103 lines
3.4 KiB
C++
103 lines
3.4 KiB
C++
#ifndef RFL_INTERNAL_REMOVEFIELDS_HPP_
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#define RFL_INTERNAL_REMOVEFIELDS_HPP_
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#include <algorithm>
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#include <tuple>
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#include <type_traits>
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#include "../NamedTuple.hpp"
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#include "../define_named_tuple.hpp"
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#include "StringLiteral.hpp"
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namespace rfl {
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namespace internal {
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/// Recursively builds a new NamedTuple type from the FieldTypes, leaving
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/// out the field signified by _name.
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template <class _OldNamedTupleType,
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StringLiteral _name,
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class _NewNamedTupleType,
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int _i>
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struct remove_single_field;
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/// Special case - _i == 0
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template <class _OldNamedTupleType,
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StringLiteral _name,
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class _NewNamedTupleType>
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struct remove_single_field<_OldNamedTupleType,
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_name,
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_NewNamedTupleType,
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0> {
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using type = _NewNamedTupleType;
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};
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/// General case.
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template <class _OldNamedTupleType,
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StringLiteral _name,
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class _NewNamedTupleType,
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int _i>
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struct remove_single_field {
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using OldNamedTupleType = std::remove_cvref_t<_OldNamedTupleType>;
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constexpr static int num_fields =
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std::tuple_size_v<typename OldNamedTupleType::Fields>;
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using FieldType = std::remove_cvref_t<typename std::tuple_element<
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num_fields - _i,
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typename OldNamedTupleType::Fields>::type>;
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using NewNamedTupleType = std::conditional_t<
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_name == FieldType::name_,
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_NewNamedTupleType,
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define_named_tuple_t<_NewNamedTupleType, FieldType>>;
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using type = typename remove_single_field<OldNamedTupleType,
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_name,
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NewNamedTupleType,
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_i - 1>::type;
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};
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/// Recursively removes all of the fields signified by _head and _tail from
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/// the NamedTupleType.
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template <class _NamedTupleType,
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StringLiteral _head,
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StringLiteral... _tail>
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struct remove_fields;
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/// Special case - only head is left.
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template <class _NamedTupleType, StringLiteral _head>
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struct remove_fields<_NamedTupleType, _head> {
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using NamedTupleType = std::remove_cvref_t<_NamedTupleType>;
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constexpr static int num_fields =
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std::tuple_size_v<typename NamedTupleType::Fields>;
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using type = typename remove_single_field<NamedTupleType,
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_head,
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NamedTuple<>,
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num_fields>::type;
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};
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/// General case.
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template <class _NamedTupleType,
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StringLiteral _head,
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StringLiteral... _tail>
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struct remove_fields {
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using NamedTupleType = std::remove_cvref_t<_NamedTupleType>;
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constexpr static int num_fields =
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std::tuple_size_v<typename NamedTupleType::Fields>;
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using NewNamedTupleType = typename remove_single_field<NamedTupleType,
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_head,
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NamedTuple<>,
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num_fields>::type;
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using type = typename remove_fields<NewNamedTupleType, _tail...>::type;
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};
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} // namespace internal
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} // namespace rfl
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#endif // RFL_REMOVEFIELDS_HPP_
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