# <!-- rdoc-file=encoding.c -->
# An Encoding instance represents a character encoding usable in Ruby. It is
# defined as a constant under the Encoding namespace. It has a name and,
# optionally, aliases:
#
#     Encoding::US_ASCII.name  # => "US-ASCII"
#     Encoding::US_ASCII.names # => ["US-ASCII", "ASCII", "ANSI_X3.4-1968", "646"]
#
# A Ruby method that accepts an encoding as an argument will accept:
#
# *   An Encoding object.
# *   The name of an encoding.
# *   An alias for an encoding name.
#
#
# These are equivalent:
#
#     'foo'.encode(Encoding::US_ASCII) # Encoding object.
#     'foo'.encode('US-ASCII')         # Encoding name.
#     'foo'.encode('ASCII')            # Encoding alias.
#
# For a full discussion of encodings and their uses, see [the Encodings
# document](rdoc-ref:encodings.rdoc).
#
# Encoding::ASCII_8BIT is a special-purpose encoding that is usually used for a
# string of bytes, not a string of characters. But as the name indicates, its
# characters in the ASCII range are considered as ASCII characters. This is
# useful when you use other ASCII-compatible encodings.
#
class Encoding
  def self._load: [T] (T) -> T

  # <!--
  #   rdoc-file=encoding.c
  #   - Encoding.locale_charmap -> string
  # -->
  # Returns the locale charmap name. It returns nil if no appropriate information.
  #
  #     Debian GNU/Linux
  #       LANG=C
  #         Encoding.locale_charmap  #=> "ANSI_X3.4-1968"
  #       LANG=ja_JP.EUC-JP
  #         Encoding.locale_charmap  #=> "EUC-JP"
  #
  #     SunOS 5
  #       LANG=C
  #         Encoding.locale_charmap  #=> "646"
  #       LANG=ja
  #         Encoding.locale_charmap  #=> "eucJP"
  #
  # The result is highly platform dependent. So
  # Encoding.find(Encoding.locale_charmap) may cause an error. If you need some
  # encoding object even for unknown locale, Encoding.find("locale") can be used.
  #
  def self.locale_charmap: () -> String

  # <!--
  #   rdoc-file=encoding.c
  #   - Encoding.aliases -> {"alias1" => "orig1", "alias2" => "orig2", ...}
  # -->
  # Returns the hash of available encoding alias and original encoding name.
  #
  #     Encoding.aliases
  #     #=> {"BINARY"=>"ASCII-8BIT", "ASCII"=>"US-ASCII", "ANSI_X3.4-1968"=>"US-ASCII",
  #           "SJIS"=>"Windows-31J", "eucJP"=>"EUC-JP", "CP932"=>"Windows-31J"}
  #
  def self.aliases: () -> Hash[String, String]

  # <!--
  #   rdoc-file=encoding.c
  #   - Encoding.compatible?(obj1, obj2) -> enc or nil
  # -->
  # Checks the compatibility of two objects.
  #
  # If the objects are both strings they are compatible when they are
  # concatenatable.  The encoding of the concatenated string will be returned if
  # they are compatible, nil if they are not.
  #
  #     Encoding.compatible?("\xa1".force_encoding("iso-8859-1"), "b")
  #     #=> #<Encoding:ISO-8859-1>
  #
  #     Encoding.compatible?(
  #       "\xa1".force_encoding("iso-8859-1"),
  #       "\xa1\xa1".force_encoding("euc-jp"))
  #     #=> nil
  #
  # If the objects are non-strings their encodings are compatible when they have
  # an encoding and:
  # *   Either encoding is US-ASCII compatible
  # *   One of the encodings is a 7-bit encoding
  #
  def self.compatible?: (untyped obj1, untyped obj2) -> Encoding?

  # <!--
  #   rdoc-file=encoding.c
  #   - Encoding.default_external -> enc
  # -->
  # Returns default external encoding.
  #
  # The default external encoding is used by default for strings created from the
  # following locations:
  #
  # *   CSV
  # *   File data read from disk
  # *   SDBM
  # *   StringIO
  # *   Zlib::GzipReader
  # *   Zlib::GzipWriter
  # *   String#inspect
  # *   Regexp#inspect
  #
  #
  # While strings created from these locations will have this encoding, the
  # encoding may not be valid.  Be sure to check String#valid_encoding?.
  #
  # File data written to disk will be transcoded to the default external encoding
  # when written, if default_internal is not nil.
  #
  # The default external encoding is initialized by the -E option. If -E isn't
  # set, it is initialized to UTF-8 on Windows and the locale on other operating
  # systems.
  #
  def self.default_external: () -> Encoding

  # <!--
  #   rdoc-file=encoding.c
  #   - Encoding.default_external = enc
  # -->
  # Sets default external encoding.  You should not set Encoding::default_external
  # in ruby code as strings created before changing the value may have a different
  # encoding from strings created after the value was changed., instead you should
  # use `ruby -E` to invoke ruby with the correct default_external.
  #
  # See Encoding::default_external for information on how the default external
  # encoding is used.
  #
  def self.default_external=: (Encoding enc) -> Encoding
                            | [T < _ToStr] (T enc) -> T

  # <!--
  #   rdoc-file=encoding.c
  #   - Encoding.default_internal -> enc
  # -->
  # Returns default internal encoding.  Strings will be transcoded to the default
  # internal encoding in the following places if the default internal encoding is
  # not nil:
  #
  # *   CSV
  # *   Etc.sysconfdir and Etc.systmpdir
  # *   File data read from disk
  # *   File names from Dir
  # *   Integer#chr
  # *   String#inspect and Regexp#inspect
  # *   Strings returned from Readline
  # *   Strings returned from SDBM
  # *   Time#zone
  # *   Values from ENV
  # *   Values in ARGV including $PROGRAM_NAME
  #
  #
  # Additionally String#encode and String#encode! use the default internal
  # encoding if no encoding is given.
  #
  # The script encoding (__ENCODING__), not default_internal, is used as the
  # encoding of created strings.
  #
  # Encoding::default_internal is initialized with -E option or nil otherwise.
  #
  def self.default_internal: () -> Encoding?

  # <!--
  #   rdoc-file=encoding.c
  #   - Encoding.default_internal = enc or nil
  # -->
  # Sets default internal encoding or removes default internal encoding when
  # passed nil.  You should not set Encoding::default_internal in ruby code as
  # strings created before changing the value may have a different encoding from
  # strings created after the change.  Instead you should use `ruby -E` to invoke
  # ruby with the correct default_internal.
  #
  # See Encoding::default_internal for information on how the default internal
  # encoding is used.
  #
  def self.default_internal=: (Encoding enc) -> Encoding
                            | [T < _ToStr] (T enc) -> T
                            | (nil) -> nil

  # <!--
  #   rdoc-file=encoding.c
  #   - Encoding.find(string) -> enc
  # -->
  # Search the encoding with specified *name*. *name* should be a string.
  #
  #     Encoding.find("US-ASCII")  #=> #<Encoding:US-ASCII>
  #
  # Names which this method accept are encoding names and aliases including
  # following special aliases
  #
  # "external"
  # :   default external encoding
  # "internal"
  # :   default internal encoding
  # "locale"
  # :   locale encoding
  # "filesystem"
  # :   filesystem encoding
  #
  #
  # An ArgumentError is raised when no encoding with *name*. Only
  # `Encoding.find("internal")` however returns nil when no encoding named
  # "internal", in other words, when Ruby has no default internal encoding.
  #
  def self.find: (encoding enc) -> Encoding?

