Reland: Refactor current GAE abstraction library to be free of the SDK*

go/src/infra/gae/libs/gae/prod/datastore_key.go

Index: go/src/infra/gae/libs/gae/prod/datastore_key.go
diff --git a/go/src/infra/gae/libs/gae/prod/datastore_key.go b/go/src/infra/gae/libs/gae/prod/datastore_key.go
new file mode 100644
index 0000000000000000000000000000000000000000..2b823114f3c6006d2124ba715420fbea9d1d47fe
--- /dev/null
+++ b/go/src/infra/gae/libs/gae/prod/datastore_key.go
@@ -0,0 +1,82 @@
+// 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 prod
+
+import (
+	"infra/gae/libs/gae"
+	"infra/gae/libs/gae/helper"
+
+	"google.golang.org/appengine/datastore"
+)
+
+type dsKeyImpl struct {
+	*datastore.Key
+}
+
+var _ gae.DSKey = dsKeyImpl{}
+
+func (k dsKeyImpl) Equal(other gae.DSKey) bool { return k.Key.Equal(dsF2R(other)) }
+func (k dsKeyImpl) Parent() gae.DSKey          { return dsR2F(k.Key.Parent()) }
+func (k dsKeyImpl) Root() gae.DSKey            { return helper.DSKeyRoot(k) }
+func (k dsKeyImpl) Valid(ns string, allowSpecial bool) bool {
+	return helper.DSKeyValid(k, ns, allowSpecial)
+}
+
+// dsR2F (DS real-to-fake) converts an SDK Key to a gae.DSKey
+func dsR2F(k *datastore.Key) gae.DSKey {
+	return dsKeyImpl{k}
+}
+
+// dsR2FErr (DS real-to-fake with error) acts like dsR2F, but is for wrapping function
+// invocations which return (*Key, error). e.g.
+//
+//   return dsR2FErr(datastore.Put(...))
+//
+// instead of:
+//
+//   k, err := datastore.Put(...)
+//   if err != nil {
+//     return nil, err
+//   }
+//   return dsR2F(k), nil
+func dsR2FErr(k *datastore.Key, err error) (gae.DSKey, error) {
+	if err != nil {
+		return nil, err
+	}
+	return dsR2F(k), nil
+}
+
+// dsF2R (DS fake-to-real) converts a DSKey back to an SDK *Key.
+func dsF2R(k gae.DSKey) *datastore.Key {
+	if rkey, ok := k.(dsKeyImpl); ok {
+		return rkey.Key
+	}
+	// we should always hit the fast case above, but just in case, safely round
+	// trip through the proto encoding.
+	rkey, err := datastore.DecodeKey(helper.DSKeyEncode(k))
+	if err != nil {
+		panic(err)
+	}
+	return rkey
+}
+
+// dsMR2F (DS multi-real-to-fake) converts a slice of SDK keys to their wrapped
+// types.
+func dsMR2F(ks []*datastore.Key) []gae.DSKey {
+	ret := make([]gae.DSKey, len(ks))
+	for i, k := range ks {
+		ret[i] = dsR2F(k)
+	}
+	return ret
+}
+
+// dsMF2R (DS multi-fake-to-fake) converts a slice of wrapped keys to SDK keys.
+func dsMF2R(ks []gae.DSKey) []*datastore.Key {
+	ret := make([]*datastore.Key, len(ks))
+	for i, k := range ks {
+		ret[i] = dsF2R(k)
+	}
+	return ret
+}