770 lines
30 KiB
C++
770 lines
30 KiB
C++
// Protocol Buffers - Google's data interchange format
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// Copyright 2014 Google Inc. All rights reserved.
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// https://developers.google.com/protocol-buffers/
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//
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are
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// met:
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//
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// * Redistributions of source code must retain the above copyright
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// notice, this list of conditions and the following disclaimer.
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// * Redistributions in binary form must reproduce the above
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// copyright notice, this list of conditions and the following disclaimer
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// in the documentation and/or other materials provided with the
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// distribution.
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// * Neither the name of Google Inc. nor the names of its
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// contributors may be used to endorse or promote products derived from
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// this software without specific prior written permission.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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// from google3/util/gtl/map_util.h
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// Author: Anton Carver
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#ifndef GOOGLE_PROTOBUF_STUBS_MAP_UTIL_H__
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#define GOOGLE_PROTOBUF_STUBS_MAP_UTIL_H__
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#include <stddef.h>
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#include <iterator>
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#include <string>
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#include <utility>
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#include <vector>
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#include <google/protobuf/stubs/common.h>
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namespace google {
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namespace protobuf {
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namespace internal {
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// Local implementation of RemoveConst to avoid including base/type_traits.h.
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template <class T> struct RemoveConst { typedef T type; };
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template <class T> struct RemoveConst<const T> : RemoveConst<T> {};
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} // namespace internal
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//
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// Find*()
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//
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// Returns a const reference to the value associated with the given key if it
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// exists. Crashes otherwise.
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//
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// This is intended as a replacement for operator[] as an rvalue (for reading)
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// when the key is guaranteed to exist.
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//
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// operator[] for lookup is discouraged for several reasons:
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// * It has a side-effect of inserting missing keys
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// * It is not thread-safe (even when it is not inserting, it can still
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// choose to resize the underlying storage)
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// * It invalidates iterators (when it chooses to resize)
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// * It default constructs a value object even if it doesn't need to
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//
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// This version assumes the key is printable, and includes it in the fatal log
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// message.
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template <class Collection>
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const typename Collection::value_type::second_type&
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FindOrDie(const Collection& collection,
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const typename Collection::value_type::first_type& key) {
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typename Collection::const_iterator it = collection.find(key);
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GOOGLE_CHECK(it != collection.end()) << "Map key not found: " << key;
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return it->second;
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}
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// Same as above, but returns a non-const reference.
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template <class Collection>
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typename Collection::value_type::second_type&
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FindOrDie(Collection& collection, // NOLINT
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const typename Collection::value_type::first_type& key) {
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typename Collection::iterator it = collection.find(key);
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GOOGLE_CHECK(it != collection.end()) << "Map key not found: " << key;
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return it->second;
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}
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// Same as FindOrDie above, but doesn't log the key on failure.
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template <class Collection>
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const typename Collection::value_type::second_type&
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FindOrDieNoPrint(const Collection& collection,
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const typename Collection::value_type::first_type& key) {
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typename Collection::const_iterator it = collection.find(key);
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GOOGLE_CHECK(it != collection.end()) << "Map key not found";
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return it->second;
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}
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// Same as above, but returns a non-const reference.
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template <class Collection>
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typename Collection::value_type::second_type&
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FindOrDieNoPrint(Collection& collection, // NOLINT
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const typename Collection::value_type::first_type& key) {
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typename Collection::iterator it = collection.find(key);
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GOOGLE_CHECK(it != collection.end()) << "Map key not found";
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return it->second;
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}
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// Returns a const reference to the value associated with the given key if it
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// exists, otherwise returns a const reference to the provided default value.
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//
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// WARNING: If a temporary object is passed as the default "value,"
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// this function will return a reference to that temporary object,
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// which will be destroyed at the end of the statement. A common
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// example: if you have a map with string values, and you pass a char*
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// as the default "value," either use the returned value immediately
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// or store it in a string (not string&).
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// Details: http://go/findwithdefault
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template <class Collection>
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const typename Collection::value_type::second_type&
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FindWithDefault(const Collection& collection,
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const typename Collection::value_type::first_type& key,
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const typename Collection::value_type::second_type& value) {
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typename Collection::const_iterator it = collection.find(key);
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if (it == collection.end()) {
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return value;
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}
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return it->second;
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}
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// Returns a pointer to the const value associated with the given key if it
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// exists, or nullptr otherwise.
