checker.h

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//
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#ifndef MYSQL_STRCONV_DECODE_CHECKER_H
#define MYSQL_STRCONV_DECODE_CHECKER_H
 
/// @file
/// Experimental API header
 
#include <concepts>                        // invocable
#include "mysql/meta/is_specialization.h"  // Is_specialization
 
/// @addtogroup GroupLibsMysqlStrconv
/// @{
 
namespace mysql::strconv {
 
// Forward declaration
class Parser;
 
/// True for types that are invocable without arguments.
///
/// Checkers should test that a parsed object is valid, and if not, call
/// `Parser::set_parse_error` in the Parser (which should be
/// captured).
template <class Test>
concept Is_checker_function = std::invocable<Test>;
 
/// Class holding a checker function, used to check the validity of a parsed
/// value.
///
/// This type only encapsulates an std::invocable object. By using a
/// distinguished wrapper type rather than using the invocable type directly, we
/// avoid making the definition of `operator|` for parse options (see
/// parse_options.h) apply to all invocable types.
template <Is_checker_function Checker_function_tp>
class Checker {
 public:
  using Checker_function_t = Checker_function_tp;
 
  /// Can't default-construct a lambda.
  Checker() = delete;
 
  /// Construct a Checker from the given checker function.
  explicit Checker(const Checker_function_t &checker_function)
      : m_checker_function(checker_function) {}
 
  /// Invoke the checker function.
  void check() const { m_checker_function(); }
 
 private:
  /// The checker function.
  Checker_function_t m_checker_function;
};
 
/// True for all Checker specializations.
template <class Test>
concept Is_checker = mysql::meta::Is_specialization<Test, Checker>;
 
}  // namespace mysql::strconv
 
// addtogroup GroupLibsMysqlStrconv
/// @}
 
#endif  // ifndef MYSQL_STRCONV_DECODE_CHECKER_H