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      1 /*
      2  * Copyright 2014 Google Inc. All rights reserved.
      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  *     http://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 
     17 #ifndef FRUIT_TYPE_INFO_H
     18 #define FRUIT_TYPE_INFO_H
     19 
     20 #include <fruit/impl/meta/vector.h>
     21 #include <fruit/impl/util/demangle_type_name.h>
     22 #include <typeinfo>
     23 
     24 #include <vector>
     25 
     26 namespace fruit {
     27 namespace impl {
     28 
     29 // Similar to std::type_index, but with a constexpr constructor and also storing the type size and alignment.
     30 // Also guaranteed to be aligned, to allow storing a TypeInfo and 1 bit together in the size of a void*.
     31 struct alignas(1) alignas(void*) TypeInfo {
     32 
     33   struct ConcreteTypeInfo {
     34     // These fields are allowed to have dummy values for abstract types.
     35     std::size_t type_size;
     36     std::size_t type_alignment;
     37     bool is_trivially_destructible;
     38 
     39 #if FRUIT_EXTRA_DEBUG
     40     bool is_abstract;
     41 #endif
     42   };
     43 
     44   // This should only be used if RTTI is disabled. Use the other constructor if possible.
     45   constexpr TypeInfo(ConcreteTypeInfo concrete_type_info);
     46 
     47   constexpr TypeInfo(const std::type_info& info, ConcreteTypeInfo concrete_type_info);
     48 
     49   std::string name() const;
     50 
     51   size_t size() const;
     52 
     53   size_t alignment() const;
     54 
     55   bool isTriviallyDestructible() const;
     56 
     57 private:
     58   // The std::type_info struct associated with the type, or nullptr if RTTI is disabled.
     59   // This is only used for the type name.
     60   const std::type_info* info;
     61   ConcreteTypeInfo concrete_type_info;
     62 };
     63 
     64 struct TypeId {
     65   const TypeInfo* type_info;
     66 
     67   operator std::string() const;
     68 
     69   bool operator==(TypeId x) const;
     70   bool operator!=(TypeId x) const;
     71   bool operator<(TypeId x) const;
     72 };
     73 
     74 // Returns the TypeId for the type T.
     75 // Multiple invocations for the same type return the same value.
     76 // This has special support for types of the form Annotated<SomeAnnotation, SomeType>, it reports
     77 // data for SomeType (except the name, that is "Annotated<SomeAnnotation, SomeType>").
     78 template <typename T>
     79 TypeId getTypeId();
     80 
     81 // A convenience function that returns an std::vector of TypeId values for the given meta-vector of types.
     82 template <typename V>
     83 std::vector<TypeId> getTypeIdsForList();
     84 
     85 } // namespace impl
     86 } // namespace fruit
     87 
     88 #if FRUIT_EXTRA_DEBUG
     89 
     90 #include <ostream>
     91 
     92 namespace fruit {
     93 namespace impl {
     94 
     95 inline std::ostream& operator<<(std::ostream& os, TypeId type);
     96 
     97 } // namespace impl
     98 } // namespace fruit
     99 
    100 #endif // FRUIT_EXTRA_DEBUG
    101 
    102 namespace std {
    103 
    104 template <>
    105 struct hash<fruit::impl::TypeId> {
    106   std::size_t operator()(fruit::impl::TypeId type) const;
    107 };
    108 
    109 } // namespace std
    110 
    111 #include <fruit/impl/util/type_info.defn.h>
    112 
    113 #endif // FRUIT_TYPE_INFO_H
    114