simdjson-simdjson/include/simdjson/error.h

#ifndef SIMDJSON_ERROR_H
#define SIMDJSON_ERROR_H

#include "simdjson/base.h"

#include <string>
#include <ostream>

namespace simdjson {

/**
 * All possible errors returned by simdjson. These error codes are subject to change
 * and not all simdjson kernel returns the same error code given the same input: it is not
 * well defined which error a given input should produce.
 *
 * Only SUCCESS evaluates to false as a Boolean. All other error codes will evaluate
 * to true as a Boolean.
 */
enum error_code {
  SUCCESS = 0,                ///< No error
  CAPACITY,                   ///< This parser can't support a document that big
  MEMALLOC,                   ///< Error allocating memory, most likely out of memory
  TAPE_ERROR,                 ///< Something went wrong, this is a generic error. Fatal/unrecoverable error.
  DEPTH_ERROR,                ///< Your document exceeds the user-specified depth limitation
  STRING_ERROR,               ///< Problem while parsing a string
  T_ATOM_ERROR,               ///< Problem while parsing an atom starting with the letter 't'
  F_ATOM_ERROR,               ///< Problem while parsing an atom starting with the letter 'f'
  N_ATOM_ERROR,               ///< Problem while parsing an atom starting with the letter 'n'
  NUMBER_ERROR,               ///< Problem while parsing a number
  BIGINT_ERROR,               ///< The integer value exceeds 64 bits
  UTF8_ERROR,                 ///< the input is not valid UTF-8
  UNINITIALIZED,              ///< unknown error, or uninitialized document
  EMPTY,                      ///< no structural element found
  UNESCAPED_CHARS,            ///< found unescaped characters in a string.
  UNCLOSED_STRING,            ///< missing quote at the end
  UNSUPPORTED_ARCHITECTURE,   ///< unsupported architecture
  INCORRECT_TYPE,             ///< JSON element has a different type than user expected
  NUMBER_OUT_OF_RANGE,        ///< JSON number does not fit in 64 bits
  INDEX_OUT_OF_BOUNDS,        ///< JSON array index too large
  NO_SUCH_FIELD,              ///< JSON field not found in object
  IO_ERROR,                   ///< Error reading a file
  INVALID_JSON_POINTER,       ///< Invalid JSON pointer syntax
  INVALID_URI_FRAGMENT,       ///< Invalid URI fragment
  UNEXPECTED_ERROR,           ///< indicative of a bug in simdjson
  PARSER_IN_USE,              ///< parser is already in use.
  OUT_OF_ORDER_ITERATION,     ///< tried to iterate an array or object out of order (checked when SIMDJSON_DEVELOPMENT_CHECKS=1)
  INSUFFICIENT_PADDING,       ///< The JSON doesn't have enough padding for simdjson to safely parse it.
  INCOMPLETE_ARRAY_OR_OBJECT, ///< The document ends early. Fatal/unrecoverable error.
  SCALAR_DOCUMENT_AS_VALUE,   ///< A scalar document is treated as a value.
  OUT_OF_BOUNDS,              ///< Attempted to access location outside of document.
  TRAILING_CONTENT,           ///< Unexpected trailing content in the JSON input
  OUT_OF_CAPACITY,            ///< The capacity was exceeded, we cannot allocate enough memory.
  NUM_ERROR_CODES             ///< Placeholder for end of error code list.
};

/**
 * Some errors are fatal and invalidate the document. This function returns true if the
 * error is fatal. It returns true for TAPE_ERROR and INCOMPLETE_ARRAY_OR_OBJECT.
 * Once a fatal error is encountered, the on-demand document is no longer valid and
 * processing should stop.
 */
 inline bool is_fatal(error_code error) noexcept;

/**
 * It is the convention throughout the code that  the macro SIMDJSON_DEVELOPMENT_CHECKS determines whether
 * we check for OUT_OF_ORDER_ITERATION. The logic behind it is that these errors only occurs when the code
 * that was written while breaking some simdjson::ondemand requirement. They should not occur in released
 * code after these issues were fixed.
 */

/**
 * Get the error message for the given error code.
 *
 *   dom::parser parser;
 *   dom::element doc;
 *   auto error = parser.parse("foo",3).get(doc);
 *   if (error) { printf("Error: %s\n", error_message(error)); }
 *
 * @return The error message.
 */
inline const char *error_message(error_code error) noexcept;

