1 // Copyright 2014 The Chromium Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 // 5 // Some helpers for quic that are for chromium codebase. 6 7 #ifndef NET_QUIC_QUIC_UTILS_CHROMIUM_H_ 8 #define NET_QUIC_QUIC_UTILS_CHROMIUM_H_ 9 10 #include "base/basictypes.h" 11 #include "base/logging.h" 12 13 namespace net { 14 15 // 16 // Find*() 17 // 18 19 // Returns a const reference to the value associated with the given key if it 20 // exists. Crashes otherwise. 21 // 22 // This is intended as a replacement for operator[] as an rvalue (for reading) 23 // when the key is guaranteed to exist. 24 // 25 // operator[] for lookup is discouraged for several reasons: 26 // * It has a side-effect of inserting missing keys 27 // * It is not thread-safe (even when it is not inserting, it can still 28 // choose to resize the underlying storage) 29 // * It invalidates iterators (when it chooses to resize) 30 // * It default constructs a value object even if it doesn't need to 31 // 32 // This version assumes the key is printable, and includes it in the fatal log 33 // message. 34 template <class Collection> 35 const typename Collection::value_type::second_type& 36 FindOrDie(const Collection& collection, 37 const typename Collection::value_type::first_type& key) { 38 typename Collection::const_iterator it = collection.find(key); 39 CHECK(it != collection.end()) << "Map key not found: " << key; 40 return it->second; 41 } 42 43 // Same as above, but returns a non-const reference. 44 template <class Collection> 45 typename Collection::value_type::second_type& 46 FindOrDie(Collection& collection, // NOLINT 47 const typename Collection::value_type::first_type& key) { 48 typename Collection::iterator it = collection.find(key); 49 CHECK(it != collection.end()) << "Map key not found: " << key; 50 return it->second; 51 } 52 53 // Returns a pointer to the const value associated with the given key if it 54 // exists, or NULL otherwise. 55 template <class Collection> 56 const typename Collection::value_type::second_type* 57 FindOrNull(const Collection& collection, 58 const typename Collection::value_type::first_type& key) { 59 typename Collection::const_iterator it = collection.find(key); 60 if (it == collection.end()) { 61 return 0; 62 } 63 return &it->second; 64 } 65 66 // Same as above but returns a pointer to the non-const value. 67 template <class Collection> 68 typename Collection::value_type::second_type* 69 FindOrNull(Collection& collection, // NOLINT 70 const typename Collection::value_type::first_type& key) { 71 typename Collection::iterator it = collection.find(key); 72 if (it == collection.end()) { 73 return 0; 74 } 75 return &it->second; 76 } 77 78 } // namespace net 79 80 #endif // NET_QUIC_QUIC_UTILS_CHROMIUM_H_ 81
