[support.rtti] - C++23 → Trunk

Files changed (1) hide show

tmp/tmppz6rdx3a/{from.md → to.md} +118 -7

tmp/tmppz6rdx3a/{from.md → to.md} RENAMED Viewed

@@ -2,11 +2,13 @@
 ### General <a id="support.rtti.general">[[support.rtti.general]]</a>
 The header `<typeinfo>` defines a type associated with type information
 generated by the implementation. It also defines two types for reporting
-dynamic type identification errors.
 ### Header `<typeinfo>` synopsis <a id="typeinfo.syn">[[typeinfo.syn]]</a>
 ``` cpp
 // all freestanding
@@ -27,12 +29,12 @@ namespace std {
     constexpr bool operator==(const type_info& rhs) const noexcept;
     bool before(const type_info& rhs) const noexcept;
     size_t hash_code() const noexcept;
     const char* name() const noexcept;
-    type_info(const type_info&) = delete;                   // cannot be copied
-    type_info& operator=(const type_info&) = delete;        // cannot be copied
   };
 }
 ```
 The class `type_info` describes type information generated by the
@@ -85,21 +87,21 @@ string [[multibyte.strings]], suitable for conversion and display as a
 ``` cpp
 namespace std {
   class bad_cast : public exception {
   public:
     // see [exception] for the specification of the special member functions
-    const char* what() const noexcept override;
   };
 }
 ```
 The class `bad_cast` defines the type of objects thrown as exceptions by
 the implementation to report the execution of an invalid `dynamic_cast`
 expression [[expr.dynamic.cast]].
 ``` cpp
-const char* what() const noexcept override;
 ```
 *Returns:* An *implementation-defined* NTBS.
 ### Class `bad_typeid` <a id="bad.typeid">[[bad.typeid]]</a>
@@ -107,20 +109,129 @@ const char* what() const noexcept override;
 ``` cpp
 namespace std {
   class bad_typeid : public exception {
   public:
     // see [exception] for the specification of the special member functions
-    const char* what() const noexcept override;
   };
 }
 ```
 The class `bad_typeid` defines the type of objects thrown as exceptions
 by the implementation to report a null pointer in a `typeid` expression
 [[expr.typeid]].
 ``` cpp
-const char* what() const noexcept override;
 ```
 *Returns:* An *implementation-defined* NTBS.

 ### General <a id="support.rtti.general">[[support.rtti.general]]</a>
 The header `<typeinfo>` defines a type associated with type information
 generated by the implementation. It also defines two types for reporting
+dynamic type identification errors. The header `<typeindex>` defines a
+wrapper type for use as an index type in associative containers
+[[associative]] and in unordered associative containers [[unord]].
 ### Header `<typeinfo>` synopsis <a id="typeinfo.syn">[[typeinfo.syn]]</a>
 ``` cpp
 // all freestanding
     constexpr bool operator==(const type_info& rhs) const noexcept;
     bool before(const type_info& rhs) const noexcept;
     size_t hash_code() const noexcept;
     const char* name() const noexcept;
+    type_info(const type_info&) = delete;
+    type_info& operator=(const type_info&) = delete;
   };
 }
 ```
 The class `type_info` describes type information generated by the
 ``` cpp
 namespace std {
   class bad_cast : public exception {
   public:
     // see [exception] for the specification of the special member functions
+ constexpr const char* what() const noexcept override;
   };
 }
 ```
 The class `bad_cast` defines the type of objects thrown as exceptions by
 the implementation to report the execution of an invalid `dynamic_cast`
 expression [[expr.dynamic.cast]].
 ``` cpp
+constexpr const char* what() const noexcept override;
 ```
 *Returns:* An *implementation-defined* NTBS.
 ### Class `bad_typeid` <a id="bad.typeid">[[bad.typeid]]</a>
 ``` cpp
 namespace std {
   class bad_typeid : public exception {
   public:
     // see [exception] for the specification of the special member functions
+ constexpr const char* what() const noexcept override;
   };
 }
 ```
 The class `bad_typeid` defines the type of objects thrown as exceptions
 by the implementation to report a null pointer in a `typeid` expression
 [[expr.typeid]].
 ``` cpp
+constexpr const char* what() const noexcept override;
 ```
 *Returns:* An *implementation-defined* NTBS.
+### Header `<typeindex>` synopsis <a id="type.index.synopsis">[[type.index.synopsis]]</a>
+``` cpp
+#include <compare>              // see [compare.syn]
+namespace std {
+  class type_index;
+  template<class T> struct hash;
+  template<> struct hash<type_index>;
+}
+```
+### Class `type_index` <a id="type.index">[[type.index]]</a>
+``` cpp
+namespace std {
+  class type_index {
+  public:
+    type_index(const type_info& rhs) noexcept;
+    bool operator==(const type_index& rhs) const noexcept;
+    bool operator< (const type_index& rhs) const noexcept;
+    bool operator> (const type_index& rhs) const noexcept;
+    bool operator<=(const type_index& rhs) const noexcept;
+    bool operator>=(const type_index& rhs) const noexcept;
+    strong_ordering operator<=>(const type_index& rhs) const noexcept;
+    size_t hash_code() const noexcept;
+    const char* name() const noexcept;
+  private:
+    const type_info* target;    // exposition only
+    // Note that the use of a pointer here, rather than a reference,
+    // means that the default copy/move constructor and assignment
+    // operators will be provided and work as expected.
+  };
+}
+```
+The class `type_index` provides a simple wrapper for `type_info` which
+can be used as an index type in associative containers [[associative]]
+and in unordered associative containers [[unord]].
+``` cpp
+type_index(const type_info& rhs) noexcept;
+```
+*Effects:* Constructs a `type_index` object, the equivalent of
+`target = &rhs`.
+``` cpp
+bool operator==(const type_index& rhs) const noexcept;
+```
+*Returns:* `*target == *rhs.target`.
+``` cpp
+bool operator<(const type_index& rhs) const noexcept;
+```
+*Returns:* `target->before(*rhs.target)`.
+``` cpp
+bool operator>(const type_index& rhs) const noexcept;
+```
+*Returns:* `rhs.target->before(*target)`.
+``` cpp
+bool operator<=(const type_index& rhs) const noexcept;
+```
+*Returns:* `!rhs.target->before(*target)`.
+``` cpp
+bool operator>=(const type_index& rhs) const noexcept;
+```
+*Returns:* `!target->before(*rhs.target)`.
+``` cpp
+strong_ordering operator<=>(const type_index& rhs) const noexcept;
+```
+*Effects:* Equivalent to:
+``` cpp
+if (*target == *rhs.target) return strong_ordering::equal;
+if (target->before(*rhs.target)) return strong_ordering::less;
+return strong_ordering::greater;
+```
+``` cpp
+size_t hash_code() const noexcept;
+```
+*Returns:* `target->hash_code()`.
+``` cpp
+const char* name() const noexcept;
+```
+*Returns:* `target->name()`.
+``` cpp
+template<> struct hash<type_index>;
+```
+For an object `index` of type `type_index`, `hash<type_index>()(index)`
+shall evaluate to the same result as `index.hash_code()`.

Diff to HTML by rtfpessoa