/**
 * Write the error message to the output stream
 */
inline std::ostream& operator<<(std::ostream& out, error_code error) noexcept;

/**
 * Exception thrown when an exception-supporting simdjson method is called
 */
struct simdjson_error : public std::exception {
  /**
   * Create an exception from a simdjson error code.
   * @param error The error code
   */
  simdjson_error(error_code error) noexcept : _error{error} { }
  /** The error message */
  const char *what() const noexcept override { return error_message(error()); }
  /** The error code */
  error_code error() const noexcept { return _error; }
private:
  /** The error code that was used */
  error_code _error;
};

namespace internal {

/**
 * The result of a simdjson operation that could fail.
 *
 * Gives the option of reading error codes, or throwing an exception by casting to the desired result.
 *
 * This is a base class for implementations that want to add functions to the result type for
 * chaining.
 *
 * Override like:
 *
 *   struct simdjson_result<T> : public internal::simdjson_result_base<T> {
 *     simdjson_result() noexcept : internal::simdjson_result_base<T>() {}
 *     simdjson_result(error_code error) noexcept : internal::simdjson_result_base<T>(error) {}
 *     simdjson_result(T &&value) noexcept : internal::simdjson_result_base<T>(std::forward(value)) {}
 *     simdjson_result(T &&value, error_code error) noexcept : internal::simdjson_result_base<T>(value, error) {}
 *     // Your extra methods here
 *   }
 *
 * Then any method returning simdjson_result<T> will be chainable with your methods.
 */
template<typename T>
struct simdjson_result_base : protected std::pair<T, error_code> {

  /**
   * Create a new empty result with error = UNINITIALIZED.
   */
  simdjson_inline simdjson_result_base() noexcept;

  /**
   * Create a new error result.
   */
  simdjson_inline simdjson_result_base(error_code error) noexcept;

  /**
   * Create a new successful result.
   */
  simdjson_inline simdjson_result_base(T &&value) noexcept;

  /**
   * Create a new result with both things (use if you don't want to branch when creating the result).
   */
  simdjson_inline simdjson_result_base(T &&value, error_code error) noexcept;

  /**
   * Move the value and the error to the provided variables.
   *
   * @param value The variable to assign the value to. May not be set if there is an error.
   * @param error The variable to assign the error to. Set to SUCCESS if there is no error.
   */
  simdjson_inline void tie(T &value, error_code &error) && noexcept;

  /**
   * Move the value to the provided variable.
   *
   * @param value The variable to assign the value to. May not be set if there is an error.
   */
  simdjson_inline error_code get(T &value) && noexcept;

  /**
   * The error.
   */
  simdjson_inline error_code error() const noexcept;

#if SIMDJSON_EXCEPTIONS

  /**
   * Get the result value.
   *
   * @throw simdjson_error if there was an error.
   */
  simdjson_inline T& value() & noexcept(false);

  /**
   * Take the result value (move it).
   *
   * @throw simdjson_error if there was an error.
   */
  simdjson_inline T&& value() && noexcept(false);

  /**
   * Take the result value (move it).
   *
   * @throw simdjson_error if there was an error.
   */
  simdjson_inline T&& take_value() && noexcept(false);

  /**
   * Cast to the value (will throw on error).
   *
   * @throw simdjson_error if there was an error.
   */
  simdjson_inline operator T&&() && noexcept(false);

#endif // SIMDJSON_EXCEPTIONS

  /**
   * Get the result value. This function is safe if and only
   * the error() method returns a value that evaluates to false.
   * We discourage the use of value_unsafe().
   *
   * The recommended pattern is:
   *
   * T value; // where T is the type
   * auto error = result.get(value);
   * if (error) {
   *   // handle error
   * }
   *
   * Or you may call 'value()' which will raise an exception
   * in case of error:
   *
   * T value = result.value();
   */
  simdjson_inline const T& value_unsafe() const& noexcept;

