContext wraps a Context to support namespaces.
31type namespacedContext struct {
32	Context
33	namespace string
34}
35
36func (n *namespacedContext) Call(service, method string, in, out appengine_internal.ProtoMessage, opts *appengine_internal.CallOptions) error {
37	// Apply any namespace mods.
38	if mod, ok := appengine_internal.NamespaceMods[service]; ok {
39		mod(in, n.namespace)
40	}
41	if service == "__go__" && method == "GetNamespace" {
42		out.(*basepb.StringProto).Value = proto.String(n.namespace)
43		return nil
44	}
45
46	return n.Context.Call(service, method, in, out, opts)
47}
48