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template <class Collection>
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const typename Collection::value_type::second_type*
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FindOrNull(const Collection& collection,
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const typename Collection::value_type::first_type& key) {
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typename Collection::const_iterator it = collection.find(key);
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if (it == collection.end()) {
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return 0;
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}
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return &it->second;
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}
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// Same as above but returns a pointer to the non-const value.
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template <class Collection>
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typename Collection::value_type::second_type*
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FindOrNull(Collection& collection, // NOLINT
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const typename Collection::value_type::first_type& key) {
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typename Collection::iterator it = collection.find(key);
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if (it == collection.end()) {
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return 0;
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}
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return &it->second;
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}
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// Returns the pointer value associated with the given key. If none is found,
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// nullptr is returned. The function is designed to be used with a map of keys to
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// pointers.
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//
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// This function does not distinguish between a missing key and a key mapped
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// to nullptr.
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template <class Collection>
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typename Collection::value_type::second_type
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FindPtrOrNull(const Collection& collection,
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const typename Collection::value_type::first_type& key) {
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typename Collection::const_iterator it = collection.find(key);
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if (it == collection.end()) {
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return typename Collection::value_type::second_type();
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}
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return it->second;
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}
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// Same as above, except takes non-const reference to collection.
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//
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// This function is needed for containers that propagate constness to the
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// pointee, such as boost::ptr_map.
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template <class Collection>
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typename Collection::value_type::second_type
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FindPtrOrNull(Collection& collection, // NOLINT
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const typename Collection::value_type::first_type& key) {
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typename Collection::iterator it = collection.find(key);
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if (it == collection.end()) {
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return typename Collection::value_type::second_type();
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}
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return it->second;
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}
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// Finds the pointer value associated with the given key in a map whose values
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// are linked_ptrs. Returns nullptr if key is not found.
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template <class Collection>
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typename Collection::value_type::second_type::element_type*
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FindLinkedPtrOrNull(const Collection& collection,
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const typename Collection::value_type::first_type& key) {
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typename Collection::const_iterator it = collection.find(key);
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if (it == collection.end()) {
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return 0;
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}
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// Since linked_ptr::get() is a const member returning a non const,
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// we do not need a version of this function taking a non const collection.
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return it->second.get();
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}
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// Same as above, but dies if the key is not found.
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template <class Collection>
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typename Collection::value_type::second_type::element_type&
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FindLinkedPtrOrDie(const Collection& collection,
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const typename Collection::value_type::first_type& key) {
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typename Collection::const_iterator it = collection.find(key);
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GOOGLE_CHECK(it != collection.end()) << "key not found: " << key;
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// Since linked_ptr::operator*() is a const member returning a non const,
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// we do not need a version of this function taking a non const collection.
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return *it->second;
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}
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// Finds the value associated with the given key and copies it to *value (if not
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// nullptr). Returns false if the key was not found, true otherwise.
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template <class Collection, class Key, class Value>
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bool FindCopy(const Collection& collection,
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const Key& key,
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Value* const value) {
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typename Collection::const_iterator it = collection.find(key);
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if (it == collection.end()) {
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return false;
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}
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if (value) {
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*value = it->second;
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}
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return true;
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}
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//
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// Contains*()
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//
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// Returns true if and only if the given collection contains the given key.
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template <class Collection, class Key>
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bool ContainsKey(const Collection& collection, const Key& key) {
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return collection.find(key) != collection.end();
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}
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// Returns true if and only if the given collection contains the given key-value
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// pair.
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template <class Collection, class Key, class Value>
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bool ContainsKeyValuePair(const Collection& collection,
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const Key& key,
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const Value& value) {
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typedef typename Collection::const_iterator const_iterator;
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std::pair<const_iterator, const_iterator> range = collection.equal_range(key);
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for (const_iterator it = range.first; it != range.second; ++it) {
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if (it->second == value) {
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return true;
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}
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}
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return false;
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}
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//
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// Insert*()
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//
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// Inserts the given key-value pair into the collection. Returns true if and
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// only if the key from the given pair didn't previously exist. Otherwise, the
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// value in the map is replaced with the value from the given pair.
