refactor conversion category customisation

Users are now meant to specialise conversion_category_of.

Author: grisumbras

doc/externals.hpp

@@ -212,6 +212,16 @@ struct bad_alloc {};
 /// @see https://en.cppreference.com/w/cpp/container/map
 struct map {};
 
+/// !EXTERNAL!
+///
+/// @see https://en.cppreference.com/cpp/utility/variant/monostate
+struct monostate {};
+
+/// !EXTERNAL!
+///
+/// @see https://en.cppreference.com/w/cpp/container/multimap
+struct multimap {};
+
 /// !EXTERNAL!
 ///
 /// @see https://en.cppreference.com/w/cpp/container/unordered_map

doc/pages/reference.adoc

@@ -33,6 +33,10 @@ a| *Classes* +
 <<ref_value_ref>> +
 <<ref_value_stack>>
 
+*Aliases* +
+<<ref_parser_for>> +
+<<ref_string_view>>
+
 a| *Functions* +
 <<ref_get>> +
 <<ref_get_null_resource>> +
@@ -47,12 +51,7 @@ a| *Functions* +
 <<ref_value_to>> +
 <<ref_visit>>
 
-*P0308R0* +
-<<ref_pilfer>> +
-<<ref_pilfered>> +
-<<ref_is_pilfer_constructible>>
-
-| *Operators* +
+*Operators* +
 <<ref_operator_eq_eq>> +
 <<ref_operator_not_eq>> +
 <<ref_operator_gt>> +
@@ -61,37 +60,61 @@ a| *Functions* +
 <<ref_operator_lt_eq>> +
 <<ref_operator_lt_lt>> +
 
-*Aliases* +
-<<ref_parser_for>> +
-<<ref_string_view>>
+| *Type Traits* +
+<<ref_boolean_category>> +
+<<ref_conversion_category_of>> +
+<<ref_described_class_category>> +
+<<ref_described_enum_category>> +
+<<ref_floating_point_category>> +
+<<ref_has_value_from>> +
+<<ref_has_value_to>> +
+<<ref_integer_category>> +
+<<ref_is_deallocate_trivial>> +
+<<ref_map_category>> +
+<<ref_null_category>> +
+<<ref_optional_category>> +
+<<ref_path_category>> +
+<<ref_result_for>> +
+<<ref_sequence_category>> +
+<<ref_string_category>> +
+<<ref_try_value_to_tag>> +
+<<ref_tuple_category>> +
+<<ref_value_from_tag>> +
+<<ref_value_to_tag>> +
+<<ref_variant_category>> +
+<<ref_unknown_category>>
 
-*Constants* +
+| *Constants* +
 <<ref_array_kind>> +
 <<ref_condition>> +
+<<ref_conversion_category>> +
 <<ref_error>> +
 <<ref_kind>> +
 <<ref_number_precision>> +
 <<ref_object_kind>> +
 <<ref_string_kind>>
 
-| *Type Traits* +
-<<ref_has_value_from>> +
-<<ref_has_value_to>> +
-<<ref_is_deallocate_trivial>> +
+*P0308R0* +
+<<ref_pilfer>> +
+<<ref_pilfered>> +
+<<ref_is_pilfer_constructible>>
+
+4+h|Deprecated
+
+a|
 <<ref_is_described_class>> +
 <<ref_is_described_enum>> +
-<<ref_is_map_like>> +
+<<ref_is_map_like>>
+a|
 <<ref_is_null_like>> +
-<<ref_is_optional_like>> +
+<<ref_is_optional_like>>
+a|
 <<ref_is_path_like>> +
 <<ref_is_sequence_like>> +
-<<ref_is_string_like>> +
+<<ref_is_string_like>>
+a|
 <<ref_is_tuple_like>> +
-<<ref_is_variant_like>> +
-<<ref_result_for>> +
-<<ref_try_value_to_tag>> +
-<<ref_value_from_tag>> +
-<<ref_value_to_tag>>
+<<ref_is_variant_like>>
 
 |===