  # <!--
  #   rdoc-file=encoding.c
  #   - Encoding.list -> [enc1, enc2, ...]
  # -->
  # Returns the list of loaded encodings.
  #
  #     Encoding.list
  #     #=> [#<Encoding:ASCII-8BIT>, #<Encoding:UTF-8>,
  #           #<Encoding:ISO-2022-JP (dummy)>]
  #
  #     Encoding.find("US-ASCII")
  #     #=> #<Encoding:US-ASCII>
  #
  #     Encoding.list
  #     #=> [#<Encoding:ASCII-8BIT>, #<Encoding:UTF-8>,
  #           #<Encoding:US-ASCII>, #<Encoding:ISO-2022-JP (dummy)>]
  #
  def self.list: () -> Array[Encoding]

  # <!--
  #   rdoc-file=encoding.c
  #   - Encoding.name_list -> ["enc1", "enc2", ...]
  # -->
  # Returns the list of available encoding names.
  #
  #     Encoding.name_list
  #     #=> ["US-ASCII", "ASCII-8BIT", "UTF-8",
  #           "ISO-8859-1", "Shift_JIS", "EUC-JP",
  #           "Windows-31J",
  #           "BINARY", "CP932", "eucJP"]
  #
  def self.name_list: () -> Array[String]

  # <!--
  #   rdoc-file=encoding.c
  #   - enc.ascii_compatible? -> true or false
  # -->
  # Returns whether ASCII-compatible or not.
  #
  #     Encoding::UTF_8.ascii_compatible?     #=> true
  #     Encoding::UTF_16BE.ascii_compatible?  #=> false
  #
  def ascii_compatible?: () -> bool

  # <!--
  #   rdoc-file=encoding.c
  #   - enc.dummy? -> true or false
  # -->
  # Returns true for dummy encodings. A dummy encoding is an encoding for which
  # character handling is not properly implemented. It is used for stateful
  # encodings.
  #
  #     Encoding::ISO_2022_JP.dummy?       #=> true
  #     Encoding::UTF_8.dummy?             #=> false
  #
  def dummy?: () -> bool

  # <!--
  #   rdoc-file=encoding.c
  #   - enc.inspect -> string
  # -->
  # Returns a string which represents the encoding for programmers.
  #
  #     Encoding::UTF_8.inspect       #=> "#<Encoding:UTF-8>"
  #     Encoding::ISO_2022_JP.inspect #=> "#<Encoding:ISO-2022-JP (dummy)>"
  #
  def inspect: () -> String

  # <!-- rdoc-file=encoding.c -->
  # Returns the name of the encoding.
  #
  #     Encoding::UTF_8.name      #=> "UTF-8"
  #
  def name: () -> String

  # <!--
  #   rdoc-file=encoding.c
  #   - enc.names -> array
  # -->
  # Returns the list of name and aliases of the encoding.
  #
  #     Encoding::WINDOWS_31J.names  #=> ["Windows-31J", "CP932", "csWindows31J", "SJIS", "PCK"]
  #
  def names: () -> Array[String]

  # <!--
  #   rdoc-file=encoding.c
  #   - enc.name -> string
  #   - enc.to_s -> string
  # -->
  # Returns the name of the encoding.
  #
  #     Encoding::UTF_8.name      #=> "UTF-8"
  #
  alias to_s name

