Varun Bahl / BahlDecrypModified

Updated

Fork of BLE_API by Bluetooth Low Energy

ble/SafeBool.h@1155:e28c7aac64ab, 2016-04-06 (annotated)

Committer:
vcoubard
Date:
Wed Apr 06 19:14:34 2016 +0100
Revision:
1155:e28c7aac64ab
Parent:
1150:45226f13ae5c
Child:
1156:e1ea38b576c6
Synchronized with git rev e20c8c58

Author: Vincent Coubard

Merge pull request #163 from ARMmbed/develop



merge version 2.5.0 into master

Who changed what in which revision?

UserRevisionLine numberNew contents of line
vcoubard 1148:0340d5bbbeba 1 /* mbed Microcontroller Library
vcoubard 1148:0340d5bbbeba 2 * Copyright (c) 2006-2013 ARM Limited
vcoubard 1148:0340d5bbbeba 3 *
vcoubard 1148:0340d5bbbeba 4 * Licensed under the Apache License, Version 2.0 (the "License");
vcoubard 1148:0340d5bbbeba 5 * you may not use this file except in compliance with the License.
vcoubard 1148:0340d5bbbeba 6 * You may obtain a copy of the License at
vcoubard 1148:0340d5bbbeba 7 *
vcoubard 1148:0340d5bbbeba 8 * http://www.apache.org/licenses/LICENSE-2.0
vcoubard 1148:0340d5bbbeba 9 *
vcoubard 1148:0340d5bbbeba 10 * Unless required by applicable law or agreed to in writing, software
vcoubard 1148:0340d5bbbeba 11 * distributed under the License is distributed on an "AS IS" BASIS,
vcoubard 1148:0340d5bbbeba 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
vcoubard 1148:0340d5bbbeba 13 * See the License for the specific language governing permissions and
vcoubard 1148:0340d5bbbeba 14 * limitations under the License.
vcoubard 1148:0340d5bbbeba 15 */
vcoubard 1148:0340d5bbbeba 16
vcoubard 1148:0340d5bbbeba 17 #ifndef BLE_API_SAFE_BOOL_H_
vcoubard 1148:0340d5bbbeba 18 #define BLE_API_SAFE_BOOL_H_
vcoubard 1148:0340d5bbbeba 19
vcoubard 1155:e28c7aac64ab 20 //safe bool idiom, see : http://www.artima.com/cppsource/safebool.html
vcoubard 1148:0340d5bbbeba 21
vcoubard 1148:0340d5bbbeba 22 namespace SafeBool_ {
vcoubard 1148:0340d5bbbeba 23 /**
vcoubard 1155:e28c7aac64ab 24 * @brief Base class for all intances of SafeBool,
vcoubard 1155:e28c7aac64ab 25 * This base class reduce instantiation of trueTag function
vcoubard 1148:0340d5bbbeba 26 */
vcoubard 1148:0340d5bbbeba 27 class base {
vcoubard 1148:0340d5bbbeba 28 template<typename>
vcoubard 1148:0340d5bbbeba 29 friend class SafeBool;
vcoubard 1148:0340d5bbbeba 30
vcoubard 1148:0340d5bbbeba 31 protected:
vcoubard 1155:e28c7aac64ab 32 //the bool type is a pointer to method which can be used in boolean context
vcoubard 1155:e28c7aac64ab 33 typedef void (base::*BoolType_t)() const;
vcoubard 1148:0340d5bbbeba 34
vcoubard 1155:e28c7aac64ab 35 // non implemented call, use to disallow conversion between unrelated types
vcoubard 1155:e28c7aac64ab 36 void invalidTag() const;
vcoubard 1148:0340d5bbbeba 37
vcoubard 1155:e28c7aac64ab 38 // member function which indicate true value
vcoubard 1155:e28c7aac64ab 39 void trueTag() const {}
vcoubard 1148:0340d5bbbeba 40 };
vcoubard 1148:0340d5bbbeba 41
vcoubard 1148:0340d5bbbeba 42
vcoubard 1148:0340d5bbbeba 43 }
vcoubard 1148:0340d5bbbeba 44
vcoubard 1148:0340d5bbbeba 45 /**
vcoubard 1148:0340d5bbbeba 46 * @brief template class SafeBool use CRTP to made boolean conversion easy and correct.
