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# Pseudo I/O on String object, with interface corresponding to IO.
#
# Commonly used to simulate `$stdio` or `$stderr`
#
# ### Examples
#
#     require 'stringio'
#
#     # Writing stream emulation
#     io = StringIO.new
#     io.puts "Hello World"
#     io.string #=> "Hello World\n"
#
#     # Reading stream emulation
#     io = StringIO.new "first\nsecond\nlast\n"
#     io.getc #=> "f"
#     io.gets #=> "irst\n"
#     io.read #=> "second\nlast\n"
#
class StringIO
  # Creates new StringIO instance from with *string* and *mode*.
  #
  def initialize: (?String string, ?String? mode) -> void

  # Equivalent to StringIO.new except that when it is called with a block, it
  # yields with the new instance and closes it, and returns the result which
  # returned from the block.
  #
  def self.open: [U] (?String string, ?String? mode) { (StringIO arg) -> U } -> U

  def <<: (untyped arg0) -> self

  # Puts stream into binary mode. See IO#binmode.
  #
  def binmode: () -> self

  # Closes a StringIO. The stream is unavailable for any further data operations;
  # an `IOError` is raised if such an attempt is made.
  #
  def close: () -> nil

  # Closes the read end of a StringIO.  Will raise an `IOError` if the receiver is
  # not readable.
  #
  def close_read: () -> nil

  # Closes the write end of a StringIO.  Will raise an  `IOError` if the receiver
  # is not writeable.
  #
  def close_write: () -> nil

  # Returns `true` if the stream is completely closed, `false` otherwise.
  #
  def closed?: () -> bool

  # Returns `true` if the stream is not readable, `false` otherwise.
  #
  def closed_read?: () -> bool

  # Returns `true` if the stream is not writable, `false` otherwise.
  #
  def closed_write?: () -> bool

  # See IO#each.
  #
  def each: (?String sep, ?Integer limit, ?chomp: boolish) { (String) -> untyped } -> self
          | (?String sep, ?Integer limit, ?chomp: boolish) -> ::Enumerator[String, self]

  # See IO#each_byte.
  #
  def each_byte: () { (Integer arg0) -> untyped } -> self
               | () -> ::Enumerator[Integer, self]

  # See IO#each_char.
  #
  def each_char: () { (String arg0) -> untyped } -> self
               | () -> ::Enumerator[String, self]

  # See IO#each_codepoint.
  #
  def each_codepoint: () { (Integer arg0) -> untyped } -> self
                    | () -> ::Enumerator[Integer, self]

  # Returns true if the stream is at the end of the data (underlying string). The
  # stream must be opened for reading or an `IOError` will be raised.
  #
  def eof: () -> bool

  # Raises NotImplementedError.
  #
  def fcntl: (Integer integer_cmd, String | Integer arg) -> Integer

  # Returns `nil`.  Just for compatibility to IO.
  #
  def fileno: () -> nil

  # Returns an object itself.  Just for compatibility to IO.
  #
  def flush: () -> self

  # Returns 0.  Just for compatibility to IO.
  #
  def fsync: () -> Integer?

  # See IO#getbyte.
  #
  def getbyte: () -> Integer?

  # See IO#getc.
  #
  def getc: () -> String?

  # See IO#gets.
  #
  def gets: (?String sep, ?Integer limit, ?chomp: boolish) -> String?

  # Returns the Encoding of the internal string if conversion is specified.
  # Otherwise returns `nil`.
  #
  def internal_encoding: () -> Encoding

  # Returns the Encoding object that represents the encoding of the file. If the
  # stream is write mode and no encoding is specified, returns `nil`.
  #
  def external_encoding: () -> Encoding

  # Returns `false`.  Just for compatibility to IO.
  #
  def isatty: () -> bool

  # Returns the current line number. The stream must be opened for reading.
  # `lineno` counts the number of times  `gets` is called, rather than the number
  # of newlines  encountered. The two values will differ if `gets` is  called with
  # a separator other than newline.  See also the  `$.` variable.
  #
  def lineno: () -> Integer

  # Manually sets the current line number to the given value. `$.` is updated only
  # on the next read.
  #
  def lineno=: (Integer arg0) -> Integer

