Maxim nexpaq / nexpaq_dev

Preliminary main mbed library for nexpaq development

features/FEATURE_BLE/ble/SafeBool.h@0:6c56fb4bc5f0, 2016-11-04 (annotated)

Committer:
nexpaq
Date:
Fri Nov 04 20:27:58 2016 +0000
Revision:
0:6c56fb4bc5f0
Moving to library for sharing updates

Who changed what in which revision?

UserRevisionLine numberNew contents of line
nexpaq 0:6c56fb4bc5f0 1 /* mbed Microcontroller Library
nexpaq 0:6c56fb4bc5f0 2 * Copyright (c) 2006-2013 ARM Limited
nexpaq 0:6c56fb4bc5f0 3 *
nexpaq 0:6c56fb4bc5f0 4 * Licensed under the Apache License, Version 2.0 (the "License");
nexpaq 0:6c56fb4bc5f0 5 * you may not use this file except in compliance with the License.
nexpaq 0:6c56fb4bc5f0 6 * You may obtain a copy of the License at
nexpaq 0:6c56fb4bc5f0 7 *
nexpaq 0:6c56fb4bc5f0 8 * http://www.apache.org/licenses/LICENSE-2.0
nexpaq 0:6c56fb4bc5f0 9 *
nexpaq 0:6c56fb4bc5f0 10 * Unless required by applicable law or agreed to in writing, software
nexpaq 0:6c56fb4bc5f0 11 * distributed under the License is distributed on an "AS IS" BASIS,
nexpaq 0:6c56fb4bc5f0 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
nexpaq 0:6c56fb4bc5f0 13 * See the License for the specific language governing permissions and
nexpaq 0:6c56fb4bc5f0 14 * limitations under the License.
nexpaq 0:6c56fb4bc5f0 15 */
nexpaq 0:6c56fb4bc5f0 16
nexpaq 0:6c56fb4bc5f0 17 #ifndef BLE_API_SAFE_BOOL_H_
nexpaq 0:6c56fb4bc5f0 18 #define BLE_API_SAFE_BOOL_H_
nexpaq 0:6c56fb4bc5f0 19
nexpaq 0:6c56fb4bc5f0 20 /* Safe bool idiom, see : http://www.artima.com/cppsource/safebool.html */
nexpaq 0:6c56fb4bc5f0 21
nexpaq 0:6c56fb4bc5f0 22 namespace SafeBool_ {
nexpaq 0:6c56fb4bc5f0 23 /**
nexpaq 0:6c56fb4bc5f0 24 * @brief Base class for all intances of SafeBool.
nexpaq 0:6c56fb4bc5f0 25 * This base class reduces instantiation of trueTag function.
nexpaq 0:6c56fb4bc5f0 26 */
nexpaq 0:6c56fb4bc5f0 27 class base {
nexpaq 0:6c56fb4bc5f0 28 template<typename>
nexpaq 0:6c56fb4bc5f0 29 friend class SafeBool;
nexpaq 0:6c56fb4bc5f0 30
nexpaq 0:6c56fb4bc5f0 31 protected:
nexpaq 0:6c56fb4bc5f0 32 /**
nexpaq 0:6c56fb4bc5f0 33 * The bool type is a pointer to method which can be used in boolean context.
nexpaq 0:6c56fb4bc5f0 34 */
nexpaq 0:6c56fb4bc5f0 35 typedef void (base::*BoolType_t)() const;
nexpaq 0:6c56fb4bc5f0 36
nexpaq 0:6c56fb4bc5f0 37 /**
nexpaq 0:6c56fb4bc5f0 38 * Non implemented call, use to disallow conversion between unrelated types.
nexpaq 0:6c56fb4bc5f0 39 */
nexpaq 0:6c56fb4bc5f0 40 void invalidTag() const;
nexpaq 0:6c56fb4bc5f0 41
nexpaq 0:6c56fb4bc5f0 42 /**
nexpaq 0:6c56fb4bc5f0 43 * Member function which indicate true value.
nexpaq 0:6c56fb4bc5f0 44 */
nexpaq 0:6c56fb4bc5f0 45 void trueTag() const {}
nexpaq 0:6c56fb4bc5f0 46 };
nexpaq 0:6c56fb4bc5f0 47
nexpaq 0:6c56fb4bc5f0 48
nexpaq 0:6c56fb4bc5f0 49 }
nexpaq 0:6c56fb4bc5f0 50
nexpaq 0:6c56fb4bc5f0 51 /**
nexpaq 0:6c56fb4bc5f0 52 * @brief template class SafeBool use CRTP to made boolean conversion easy and correct.
