datastore: Update AllocateIDs to take keys.

service/datastore/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 (
         "bytes"
         "encoding/base64"
         "encoding/json"
@@ skipping 396 matching lines @@
                         fmt.Fprintf(ret, ", %s, %s", gqlQuoteString(t.Kind), gqlQuoteString(t.StringID))
                 }
         }
         if _, err := ret.WriteString(")"); err != nil {
                 panic(err)
         }
         return ret.String()
 }
 
 // Equal returns true iff the two keys represent identical key values.
-func (k *Key) Equal(other *Key) (ret bool) {
+func (k *Key) Equal(other *Key) bool {
+        return k.SameKind(other) && (k.LastTok() == other.LastTok())
+}
+
+// SameKind asserts that other refers to the same entity as k. This checks the
+// full lineage of the key.
+func (k *Key) SameKind(other *Key) (ret bool) {
         ret = (k.appID == other.appID &&
                 k.namespace == other.namespace &&
                 len(k.toks) == len(other.toks))
         if ret {
                 for i, t := range k.toks {
-                        if ret = t == other.toks[i]; !ret {
-                                return
+                        if i == len(k.toks)-1 {
+                                // Last token: check only Kind.
+                                if ret = (t.Kind == other.toks[i].Kind); !ret {
+                                        return
+                                }
+                        } else {
+                                if ret = t == other.toks[i]; !ret {
+                                        return
+                                }
                         }
                 }
         }
         return
 }
 
 // Split componentizes the key into pieces (AppID, Namespace and tokens)
 //
 // Each token represents one piece of they key's 'path'.
 //
@@ skipping 17 matching lines @@
         for _, t := range k.toks {
                 ret += int64(len(t.Kind))
                 if t.StringID != "" {
                         ret += int64(len(t.StringID))
                 } else {
                         ret += 8
                 }
         }
         return ret
 }