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template <class Collection>
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bool InsertOrUpdate(Collection* const collection,
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const typename Collection::value_type& vt) {
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std::pair<typename Collection::iterator, bool> ret = collection->insert(vt);
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if (!ret.second) {
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// update
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ret.first->second = vt.second;
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return false;
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}
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return true;
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}
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// Same as above, except that the key and value are passed separately.
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template <class Collection>
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bool InsertOrUpdate(Collection* const collection,
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const typename Collection::value_type::first_type& key,
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const typename Collection::value_type::second_type& value) {
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return InsertOrUpdate(
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collection, typename Collection::value_type(key, value));
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}
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// Inserts/updates all the key-value pairs from the range defined by the
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// iterators "first" and "last" into the given collection.
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template <class Collection, class InputIterator>
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void InsertOrUpdateMany(Collection* const collection,
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InputIterator first, InputIterator last) {
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for (; first != last; ++first) {
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InsertOrUpdate(collection, *first);
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}
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}
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// Change the value associated with a particular key in a map or hash_map
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// of the form map<Key, Value*> which owns the objects pointed to by the
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// value pointers. If there was an existing value for the key, it is deleted.
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// True indicates an insert took place, false indicates an update + delete.
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template <class Collection>
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bool InsertAndDeleteExisting(
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Collection* const collection,
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const typename Collection::value_type::first_type& key,
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const typename Collection::value_type::second_type& value) {
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std::pair<typename Collection::iterator, bool> ret =
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collection->insert(typename Collection::value_type(key, value));
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if (!ret.second) {
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delete ret.first->second;
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ret.first->second = value;
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return false;
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}
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return true;
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}
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// Inserts the given key and value into the given collection if and only if the
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// given key did NOT already exist in the collection. If the key previously
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// existed in the collection, the value is not changed. Returns true if the
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// key-value pair was inserted; returns false if the key was already present.
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template <class Collection>
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bool InsertIfNotPresent(Collection* const collection,
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const typename Collection::value_type& vt) {
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return collection->insert(vt).second;
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}
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// Same as above except the key and value are passed separately.
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template <class Collection>
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bool InsertIfNotPresent(
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Collection* const collection,
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const typename Collection::value_type::first_type& key,
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const typename Collection::value_type::second_type& value) {
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return InsertIfNotPresent(
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collection, typename Collection::value_type(key, value));
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}
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// Same as above except dies if the key already exists in the collection.
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template <class Collection>
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void InsertOrDie(Collection* const collection,
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const typename Collection::value_type& value) {
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GOOGLE_CHECK(InsertIfNotPresent(collection, value))
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<< "duplicate value: " << value;
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}
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// Same as above except doesn't log the value on error.
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template <class Collection>
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void InsertOrDieNoPrint(Collection* const collection,
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const typename Collection::value_type& value) {
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GOOGLE_CHECK(InsertIfNotPresent(collection, value)) << "duplicate value.";
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}
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// Inserts the key-value pair into the collection. Dies if key was already
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// present.
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template <class Collection>
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void InsertOrDie(Collection* const collection,
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const typename Collection::value_type::first_type& key,
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const typename Collection::value_type::second_type& data) {
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GOOGLE_CHECK(InsertIfNotPresent(collection, key, data))
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<< "duplicate key: " << key;
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}
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// Same as above except doesn't log the key on error.
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template <class Collection>
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void InsertOrDieNoPrint(
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Collection* const collection,
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const typename Collection::value_type::first_type& key,
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const typename Collection::value_type::second_type& data) {
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GOOGLE_CHECK(InsertIfNotPresent(collection, key, data)) << "duplicate key.";
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}
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// Inserts a new key and default-initialized value. Dies if the key was already
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// present. Returns a reference to the value. Example usage:
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//
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// map<int, SomeProto> m;
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// SomeProto& proto = InsertKeyOrDie(&m, 3);
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// proto.set_field("foo");
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template <class Collection>
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typename Collection::value_type::second_type& InsertKeyOrDie(
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Collection* const collection,
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const typename Collection::value_type::first_type& key) {
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typedef typename Collection::value_type value_type;
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std::pair<typename Collection::iterator, bool> res =
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collection->insert(value_type(key, typename value_type::second_type()));
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GOOGLE_CHECK(res.second) << "duplicate key: " << key;
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return res.first->second;
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}
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//
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// Lookup*()
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//
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// Looks up a given key and value pair in a collection and inserts the key-value
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// pair if it's not already present. Returns a reference to the value associated
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// with the key.
