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-rw-r--r--absl/random/internal/distribution_caller.h51
1 files changed, 47 insertions, 4 deletions
diff --git a/absl/random/internal/distribution_caller.h b/absl/random/internal/distribution_caller.h
index 4e07244..87a7684 100644
--- a/absl/random/internal/distribution_caller.h
+++ b/absl/random/internal/distribution_caller.h
@@ -20,6 +20,8 @@
#include <utility>
#include "absl/base/config.h"
+#include "absl/base/internal/fast_type_id.h"
+#include "absl/utility/utility.h"
namespace absl {
ABSL_NAMESPACE_BEGIN
@@ -30,14 +32,55 @@ namespace random_internal {
// to intercept such calls.
template <typename URBG>
struct DistributionCaller {
- // Call the provided distribution type. The parameters are expected
- // to be explicitly specified.
- // DistrT is the distribution type.
+ // SFINAE to detect whether the URBG type includes a member matching
+ // bool InvokeMock(base_internal::FastTypeIdType, void*, void*).
+ //
+ // These live inside BitGenRef so that they have friend access
+ // to MockingBitGen. (see similar methods in DistributionCaller).
+ template <template <class...> class Trait, class AlwaysVoid, class... Args>
+ struct detector : std::false_type {};
+ template <template <class...> class Trait, class... Args>
+ struct detector<Trait, absl::void_t<Trait<Args...>>, Args...>
+ : std::true_type {};
+
+ template <class T>
+ using invoke_mock_t = decltype(std::declval<T*>()->InvokeMock(
+ std::declval<::absl::base_internal::FastTypeIdType>(),
+ std::declval<void*>(), std::declval<void*>()));
+
+ using HasInvokeMock = typename detector<invoke_mock_t, void, URBG>::type;
+
+ // Default implementation of distribution caller.
template <typename DistrT, typename... Args>
- static typename DistrT::result_type Call(URBG* urbg, Args&&... args) {
+ static inline typename DistrT::result_type Impl(std::false_type, URBG* urbg,
+ Args&&... args) {
DistrT dist(std::forward<Args>(args)...);
return dist(*urbg);
}
+
+ // Mock implementation of distribution caller.
+ template <typename DistrT, typename... Args>
+ static inline typename DistrT::result_type Impl(std::true_type, URBG* urbg,
+ Args&&... args) {
+ using ResultT = typename DistrT::result_type;
+ using ArgTupleT = std::tuple<absl::decay_t<Args>...>;
+ ArgTupleT arg_tuple(std::forward<Args>(args)...);
+ ResultT result;
+ if (!urbg->InvokeMock(
+ ::absl::base_internal::FastTypeId<ResultT(DistrT, ArgTupleT)>(),
+ &arg_tuple, &result)) {
+ auto dist = absl::make_from_tuple<DistrT>(arg_tuple);
+ result = dist(*urbg);
+ }
+ return result;
+ }
+
+ // Default implementation of distribution caller.
+ template <typename DistrT, typename... Args>
+ static inline typename DistrT::result_type Call(URBG* urbg, Args&&... args) {
+ return Impl<DistrT, Args...>(HasInvokeMock{}, urbg,
+ std::forward<Args>(args)...);
+ }
};
} // namespace random_internal