  ANSI_X3_4_1968: Encoding
  ASCII: Encoding
  ASCII_8BIT: Encoding
  BIG5: Encoding
  BIG5_HKSCS: Encoding
  BIG5_HKSCS_2008: Encoding
  BIG5_UAO: Encoding
  BINARY: Encoding
  Big5: Encoding
  Big5_HKSCS: Encoding
  Big5_HKSCS_2008: Encoding
  Big5_UAO: Encoding
  CESU_8: Encoding
  CP1250: Encoding
  CP1251: Encoding
  CP1252: Encoding
  CP1253: Encoding
  CP1254: Encoding
  CP1255: Encoding
  CP1256: Encoding
  CP1257: Encoding
  CP1258: Encoding
  CP437: Encoding
  CP50220: Encoding
  CP50221: Encoding
  CP51932: Encoding
  CP65000: Encoding
  CP65001: Encoding
  CP737: Encoding
  CP775: Encoding
  CP850: Encoding
  CP852: Encoding
  CP855: Encoding
  CP857: Encoding
  CP860: Encoding
  CP861: Encoding
  CP862: Encoding
  CP863: Encoding
  CP864: Encoding
  CP865: Encoding
  CP866: Encoding
  CP869: Encoding
  CP874: Encoding
  CP878: Encoding
  CP932: Encoding
  CP936: Encoding
  CP949: Encoding
  CP950: Encoding
  CP951: Encoding
  CSWINDOWS31J: Encoding
  CsWindows31J: Encoding
  EBCDIC_CP_US: Encoding
  EMACS_MULE: Encoding
  EUCCN: Encoding
  EUCJP: Encoding
  EUCJP_MS: Encoding
  EUCKR: Encoding
  EUCTW: Encoding
  EUC_CN: Encoding
  EUC_JISX0213: Encoding
  EUC_JIS_2004: Encoding
  EUC_JP: Encoding
  EUC_JP_MS: Encoding
  EUC_KR: Encoding
  EUC_TW: Encoding
  Emacs_Mule: Encoding
  EucCN: Encoding
  EucJP: Encoding
  EucJP_ms: Encoding
  EucKR: Encoding
  EucTW: Encoding
  GB12345: Encoding
  GB18030: Encoding
  GB1988: Encoding
  GB2312: Encoding
  GBK: Encoding
  IBM037: Encoding
  IBM437: Encoding
  IBM737: Encoding
  IBM720: Encoding
  CP720: Encoding
  IBM775: Encoding
  IBM850: Encoding
  IBM852: Encoding
  IBM855: Encoding
  IBM857: Encoding
  IBM860: Encoding
  IBM861: Encoding
  IBM862: Encoding
  IBM863: Encoding
  IBM864: Encoding
  IBM865: Encoding
  IBM866: Encoding
  IBM869: Encoding
  ISO2022_JP: Encoding
  ISO2022_JP2: Encoding
  ISO8859_1: Encoding
  ISO8859_10: Encoding
  ISO8859_11: Encoding
  ISO8859_13: Encoding
  ISO8859_14: Encoding
  ISO8859_15: Encoding
  ISO8859_16: Encoding
  ISO8859_2: Encoding
  ISO8859_3: Encoding
  ISO8859_4: Encoding
  ISO8859_5: Encoding
  ISO8859_6: Encoding
  ISO8859_7: Encoding
  ISO8859_8: Encoding
  ISO8859_9: Encoding
  ISO_2022_JP: Encoding
  ISO_2022_JP_2: Encoding
  ISO_2022_JP_KDDI: Encoding
  ISO_8859_1: Encoding
  ISO_8859_10: Encoding
  ISO_8859_11: Encoding
  ISO_8859_13: Encoding
  ISO_8859_14: Encoding
  ISO_8859_15: Encoding
  ISO_8859_16: Encoding
  ISO_8859_2: Encoding
  ISO_8859_3: Encoding
  ISO_8859_4: Encoding
  ISO_8859_5: Encoding
  ISO_8859_6: Encoding
  ISO_8859_7: Encoding
  ISO_8859_8: Encoding
  ISO_8859_9: Encoding
  KOI8_R: Encoding
  KOI8_U: Encoding
  MACCENTEURO: Encoding
  MACCROATIAN: Encoding
  MACCYRILLIC: Encoding
  MACGREEK: Encoding
  MACICELAND: Encoding
  MACJAPAN: Encoding
  MACJAPANESE: Encoding
  MACROMAN: Encoding
  MACROMANIA: Encoding
  MACTHAI: Encoding
  MACTURKISH: Encoding
  MACUKRAINE: Encoding
  MacCentEuro: Encoding
  MacCroatian: Encoding
  MacCyrillic: Encoding
  MacGreek: Encoding
  MacIceland: Encoding
  MacJapan: Encoding
  MacJapanese: Encoding
  MacRoman: Encoding
  MacRomania: Encoding
  MacThai: Encoding
  MacTurkish: Encoding
  MacUkraine: Encoding
  PCK: Encoding
  SHIFT_JIS: Encoding
  SJIS: Encoding
  SJIS_DOCOMO: Encoding
  SJIS_DoCoMo: Encoding
  SJIS_KDDI: Encoding
  SJIS_SOFTBANK: Encoding
  SJIS_SoftBank: Encoding
  STATELESS_ISO_2022_JP: Encoding
  STATELESS_ISO_2022_JP_KDDI: Encoding
  Shift_JIS: Encoding
  Stateless_ISO_2022_JP: Encoding
  Stateless_ISO_2022_JP_KDDI: Encoding
  TIS_620: Encoding
  UCS_2BE: Encoding
  UCS_4BE: Encoding
  UCS_4LE: Encoding
  US_ASCII: Encoding
  UTF8_DOCOMO: Encoding
  UTF8_DoCoMo: Encoding
  UTF8_KDDI: Encoding
  UTF8_MAC: Encoding
  UTF8_SOFTBANK: Encoding
  UTF8_SoftBank: Encoding
  UTF_16: Encoding
  UTF_16BE: Encoding
  UTF_16LE: Encoding
  UTF_32: Encoding
  UTF_32BE: Encoding
  UTF_32LE: Encoding
  UTF_7: Encoding
  UTF_8: Encoding
  UTF_8_HFS: Encoding
  UTF_8_MAC: Encoding
  WINDOWS_1250: Encoding
  WINDOWS_1251: Encoding
  WINDOWS_1252: Encoding
  WINDOWS_1253: Encoding
  WINDOWS_1254: Encoding
  WINDOWS_1255: Encoding
  WINDOWS_1256: Encoding
  WINDOWS_1257: Encoding
  WINDOWS_1258: Encoding
  WINDOWS_31J: Encoding
  WINDOWS_874: Encoding
  Windows_1250: Encoding
  Windows_1251: Encoding
  Windows_1252: Encoding
  Windows_1253: Encoding
  Windows_1254: Encoding
  Windows_1255: Encoding
  Windows_1256: Encoding
  Windows_1257: Encoding
  Windows_1258: Encoding
  Windows_31J: Encoding
  Windows_874: Encoding

  # <!-- rdoc-file=error.c -->
  # Raised by Encoding and String methods when the source encoding is incompatible
  # with the target encoding.
  #
  class CompatibilityError < EncodingError
  end

  # <!-- rdoc-file=transcode.c -->
  # Raised by transcoding methods when a named encoding does not correspond with a
  # known converter.
  #
  class ConverterNotFoundError < EncodingError
  end

  # <!-- rdoc-file=transcode.c -->
  # Raised by Encoding and String methods when the string being transcoded
  # contains a byte invalid for the either the source or target encoding.
  #
  class InvalidByteSequenceError < EncodingError
    # <!--
    #   rdoc-file=transcode.c
    #   - ecerr.destination_encoding         -> string
    # -->
    # Returns the destination encoding as an encoding object.
    #
    def destination_encoding: () -> Encoding

    # <!--
    #   rdoc-file=transcode.c
    #   - ecerr.destination_encoding_name         -> string
    # -->
    # Returns the destination encoding name as a string.
    #
    def destination_encoding_name: () -> String

    # <!--
    #   rdoc-file=transcode.c
    #   - ecerr.error_bytes         -> string
    # -->
    # Returns the discarded bytes when Encoding::InvalidByteSequenceError occurs.
    #
    #     ec = Encoding::Converter.new("EUC-JP", "ISO-8859-1")
    #     begin
    #       ec.convert("abc\xA1\xFFdef")
    #     rescue Encoding::InvalidByteSequenceError
    #       p $!      #=> #<Encoding::InvalidByteSequenceError: "\xA1" followed by "\xFF" on EUC-JP>
    #       puts $!.error_bytes.dump          #=> "\xA1"
    #       puts $!.readagain_bytes.dump      #=> "\xFF"
    #     end
    #
    def error_bytes: () -> String

    # <!--
    #   rdoc-file=transcode.c
    #   - ecerr.incomplete_input?         -> true or false
    # -->
    # Returns true if the invalid byte sequence error is caused by premature end of
    # string.
    #
    #     ec = Encoding::Converter.new("EUC-JP", "ISO-8859-1")
    #
    #     begin
    #       ec.convert("abc\xA1z")
    #     rescue Encoding::InvalidByteSequenceError
    #       p $!      #=> #<Encoding::InvalidByteSequenceError: "\xA1" followed by "z" on EUC-JP>
    #       p $!.incomplete_input?    #=> false
    #     end
    #
    #     begin
    #       ec.convert("abc\xA1")
    #       ec.finish
    #     rescue Encoding::InvalidByteSequenceError
    #       p $!      #=> #<Encoding::InvalidByteSequenceError: incomplete "\xA1" on EUC-JP>
    #       p $!.incomplete_input?    #=> true
    #     end
    #
    def incomplete_input?: () -> bool

