Split off serialization and key functions to their own packages.

service/datastore/dskey/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.
 
 // adapted from github.com/golang/appengine/datastore
 
-package datastore
+package dskey
 
 import (
         "bytes"
         "encoding/base64"
         "errors"
         "strconv"
         "strings"
 
+        "github.com/golang/protobuf/proto"
+        ds "github.com/luci/gae/service/datastore"
         pb "github.com/luci/gae/service/datastore/internal/protos/datastore"
-
-        "github.com/golang/protobuf/proto"
 )
 
-// KeyEncode encodes the provided key as a base64-encoded protobuf.
+// Encode encodes the provided key as a base64-encoded protobuf.
 //
 // This encoding is compatible with the SDK-provided encoding and is agnostic
 // to the underlying implementation of the Key.
-func KeyEncode(k Key) string {
+//
+// It's encoded with the urlsafe base64 table.
+func Encode(k ds.Key) string {
         n := 0
         for i := k; i != nil; i = i.Parent() {
                 n++
         }
         e := make([]*pb.Path_Element, n)
         for i := k; i != nil; i = i.Parent() {
                 n--
                 kind := i.Kind()
                 e[n] = &pb.Path_Element{
                         Type: &kind,
@@ skipping 20 matching lines @@
                 },
         })
         if err != nil {
                 panic(err)
         }
 
         // trim padding
         return strings.TrimRight(base64.URLEncoding.EncodeToString(r), "=")
 }
 
-// KeyToksDecode decodes a base64-encoded protobuf representation of a Key
+// ToksDecode decodes a base64-encoded protobuf representation of a Key
 // into a tokenized form. This is so that implementations of the gae wrapper
 // can decode to their own implementation of Key.
 //
 // This encoding is compatible with the SDK-provided encoding and is agnostic
 // to the underlying implementation of the Key.
-func KeyToksDecode(encoded string) (appID, namespace string, toks []KeyTok, err error) {
+func ToksDecode(encoded string) (appID, namespace string, toks []ds.KeyTok, err error) {
         // Re-add padding
         if m := len(encoded) % 4; m != 0 {
                 encoded += strings.Repeat("=", 4-m)
         }
         b, err := base64.URLEncoding.DecodeString(encoded)
         if err != nil {
                 return
         }
 
         r := &pb.Reference{}
         if err = proto.Unmarshal(b, r); err != nil {
                 return
         }
 
         appID = r.GetApp()
         namespace = r.GetNameSpace()
-        toks = make([]KeyTok, len(r.Path.Element))
+        toks = make([]ds.KeyTok, len(r.Path.Element))
         for i, e := range r.Path.Element {
-                toks[i] = KeyTok{
+                toks[i] = ds.KeyTok{
                         Kind:     e.GetType(),
                         IntID:    e.GetId(),
                         StringID: e.GetName(),
                 }
         }
         return
 }
 
-// KeyMarshalJSON returns a MarshalJSON-compatible serialization of a Key.
-func KeyMarshalJSON(k Key) ([]byte, error) {
-        return []byte(`"` + KeyEncode(k) + `"`), nil
+// MarshalJSON returns a MarshalJSON-compatible serialization of a Key.
+func MarshalJSON(k ds.Key) ([]byte, error) {
+        return []byte(`"` + Encode(k) + `"`), nil
 }
 
-// KeyUnmarshalJSON returns the tokenized version of a Key as encoded by
-// KeyMarshalJSON.
-func KeyUnmarshalJSON(buf []byte) (appID, namespace string, toks []KeyTok, err error) {
+// UnmarshalJSON returns the tokenized version of a ds.Key as encoded by
+// MarshalJSON.
+func UnmarshalJSON(buf []byte) (appID, namespace string, toks []ds.KeyTok, err error) {
         if len(buf) < 2 || buf[0] != '"' || buf[len(buf)-1] != '"' {
                 err = errors.New("datastore: bad JSON key")
         } else {
-                appID, namespace, toks, err = KeyToksDecode(string(buf[1 : len(buf)-1]))
+                appID, namespace, toks, err = ToksDecode(string(buf[1 : len(buf)-1]))
         }
         return
 }
 
-// KeyIncomplete returns true iff k doesn't have an id yet.
-func KeyIncomplete(k Key) bool {
+// Incomplete returns true iff k doesn't have an id yet.
+func Incomplete(k ds.Key) bool {
         return k != nil && k.StringID() == "" && k.IntID() == 0
 }
 
