Split off serialization and key functions to their own packages.

service/datastore/generic_key.go

-// Copyright 2015 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-package datastore
-
-import (
-        "encoding/json"
-)
-
-// GenericKey is an implementation of Key which doesn't rely on the
-// SDK's implementation. It differs slightly in that it's not recursive (and
-// thus cannot express some of the invalid Key's that the SDK implementation
-// can). In particular, it's not possible to have a GenericKey in a namespace
-// whose Parent() is in a different namespace.
-//
-// GenericKey also implements json.Marshaler and json.Unmarshaler so it's
-// suitable for use in structs which need to serialize both to json and to
-// datastore.
-type GenericKey struct {
-        appID     string
-        namespace string
-        toks      []KeyTok
-}
-
-var _ interface {
-        Key
-        json.Marshaler
-        json.Unmarshaler
-} = (*GenericKey)(nil)
-
-// NewKeyToks creates a new GenericKey. It is the Key implementation
-// returned from the various PropertyMap serialization routines, as well as
-// the native key implementation for the in-memory implementation of gae.
-func NewKeyToks(appID, ns string, toks []KeyTok) *GenericKey {
-        newToks := make([]KeyTok, len(toks))
-        copy(newToks, toks)
-        return &GenericKey{appID, ns, newToks}
-}
-
-// NewKey is a wrapper around NewKeyToks which has an interface similar
-// to NewKey in the SDK.
-func NewKey(appID, ns, kind, stringID string, intID int64, parent Key) *GenericKey {
-        _, _, toks := KeySplit(parent)
-        newToks := make([]KeyTok, len(toks))
-        copy(newToks, toks)
-        newToks = append(newToks, KeyTok{Kind: kind, StringID: stringID, IntID: intID})
-        return &GenericKey{appID, ns, newToks}
-}
-
-// NewKeyFromEncoded decodes and returns a *GenericKey
-func NewKeyFromEncoded(encoded string) (ret *GenericKey, err error) {
-        ret = &GenericKey{}
-        ret.appID, ret.namespace, ret.toks, err = KeyToksDecode(encoded)
-        return
-}
-
-func (k *GenericKey) lastTok() (ret KeyTok) {
-        if len(k.toks) > 0 {
-                ret = k.toks[len(k.toks)-1]
-        }
-        return
-}
-
-// AppID returns the application ID that this Key is for.
-func (k *GenericKey) AppID() string { return k.appID }
-
-// Namespace returns the namespace that this Key is for.
-func (k *GenericKey) Namespace() string { return k.namespace }
-
-// Kind returns the datastore kind of the entity.
-func (k *GenericKey) Kind() string { return k.lastTok().Kind }
-
-// StringID returns the string ID of the entity (if defined, otherwise "").
-func (k *GenericKey) StringID() string { return k.lastTok().StringID }
-
-// IntID returns the int64 ID of the entity (if defined, otherwise 0).
-func (k *GenericKey) IntID() int64 { return k.lastTok().IntID }
-
-// String returns a human-readable version of this Key.
-func (k *GenericKey) String() string { return KeyString(k) }
-
-// Parent returns the parent Key of this *GenericKey, or nil. The parent
-// will always have the concrete type of *GenericKey.
-func (k *GenericKey) Parent() Key {
-        if len(k.toks) <= 1 {
-                return nil
-        }
-        return &GenericKey{k.appID, k.namespace, k.toks[:len(k.toks)-1]}
-}
-
-// MarshalJSON allows this key to be automatically marshaled by encoding/json.
-func (k *GenericKey) MarshalJSON() ([]byte, error) {
-        return KeyMarshalJSON(k)
-}
-
-// UnmarshalJSON allows this key to be automatically unmarshaled by encoding/json.
-func (k *GenericKey) UnmarshalJSON(buf []byte) error {
-        appID, namespace, toks, err := KeyUnmarshalJSON(buf)
-        if err != nil {
-                return err
-        }
-        *k = *NewKeyToks(appID, namespace, toks)
-        return nil
-}