  /**
   * Take the result value (move it). This function is safe if and only
   * the error() method returns a value that evaluates to false.
   * We discourage the use of value_unsafe().
   *
   * The recommended pattern is:
   *
   * T value; // where T is the type
   * auto error = result.get(value);
   * if (error) {
   *   // handle error, return, exit, abort
   * } else {
   *   // use value here.
   * }
   *
   * Or you may call 'value()' which will raise an exception
   * in case of error:
   *
   * T value = result.value();
   */
  simdjson_inline T&& value_unsafe() && noexcept;

}; // struct simdjson_result_base

} // namespace internal

/**
 * The result of a simdjson operation that could fail.
 *
 * Gives the option of reading error codes, or throwing an exception by casting to the desired result.
 */
template<typename T>
struct simdjson_result : public internal::simdjson_result_base<T> {
  /**
   * @private Create a new empty result with error = UNINITIALIZED.
   */
  simdjson_inline simdjson_result() noexcept;
  /**
   * @private Create a new successful result.
   */
  simdjson_inline simdjson_result(T &&value) noexcept;
  /**
   * @private Create a new error result.
   */
  simdjson_inline simdjson_result(error_code error_code) noexcept;
  /**
   * @private Create a new result with both things (use if you don't want to branch when creating the result).
   */
  simdjson_inline simdjson_result(T &&value, error_code error) noexcept;

  /**
   * Move the value and the error to the provided variables.
   *
   * @param value The variable to assign the value to. May not be set if there is an error.
   * @param error The variable to assign the error to. Set to SUCCESS if there is no error.
   */
  simdjson_inline void tie(T &value, error_code &error) && noexcept;

  /**
   * Move the value to the provided variable.
   *
   * @param value The variable to assign the value to. May not be set if there is an error.
   */
  simdjson_warn_unused simdjson_inline error_code get(T &value) && noexcept;
//
  /**
   * Copy the value to a provided std::string, only enabled for std::string_view.
   *
   * @param value The variable to assign the value to. May not be set if there is an error.
   */
  simdjson_warn_unused simdjson_inline error_code get(std::string &value) && noexcept
#if SIMDJSON_SUPPORTS_DESERIALIZATION
  requires (!std::is_same_v<T, std::string>)
#endif // SIMDJSON_SUPPORTS_DESERIALIZATION
  ;
  /**
   * The error.
   */
  simdjson_inline error_code error() const noexcept;

#if SIMDJSON_EXCEPTIONS

  /**
   * Get the result value.
   *
   * @throw simdjson_error if there was an error.
   */
  simdjson_inline T& value() & noexcept(false);

  /**
   * Take the result value (move it).
   *
   * @throw simdjson_error if there was an error.
   */
  simdjson_inline T&& value() && noexcept(false);

  /**
   * Take the result value (move it).
   *
   * @throw simdjson_error if there was an error.
   */
  simdjson_inline T&& take_value() && noexcept(false);

  /**
   * Cast to the value (will throw on error).
   *
   * @throw simdjson_error if there was an error.
   */
  simdjson_inline operator T&&() && noexcept(false);
#endif // SIMDJSON_EXCEPTIONS

  /**
   * Get the result value. This function is safe if and only
   * the error() method returns a value that evaluates to false.
   */
  simdjson_inline const T& value_unsafe() const& noexcept;

  /**
   * Take the result value (move it). This function is safe if and only
   * the error() method returns a value that evaluates to false.
   */
  simdjson_inline T&& value_unsafe() && noexcept;

}; // struct simdjson_result

#if SIMDJSON_EXCEPTIONS

template<typename T>
inline std::ostream& operator<<(std::ostream& out, simdjson_result<T> value) { return out << value.value(); }
#endif // SIMDJSON_EXCEPTIONS

#ifndef SIMDJSON_DISABLE_DEPRECATED_API
/**
 * @deprecated This is an alias and will be removed, use error_code instead
 */
using ErrorValues [[deprecated("This is an alias and will be removed, use error_code instead")]] = error_code;

/**
 * @deprecated Error codes should be stored and returned as `error_code`, use `error_message()` instead.
 */
[[deprecated("Error codes should be stored and returned as `error_code`, use `error_message()` instead.")]]
inline const std::string error_message(int error) noexcept;
#endif // SIMDJSON_DISABLE_DEPRECATED_API
} // namespace simdjson

#endif // SIMDJSON_ERROR_H