-// KeyValid determines if a key is valid, according to a couple rules:
+// Valid determines if a key is valid, according to a couple rules:
 //   - k is not nil
 //   - every token of k:
 //     - (if !allowSpecial) token's kind doesn't start with '__'
 //     - token's kind and appid are non-blank
 //     - token is not incomplete
 //   - all tokens have the same namespace and appid
-func KeyValid(k Key, allowSpecial bool, aid, ns string) bool {
+func Valid(k ds.Key, allowSpecial bool, aid, ns string) bool {
         if k == nil {
                 return false
         }
         if aid != k.AppID() || ns != k.Namespace() {
                 return false
         }
         for ; k != nil; k = k.Parent() {
                 if !allowSpecial && len(k.Kind()) >= 2 && k.Kind()[:2] == "__" {
                         return false
                 }
                 if k.Kind() == "" || k.AppID() == "" {
                         return false
                 }
                 if k.StringID() != "" && k.IntID() != 0 {
                         return false
                 }
                 if k.Parent() != nil {
-                        if KeyIncomplete(k.Parent()) {
+                        if k.Parent().Incomplete() {
                                 return false
                         }
                         if k.Parent().AppID() != k.AppID() || k.Parent().Namespace() != k.Namespace() {
                                 return false
                         }
                 }
         }
         return true
 }
 
-// KeyRoot returns the entity root for the given key.
-func KeyRoot(k Key) Key {
+// PartialValid returns true iff this key is suitable for use in a Put
+// operation. This is the same as Valid(k, false, ...), but also allowing k to
+// be Incomplete().
+func PartialValid(k ds.Key, aid, ns string) bool {
+        if k.Incomplete() {
+                k = New(k.AppID(), k.Namespace(), k.Kind(), "", 1, k.Parent())
+        }
+        return Valid(k, false, aid, ns)
+}
+
+// Root returns the entity root for the given key.
+func Root(k ds.Key) ds.Key {
         for k != nil && k.Parent() != nil {
                 k = k.Parent()
         }
         return k
 }
 
-// KeysEqual returns true iff the two keys represent identical key values.
-func KeysEqual(a, b Key) (ret bool) {
+// Equal returns true iff the two keys represent identical key values.
+func Equal(a, b ds.Key) (ret bool) {
         ret = (a.Kind() == b.Kind() &&
                 a.StringID() == b.StringID() &&
                 a.IntID() == b.IntID() &&
                 a.AppID() == b.AppID() &&
                 a.Namespace() == b.Namespace())
         if !ret {
                 return
         }
         ap, bp := a.Parent(), b.Parent()
-        return (ap == nil && bp == nil) || KeysEqual(ap, bp)
+        return (ap == nil && bp == nil) || Equal(ap, bp)
 }
 
-func marshalDSKey(b *bytes.Buffer, k Key) {
+func marshalDSKey(b *bytes.Buffer, k ds.Key) {
         if k.Parent() != nil {
                 marshalDSKey(b, k.Parent())
         }
         b.WriteByte('/')
         b.WriteString(k.Kind())
         b.WriteByte(',')
         if k.StringID() != "" {
                 b.WriteString(k.StringID())
         } else {
                 b.WriteString(strconv.FormatInt(k.IntID(), 10))
         }
 }
 
-// KeyString returns a human-readable representation of the key, and is the
+// String returns a human-readable representation of the key, and is the
 // typical implementation of Key.String() (though it isn't guaranteed to be)
-func KeyString(k Key) string {
+func String(k ds.Key) string {
         if k == nil {
                 return ""
         }
         b := bytes.NewBuffer(make([]byte, 0, 512))
         marshalDSKey(b, k)
         return b.String()
 }
 
-// KeySplit splits the key into its constituent parts. Note that if the key is
-// not KeyValid, this method may not provide a round-trip for k.
-func KeySplit(k Key) (appID, namespace string, toks []KeyTok) {
+// Split splits the key into its constituent parts. Note that if the key is
+// not Valid, this method may not provide a round-trip for k.
+func Split(k ds.Key) (appID, namespace string, toks []ds.KeyTok) {
         if k == nil {
                 return
         }
 
-        if sk, ok := k.(*GenericKey); ok {
+        if sk, ok := k.(*Generic); ok {
                 if sk == nil {
                         return
                 }
                 return sk.appID, sk.namespace, sk.toks
         }
 
         n := 0
         for i := k; i != nil; i = i.Parent() {
                 n++
         }
-        toks = make([]KeyTok, n)
+        toks = make([]ds.KeyTok, n)
         for i := k; i != nil; i = i.Parent() {
                 n--
                 toks[n].IntID = i.IntID()
                 toks[n].StringID = i.StringID()
                 toks[n].Kind = i.Kind()
         }
         appID = k.AppID()
         namespace = k.Namespace()
         return
 }