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| 1 | +#ifndef PERCY_PARSER |
| 2 | +#define PERCY_PARSER |
| 3 | + |
| 4 | +#include <percy/result.hpp> |
| 5 | +#include <percy/rules.hpp> |
| 6 | +#include <percy/type_traits.hpp> |
| 7 | + |
| 8 | +#include <tuple> |
| 9 | +#include <variant> |
| 10 | +#include <vector> |
| 11 | + |
| 12 | +namespace percy { |
| 13 | +template <typename Rule> |
| 14 | +struct parser { |
| 15 | + template <typename Input> |
| 16 | + constexpr static auto parse(Input input) { |
| 17 | + using result_type = result<action_return_t<Rule>>; |
| 18 | + |
| 19 | + auto raw_result = parser<typename Rule::rule>::parse(input); |
| 20 | + |
| 21 | + if (raw_result.is_failure()) { |
| 22 | + return result_type::failure(raw_result.span()); |
| 23 | + } |
| 24 | + |
| 25 | + return result_type::success(Rule::action(raw_result), raw_result.span()); |
| 26 | + } |
| 27 | +}; |
| 28 | + |
| 29 | +template <> |
| 30 | +struct parser<end> { |
| 31 | + template <typename Input> |
| 32 | + constexpr static auto parse(Input input) { |
| 33 | + using result_type = result<std::true_type>; |
| 34 | + |
| 35 | + if (!input.ended()) { |
| 36 | + return result_type::failure({input.position(), input.position()}); |
| 37 | + } |
| 38 | + |
| 39 | + return result_type::success(std::true_type(), {input.position(), input.position()}); |
| 40 | + } |
| 41 | +}; |
| 42 | + |
| 43 | +template <char Symbol> |
| 44 | +struct parser<symbol<Symbol>> { |
| 45 | + template <typename Input> |
| 46 | + constexpr static auto parse(Input input) { |
| 47 | + using result_type = result<char>; |
| 48 | + |
| 49 | + if (input.ended()) { |
| 50 | + return result_type::failure({input.position(), input.position()}); |
| 51 | + } |
| 52 | + |
| 53 | + if (input.peek() != Symbol) { |
| 54 | + return result_type::failure({input.position(), input.position() + 1}); |
| 55 | + } |
| 56 | + |
| 57 | + return result_type::success(Symbol, {input.position(), input.position() + 1}); |
| 58 | + } |
| 59 | +}; |
| 60 | + |
| 61 | +template <typename Rule> |
| 62 | +struct parser<sequence<Rule>> { |
| 63 | + template <typename Input> |
| 64 | + constexpr static auto parse(Input input) { |
| 65 | + using result_type = result<std::tuple<result_value_t<parser_result_t<Input, Rule>>>>; |
| 66 | + |
| 67 | + auto result = parser<Rule>::parse(input); |
| 68 | + |
| 69 | + if (result.is_failure()) { |
| 70 | + return result_type::failure(result.span()); |
| 71 | + } |
| 72 | + |
| 73 | + return result_type::success(result.get(), result.span()); |
| 74 | + } |
| 75 | +}; |
| 76 | + |
| 77 | +template <typename Rule, typename FollowingRule, typename ...FollowingRules> |
| 78 | +struct parser<sequence<Rule, FollowingRule, FollowingRules...>> { |
| 79 | + template <typename Input> |
| 80 | + constexpr static auto parse(Input input) { |
| 81 | + using result_type = result_followed_by_t<parser_result_t<Input, Rule>, |
| 82 | + parser_result_t<Input, sequence<FollowingRule, FollowingRules...>>>; |
| 83 | + |
| 84 | + auto result = parser<Rule>::parse(input); |
| 85 | + |
| 86 | + if (result.is_failure()) { |
| 87 | + return result_type::failure(result.span()); |
| 88 | + } |
| 89 | + |
| 90 | + auto result_following = parser<sequence<FollowingRule, FollowingRules...>>::parse(input.advanced_to(result.end())); |