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template <class Collection>
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typename Collection::value_type::second_type&
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LookupOrInsert(Collection* const collection,
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const typename Collection::value_type& vt) {
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return collection->insert(vt).first->second;
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}
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// Same as above except the key-value are passed separately.
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template <class Collection>
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typename Collection::value_type::second_type&
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LookupOrInsert(Collection* const collection,
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const typename Collection::value_type::first_type& key,
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const typename Collection::value_type::second_type& value) {
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return LookupOrInsert(
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collection, typename Collection::value_type(key, value));
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}
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// Counts the number of equivalent elements in the given "sequence", and stores
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// the results in "count_map" with element as the key and count as the value.
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//
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// Example:
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// vector<string> v = {"a", "b", "c", "a", "b"};
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// map<string, int> m;
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// AddTokenCounts(v, 1, &m);
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// assert(m["a"] == 2);
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// assert(m["b"] == 2);
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// assert(m["c"] == 1);
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template <typename Sequence, typename Collection>
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void AddTokenCounts(
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const Sequence& sequence,
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const typename Collection::value_type::second_type& increment,
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Collection* const count_map) {
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for (typename Sequence::const_iterator it = sequence.begin();
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it != sequence.end(); ++it) {
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typename Collection::value_type::second_type& value =
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LookupOrInsert(count_map, *it,
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typename Collection::value_type::second_type());
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value += increment;
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}
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}
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// Returns a reference to the value associated with key. If not found, a value
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// is default constructed on the heap and added to the map.
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//
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// This function is useful for containers of the form map<Key, Value*>, where
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// inserting a new key, value pair involves constructing a new heap-allocated
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// Value, and storing a pointer to that in the collection.
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template <class Collection>
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typename Collection::value_type::second_type&
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LookupOrInsertNew(Collection* const collection,
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const typename Collection::value_type::first_type& key) {
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typedef typename std::iterator_traits<
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typename Collection::value_type::second_type>::value_type Element;
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std::pair<typename Collection::iterator, bool> ret =
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collection->insert(typename Collection::value_type(
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key,
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static_cast<typename Collection::value_type::second_type>(nullptr)));
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if (ret.second) {
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ret.first->second = new Element();
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}
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return ret.first->second;
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}
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// Same as above but constructs the value using the single-argument constructor
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// and the given "arg".
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template <class Collection, class Arg>
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typename Collection::value_type::second_type&
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LookupOrInsertNew(Collection* const collection,
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const typename Collection::value_type::first_type& key,
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const Arg& arg) {
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typedef typename std::iterator_traits<
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typename Collection::value_type::second_type>::value_type Element;
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std::pair<typename Collection::iterator, bool> ret =
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collection->insert(typename Collection::value_type(
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key,
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static_cast<typename Collection::value_type::second_type>(nullptr)));
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if (ret.second) {
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ret.first->second = new Element(arg);
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}
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return ret.first->second;
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}
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// Lookup of linked/shared pointers is used in two scenarios:
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//
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// Use LookupOrInsertNewLinkedPtr if the container owns the elements.
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// In this case it is fine working with the raw pointer as long as it is
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// guaranteed that no other thread can delete/update an accessed element.
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// A mutex will need to lock the container operation as well as the use
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// of the returned elements. Finding an element may be performed using
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// FindLinkedPtr*().