    # <!--
    #   rdoc-file=transcode.c
    #   - ecerr.readagain_bytes         -> string
    # -->
    # Returns the bytes to be read again when Encoding::InvalidByteSequenceError
    # occurs.
    #
    def readagain_bytes: () -> String

    # <!--
    #   rdoc-file=transcode.c
    #   - ecerr.source_encoding              -> encoding
    # -->
    # Returns the source encoding as an encoding object.
    #
    # Note that the result may not be equal to the source encoding of the encoding
    # converter if the conversion has multiple steps.
    #
    #     ec = Encoding::Converter.new("ISO-8859-1", "EUC-JP") # ISO-8859-1 -> UTF-8 -> EUC-JP
    #     begin
    #       ec.convert("\xa0") # NO-BREAK SPACE, which is available in UTF-8 but not in EUC-JP.
    #     rescue Encoding::UndefinedConversionError
    #       p $!.source_encoding              #=> #<Encoding:UTF-8>
    #       p $!.destination_encoding         #=> #<Encoding:EUC-JP>
    #       p $!.source_encoding_name         #=> "UTF-8"
    #       p $!.destination_encoding_name    #=> "EUC-JP"
    #     end
    #
    def source_encoding: () -> Encoding

    # <!--
    #   rdoc-file=transcode.c
    #   - ecerr.source_encoding_name         -> string
    # -->
    # Returns the source encoding name as a string.
    #
    def source_encoding_name: () -> String
  end

  # <!-- rdoc-file=transcode.c -->
  # Raised by Encoding and String methods when a transcoding operation fails.
  #
  class UndefinedConversionError < EncodingError
    # <!--
    #   rdoc-file=transcode.c
    #   - ecerr.destination_encoding         -> string
    # -->
    # Returns the destination encoding as an encoding object.
    #
    def destination_encoding: () -> Encoding

    # <!--
    #   rdoc-file=transcode.c
    #   - ecerr.destination_encoding_name         -> string
    # -->
    # Returns the destination encoding name as a string.
    #
    def destination_encoding_name: () -> String

    # <!--
    #   rdoc-file=transcode.c
    #   - ecerr.error_char         -> string
    # -->
    # Returns the one-character string which cause
    # Encoding::UndefinedConversionError.
    #
    #     ec = Encoding::Converter.new("ISO-8859-1", "EUC-JP")
    #     begin
    #       ec.convert("\xa0")
    #     rescue Encoding::UndefinedConversionError
    #       puts $!.error_char.dump   #=> "\xC2\xA0"
    #       p $!.error_char.encoding  #=> #<Encoding:UTF-8>
    #     end
    #
    def error_char: () -> String

    # <!--
    #   rdoc-file=transcode.c
    #   - ecerr.source_encoding              -> encoding
    # -->
    # Returns the source encoding as an encoding object.
    #
    # Note that the result may not be equal to the source encoding of the encoding
    # converter if the conversion has multiple steps.
    #
    #     ec = Encoding::Converter.new("ISO-8859-1", "EUC-JP") # ISO-8859-1 -> UTF-8 -> EUC-JP
    #     begin
    #       ec.convert("\xa0") # NO-BREAK SPACE, which is available in UTF-8 but not in EUC-JP.
    #     rescue Encoding::UndefinedConversionError
    #       p $!.source_encoding              #=> #<Encoding:UTF-8>
    #       p $!.destination_encoding         #=> #<Encoding:EUC-JP>
    #       p $!.source_encoding_name         #=> "UTF-8"
    #       p $!.destination_encoding_name    #=> "EUC-JP"
    #     end
    #
    def source_encoding: () -> Encoding

    # <!--
    #   rdoc-file=transcode.c
    #   - ecerr.source_encoding_name         -> string
    # -->
    # Returns the source encoding name as a string.
    #
    def source_encoding_name: () -> String
  end
end

# <!-- rdoc-file=transcode.c -->
# Encoding conversion class.
#
class Encoding::Converter < Object
  type encoding = String | Encoding
  type decorator = "universal_newline"
                  | "crlf_newline"
                  | "cr_newline"
                  | "xml_text_escape"
                  | "xml_attr_content_escape"
                  | "xml_attr_quote"
  type conversion_path = Array[[encoding, encoding] | decorator]
  type convert_result = :invalid_byte_sequence
                      | :incomplete_input
                      | :undefined_conversion
                      | :after_output
                      | :destination_buffer_full
                      | :source_buffer_empty
                      | :finished

  # <!--
  #   rdoc-file=transcode.c
  #   - Encoding::Converter.asciicompat_encoding(string) -> encoding or nil
  #   - Encoding::Converter.asciicompat_encoding(encoding) -> encoding or nil
  # -->
  # Returns the corresponding ASCII compatible encoding.
  #
  # Returns nil if the argument is an ASCII compatible encoding.
  #
  # "corresponding ASCII compatible encoding" is an ASCII compatible encoding
  # which can represents exactly the same characters as the given ASCII
  # incompatible encoding. So, no conversion undefined error occurs when
  # converting between the two encodings.
  #
  #     Encoding::Converter.asciicompat_encoding("ISO-2022-JP") #=> #<Encoding:stateless-ISO-2022-JP>
  #     Encoding::Converter.asciicompat_encoding("UTF-16BE") #=> #<Encoding:UTF-8>
  #     Encoding::Converter.asciicompat_encoding("UTF-8") #=> nil
  #
  def self.asciicompat_encoding: (encoding enc) -> Encoding?

  # <!--
  #   rdoc-file=transcode.c
  #   - Encoding::Converter.search_convpath(source_encoding, destination_encoding)         -> ary
  #   - Encoding::Converter.search_convpath(source_encoding, destination_encoding, opt)    -> ary
  # -->
  # Returns a conversion path.
  #
  #     p Encoding::Converter.search_convpath("ISO-8859-1", "EUC-JP")
  #     #=> [[#<Encoding:ISO-8859-1>, #<Encoding:UTF-8>],
  #     #    [#<Encoding:UTF-8>, #<Encoding:EUC-JP>]]
  #
  #     p Encoding::Converter.search_convpath("ISO-8859-1", "EUC-JP", universal_newline: true)
  #     or
  #     p Encoding::Converter.search_convpath("ISO-8859-1", "EUC-JP", newline: :universal)
  #     #=> [[#<Encoding:ISO-8859-1>, #<Encoding:UTF-8>],
  #     #    [#<Encoding:UTF-8>, #<Encoding:EUC-JP>],
  #     #    "universal_newline"]
  #
  #     p Encoding::Converter.search_convpath("ISO-8859-1", "UTF-32BE", universal_newline: true)
  #     or
  #     p Encoding::Converter.search_convpath("ISO-8859-1", "UTF-32BE", newline: :universal)
  #     #=> [[#<Encoding:ISO-8859-1>, #<Encoding:UTF-8>],
  #     #    "universal_newline",
  #     #    [#<Encoding:UTF-8>, #<Encoding:UTF-32BE>]]
  #
  def self.search_convpath: (
                              encoding source,
                              encoding destination,
                              ?newline: :universal | :crlf | :cr,
                              ?universal_newline: bool,
                              ?crlf_newline: bool,
                              ?cr_newline: bool,
                              ?xml: :text | :attr
                            ) -> conversion_path

