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#ifndef GRAMMAR_HH
#define GRAMMAR_HH
#include "errors.hh"
#include "io.hh"
#include <cstdint>
#include <span>
#include <string>
#include <vector>
namespace grammar {
struct Element;
struct Symbol {
enum class Type : uint8_t {
// value == terminal, as UTF-8
kTerminal,
// element != nullptr
kNonTerminal,
// char_class != 0
kCharacterClass,
};
Type type;
enum class Optional : uint8_t {
// Symbol is NOT optional.
kRequired,
// Symbol is optional.
kZeroOrOne,
// Symbol is optional and can repeat.
kZeroOrMore,
// Symbol should be excluded from previous symbol.
// Example: InputCharacter but not * or /
kExcluded,
};
Optional optional{Optional::kRequired};
uint8_t char_class{0};
Element const* element{nullptr};
std::string value;
};
struct Definition {
std::vector<Symbol> symbols;
};
struct Element {
std::string name;
std::vector<Definition> definitions;
};
class Grammar {
public:
virtual ~Grammar() = default;
Grammar(Grammar const&) = delete;
Grammar& operator=(Grammar const&) = delete;
[[nodiscard]]
virtual Element const& root() const = 0;
protected:
Grammar() = default;
};
std::unique_ptr<Grammar> load(std::unique_ptr<io::Reader> reader,
std::vector<std::string> const& character_classes,
src::Errors& errors);
} // namespace grammar
#endif // GRAMMAR_HH
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