ZeroTierOne/ext/libpqxx-7.7.3/include/pqxx/array.hxx

/* Handling of SQL arrays.
 *
 * DO NOT INCLUDE THIS FILE DIRECTLY; include pqxx/field instead.
 *
 * Copyright (c) 2000-2022, Jeroen T. Vermeulen.
 *
 * See COPYING for copyright license.  If you did not receive a file called
 * COPYING with this source code, please notify the distributor of this
 * mistake, or contact the author.
 */
#ifndef PQXX_H_ARRAY
#define PQXX_H_ARRAY

#if !defined(PQXX_HEADER_PRE)
#  error "Include libpqxx headers as <pqxx/header>, not <pqxx/header.hxx>."
#endif

#include <stdexcept>
#include <string>
#include <utility>

#include "pqxx/internal/encoding_group.hxx"
#include "pqxx/internal/encodings.hxx"


namespace pqxx
{
/// Low-level array parser.
/** Use this to read an array field retrieved from the database.
 *
 * This parser will only work reliably if your client encoding is UTF-8, ASCII,
 * or a single-byte encoding which is a superset of ASCII (such as Latin-1).
 *
 * Also, the parser only supports array element types which use either a comma
 * or a semicolon ("," or ";") as the separator between array elements.  All
 * built-in types use comma, except for one which uses semicolon, but some
 * custom types may not work.
 *
 * The input is a C-style string containing the textual representation of an
 * array, as returned by the database.  The parser reads this representation
 * on the fly.  The string must remain in memory until parsing is done.
 *
 * Parse the array by making calls to @ref get_next until it returns a
 * @ref juncture of "done".  The @ref juncture tells you what the parser found
 * in that step: did the array "nest" to a deeper level, or "un-nest" back up?
 */
class PQXX_LIBEXPORT array_parser
{
public:
  /// What's the latest thing found in the array?
  enum class juncture
  {
    /// Starting a new row.
    row_start,
    /// Ending the current row.
    row_end,
    /// Found a NULL value.
    null_value,
    /// Found a string value.
    string_value,
    /// Parsing has completed.
    done,
  };

  // TODO: constexpr noexcept.  Breaks ABI.
  /// Constructor.  You don't need this; use @ref field::as_array instead.
  /** The parser only remains valid while the data underlying the @ref result
   * remains valid.  Once all `result` objects referring to that data have been
   * destroyed, the parser will no longer refer to valid memory.
   */
  explicit array_parser(
    std::string_view input,
    internal::encoding_group = internal::encoding_group::MONOBYTE);

  /// Parse the next step in the array.
  /** Returns what it found.  If the juncture is @ref juncture::string_value,
   * the string will contain the value.  Otherwise, it will be empty.
   *
   * Call this until the @ref array_parser::juncture it returns is
   * @ref juncture::done.
   */
  std::pair<juncture, std::string> get_next();

private:
  std::string_view m_input;
  internal::glyph_scanner_func *const m_scan;

  /// Current parsing position in the input.
  std::string::size_type m_pos = 0u;

  std::string::size_type scan_single_quoted_string() const;
  std::string parse_single_quoted_string(std::string::size_type end) const;
  std::string::size_type scan_double_quoted_string() const;
  std::string parse_double_quoted_string(std::string::size_type end) const;
  std::string::size_type scan_unquoted_string() const;
  std::string parse_unquoted_string(std::string::size_type end) const;

  std::string::size_type scan_glyph(std::string::size_type pos) const;
  std::string::size_type
  scan_glyph(std::string::size_type pos, std::string::size_type end) const;
};
} // namespace pqxx
#endif