  # <!--
  #   rdoc-file=transcode.c
  #   - ec == other        -> true or false
  # -->
  #
  def ==: (self) -> bool

  # <!--
  #   rdoc-file=transcode.c
  #   - ec.convert(source_string) -> destination_string
  # -->
  # Convert source_string and return destination_string.
  #
  # source_string is assumed as a part of source. i.e.  :partial_input=>true is
  # specified internally. finish method should be used last.
  #
  #     ec = Encoding::Converter.new("utf-8", "euc-jp")
  #     puts ec.convert("\u3042").dump     #=> "\xA4\xA2"
  #     puts ec.finish.dump                #=> ""
  #
  #     ec = Encoding::Converter.new("euc-jp", "utf-8")
  #     puts ec.convert("\xA4").dump       #=> ""
  #     puts ec.convert("\xA2").dump       #=> "\xE3\x81\x82"
  #     puts ec.finish.dump                #=> ""
  #
  #     ec = Encoding::Converter.new("utf-8", "iso-2022-jp")
  #     puts ec.convert("\xE3").dump       #=> "".force_encoding("ISO-2022-JP")
  #     puts ec.convert("\x81").dump       #=> "".force_encoding("ISO-2022-JP")
  #     puts ec.convert("\x82").dump       #=> "\e$B$\"".force_encoding("ISO-2022-JP")
  #     puts ec.finish.dump                #=> "\e(B".force_encoding("ISO-2022-JP")
  #
  # If a conversion error occur, Encoding::UndefinedConversionError or
  # Encoding::InvalidByteSequenceError is raised. Encoding::Converter#convert
  # doesn't supply methods to recover or restart from these exceptions. When you
  # want to handle these conversion errors, use
  # Encoding::Converter#primitive_convert.
  #
  def convert: (String source) -> String

  # <!--
  #   rdoc-file=transcode.c
  #   - ec.convpath        -> ary
  # -->
  # Returns the conversion path of ec.
  #
  # The result is an array of conversions.
  #
  #     ec = Encoding::Converter.new("ISO-8859-1", "EUC-JP", crlf_newline: true)
  #     p ec.convpath
  #     #=> [[#<Encoding:ISO-8859-1>, #<Encoding:UTF-8>],
  #     #    [#<Encoding:UTF-8>, #<Encoding:EUC-JP>],
  #     #    "crlf_newline"]
  #
  # Each element of the array is a pair of encodings or a string. A pair means an
  # encoding conversion. A string means a decorator.
  #
  # In the above example, [#<Encoding:ISO-8859-1>, #<Encoding:UTF-8>] means a
  # converter from ISO-8859-1 to UTF-8. "crlf_newline" means newline converter
  # from LF to CRLF.
  #
  def convpath: () -> conversion_path

  # <!--
  #   rdoc-file=transcode.c
  #   - ec.destination_encoding -> encoding
  # -->
  # Returns the destination encoding as an Encoding object.
  #
  def destination_encoding: () -> Encoding

  # <!--
  #   rdoc-file=transcode.c
  #   - ec.finish -> string
  # -->
  # Finishes the converter. It returns the last part of the converted string.
  #
  #     ec = Encoding::Converter.new("utf-8", "iso-2022-jp")
  #     p ec.convert("\u3042")     #=> "\e$B$\""
  #     p ec.finish                #=> "\e(B"
  #
  def finish: () -> String

  # <!--
  #   rdoc-file=transcode.c
  #   - ec.insert_output(string) -> nil
  # -->
  # Inserts string into the encoding converter. The string will be converted to
  # the destination encoding and output on later conversions.
  #
  # If the destination encoding is stateful, string is converted according to the
  # state and the state is updated.
  #
  # This method should be used only when a conversion error occurs.
  #
  #     ec = Encoding::Converter.new("utf-8", "iso-8859-1")
  #     src = "HIRAGANA LETTER A is \u{3042}."
  #     dst = ""
  #     p ec.primitive_convert(src, dst)    #=> :undefined_conversion
  #     puts "[#{dst.dump}, #{src.dump}]"   #=> ["HIRAGANA LETTER A is ", "."]
  #     ec.insert_output("<err>")
  #     p ec.primitive_convert(src, dst)    #=> :finished
  #     puts "[#{dst.dump}, #{src.dump}]"   #=> ["HIRAGANA LETTER A is <err>.", ""]
  #
  #     ec = Encoding::Converter.new("utf-8", "iso-2022-jp")
  #     src = "\u{306F 3041 3068 2661 3002}" # U+2661 is not representable in iso-2022-jp
  #     dst = ""
  #     p ec.primitive_convert(src, dst)    #=> :undefined_conversion
  #     puts "[#{dst.dump}, #{src.dump}]"   #=> ["\e$B$O$!$H".force_encoding("ISO-2022-JP"), "\xE3\x80\x82"]
  #     ec.insert_output "?"                # state change required to output "?".
  #     p ec.primitive_convert(src, dst)    #=> :finished
  #     puts "[#{dst.dump}, #{src.dump}]"   #=> ["\e$B$O$!$H\e(B?\e$B!#\e(B".force_encoding("ISO-2022-JP"), ""]
  #
  def insert_output: (String) -> nil

  # <!--
  #   rdoc-file=transcode.c
  #   - ec.inspect         -> string
  # -->
  # Returns a printable version of *ec*
  #
  #     ec = Encoding::Converter.new("iso-8859-1", "utf-8")
  #     puts ec.inspect    #=> #<Encoding::Converter: ISO-8859-1 to UTF-8>
  #
  def inspect: () -> String

  # <!--
  #   rdoc-file=transcode.c
  #   - ec.last_error -> exception or nil
  # -->
  # Returns an exception object for the last conversion. Returns nil if the last
  # conversion did not produce an error.
  #
  # "error" means that Encoding::InvalidByteSequenceError and
  # Encoding::UndefinedConversionError for Encoding::Converter#convert and
  # :invalid_byte_sequence, :incomplete_input and :undefined_conversion for
  # Encoding::Converter#primitive_convert.
  #
  #     ec = Encoding::Converter.new("utf-8", "iso-8859-1")
  #     p ec.primitive_convert(src="\xf1abcd", dst="")       #=> :invalid_byte_sequence
  #     p ec.last_error      #=> #<Encoding::InvalidByteSequenceError: "\xF1" followed by "a" on UTF-8>
  #     p ec.primitive_convert(src, dst, nil, 1)             #=> :destination_buffer_full
  #     p ec.last_error      #=> nil
  #
  def last_error: () -> Encoding::InvalidByteSequenceError?
                | () -> Encoding::UndefinedConversionError?

