Alex Cordonnier / BLE_API

High level Bluetooth Low Energy API and radio abstraction layer

Fork of BLE_API by Bluetooth Low Energy

ble/SafeBool.h@1150:45226f13ae5c, 2016-04-06 (annotated)

Committer:
vcoubard
Date:
Wed Apr 06 19:14:18 2016 +0100
Revision:
1150:45226f13ae5c
Parent:
1149:c188d5238d62
Child:
1155:e28c7aac64ab
Synchronized with git rev 0852e81e

Author: Andres Amaya Garcia

Put back removed comments from SafeBool

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 1149:c188d5238d62 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 1149:c188d5238d62 24 * @brief Base class for all intances of SafeBool.
vcoubard 1149:c188d5238d62 25 * This base class reduces 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 1149:c188d5238d62 32 /**
vcoubard 1149:c188d5238d62 33 * The bool type is a pointer to method which can be used in boolean context.
vcoubard 1149:c188d5238d62 34 */
vcoubard 1149:c188d5238d62 35 typedef void (base::*BoolType_t)() const;
vcoubard 1148:0340d5bbbeba 36
vcoubard 1149:c188d5238d62 37 /**
vcoubard 1149:c188d5238d62 38 * Non implemented call, use to disallow conversion between unrelated types.
vcoubard 1149:c188d5238d62 39 */
vcoubard 1149:c188d5238d62 40 void invalidTag() const;
vcoubard 1148:0340d5bbbeba 41
vcoubard 1149:c188d5238d62 42 /**
vcoubard 1149:c188d5238d62 43 * Member function which indicate true value.
vcoubard 1149:c188d5238d62 44 */
vcoubard 1149:c188d5238d62 45 void trueTag() const {}
vcoubard 1148:0340d5bbbeba 46 };
vcoubard 1148:0340d5bbbeba 47
vcoubard 1148:0340d5bbbeba 48
vcoubard 1148:0340d5bbbeba 49 }
vcoubard 1148:0340d5bbbeba 50
vcoubard 1148:0340d5bbbeba 51 /**
vcoubard 1148:0340d5bbbeba 52 * @brief template class SafeBool use CRTP to made boolean conversion easy and correct.
vcoubard 1148:0340d5bbbeba 53 * Derived class should implement the function bool toBool() const to make this work. Inheritance
vcoubard 1148:0340d5bbbeba 54 * should be public.
vcoubard 1148:0340d5bbbeba 55 *
vcoubard 1148:0340d5bbbeba 56 * @tparam T Type of the derived class
vcoubard 1148:0340d5bbbeba 57 *
vcoubard 1149:c188d5238d62 58 * @code
vcoubard 1148:0340d5bbbeba 59 *
vcoubard 1148:0340d5bbbeba 60 * class A : public SafeBool<A> {
vcoubard 1148:0340d5bbbeba 61 * public:
vcoubard 1148:0340d5bbbeba 62 *
vcoubard 1148:0340d5bbbeba 63 * // boolean conversion
vcoubard 1148:0340d5bbbeba 64 * bool toBool() {
vcoubard 1148:0340d5bbbeba 65 *
vcoubard 1148:0340d5bbbeba 66 * }
vcoubard 1148:0340d5bbbeba 67 * };
vcoubard 1148:0340d5bbbeba 68 *
vcoubard 1148:0340d5bbbeba 69 * class B : public SafeBool<B> {
vcoubard 1148:0340d5bbbeba 70 * public:
vcoubard 1148:0340d5bbbeba 71 *
vcoubard 1148:0340d5bbbeba 72 * // boolean conversion
vcoubard 1148:0340d5bbbeba 73 * bool toBool() const {
vcoubard 1148:0340d5bbbeba 74 *
vcoubard 1148:0340d5bbbeba 75 * }
vcoubard 1148:0340d5bbbeba 76 * };
vcoubard 1148:0340d5bbbeba 77 *
vcoubard 1148:0340d5bbbeba 78 * A a;
vcoubard 1148:0340d5bbbeba 79 * B b;
vcoubard 1148:0340d5bbbeba 80 *
vcoubard 1148:0340d5bbbeba 81 * // will compile
vcoubard 1148:0340d5bbbeba 82 * if(a) {
vcoubard 1148:0340d5bbbeba 83 *
vcoubard 1148:0340d5bbbeba 84 * }
vcoubard 1148:0340d5bbbeba 85 *
vcoubard 1148:0340d5bbbeba 86 * // compilation error
vcoubard 1148:0340d5bbbeba 87 * if(a == b) {
vcoubard 1148:0340d5bbbeba 88 *
vcoubard 1148:0340d5bbbeba 89 * }
vcoubard 1148:0340d5bbbeba 90 *
vcoubard 1148:0340d5bbbeba 91 *
vcoubard 1149:c188d5238d62 92 * @endcode
vcoubard 1148:0340d5bbbeba 93 */
vcoubard 1148:0340d5bbbeba 94 template <typename T>
vcoubard 1148:0340d5bbbeba 95 class SafeBool : public SafeBool_::base {
vcoubard 1148:0340d5bbbeba 96 public:
vcoubard 1149:c188d5238d62 97 /**
vcoubard 1149:c188d5238d62 98 * Bool operator implementation, derived class has to provide bool toBool() const function.
vcoubard 1149:c188d5238d62 99 */
vcoubard 1149:c188d5238d62 100 operator BoolType_t() const {
vcoubard 1149:c188d5238d62 101 return (static_cast<const T*>(this))->toBool()
vcoubard 1149:c188d5238d62 102 ? &SafeBool<T>::trueTag : 0;
vcoubard 1149:c188d5238d62 103 }
vcoubard 1148:0340d5bbbeba 104 };
vcoubard 1148:0340d5bbbeba 105
vcoubard 1149:c188d5238d62 106 /**
vcoubard 1149:c188d5238d62 107 * Avoid conversion to bool between different classes.
vcoubard 1149:c188d5238d62 108 */
vcoubard 1148:0340d5bbbeba 109 template <typename T, typename U>
vcoubard 1148:0340d5bbbeba 110 void operator==(const SafeBool<T>& lhs,const SafeBool<U>& rhs) {
vcoubard 1148:0340d5bbbeba 111 lhs.invalidTag();
vcoubard 1150:45226f13ae5c 112 // return false;
vcoubard 1148:0340d5bbbeba 113 }
vcoubard 1148:0340d5bbbeba 114
vcoubard 1149:c188d5238d62 115 /**
vcoubard 1149:c188d5238d62 116 * Avoid conversion to bool between different classes.
vcoubard 1149:c188d5238d62 117 */
vcoubard 1148:0340d5bbbeba 118 template <typename T,typename U>
vcoubard 1148:0340d5bbbeba 119 void operator!=(const SafeBool<T>& lhs,const SafeBool<U>& rhs) {
vcoubard 1149:c188d5238d62 120 lhs.invalidTag();
vcoubard 1150:45226f13ae5c 121 // return false;
vcoubard 1148:0340d5bbbeba 122 }
vcoubard 1148:0340d5bbbeba 123
rgrover1 948:1bb402105289 124 #endif /* BLE_API_SAFE_BOOL_H_ */