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abstract_parser.h
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abstract_parser.h
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#pragma once
#include <optional>
template <typename T>
class Parser {
public:
using DataType = T;
virtual ~Parser() = default;
virtual std::optional<DataType> Parse(const DataType& data) = 0;
};
template <typename FirstParser, typename... RestParsers>
class ParserChain : public Parser<typename FirstParser::DataType> {
// If Parser return std::nullopt, further processing will not happen
public:
using DataType = typename FirstParser::DataType;
explicit ParserChain(FirstParser first_parser, RestParsers... rest_parsers)
: first_parser_(first_parser), rest_parsers_(rest_parsers...) {}
std::optional<DataType> Parse(const DataType& data) override {
auto processed_data = first_parser_.Parse(data);
if (!processed_data) {
return std::nullopt;
}
return rest_parsers_.Parse(*processed_data);
}
private:
FirstParser first_parser_;
ParserChain<RestParsers...> rest_parsers_;
};
template <typename LastParser>
class ParserChain<LastParser> : public Parser<typename LastParser::DataType> {
public:
using DataType = typename LastParser::DataType;
explicit ParserChain(LastParser last_parser)
: last_parser_(last_parser) {}
std::optional<DataType> Parse(const DataType& data) override {
return last_parser_.Parse(data);
}
private:
LastParser last_parser_;
};