nexpaq 0:6c56fb4bc5f0 53 * Derived class should implement the function bool toBool() const to make this work. Inheritance
nexpaq 0:6c56fb4bc5f0 54 * should be public.
nexpaq 0:6c56fb4bc5f0 55 *
nexpaq 0:6c56fb4bc5f0 56 * @tparam T Type of the derived class
nexpaq 0:6c56fb4bc5f0 57 *
nexpaq 0:6c56fb4bc5f0 58 * @code
nexpaq 0:6c56fb4bc5f0 59 *
nexpaq 0:6c56fb4bc5f0 60 * class A : public SafeBool<A> {
nexpaq 0:6c56fb4bc5f0 61 * public:
nexpaq 0:6c56fb4bc5f0 62 *
nexpaq 0:6c56fb4bc5f0 63 * // boolean conversion
nexpaq 0:6c56fb4bc5f0 64 * bool toBool() {
nexpaq 0:6c56fb4bc5f0 65 *
nexpaq 0:6c56fb4bc5f0 66 * }
nexpaq 0:6c56fb4bc5f0 67 * };
nexpaq 0:6c56fb4bc5f0 68 *
nexpaq 0:6c56fb4bc5f0 69 * class B : public SafeBool<B> {
nexpaq 0:6c56fb4bc5f0 70 * public:
nexpaq 0:6c56fb4bc5f0 71 *
nexpaq 0:6c56fb4bc5f0 72 * // boolean conversion
nexpaq 0:6c56fb4bc5f0 73 * bool toBool() const {
nexpaq 0:6c56fb4bc5f0 74 *
nexpaq 0:6c56fb4bc5f0 75 * }
nexpaq 0:6c56fb4bc5f0 76 * };
nexpaq 0:6c56fb4bc5f0 77 *
nexpaq 0:6c56fb4bc5f0 78 * A a;
nexpaq 0:6c56fb4bc5f0 79 * B b;
nexpaq 0:6c56fb4bc5f0 80 *
nexpaq 0:6c56fb4bc5f0 81 * // will compile
nexpaq 0:6c56fb4bc5f0 82 * if(a) {
nexpaq 0:6c56fb4bc5f0 83 *
nexpaq 0:6c56fb4bc5f0 84 * }
nexpaq 0:6c56fb4bc5f0 85 *
nexpaq 0:6c56fb4bc5f0 86 * // compilation error
nexpaq 0:6c56fb4bc5f0 87 * if(a == b) {
nexpaq 0:6c56fb4bc5f0 88 *
nexpaq 0:6c56fb4bc5f0 89 * }
nexpaq 0:6c56fb4bc5f0 90 *
nexpaq 0:6c56fb4bc5f0 91 *
nexpaq 0:6c56fb4bc5f0 92 * @endcode
nexpaq 0:6c56fb4bc5f0 93 */
nexpaq 0:6c56fb4bc5f0 94 template <typename T>
nexpaq 0:6c56fb4bc5f0 95 class SafeBool : public SafeBool_::base {
nexpaq 0:6c56fb4bc5f0 96 public:
nexpaq 0:6c56fb4bc5f0 97 /**
nexpaq 0:6c56fb4bc5f0 98 * Bool operator implementation, derived class has to provide bool toBool() const function.
nexpaq 0:6c56fb4bc5f0 99 */
nexpaq 0:6c56fb4bc5f0 100 operator BoolType_t() const {
nexpaq 0:6c56fb4bc5f0 101 return (static_cast<const T*>(this))->toBool()
nexpaq 0:6c56fb4bc5f0 102 ? &SafeBool<T>::trueTag : 0;
nexpaq 0:6c56fb4bc5f0 103 }
nexpaq 0:6c56fb4bc5f0 104 };
nexpaq 0:6c56fb4bc5f0 105
nexpaq 0:6c56fb4bc5f0 106 /**
nexpaq 0:6c56fb4bc5f0 107 * Avoid conversion to bool between different classes.
nexpaq 0:6c56fb4bc5f0 108 */
nexpaq 0:6c56fb4bc5f0 109 template <typename T, typename U>
nexpaq 0:6c56fb4bc5f0 110 void operator==(const SafeBool<T>& lhs,const SafeBool<U>& rhs) {
nexpaq 0:6c56fb4bc5f0 111 lhs.invalidTag();
nexpaq 0:6c56fb4bc5f0 112 // return false;
nexpaq 0:6c56fb4bc5f0 113 }
nexpaq 0:6c56fb4bc5f0 114
nexpaq 0:6c56fb4bc5f0 115 /**
nexpaq 0:6c56fb4bc5f0 116 * Avoid conversion to bool between different classes.
nexpaq 0:6c56fb4bc5f0 117 */
nexpaq 0:6c56fb4bc5f0 118 template <typename T,typename U>
nexpaq 0:6c56fb4bc5f0 119 void operator!=(const SafeBool<T>& lhs,const SafeBool<U>& rhs) {
nexpaq 0:6c56fb4bc5f0 120 lhs.invalidTag();
nexpaq 0:6c56fb4bc5f0 121 // return false;
nexpaq 0:6c56fb4bc5f0 122 }
nexpaq 0:6c56fb4bc5f0 123
nexpaq 0:6c56fb4bc5f0 124 #endif /* BLE_API_SAFE_BOOL_H_ */