  # <!--
  #   rdoc-file=transcode.c
  #   - ec.primitive_convert(source_buffer, destination_buffer) -> symbol
  #   - ec.primitive_convert(source_buffer, destination_buffer, destination_byteoffset) -> symbol
  #   - ec.primitive_convert(source_buffer, destination_buffer, destination_byteoffset, destination_bytesize) -> symbol
  #   - ec.primitive_convert(source_buffer, destination_buffer, destination_byteoffset, destination_bytesize, opt) -> symbol
  # -->
  # possible opt elements:
  #     hash form:
  #       :partial_input => true           # source buffer may be part of larger source
  #       :after_output => true            # stop conversion after output before input
  #     integer form:
  #       Encoding::Converter::PARTIAL_INPUT
  #       Encoding::Converter::AFTER_OUTPUT
  #
  # possible results:
  #     :invalid_byte_sequence
  #     :incomplete_input
  #     :undefined_conversion
  #     :after_output
  #     :destination_buffer_full
  #     :source_buffer_empty
  #     :finished
  #
  # primitive_convert converts source_buffer into destination_buffer.
  #
  # source_buffer should be a string or nil. nil means an empty string.
  #
  # destination_buffer should be a string.
  #
  # destination_byteoffset should be an integer or nil. nil means the end of
  # destination_buffer. If it is omitted, nil is assumed.
  #
  # destination_bytesize should be an integer or nil. nil means unlimited. If it
  # is omitted, nil is assumed.
  #
  # opt should be nil, a hash or an integer. nil means no flags. If it is omitted,
  # nil is assumed.
  #
  # primitive_convert converts the content of source_buffer from beginning and
  # store the result into destination_buffer.
  #
  # destination_byteoffset and destination_bytesize specify the region which the
  # converted result is stored. destination_byteoffset specifies the start
  # position in destination_buffer in bytes. If destination_byteoffset is nil,
  # destination_buffer.bytesize is used for appending the result.
  # destination_bytesize specifies maximum number of bytes. If
  # destination_bytesize is nil, destination size is unlimited. After conversion,
  # destination_buffer is resized to destination_byteoffset + actually produced
  # number of bytes. Also destination_buffer's encoding is set to
  # destination_encoding.
  #
  # primitive_convert drops the converted part of source_buffer. the dropped part
  # is converted in destination_buffer or buffered in Encoding::Converter object.
  #
  # primitive_convert stops conversion when one of following condition met.
  # *   invalid byte sequence found in source buffer (:invalid_byte_sequence)
  #     `primitive_errinfo` and `last_error` methods returns the detail of the
  #     error.
  # *   unexpected end of source buffer (:incomplete_input) this occur only when
  #     :partial_input is not specified. `primitive_errinfo` and `last_error`
  #     methods returns the detail of the error.
  # *   character not representable in output encoding (:undefined_conversion)
  #     `primitive_errinfo` and `last_error` methods returns the detail of the
  #     error.
  # *   after some output is generated, before input is done (:after_output) this
  #     occur only when :after_output is specified.
  # *   destination buffer is full (:destination_buffer_full) this occur only when
  #     destination_bytesize is non-nil.
  # *   source buffer is empty (:source_buffer_empty) this occur only when
  #     :partial_input is specified.
  # *   conversion is finished (:finished)
  #
  #
  # example:
  #     ec = Encoding::Converter.new("UTF-8", "UTF-16BE")
  #     ret = ec.primitive_convert(src="pi", dst="", nil, 100)
  #     p [ret, src, dst] #=> [:finished, "", "\x00p\x00i"]
  #
  #     ec = Encoding::Converter.new("UTF-8", "UTF-16BE")
  #     ret = ec.primitive_convert(src="pi", dst="", nil, 1)
  #     p [ret, src, dst] #=> [:destination_buffer_full, "i", "\x00"]
  #     ret = ec.primitive_convert(src, dst="", nil, 1)
  #     p [ret, src, dst] #=> [:destination_buffer_full, "", "p"]
  #     ret = ec.primitive_convert(src, dst="", nil, 1)
  #     p [ret, src, dst] #=> [:destination_buffer_full, "", "\x00"]
  #     ret = ec.primitive_convert(src, dst="", nil, 1)
  #     p [ret, src, dst] #=> [:finished, "", "i"]
  #
  def primitive_convert: (
                          String? source,
                          String destination,
                          ?Integer? destination_byteoffset,
                          ?Integer? destination_bytesize,
                          ?partial_input: bool,
                          ?after_output: bool
                        ) -> convert_result
                       | (
                          String? source,
                          String destination,
                          ?Integer? destination_byteoffset,
                          ?Integer? destination_bytesize,
                          ?Integer opt
                        ) -> convert_result

