1 // 2 // Copyright 2018 The Abseil Authors. 3 // 4 // Licensed under the Apache License, Version 2.0 (the "License"); 5 // you may not use this file except in compliance with the License. 6 // You may obtain a copy of the License at 7 // 8 // https://www.apache.org/licenses/LICENSE-2.0 9 // 10 // Unless required by applicable law or agreed to in writing, software 11 // distributed under the License is distributed on an "AS IS" BASIS, 12 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 // See the License for the specific language governing permissions and 14 // limitations under the License. 15 // 16 #ifndef ABSL_RANDOM_INTERNAL_MOCKING_BIT_GEN_BASE_H_ 17 #define ABSL_RANDOM_INTERNAL_MOCKING_BIT_GEN_BASE_H_ 18 19 #include <atomic> 20 #include <deque> 21 #include <string> 22 #include <typeinfo> 23 24 #include "absl/random/random.h" 25 #include "absl/strings/str_cat.h" 26 27 namespace absl { 28 ABSL_NAMESPACE_BEGIN 29 namespace random_internal { 30 31 // MockingBitGenExpectationFormatter is invoked to format unsatisfied mocks 32 // and remaining results into a description string. 33 template <typename DistrT, typename FormatT> 34 struct MockingBitGenExpectationFormatter { operatorMockingBitGenExpectationFormatter35 std::string operator()(absl::string_view args) { 36 return absl::StrCat(FormatT::FunctionName(), "(", args, ")"); 37 } 38 }; 39 40 // MockingBitGenCallFormatter is invoked to format each distribution call 41 // into a description string for the mock log. 42 template <typename DistrT, typename FormatT> 43 struct MockingBitGenCallFormatter { operatorMockingBitGenCallFormatter44 std::string operator()(const DistrT& dist, 45 const typename DistrT::result_type& result) { 46 return absl::StrCat( 47 FormatT::FunctionName(), "(", FormatT::FormatArgs(dist), ") => {", 48 FormatT::FormatResults(absl::MakeSpan(&result, 1)), "}"); 49 } 50 }; 51 52 class MockingBitGenBase { 53 template <typename> 54 friend struct DistributionCaller; 55 using generator_type = absl::BitGen; 56 57 public: 58 // URBG interface 59 using result_type = generator_type::result_type; result_type(min)60 static constexpr result_type(min)() { return (generator_type::min)(); } result_type(max)61 static constexpr result_type(max)() { return (generator_type::max)(); } operator()62 result_type operator()() { return gen_(); } 63 MockingBitGenBase()64 MockingBitGenBase() : gen_(), observed_call_log_() {} 65 virtual ~MockingBitGenBase() = default; 66 67 protected: observed_call_log()68 const std::deque<std::string>& observed_call_log() { 69 return observed_call_log_; 70 } 71 72 // CallImpl is the type-erased virtual dispatch. 73 // The type of dist is always distribution<T>, 74 // The type of result is always distribution<T>::result_type. 75 virtual bool CallImpl(const std::type_info& distr_type, void* dist_args, 76 void* result) = 0; 77 78 template <typename DistrT, typename ArgTupleT> GetTypeId()79 static const std::type_info& GetTypeId() { 80 return typeid(std::pair<absl::decay_t<DistrT>, absl::decay_t<ArgTupleT>>); 81 } 82 83 // Call the generating distribution function. 84 // Invoked by DistributionCaller<>::Call<DistT, FormatT>. 85 // DistT is the distribution type. 86 // FormatT is the distribution formatter traits type. 87 template <typename DistrT, typename FormatT, typename... Args> Call(Args &&...args)88 typename DistrT::result_type Call(Args&&... args) { 89 using distr_result_type = typename DistrT::result_type; 90 using ArgTupleT = std::tuple<absl::decay_t<Args>...>; 91 92 ArgTupleT arg_tuple(std::forward<Args>(args)...); 93 auto dist = absl::make_from_tuple<DistrT>(arg_tuple); 94 95 distr_result_type result{}; 96 bool found_match = 97 CallImpl(GetTypeId<DistrT, ArgTupleT>(), &arg_tuple, &result); 98 99 if (!found_match) { 100 result = dist(gen_); 101 } 102 103 // TODO(asoffer): Forwarding the args through means we no longer need to 104 // extract them from the from the distribution in formatter traits. We can 105 // just StrJoin them. 106 observed_call_log_.push_back( 107 MockingBitGenCallFormatter<DistrT, FormatT>{}(dist, result)); 108 return result; 109 } 110 111 private: 112 generator_type gen_; 113 std::deque<std::string> observed_call_log_; 114 }; // namespace random_internal 115 116 } // namespace random_internal 117 ABSL_NAMESPACE_END 118 } // namespace absl 119 120 #endif // ABSL_RANDOM_INTERNAL_MOCKING_BIT_GEN_BASE_H_ 121