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//
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// Use LookupOrInsertNewSharedPtr if the container does not own the elements
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// for their whole lifetime. This is typically the case when a reader allows
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// parallel updates to the container. In this case a Mutex only needs to lock
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// container operations, but all element operations must be performed on the
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// shared pointer. Finding an element must be performed using FindPtr*() and
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// cannot be done with FindLinkedPtr*() even though it compiles.
|
|
|
|
// Lookup a key in a map or hash_map whose values are linked_ptrs. If it is
|
|
// missing, set collection[key].reset(new Value::element_type) and return that.
|
|
// Value::element_type must be default constructable.
|
|
template <class Collection>
|
|
typename Collection::value_type::second_type::element_type*
|
|
LookupOrInsertNewLinkedPtr(
|
|
Collection* const collection,
|
|
const typename Collection::value_type::first_type& key) {
|
|
typedef typename Collection::value_type::second_type Value;
|
|
std::pair<typename Collection::iterator, bool> ret =
|
|
collection->insert(typename Collection::value_type(key, Value()));
|
|
if (ret.second) {
|
|
ret.first->second.reset(new typename Value::element_type);
|
|
}
|
|
return ret.first->second.get();
|
|
}
|
|
|
|
// A variant of LookupOrInsertNewLinkedPtr where the value is constructed using
|
|
// a single-parameter constructor. Note: the constructor argument is computed
|
|
// even if it will not be used, so only values cheap to compute should be passed
|
|
// here. On the other hand it does not matter how expensive the construction of
|
|
// the actual stored value is, as that only occurs if necessary.
|
|
template <class Collection, class Arg>
|
|
typename Collection::value_type::second_type::element_type*
|
|
LookupOrInsertNewLinkedPtr(
|
|
Collection* const collection,
|
|
const typename Collection::value_type::first_type& key,
|
|
const Arg& arg) {
|
|
typedef typename Collection::value_type::second_type Value;
|
|
std::pair<typename Collection::iterator, bool> ret =
|
|
collection->insert(typename Collection::value_type(key, Value()));
|
|
if (ret.second) {
|
|
ret.first->second.reset(new typename Value::element_type(arg));
|
|
}
|
|
return ret.first->second.get();
|
|
}
|
|
|
|
// Lookup a key in a map or hash_map whose values are shared_ptrs. If it is
|
|
// missing, set collection[key].reset(new Value::element_type). Unlike
|
|
// LookupOrInsertNewLinkedPtr, this function returns the shared_ptr instead of
|
|
// the raw pointer. Value::element_type must be default constructable.
|
|
template <class Collection>
|
|
typename Collection::value_type::second_type&
|
|
LookupOrInsertNewSharedPtr(
|
|
Collection* const collection,
|
|
const typename Collection::value_type::first_type& key) {
|
|
typedef typename Collection::value_type::second_type SharedPtr;
|
|
typedef typename Collection::value_type::second_type::element_type Element;
|
|
std::pair<typename Collection::iterator, bool> ret =
|
|
collection->insert(typename Collection::value_type(key, SharedPtr()));
|
|
if (ret.second) {
|
|
ret.first->second.reset(new Element());
|
|
}
|
|
return ret.first->second;
|
|
}
|
|
|
|
// A variant of LookupOrInsertNewSharedPtr where the value is constructed using
|
|
// a single-parameter constructor. Note: the constructor argument is computed
|
|
// even if it will not be used, so only values cheap to compute should be passed
|
|
// here. On the other hand it does not matter how expensive the construction of
|
|
// the actual stored value is, as that only occurs if necessary.
|
|
template <class Collection, class Arg>
|
|
typename Collection::value_type::second_type&
|
|
LookupOrInsertNewSharedPtr(
|
|
Collection* const collection,
|
|
const typename Collection::value_type::first_type& key,
|
|
const Arg& arg) {
|
|
typedef typename Collection::value_type::second_type SharedPtr;
|
|
typedef typename Collection::value_type::second_type::element_type Element;
|
|
std::pair<typename Collection::iterator, bool> ret =
|
|
collection->insert(typename Collection::value_type(key, SharedPtr()));
|
|
if (ret.second) {
|
|
ret.first->second.reset(new Element(arg));
|
|
}
|
|
return ret.first->second;
|
|
}
|
|
|
|
//
|
|
// Misc Utility Functions
|
|
//
|
|
|
|
// Updates the value associated with the given key. If the key was not already
|
|
// present, then the key-value pair are inserted and "previous" is unchanged. If
|
|
// the key was already present, the value is updated and "*previous" will
|
|
// contain a copy of the old value.
|
|
//
|
|
// InsertOrReturnExisting has complementary behavior that returns the
|
|
// address of an already existing value, rather than updating it.
