Split off serialization and key functions to their own packages.

service/datastore/raw_interface.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 (
         "fmt"
 
         "golang.org/x/net/context"
 )
 
 // Key is the equivalent of *datastore.Key from the original SDK, except that
 // it can have multiple implementations. See helper.Key* methods for missing
 // methods like KeyIncomplete (and some new ones like KeyValid).
 type Key interface {
         Kind() string
         StringID() string
         IntID() int64
         Parent() Key
         AppID() string
         Namespace() string
 
+        // Incomplete returns true iff k doesn't have an id yet.
+        Incomplete() bool
+
+        // 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
+        Valid(allowSpecial bool, aid, ns string) bool
+
+        // PartialValid determines if a key is valid for a Put operation. This is
+        // like Valid(false, aid, ns), except that the childmost key is allowed to
+        // be Incomplete().
+        PartialValid(aid, ns string) bool
+
         String() string
 }
 
 // KeyTok is a single token from a multi-part Key.
 type KeyTok struct {
         Kind     string
         IntID    int64
         StringID string
 }
 
@@ skipping 156 matching lines @@
         //   - len(keys) > 0
         //   - all keys are Valid, !Incomplete, and in the current namespace
         //   - none keys of the keys are 'special' (use a kind prefixed with '__')
         //   - cb is not nil
         DeleteMulti(keys []Key, cb DeleteMultiCB) error
 
         // Testable returns the Testable interface for the implementation, or nil if
         // there is none.
         Testable() Testable
 }