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diff --git a/src/google/protobuf/stubs/map-util.h b/src/google/protobuf/stubs/map-util.h
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+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.
+// http://code.google.com/p/protobuf/
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// from google3/util/gtl/map-util.h
+// Author: Anton Carver
+
+#ifndef GOOGLE_PROTOBUF_STUBS_MAP_UTIL_H__
+#define GOOGLE_PROTOBUF_STUBS_MAP_UTIL_H__
+
+#include <google/protobuf/stubs/common.h>
+
+namespace google {
+namespace protobuf {
+
+// Perform a lookup in a map or hash_map.
+// If the key is present a const pointer to the associated value is returned,
+// otherwise a NULL pointer is returned.
+template <class Collection>
+const typename Collection::value_type::second_type*
+FindOrNull(const Collection& collection,
+           const typename Collection::value_type::first_type& key) {
+  typename Collection::const_iterator it = collection.find(key);
+  if (it == collection.end()) {
+    return 0;
+  }
+  return &it->second;
+}
+
+// Perform a lookup in a map or hash_map whose values are pointers.
+// If the key is present a const pointer to the associated value is returned,
+// otherwise a NULL pointer is returned.
+// This function does not distinguish between a missing key and a key mapped
+// to a NULL value.
+template <class Collection>
+const typename Collection::value_type::second_type
+FindPtrOrNull(const Collection& collection,
+              const typename Collection::value_type::first_type& key) {
+  typename Collection::const_iterator it = collection.find(key);
+  if (it == collection.end()) {
+    return 0;
+  }
+  return it->second;
+}
+
+// Change the value associated with a particular key in a map or hash_map.
+// If the key is not present in the map the key and value are inserted,
+// otherwise the value is updated to be a copy of the value provided.
+// True indicates that an insert took place, false indicates an update.
+template <class Collection, class Key, class Value>
+bool InsertOrUpdate(Collection * const collection,
+                   const Key& key, const Value& value) {
+  pair<typename Collection::iterator, bool> ret =
+    collection->insert(typename Collection::value_type(key, value));
+  if (!ret.second) {
+    // update
+    ret.first->second = value;
+    return false;
+  }
+  return true;
+}
+
+// Insert a new key and value into a map or hash_map.
+// If the key is not present in the map the key and value are
+// inserted, otherwise nothing happens. True indicates that an insert
+// took place, false indicates the key was already present.
+template <class Collection, class Key, class Value>
+bool InsertIfNotPresent(Collection * const collection,
+                        const Key& key, const Value& value) {
+  pair<typename Collection::iterator, bool> ret =
+    collection->insert(typename Collection::value_type(key, value));
+  return ret.second;
+}
+
+}  // namespace protobuf
+}  // namespace google
+
+#endif  // GOOGLE_PROTOBUF_STUBS_MAP_UTIL_H__