|
|
template <class Collection>
|
|
bool UpdateReturnCopy(Collection* const collection,
|
|
const typename Collection::value_type::first_type& key,
|
|
const typename Collection::value_type::second_type& value,
|
|
typename Collection::value_type::second_type* previous) {
|
|
std::pair<typename Collection::iterator, bool> ret =
|
|
collection->insert(typename Collection::value_type(key, value));
|
|
if (!ret.second) {
|
|
// update
|
|
if (previous) {
|
|
*previous = ret.first->second;
|
|
}
|
|
ret.first->second = value;
|
|
return true;
|
|
}
|
|
return false;
|
|
}
|
|
|
|
// Same as above except that the key and value are passed as a pair.
|
|
template <class Collection>
|
|
bool UpdateReturnCopy(Collection* const collection,
|
|
const typename Collection::value_type& vt,
|
|
typename Collection::value_type::second_type* previous) {
|
|
std::pair<typename Collection::iterator, bool> ret = collection->insert(vt);
|
|
if (!ret.second) {
|
|
// update
|
|
if (previous) {
|
|
*previous = ret.first->second;
|
|
}
|
|
ret.first->second = vt.second;
|
|
return true;
|
|
}
|
|
return false;
|
|
}
|
|
|
|
// Tries to insert the given key-value pair into the collection. Returns nullptr if
|
|
// the insert succeeds. Otherwise, returns a pointer to the existing value.
|
|
//
|
|
// This complements UpdateReturnCopy in that it allows to update only after
|
|
// verifying the old value and still insert quickly without having to look up
|
|
// twice. Unlike UpdateReturnCopy this also does not come with the issue of an
|
|
// undefined previous* in case new data was inserted.
|
|
template <class Collection>
|
|
typename Collection::value_type::second_type* InsertOrReturnExisting(
|
|
Collection* const collection, const typename Collection::value_type& vt) {
|
|
std::pair<typename Collection::iterator, bool> ret = collection->insert(vt);
|
|
if (ret.second) {
|
|
return nullptr; // Inserted, no existing previous value.
|
|
} else {
|
|
return &ret.first->second; // Return address of already existing value.
|
|
}
|
|
}
|
|
|
|
// Same as above, except for explicit key and data.
|
|
template <class Collection>
|
|
typename Collection::value_type::second_type* InsertOrReturnExisting(
|
|
Collection* const collection,
|
|
const typename Collection::value_type::first_type& key,
|
|
const typename Collection::value_type::second_type& data) {
|
|
return InsertOrReturnExisting(collection,
|
|
typename Collection::value_type(key, data));
|
|
}
|
|
|
|
// Erases the collection item identified by the given key, and returns the value
|
|
// associated with that key. It is assumed that the value (i.e., the
|
|
// mapped_type) is a pointer. Returns nullptr if the key was not found in the
|
|
// collection.
|
|
//
|
|
// Examples:
|
|
// map<string, MyType*> my_map;
|
|
//
|
|
// One line cleanup:
|
|
// delete EraseKeyReturnValuePtr(&my_map, "abc");
|
|
//
|
|
// Use returned value:
|
|
// std::unique_ptr<MyType> value_ptr(
|
|
// EraseKeyReturnValuePtr(&my_map, "abc"));
|
|
// if (value_ptr.get())
|
|
// value_ptr->DoSomething();
|
|
//
|
|
template <class Collection>
|
|
typename Collection::value_type::second_type EraseKeyReturnValuePtr(
|
|
Collection* const collection,
|
|
const typename Collection::value_type::first_type& key) {
|
|
typename Collection::iterator it = collection->find(key);
|
|
if (it == collection->end()) {
|
|
return nullptr;
|
|
}
|
|
typename Collection::value_type::second_type v = it->second;
|
|
collection->erase(it);
|
|
return v;
|
|
}
|
|
|
|
// Inserts all the keys from map_container into key_container, which must
|
|
// support insert(MapContainer::key_type).
|
|
//
|
|
// Note: any initial contents of the key_container are not cleared.
|
|
template <class MapContainer, class KeyContainer>
|
|
void InsertKeysFromMap(const MapContainer& map_container,
|
|
KeyContainer* key_container) {
|
|
GOOGLE_CHECK(key_container != nullptr);
|
|
for (typename MapContainer::const_iterator it = map_container.begin();
|
|
it != map_container.end(); ++it) {
|
|
key_container->insert(it->first);
|
|
}
|
|
}
|
|
|
|
// Appends all the keys from map_container into key_container, which must
|
|
// support push_back(MapContainer::key_type).
