1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
|
#ifndef RFL_PARSING_FIELD_VARIANT_PARSER_HPP_
#define RFL_PARSING_FIELD_VARIANT_PARSER_HPP_
#include <map>
#include <stdexcept>
#include <string>
#include <type_traits>
#include "../Result.hpp"
#include "../Tuple.hpp"
#include "../Variant.hpp"
#include "../always_false.hpp"
#include "../visit.hpp"
#include "FieldVariantReader.hpp"
#include "Parser_base.hpp"
#include "schema/Type.hpp"
namespace rfl {
namespace parsing {
/// To be used when all options of the variants are rfl::Field. Essentially,
/// this is an externally tagged union.
template <class R, class W, class ProcessorsType, class... FieldTypes>
requires AreReaderAndWriter<R, W, rfl::Variant<FieldTypes...>>
struct FieldVariantParser {
using FieldVariantType = rfl::Variant<FieldTypes...>;
using ResultType = Result<FieldVariantType>;
public:
using InputObjectType = typename R::InputObjectType;
using InputVarType = typename R::InputVarType;
static ResultType read(const R& _r, const InputVarType& _var) noexcept {
static_assert(
internal::no_duplicate_field_names<rfl::Tuple<FieldTypes...>>(),
"Externally tagged variants cannot have duplicate field "
"names.");
const auto to_result = [&](const auto _obj) -> ResultType {
auto field_variant = std::optional<Result<FieldVariantType>>();
const auto reader =
FieldVariantReader<R, W, ProcessorsType, FieldTypes...>(
&_r, &field_variant);
auto err = _r.read_object(reader, _obj);
if (err) {
return error(*err);
}
if (!field_variant) {
return error(
"Could not parse: Expected the object to have "
"exactly one field, but found more than one.");
}
return std::move(*field_variant);
};
return _r.to_object(_var).and_then(to_result);
}
template <class P>
static void write(const W& _w, const rfl::Variant<FieldTypes...>& _v,
const P& _parent) noexcept {
static_assert(
internal::no_duplicate_field_names<rfl::Tuple<FieldTypes...>>(),
"Externally tagged variants cannot have duplicate field "
"names.");
_v.visit([&](const auto& _field) {
const auto named_tuple = make_named_tuple(internal::to_ptr_field(_field));
using NamedTupleType = std::remove_cvref_t<decltype(named_tuple)>;
Parser<R, W, NamedTupleType, ProcessorsType>::write(_w, named_tuple,
_parent);
});
}
static schema::Type to_schema(
std::map<std::string, schema::Type>* _definitions,
std::vector<schema::Type> _types = {}) {
using VariantType = rfl::Variant<NamedTuple<FieldTypes>...>;
return Parser<R, W, VariantType, ProcessorsType>::to_schema(_definitions);
}
};
} // namespace parsing
} // namespace rfl
#endif
|
