Adapts a visitor for use as a function object. Adapts the function given at construction for use as a function object. This is useful, for example, when one needs to operate on each element of a sequence of variant objects using a standard library algorithm such as std::for_each. See the "visitor-only" form of apply_visitor for a simple way to create apply_visitor_delayed_t objects. See apply_visitor_delayed_cpp14_t which is used on C++14 compatible compilers when Visitor has no result_type typedef. typename Visitor::result_type Visitor & Constructs the function object with the given visitor. result_type Variant&... result_type Variant & result_type Variant1 & Variant2 & Function call operator. Invokes apply_visitor on the stored visitor using the given operands. Version with variadic templates is used by default if BOOST_VARIANT_DO_NOT_USE_VARIADIC_TEMPLATES is not defined. Adapts a visitor for use as a function object. Adapts the function given at construction for use as a function object. This is useful, for example, when one needs to operate on each element of a sequence of variant objects using a standard library algorithm such as std::for_each. See the "visitor-only" form of apply_visitor for a simple way to create apply_visitor_delayed_t objects. See apply_visitor_delayed_t which is used when Visitor has result_type typedef. Available only if macro BOOST_VARIANT_DO_NOT_USE_VARIADIC_TEMPLATES is not defined and compiler supports decltype(auto) and decltype(some-expression). Visitor & Constructs the function object with the given visitor. decltype(auto) Variant&... Function call operator. Invokes apply_visitor on the stored visitor using the given operands. typename Visitor::result_type Visitor & Variant&& typename Visitor::result_type const Visitor & Variant&& typename BinaryVisitor::result_type OR decltype(auto) BinaryVisitor & Variant1&& Variant2&& typename BinaryVisitor::result_type OR decltype(auto) const BinaryVisitor & Variant1&& Variant2&& typename MultiVisitor::result_type OR decltype(auto) MultiVisitor & Variant1&& Variant2&& Variant3&& ... typename MultiVisitor::result_type OR decltype(auto) const MultiVisitor & Variant1&& Variant2&& Variant3&& ... apply_visitor_delayed_t<Visitor> Visitor & apply_visitor_delayed_cpp14_t<Visitor> Visitor & Allows compile-time checked type-safe application of the given visitor to the content of the given variant, ensuring that all types are handled by the visitor. The behavior of apply_visitor is dependent on the number of arguments on which it operates (i.e., other than the visitor). If your compiler does not support the rvalue references or reference qualifiers then all the forwarding references from above degrade to non const lvalue reference. The function behaves as follows: Overloads accepting one operand invoke the unary function call operator of the given visitor on the content of the given variant operand. Overloads accepting two operands invoke the binary function call operator of the given visitor on the content of the given variant operands. Overloads accepting three or more operands invoke the function call operator of the given visitor on the content of the given variant operands. Maximum amount of parameters controlled by BOOST_VARAINT_MAX_MULTIVIZITOR_PARAMS macro. Those functions are actually defined in a header boost/variant/multivisitors.hpp (See ). That header must be manually included if multi visitors are meant for use. The overloads accepting only a visitor return a C++03 compatible generic function object or C++14 compatible generic function object that accepts either one, two or arbitrary count of arguments and invoke apply_visitor using these arguments and visitor, thus behaving as specified above. (This behavior is particularly useful, for example, when one needs to operate on each element of a sequence of variant objects using a standard library algorithm.) The overloads acccepting operands return the result of applying the given visitor to the content of the given operands. The overload accepting only a visitor return a function object, thus delaying application of the visitor to any operands. The given visitor must fulfill the StaticVisitor concept requirements with respect to each of the bounded types of the given variant. The overloads accepting operands throw only if the given visitor throws when applied. The overload accepting only a visitor will not throw. (Note, however, that the returned function object may throw when invoked.)