|
|
//
|
|
// Note: any initial contents of the key_container are not cleared.
|
|
template <class MapContainer, class KeyContainer>
|
|
void AppendKeysFromMap(const MapContainer& map_container,
|
|
KeyContainer* key_container) {
|
|
GOOGLE_CHECK(key_container != nullptr);
|
|
for (typename MapContainer::const_iterator it = map_container.begin();
|
|
it != map_container.end(); ++it) {
|
|
key_container->push_back(it->first);
|
|
}
|
|
}
|
|
|
|
// A more specialized overload of AppendKeysFromMap to optimize reallocations
|
|
// for the common case in which we're appending keys to a vector and hence can
|
|
// (and sometimes should) call reserve() first.
|
|
//
|
|
// (It would be possible to play SFINAE games to call reserve() for any
|
|
// container that supports it, but this seems to get us 99% of what we need
|
|
// without the complexity of a SFINAE-based solution.)
|
|
template <class MapContainer, class KeyType>
|
|
void AppendKeysFromMap(const MapContainer& map_container,
|
|
std::vector<KeyType>* key_container) {
|
|
GOOGLE_CHECK(key_container != nullptr);
|
|
// We now have the opportunity to call reserve(). Calling reserve() every
|
|
// time is a bad idea for some use cases: libstdc++'s implementation of
|
|
// vector<>::reserve() resizes the vector's backing store to exactly the
|
|
// given size (unless it's already at least that big). Because of this,
|
|
// the use case that involves appending a lot of small maps (total size
|
|
// N) one by one to a vector would be O(N^2). But never calling reserve()
|
|
// loses the opportunity to improve the use case of adding from a large
|
|
// map to an empty vector (this improves performance by up to 33%). A
|
|
// number of heuristics are possible; see the discussion in
|
|
// cl/34081696. Here we use the simplest one.
|
|
if (key_container->empty()) {
|
|
key_container->reserve(map_container.size());
|
|
}
|
|
for (typename MapContainer::const_iterator it = map_container.begin();
|
|
it != map_container.end(); ++it) {
|
|
key_container->push_back(it->first);
|
|
}
|
|
}
|
|
|
|
// Inserts all the values from map_container into value_container, which must
|
|
// support push_back(MapContainer::mapped_type).
|
|
//
|
|
// Note: any initial contents of the value_container are not cleared.
|
|
template <class MapContainer, class ValueContainer>
|
|
void AppendValuesFromMap(const MapContainer& map_container,
|
|
ValueContainer* value_container) {
|
|
GOOGLE_CHECK(value_container != nullptr);
|
|
for (typename MapContainer::const_iterator it = map_container.begin();
|
|
it != map_container.end(); ++it) {
|
|
value_container->push_back(it->second);
|
|
}
|
|
}
|
|
|
|
// A more specialized overload of AppendValuesFromMap to optimize reallocations
|
|
// for the common case in which we're appending values to a vector and hence
|
|
// can (and sometimes should) call reserve() first.
|
|
//
|
|
// (It would be possible to play SFINAE games to call reserve() for any
|
|
// container that supports it, but this seems to get us 99% of what we need
|
|
// without the complexity of a SFINAE-based solution.)
|
|
template <class MapContainer, class ValueType>
|
|
void AppendValuesFromMap(const MapContainer& map_container,
|
|
std::vector<ValueType>* value_container) {
|
|
GOOGLE_CHECK(value_container != nullptr);
|
|
// See AppendKeysFromMap for why this is done.
|
|
if (value_container->empty()) {
|
|
value_container->reserve(map_container.size());
|
|
}
|
|
for (typename MapContainer::const_iterator it = map_container.begin();
|
|
it != map_container.end(); ++it) {
|
|
value_container->push_back(it->second);
|
|
}
|
|
}
|
|
|
|
} // namespace protobuf
|
|
} // namespace google
|
|
|
|
#endif // GOOGLE_PROTOBUF_STUBS_MAP_UTIL_H__
|