Refactor keys and queries in datastore service and implementation.

service/datastore/dskey/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 dskey
-
-import (
-        "encoding/json"
-
-        ds "github.com/luci/gae/service/datastore"
-)
-
-// Generic 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 Generic in a namespace
-// whose Parent() is in a different namespace.
-//
-// Generic 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 Generic struct {
-        appID     string
-        namespace string
-        toks      []ds.KeyTok
-}
-
-var _ interface {
-        ds.Key
-        json.Marshaler
-        json.Unmarshaler
-} = (*Generic)(nil)
-
-// NewToks creates a new Generic. 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 NewToks(appID, ns string, toks []ds.KeyTok) *Generic {
-        newToks := make([]ds.KeyTok, len(toks))
-        copy(newToks, toks)
-        return &Generic{appID, ns, newToks}
-}
-
-// New is a wrapper around NewToks which has an interface similar
-// to NewKey in the SDK.
-func New(appID, ns, kind, stringID string, intID int64, parent ds.Key) *Generic {
-        _, _, toks := Split(parent)
-        newToks := make([]ds.KeyTok, len(toks))
-        copy(newToks, toks)
-        newToks = append(newToks, ds.KeyTok{Kind: kind, StringID: stringID, IntID: intID})
-        return &Generic{appID, ns, newToks}
-}
-
-// NewFromEncoded decodes and returns a *Generic
-func NewFromEncoded(encoded string) (ret *Generic, err error) {
-        ret = &Generic{}
-        ret.appID, ret.namespace, ret.toks, err = ToksDecode(encoded)
-        return
-}
-
-func (k *Generic) lastTok() ds.KeyTok {
-        if len(k.toks) > 0 {
-                return k.toks[len(k.toks)-1]
-        }
-        return ds.KeyTok{}
-}
-
-// AppID returns the application ID that this Key is for.
-func (k *Generic) AppID() string { return k.appID }
-
-// Namespace returns the namespace that this Key is for.
-func (k *Generic) Namespace() string { return k.namespace }
-
-// Kind returns the datastore kind of the entity.
-func (k *Generic) Kind() string { return k.lastTok().Kind }
-
-// StringID returns the string ID of the entity (if defined, otherwise "").
-func (k *Generic) StringID() string { return k.lastTok().StringID }
-
-// IntID returns the int64 ID of the entity (if defined, otherwise 0).
-func (k *Generic) IntID() int64 { return k.lastTok().IntID }
-
-// String returns a human-readable version of this Key.
-func (k *Generic) String() string { return String(k) }
-
-// Incomplete returns true iff k doesn't have an id yet
-func (k *Generic) Incomplete() bool { return Incomplete(k) }
-
-// Valid returns true if this key is complete and suitable for use with the
-// datastore. See the package-level Valid function for more information.
-func (k *Generic) Valid(allowSpecial bool, aid, ns string) bool {
-        return Valid(k, allowSpecial, aid, ns)
-}
-
-// PartialValid returns true if this key is suitable for use with a Put
-// operation. See the package-level PartialValid function for more information.
-func (k *Generic) PartialValid(aid, ns string) bool {
-        return PartialValid(k, aid, ns)
-}
-
-// Parent returns the parent Key of this *Generic, or nil. The parent
-// will always have the concrete type of *Generic.
-func (k *Generic) Parent() ds.Key {
-        if len(k.toks) <= 1 {
-                return nil
-        }
-        return &Generic{k.appID, k.namespace, k.toks[:len(k.toks)-1]}
-}
-
-// MarshalJSON allows this key to be automatically marshaled by encoding/json.
-func (k *Generic) MarshalJSON() ([]byte, error) {
-        return MarshalJSON(k)
-}
-
-// UnmarshalJSON allows this key to be automatically unmarshaled by encoding/json.
-func (k *Generic) UnmarshalJSON(buf []byte) error {
-        appID, namespace, toks, err := UnmarshalJSON(buf)
-        if err != nil {
-                return err
-        }
-        *k = *NewToks(appID, namespace, toks)
-        return nil
-}