  # Returns `nil`.  Just for compatibility to IO.
  #
  def pid: () -> nil

  # Returns the current offset (in bytes).
  #
  def pos: () -> Integer

  # Seeks to the given position (in bytes).
  #
  def pos=: (Integer arg0) -> Integer

  def print: (*untyped arg0) -> nil

  def printf: (String format_string, *untyped arg0) -> nil

  # See IO#putc.
  #
  def putc: (Numeric | String arg0) -> untyped

  def puts: (*untyped arg0) -> nil

  # See IO#read.
  #
  def read: (?Integer length, ?String outbuf) -> String?

  def read_nonblock: (Integer len) -> String
                   | (Integer len, ?String buf) -> String

  def readbyte: () -> Integer

  def readchar: () -> String

  def readline: (?String sep, ?Integer limit) -> String

  # See IO#readlines.
  #
  def readlines: (?String sep, ?Integer limit, ?chomp: boolish) -> ::Array[String]

  def readpartial: (Integer maxlen) -> String
                 | (Integer maxlen, ?String outbuf) -> String

  # Reinitializes the stream with the given *other_StrIO* or *string* and *mode*
  # (see StringIO#new).
  #
  def reopen: (StringIO other) -> self
            | (String other, ?String mode_str) -> self

  # Positions the stream to the beginning of input, resetting `lineno` to zero.
  #
  def rewind: () -> Integer

  # Seeks to a given offset *amount* in the stream according to the value of
  # *whence* (see IO#seek).
  #
  def seek: (Integer amount, ?Integer whence) -> Integer

  # Specify the encoding of the StringIO as *ext_enc*. Use the default external
  # encoding if *ext_enc* is nil. 2nd argument *int_enc* and optional hash *opt*
  # argument are ignored; they are for API compatibility to IO.
  #
  def set_encoding: (?String | Encoding ext_or_ext_int_enc) -> self
                  | (?String | Encoding ext_or_ext_int_enc, ?String | Encoding int_enc) -> self

  # Returns underlying String object, the subject of IO.
  #
  def string: () -> String

  # Changes underlying String object, the subject of IO.
  #
  def string=: (String str) -> String

  # Returns the size of the buffer string.
  #
  def size: () -> Integer

  # Returns `true` always.
  #
  def sync: () -> bool

  # Returns the argument unchanged.  Just for compatibility to IO.
  #
  def sync=: (boolish) -> bool

  def sysread: (Integer maxlen, String outbuf) -> String

  def syswrite: (String arg0) -> Integer

  # Returns the current offset (in bytes).
  #
  def tell: () -> Integer

  # Returns `false`.  Just for compatibility to IO.
  #
  def tty?: () -> bool

  # See IO#ungetbyte
  #
  def ungetbyte: (String | Integer arg0) -> nil

  # Pushes back one character (passed as a parameter) such that a subsequent
  # buffered read will return it.  There is no limitation for multiple pushbacks
  # including pushing back behind the beginning of the buffer string.
  #
  def ungetc: (String arg0) -> nil

  # Appends the given string to the underlying buffer string. The stream must be
  # opened for writing.  If the argument is not a string, it will be converted to
  # a string using `to_s`. Returns the number of bytes written.  See IO#write.
  #
  def write: (String arg0) -> Integer

  # This is a deprecated alias for #each_byte.
  #
  def bytes: () { (Integer arg0) -> untyped } -> self
           | () -> ::Enumerator[Integer, self]

  # This is a deprecated alias for #each_char.
  #
  def chars: () { (String arg0) -> untyped } -> self
           | () -> ::Enumerator[String, self]

  # This is a deprecated alias for #each_codepoint.
  #
  def codepoints: () { (Integer arg0) -> untyped } -> self
                | () -> ::Enumerator[Integer, self]

  # See IO#each.
  #
  def each_line: (?String sep, ?Integer limit, ?chomp: boolish) { (String) -> untyped } -> self
               | (?String sep, ?Integer limit, ?chomp: boolish) -> ::Enumerator[String, self]

  # Returns true if the stream is at the end of the data (underlying string). The
  # stream must be opened for reading or an `IOError` will be raised.
  #
  def eof?: () -> bool

  # This is a deprecated alias for #each_line.
  #
  def lines: (?String sep, ?Integer limit) { (String arg0) -> untyped } -> self
           | (?String sep, ?Integer limit) -> ::Enumerator[String, self]
end