Refactor a bit.

helper/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 helper
-
-import (
-        "encoding/json"
-
-        "github.com/luci/gae"
-)
-
-// GenericDSKey is an implementation of gae.DSKey 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 GenericDSKey in a namespace
-// whose Parent() is in a different namespace.
-//
-// GenericDSKey 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 GenericDSKey struct {
-        appID     string
-        namespace string
-        toks      []gae.DSKeyTok
-}
-
-var _ interface {
-        gae.DSKey
-        json.Marshaler
-        json.Unmarshaler
-} = (*GenericDSKey)(nil)
-
-// NewDSKeyToks creates a new GenericDSKey. It is the DSKey implementation
-// returned from the various DSPropertyMap serialization routines, as well as
-// the native key implementation for the in-memory implementation of gae.
-func NewDSKeyToks(appID, ns string, toks []gae.DSKeyTok) *GenericDSKey {
-        newToks := make([]gae.DSKeyTok, len(toks))
-        copy(newToks, toks)
-        return &GenericDSKey{appID, ns, newToks}
-}
-
-// NewDSKey is a wrapper around NewDSKeyToks which has an interface similar
-// to NewKey in the SDK.
-func NewDSKey(appID, ns, kind, stringID string, intID int64, parent gae.DSKey) *GenericDSKey {
-        _, _, toks := DSKeySplit(parent)
-        newToks := make([]gae.DSKeyTok, len(toks))
-        copy(newToks, toks)
-        newToks = append(newToks, gae.DSKeyTok{Kind: kind, StringID: stringID, IntID: intID})
-        return &GenericDSKey{appID, ns, newToks}
-}
-
-// NewDSKeyFromEncoded decodes and returns a *GenericDSKey
-func NewDSKeyFromEncoded(encoded string) (ret *GenericDSKey, err error) {
-        ret = &GenericDSKey{}
-        ret.appID, ret.namespace, ret.toks, err = DSKeyToksDecode(encoded)
-        return
-}
-
-func (k *GenericDSKey) lastTok() (ret gae.DSKeyTok) {
-        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 *GenericDSKey) AppID() string { return k.appID }
-
-// Namespace returns the namespace that this Key is for.
-func (k *GenericDSKey) Namespace() string { return k.namespace }
-
-// Kind returns the datastore kind of the entity.
-func (k *GenericDSKey) Kind() string { return k.lastTok().Kind }
-
-// StringID returns the string ID of the entity (if defined, otherwise "").
-func (k *GenericDSKey) StringID() string { return k.lastTok().StringID }
-
-// IntID returns the int64 ID of the entity (if defined, otherwise 0).
-func (k *GenericDSKey) IntID() int64 { return k.lastTok().IntID }
-
-// String returns a human-readable version of this Key.
-func (k *GenericDSKey) String() string { return DSKeyString(k) }
-
-// Parent returns the parent DSKey of this *GenericDSKey, or nil. The parent
-// will always have the concrete type of *GenericDSKey.
-func (k *GenericDSKey) Parent() gae.DSKey {
-        if len(k.toks) <= 1 {
-                return nil
-        }
-        return &GenericDSKey{k.appID, k.namespace, k.toks[:len(k.toks)-1]}
-}
-
-// MarshalJSON allows this key to be automatically marshaled by encoding/json.
-func (k *GenericDSKey) MarshalJSON() ([]byte, error) {
-        return DSKeyMarshalJSON(k)
-}
-
-// UnmarshalJSON allows this key to be automatically unmarshaled by encoding/json.
-func (k *GenericDSKey) UnmarshalJSON(buf []byte) error {
-        appID, namespace, toks, err := DSKeyUnmarshalJSON(buf)
-        if err != nil {
-                return err
-        }
-        *k = *NewDSKeyToks(appID, namespace, toks)
-        return nil
-}