vcoubard 1155:e28c7aac64ab 47 * Derived class should implement the function bool toBool() const to make this work. Inheritance
vcoubard 1148:0340d5bbbeba 48 * should be public.
vcoubard 1148:0340d5bbbeba 49 *
vcoubard 1148:0340d5bbbeba 50 * @tparam T Type of the derived class
vcoubard 1155:e28c7aac64ab 51 *
vcoubard 1155:e28c7aac64ab 52 * \code
vcoubard 1155:e28c7aac64ab 53 *
vcoubard 1155:e28c7aac64ab 54 * class A : public SafeBool<A> {
vcoubard 1148:0340d5bbbeba 55 * public:
vcoubard 1155:e28c7aac64ab 56 *
vcoubard 1148:0340d5bbbeba 57 * // boolean conversion
vcoubard 1155:e28c7aac64ab 58 * bool toBool() {
vcoubard 1155:e28c7aac64ab 59 *
vcoubard 1155:e28c7aac64ab 60 * }
vcoubard 1148:0340d5bbbeba 61 * };
vcoubard 1155:e28c7aac64ab 62 *
vcoubard 1155:e28c7aac64ab 63 * class B : public SafeBool<B> {
vcoubard 1148:0340d5bbbeba 64 * public:
vcoubard 1155:e28c7aac64ab 65 *
vcoubard 1148:0340d5bbbeba 66 * // boolean conversion
vcoubard 1155:e28c7aac64ab 67 * bool toBool() const {
vcoubard 1155:e28c7aac64ab 68 *
vcoubard 1155:e28c7aac64ab 69 * }
vcoubard 1148:0340d5bbbeba 70 * };
vcoubard 1155:e28c7aac64ab 71 *
vcoubard 1148:0340d5bbbeba 72 * A a;
vcoubard 1148:0340d5bbbeba 73 * B b;
vcoubard 1155:e28c7aac64ab 74 *
vcoubard 1155:e28c7aac64ab 75 * // will compile
vcoubard 1155:e28c7aac64ab 76 * if(a) {
vcoubard 1155:e28c7aac64ab 77 *
vcoubard 1148:0340d5bbbeba 78 * }
vcoubard 1155:e28c7aac64ab 79 *
vcoubard 1155:e28c7aac64ab 80 * // compilation error
vcoubard 1155:e28c7aac64ab 81 * if(a == b) {
vcoubard 1155:e28c7aac64ab 82 *
vcoubard 1148:0340d5bbbeba 83 * }
vcoubard 1155:e28c7aac64ab 84 *
vcoubard 1155:e28c7aac64ab 85 *
vcoubard 1155:e28c7aac64ab 86 * \endcode
vcoubard 1148:0340d5bbbeba 87 */
vcoubard 1155:e28c7aac64ab 88 template <typename T>
vcoubard 1148:0340d5bbbeba 89 class SafeBool : public SafeBool_::base {
vcoubard 1148:0340d5bbbeba 90 public:
vcoubard 1155:e28c7aac64ab 91 /**
vcoubard 1155:e28c7aac64ab 92 * bool operator implementation, derived class has to provide bool toBool() const function.
vcoubard 1155:e28c7aac64ab 93 */
vcoubard 1155:e28c7aac64ab 94 operator BoolType_t() const {
vcoubard 1155:e28c7aac64ab 95 return (static_cast<const T*>(this))->toBool()
vcoubard 1155:e28c7aac64ab 96 ? &SafeBool<T>::trueTag : 0;
vcoubard 1155:e28c7aac64ab 97 }
vcoubard 1148:0340d5bbbeba 98 };
vcoubard 1148:0340d5bbbeba 99
vcoubard 1155:e28c7aac64ab 100 //Avoid conversion to bool between different classes
vcoubard 1148:0340d5bbbeba 101 template <typename T, typename U>
vcoubard 1148:0340d5bbbeba 102 void operator==(const SafeBool<T>& lhs,const SafeBool<U>& rhs) {
vcoubard 1148:0340d5bbbeba 103 lhs.invalidTag();
vcoubard 1155:e28c7aac64ab 104 // return false;
vcoubard 1148:0340d5bbbeba 105 }
vcoubard 1148:0340d5bbbeba 106
vcoubard 1155:e28c7aac64ab 107 //Avoid conversion to bool between different classes
vcoubard 1148:0340d5bbbeba 108 template <typename T,typename U>
vcoubard 1148:0340d5bbbeba 109 void operator!=(const SafeBool<T>& lhs,const SafeBool<U>& rhs) {
vcoubard 1155:e28c7aac64ab 110 lhs.invalidTag();
vcoubard 1155:e28c7aac64ab 111 // return false;
vcoubard 1148:0340d5bbbeba 112 }
vcoubard 1148:0340d5bbbeba 113
rgrover1 948:1bb402105289 114 #endif /* BLE_API_SAFE_BOOL_H_ */