| 91 | + |
| 92 | + if (result_following.is_failure()) { |
| 93 | + return result_type::failure({input.position(), result_following.end()}); |
| 94 | + } |
| 95 | + |
| 96 | + return result.followed_by(result_following); |
| 97 | + } |
| 98 | +}; |
| 99 | + |
| 100 | +template <typename Rule> |
| 101 | +struct parser<repeat<Rule>> { |
| 102 | + template <typename Input> |
| 103 | + constexpr static auto parse(Input input) { |
| 104 | + using result_type = result<std::vector<result_value_t<parser_result_t<Input, Rule>>>>; |
| 105 | + using vector_type = result_value_t<result_type>; |
| 106 | + |
| 107 | + vector_type values; |
| 108 | + auto input_current = input; |
| 109 | + |
| 110 | + while (auto result = parser<Rule>::parse(input_current)) { |
| 111 | + auto value = result.get(); |
| 112 | + values.push_back(value); |
| 113 | + input_current = input.advanced_after(result); |
| 114 | + } |
| 115 | + |
| 116 | + return result_type::success(values, {input.position(), input_current.position()}); |
| 117 | + } |
| 118 | +}; |
| 119 | + |
| 120 | +template <typename ResultType, std::size_t Index, typename Input, typename ...Rules> |
| 121 | +struct one_of_parser {}; |
| 122 | + |
| 123 | +template <typename ResultType, std::size_t Index, typename Input, typename Rule> |
| 124 | +struct one_of_parser<ResultType, Index, Input, Rule> { |
| 125 | + constexpr static auto parse(Input input) { |
| 126 | + using variant_type = result_value_t<ResultType>; |
| 127 | + |
| 128 | + auto result = parser<Rule>::parse(input); |
| 129 | + |
| 130 | + if (result.is_failure()) { |
| 131 | + return ResultType::failure(result.span()); |
| 132 | + } |
| 133 | + |
| 134 | + auto value = variant_type(std::in_place_index<Index>, result.get()); |
| 135 | + return ResultType::success(value, result.span()); |
| 136 | + } |
| 137 | +}; |
| 138 | + |
| 139 | +template <typename ResultType, std::size_t Index, typename Input, typename Rule, typename AlternativeRule, typename ...AlternativeRules> |
| 140 | +struct one_of_parser<ResultType, Index, Input, Rule, AlternativeRule, AlternativeRules...> { |
| 141 | + constexpr static auto parse(Input input) { |
| 142 | + using variant_type = result_value_t<ResultType>; |
| 143 | + |
| 144 | + if (auto result = one_of_parser<ResultType, Index, Input, Rule>::parse(input)) { |
| 145 | + return result; |
| 146 | + } |
| 147 | + |
| 148 | + return one_of_parser<ResultType, Index + 1, Input, AlternativeRule, AlternativeRules...>::parse(input); |
| 149 | + } |
| 150 | +}; |
| 151 | + |
| 152 | +template <typename ...Rules> |
| 153 | +struct parser<one_of<Rules...>> { |
| 154 | + template <typename Input> |
| 155 | + constexpr static auto parse(Input input) { |
| 156 | + using result_type = result<std::variant<result_value_t<parser_result_t<Input, Rules>>...>>; |
| 157 | + |
| 158 | + return one_of_parser<result_type, 0, Input, Rules...>::parse(input); |
| 159 | + } |
| 160 | +}; |
| 161 | + |
| 162 | +template <typename Rule> |
| 163 | +struct parser<unwrap<Rule>> { |
| 164 | + template <typename Input> |
| 165 | + constexpr static auto parse(Input input) { |
| 166 | + auto result = parser<Rule>::parse(input); |
| 167 | + return result.get(); |
| 168 | + } |
| 169 | +}; |
| 170 | +} |
| 171 | + |
| 172 | +#endif |
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