  # <!--
  #   rdoc-file=transcode.c
  #   - ec.primitive_errinfo -> array
  # -->
  # primitive_errinfo returns important information regarding the last error as a
  # 5-element array:
  #
  #     [result, enc1, enc2, error_bytes, readagain_bytes]
  #
  # result is the last result of primitive_convert.
  #
  # Other elements are only meaningful when result is :invalid_byte_sequence,
  # :incomplete_input or :undefined_conversion.
  #
  # enc1 and enc2 indicate a conversion step as a pair of strings. For example, a
  # converter from EUC-JP to ISO-8859-1 converts a string as follows: EUC-JP ->
  # UTF-8 -> ISO-8859-1. So [enc1, enc2] is either ["EUC-JP", "UTF-8"] or
  # ["UTF-8", "ISO-8859-1"].
  #
  # error_bytes and readagain_bytes indicate the byte sequences which caused the
  # error. error_bytes is discarded portion. readagain_bytes is buffered portion
  # which is read again on next conversion.
  #
  # Example:
  #
  #     # \xff is invalid as EUC-JP.
  #     ec = Encoding::Converter.new("EUC-JP", "Shift_JIS")
  #     ec.primitive_convert(src="\xff", dst="", nil, 10)
  #     p ec.primitive_errinfo
  #     #=> [:invalid_byte_sequence, "EUC-JP", "Shift_JIS", "\xFF", ""]
  #
  #     # HIRAGANA LETTER A (\xa4\xa2 in EUC-JP) is not representable in ISO-8859-1.
  #     # Since this error is occur in UTF-8 to ISO-8859-1 conversion,
  #     # error_bytes is HIRAGANA LETTER A in UTF-8 (\xE3\x81\x82).
  #     ec = Encoding::Converter.new("EUC-JP", "ISO-8859-1")
  #     ec.primitive_convert(src="\xa4\xa2", dst="", nil, 10)
  #     p ec.primitive_errinfo
  #     #=> [:undefined_conversion, "UTF-8", "ISO-8859-1", "\xE3\x81\x82", ""]
  #
  #     # partial character is invalid
  #     ec = Encoding::Converter.new("EUC-JP", "ISO-8859-1")
  #     ec.primitive_convert(src="\xa4", dst="", nil, 10)
  #     p ec.primitive_errinfo
  #     #=> [:incomplete_input, "EUC-JP", "UTF-8", "\xA4", ""]
  #
  #     # Encoding::Converter::PARTIAL_INPUT prevents invalid errors by
  #     # partial characters.
  #     ec = Encoding::Converter.new("EUC-JP", "ISO-8859-1")
  #     ec.primitive_convert(src="\xa4", dst="", nil, 10, Encoding::Converter::PARTIAL_INPUT)
  #     p ec.primitive_errinfo
  #     #=> [:source_buffer_empty, nil, nil, nil, nil]
  #
  #     # \xd8\x00\x00@ is invalid as UTF-16BE because
  #     # no low surrogate after high surrogate (\xd8\x00).
  #     # It is detected by 3rd byte (\00) which is part of next character.
  #     # So the high surrogate (\xd8\x00) is discarded and
  #     # the 3rd byte is read again later.
  #     # Since the byte is buffered in ec, it is dropped from src.
  #     ec = Encoding::Converter.new("UTF-16BE", "UTF-8")
  #     ec.primitive_convert(src="\xd8\x00\x00@", dst="", nil, 10)
  #     p ec.primitive_errinfo
  #     #=> [:invalid_byte_sequence, "UTF-16BE", "UTF-8", "\xD8\x00", "\x00"]
  #     p src
  #     #=> "@"
  #
  #     # Similar to UTF-16BE, \x00\xd8@\x00 is invalid as UTF-16LE.
  #     # The problem is detected by 4th byte.
  #     ec = Encoding::Converter.new("UTF-16LE", "UTF-8")
  #     ec.primitive_convert(src="\x00\xd8@\x00", dst="", nil, 10)
  #     p ec.primitive_errinfo
  #     #=> [:invalid_byte_sequence, "UTF-16LE", "UTF-8", "\x00\xD8", "@\x00"]
  #     p src
  #     #=> ""
  #
  def primitive_errinfo: () -> [convert_result, String?, String?, String?, String?]

  # <!--
  #   rdoc-file=transcode.c
  #   - ec.putback                    -> string
  #   - ec.putback(max_numbytes)      -> string
  # -->
  # Put back the bytes which will be converted.
  #
  # The bytes are caused by invalid_byte_sequence error. When
  # invalid_byte_sequence error, some bytes are discarded and some bytes are
  # buffered to be converted later. The latter bytes can be put back. It can be
  # observed by Encoding::InvalidByteSequenceError#readagain_bytes and
  # Encoding::Converter#primitive_errinfo.
  #
  #     ec = Encoding::Converter.new("utf-16le", "iso-8859-1")
  #     src = "\x00\xd8\x61\x00"
  #     dst = ""
  #     p ec.primitive_convert(src, dst)   #=> :invalid_byte_sequence
  #     p ec.primitive_errinfo     #=> [:invalid_byte_sequence, "UTF-16LE", "UTF-8", "\x00\xD8", "a\x00"]
  #     p ec.putback               #=> "a\x00"
  #     p ec.putback               #=> ""          # no more bytes to put back
  #
  def putback: (?Integer max_numbytes) -> String

  # <!--
  #   rdoc-file=transcode.c
  #   - ec.replacement -> string
  # -->
  # Returns the replacement string.
  #
  #     ec = Encoding::Converter.new("euc-jp", "us-ascii")
  #     p ec.replacement    #=> "?"
  #
  #     ec = Encoding::Converter.new("euc-jp", "utf-8")
  #     p ec.replacement    #=> "\uFFFD"
  #
  def replacement: () -> String

  # <!--
  #   rdoc-file=transcode.c
  #   - ec.replacement = string
  # -->
  # Sets the replacement string.
  #
  #     ec = Encoding::Converter.new("utf-8", "us-ascii", :undef => :replace)
  #     ec.replacement = "<undef>"
  #     p ec.convert("a \u3042 b")      #=> "a <undef> b"
  #
  def replacement=: (String str) -> String

  # <!--
  #   rdoc-file=transcode.c
  #   - ec.source_encoding -> encoding
  # -->
  # Returns the source encoding as an Encoding object.
  #
  def source_encoding: () -> Encoding

