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// Copyright 2014 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.
//
// Some helpers for quic that are for chromium codebase.
#ifndef NET_QUIC_QUIC_UTILS_CHROMIUM_H_
#define NET_QUIC_QUIC_UTILS_CHROMIUM_H_
#include "base/basictypes.h"
#include "base/logging.h"
namespace net {
//
// Find*()
//
// Returns a const reference to the value associated with the given key if it
// exists. Crashes otherwise.
//
// This is intended as a replacement for operator[] as an rvalue (for reading)
// when the key is guaranteed to exist.
//
// operator[] for lookup is discouraged for several reasons:
// * It has a side-effect of inserting missing keys
// * It is not thread-safe (even when it is not inserting, it can still
// choose to resize the underlying storage)
// * It invalidates iterators (when it chooses to resize)
// * It default constructs a value object even if it doesn't need to
//
// This version assumes the key is printable, and includes it in the fatal log
// message.
template <class Collection>
const typename Collection::value_type::second_type&
FindOrDie(const Collection& collection,
const typename Collection::value_type::first_type& key) {
typename Collection::const_iterator it = collection.find(key);
CHECK(it != collection.end()) << "Map key not found: " << key;
return it->second;
}
// Same as above, but returns a non-const reference.
template <class Collection>
typename Collection::value_type::second_type&
FindOrDie(Collection& collection, // NOLINT
const typename Collection::value_type::first_type& key) {
typename Collection::iterator it = collection.find(key);
CHECK(it != collection.end()) << "Map key not found: " << key;
return it->second;
}
// Returns a pointer to the const value associated with the given key if it
// exists, or NULL otherwise.
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;
}
// Same as above but returns a pointer to the non-const value.
template <class Collection>
typename Collection::value_type::second_type*
FindOrNull(Collection& collection, // NOLINT
const typename Collection::value_type::first_type& key) {
typename Collection::iterator it = collection.find(key);
if (it == collection.end()) {
return 0;
}
return &it->second;
}
} // namespace net
#endif // NET_QUIC_QUIC_UTILS_CHROMIUM_H_
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