better document visit

Author: grisumbras

include/boost/json/visit.hpp

@@ -20,34 +20,102 @@ namespace json {
 
 /** Invoke a function object with the contents of a @ref value
 
+    Invokes `v` as if by `std::forward<Visitor>(v)( X )`, where `X` is
+
+    @li `jv.get_array()` if `jv.is_array()`, or
+
+    @li `jv.get_object()` if `jv.is_object()`, or
+
+    @li `jv.get_string()` if `jv.is_string()`, or
+
+    @li `jv.get_int64()` if `jv.is_int64()`, or
+
+    @li `jv.get_uint64()` if `jv.is_uint64()`, or
+
+    @li `jv.get_double()` if `jv.is_double()`, or
+
+    @li `jv.get_bool()` if `jv.is_bool()`, or
+
+    @li reference to an object of type `std::nullptr_t` if `jv.is_null()`.
+
     @return The value returned by Visitor.
 
     @param v The visitation function to invoke
 
     @param jv The value to visit.
 */
-/** @{ */
 template<class Visitor>
 auto
 visit(
     Visitor&& v,
     value& jv) -> decltype(
         static_cast<Visitor&&>(v)( std::declval<std::nullptr_t&>() ) );
 
+/** Invoke a function object with the contents of a @ref value
+
+    Invokes `v` as if by `std::forward<Visitor>(v)( X )`, where `X` is
+
+    @li `jv.get_array()` if `jv.is_array()`, or
+
+    @li `jv.get_object()` if `jv.is_object()`, or
+
+    @li `jv.get_string()` if `jv.is_string()`, or
+
+    @li `jv.get_int64()` if `jv.is_int64()`, or
+
+    @li `jv.get_uint64()` if `jv.is_uint64()`, or
+
+    @li `jv.get_double()` if `jv.is_double()`, or
+
+    @li `jv.get_bool()` if `jv.is_bool()`, or
+
+    @li reference to an object of type `const std::nullptr_t` if `jv.is_null()`.
+
+    @return The value returned by Visitor.
+
+    @param v The visitation function to invoke
+
+    @param jv The value to visit.
+*/
 template<class Visitor>
 auto
 visit(
     Visitor &&v,
     value const &jv) -> decltype(
         static_cast<Visitor&&>(v)( std::declval<std::nullptr_t const&>() ) );
 
+/** Invoke a function object with the contents of a @ref value
+
+    Invokes `v` as if by `std::forward<Visitor>(v)( X )`, where `X` is
+
+    @li `std::move( jv.get_array() )` if `jv.is_array()`, or
+
+    @li `std::move( jv.get_object() )` if `jv.is_object()`, or
+
+    @li `std::move( jv.get_string() )` if `jv.is_string()`, or
+
+    @li `std::move( jv.get_int64() )` if `jv.is_int64()`, or
+
+    @li `std::move( jv.get_uint64() )` if `jv.is_uint64()`, or
+
+    @li `std::move( jv.get_double() )` if `jv.is_double()`, or
+
+    @li `std::move( jv.get_bool() )` if `jv.is_bool()`, or
+
+    @li `std::nullptr_t()` if `jv.is_null()`.
+
+    @return The value returned by Visitor.
+
+    @param v The visitation function to invoke
+
+    @param jv The value to visit.
+*/
 template<class Visitor>
 auto
 visit(
     Visitor &&v,
     value&& jv) -> decltype(
         static_cast<Visitor&&>(v)( std::declval<std::nullptr_t&&>() ) );
-/** @} */
 
 } // namespace json
 } // namespace boost