  private

  # <!--
  #   rdoc-file=transcode.c
  #   - Encoding::Converter.new(source_encoding, destination_encoding)
  #   - Encoding::Converter.new(source_encoding, destination_encoding, opt)
  #   - Encoding::Converter.new(convpath)
  # -->
  # possible options elements:
  #     hash form:
  #       :invalid => nil            # raise error on invalid byte sequence (default)
  #       :invalid => :replace       # replace invalid byte sequence
  #       :undef => nil              # raise error on undefined conversion (default)
  #       :undef => :replace         # replace undefined conversion
  #       :replace => string         # replacement string ("?" or "\uFFFD" if not specified)
  #       :newline => :universal     # decorator for converting CRLF and CR to LF
  #       :newline => :lf            # decorator for converting CRLF and CR to LF when writing
  #       :newline => :crlf          # decorator for converting LF to CRLF
  #       :newline => :cr            # decorator for converting LF to CR
  #       :universal_newline => true # decorator for converting CRLF and CR to LF
  #       :crlf_newline => true      # decorator for converting LF to CRLF
  #       :cr_newline => true        # decorator for converting LF to CR
  #       :lf_newline => true        # decorator for converting CRLF and CR to LF when writing
  #       :xml => :text              # escape as XML CharData.
  #       :xml => :attr              # escape as XML AttValue
  #     integer form:
  #       Encoding::Converter::INVALID_REPLACE
  #       Encoding::Converter::UNDEF_REPLACE
  #       Encoding::Converter::UNDEF_HEX_CHARREF
  #       Encoding::Converter::UNIVERSAL_NEWLINE_DECORATOR
  #       Encoding::Converter::LF_NEWLINE_DECORATOR
  #       Encoding::Converter::CRLF_NEWLINE_DECORATOR
  #       Encoding::Converter::CR_NEWLINE_DECORATOR
  #       Encoding::Converter::XML_TEXT_DECORATOR
  #       Encoding::Converter::XML_ATTR_CONTENT_DECORATOR
  #       Encoding::Converter::XML_ATTR_QUOTE_DECORATOR
  #
  # Encoding::Converter.new creates an instance of Encoding::Converter.
  #
  # Source_encoding and destination_encoding should be a string or Encoding
  # object.
  #
  # opt should be nil, a hash or an integer.
  #
  # convpath should be an array. convpath may contain
  # *   two-element arrays which contain encodings or encoding names, or
  # *   strings representing decorator names.
  #
  #
  # Encoding::Converter.new optionally takes an option. The option should be a
  # hash or an integer. The option hash can contain :invalid => nil, etc. The
  # option integer should be logical-or of constants such as
  # Encoding::Converter::INVALID_REPLACE, etc.
  #
  # :invalid => nil
  # :   Raise error on invalid byte sequence.  This is a default behavior.
  # :invalid => :replace
  # :   Replace invalid byte sequence by replacement string.
  # :undef => nil
  # :   Raise an error if a character in source_encoding is not defined in
  #     destination_encoding. This is a default behavior.
  # :undef => :replace
  # :   Replace undefined character in destination_encoding with replacement
  #     string.
  # :replace => string
  # :   Specify the replacement string. If not specified, "uFFFD" is used for
  #     Unicode encodings and "?" for others.
  # :universal_newline => true
  # :   Convert CRLF and CR to LF.
  # :crlf_newline => true
  # :   Convert LF to CRLF.
  # :cr_newline => true
  # :   Convert LF to CR.
  # :lf_newline => true
  # :   Convert CRLF and CR to LF (when writing).
  # :xml => :text
  # :   Escape as XML CharData. This form can be used as an HTML 4.0 #PCDATA.
  #     *   '&' -> '&amp;'
  #     *   '<' -> '&lt;'
  #     *   '>' -> '&gt;'
  #     *   undefined characters in destination_encoding -> hexadecimal CharRef
  #         such as &#xHH;
  #
  # :xml => :attr
  # :   Escape as XML AttValue. The converted result is quoted as "...". This form
  #     can be used as an HTML 4.0 attribute value.
  #     *   '&' -> '&amp;'
  #     *   '<' -> '&lt;'
  #     *   '>' -> '&gt;'
  #     *   '"' -> '&quot;'
  #     *   undefined characters in destination_encoding -> hexadecimal CharRef
  #         such as &#xHH;
  #
  #
  #
  # Examples:
  #     # UTF-16BE to UTF-8
  #     ec = Encoding::Converter.new("UTF-16BE", "UTF-8")
  #
  #     # Usually, decorators such as newline conversion are inserted last.
  #     ec = Encoding::Converter.new("UTF-16BE", "UTF-8", :universal_newline => true)
  #     p ec.convpath #=> [[#<Encoding:UTF-16BE>, #<Encoding:UTF-8>],
  #                   #    "universal_newline"]
  #
  #     # But, if the last encoding is ASCII incompatible,
  #     # decorators are inserted before the last conversion.
  #     ec = Encoding::Converter.new("UTF-8", "UTF-16BE", :crlf_newline => true)
  #     p ec.convpath #=> ["crlf_newline",
  #                   #    [#<Encoding:UTF-8>, #<Encoding:UTF-16BE>]]
  #
  #     # Conversion path can be specified directly.
  #     ec = Encoding::Converter.new(["universal_newline", ["EUC-JP", "UTF-8"], ["UTF-8", "UTF-16BE"]])
  #     p ec.convpath #=> ["universal_newline",
  #                   #    [#<Encoding:EUC-JP>, #<Encoding:UTF-8>],
  #                   #    [#<Encoding:UTF-8>, #<Encoding:UTF-16BE>]]
  #
  def initialize: (encoding source, encoding destination) -> void
                | (encoding source, encoding destination,
                    ?invalid: :replace | nil,
                    ?undef: :replace | nil,
                    ?replace: String,
                    ?newline: :universal | :crlf | :cr,
                    ?universal_newline: bool,
                    ?crlf_newline: bool,
                    ?cr_newline: bool,
                    ?xml: :text | :attr
                  ) -> void
                | (encoding source, encoding destination, Integer opts) -> void
                | (conversion_path convpath) -> void
end

# <!-- rdoc-file=transcode.c -->
# AFTER_OUTPUT
#
# Stop converting after some output is complete but before all of the input was
# consumed.  See primitive_convert for an example.
#
Encoding::Converter::AFTER_OUTPUT: Integer

# <!-- rdoc-file=transcode.c -->
# CRLF_NEWLINE_DECORATOR
#
# Decorator for converting LF to CRLF
#
Encoding::Converter::CRLF_NEWLINE_DECORATOR: Integer

# <!-- rdoc-file=transcode.c -->
# CR_NEWLINE_DECORATOR
#
# Decorator for converting LF to CR
#
Encoding::Converter::CR_NEWLINE_DECORATOR: Integer

# <!-- rdoc-file=transcode.c -->
# INVALID_MASK
#
# Mask for invalid byte sequences
#
Encoding::Converter::INVALID_MASK: Integer

# <!-- rdoc-file=transcode.c -->
# INVALID_REPLACE
#
# Replace invalid byte sequences
#
Encoding::Converter::INVALID_REPLACE: Integer

# <!-- rdoc-file=transcode.c -->
# PARTIAL_INPUT
#
# Indicates the source may be part of a larger string.  See primitive_convert
# for an example.
#
Encoding::Converter::PARTIAL_INPUT: Integer

# <!-- rdoc-file=transcode.c -->
# UNDEF_HEX_CHARREF
#
# Replace byte sequences that are undefined in the destination encoding with an
# XML hexadecimal character reference.  This is valid for XML conversion.
#
Encoding::Converter::UNDEF_HEX_CHARREF: Integer

# <!-- rdoc-file=transcode.c -->
# UNDEF_MASK
#
# Mask for a valid character in the source encoding but no related character(s)
# in destination encoding.
#
Encoding::Converter::UNDEF_MASK: Integer

# <!-- rdoc-file=transcode.c -->
# UNDEF_REPLACE
#
# Replace byte sequences that are undefined in the destination encoding.
#
Encoding::Converter::UNDEF_REPLACE: Integer

# <!-- rdoc-file=transcode.c -->
# UNIVERSAL_NEWLINE_DECORATOR
#
# Decorator for converting CRLF and CR to LF
#
Encoding::Converter::UNIVERSAL_NEWLINE_DECORATOR: Integer

# <!-- rdoc-file=transcode.c -->
# XML_ATTR_CONTENT_DECORATOR
#
# Escape as XML AttValue
#
Encoding::Converter::XML_ATTR_CONTENT_DECORATOR: Integer

# <!-- rdoc-file=transcode.c -->
# XML_ATTR_QUOTE_DECORATOR
#
# Escape as XML AttValue
#
Encoding::Converter::XML_ATTR_QUOTE_DECORATOR: Integer

# <!-- rdoc-file=transcode.c -->
# XML_TEXT_DECORATOR
#
# Escape as XML CharData
#
Encoding::Converter::XML_TEXT_DECORATOR: Integer