module Zip::IOExtras::AbstractInputStream

def each_line(a_sep_string = $INPUT_RECORD_SEPARATOR)
  loop { yield readline(a_sep_string) }
rescue EOFError
  # We just need to catch this; we don't need to handle it.
end

def eof
  @output_buffer.empty? && input_finished?
end

def flush
  ret_val        = @output_buffer
  @output_buffer = ''
  ret_val
end

def gets(a_sep_string = $INPUT_RECORD_SEPARATOR, number_of_bytes = nil)
  @lineno = @lineno.next
  if number_of_bytes.respond_to?(:to_int)
    number_of_bytes = number_of_bytes.to_int
    a_sep_string = a_sep_string.to_str if a_sep_string
  elsif a_sep_string.respond_to?(:to_int)
    number_of_bytes = a_sep_string.to_int
    a_sep_string    = $INPUT_RECORD_SEPARATOR
  else
    number_of_bytes = nil
    a_sep_string = a_sep_string.to_str if a_sep_string
  end
  return read(number_of_bytes) if a_sep_string.nil?
  a_sep_string = "#{$INPUT_RECORD_SEPARATOR}#{$INPUT_RECORD_SEPARATOR}" if a_sep_string.empty?
  buffer_index = 0
  over_limit   = (number_of_bytes && @output_buffer.bytesize >= number_of_bytes)
  while (match_index = @output_buffer.index(a_sep_string, buffer_index)).nil? && !over_limit
    buffer_index = [buffer_index, @output_buffer.bytesize - a_sep_string.bytesize].max
    return @output_buffer.empty? ? nil : flush if input_finished?
    @output_buffer << produce_input
    over_limit = (number_of_bytes && @output_buffer.bytesize >= number_of_bytes)
  end
  sep_index = [match_index + a_sep_string.bytesize, number_of_bytes || @output_buffer.bytesize].min
  @pos += sep_index
  @output_buffer.slice!(0...sep_index)
end

def initialize
  super
  @lineno        = 0
  @pos           = 0
  @output_buffer = ''
end

def read(number_of_bytes = nil, buf = '')
  tbuf = if @output_buffer.bytesize > 0
           if number_of_bytes <= @output_buffer.bytesize
             @output_buffer.slice!(0, number_of_bytes)
           else
             number_of_bytes -= @output_buffer.bytesize if number_of_bytes
             rbuf = sysread(number_of_bytes, buf)
             out  = @output_buffer
             out << rbuf if rbuf
             @output_buffer = ''
             out
           end
         else
           sysread(number_of_bytes, buf)
         end
  if tbuf.nil? || tbuf.empty?
    return nil if number_of_bytes
    return ''
  end
  @pos += tbuf.length
  if buf
    buf.replace(tbuf)
  else
    buf = tbuf
  end
  buf
end

def readline(a_sep_string = $INPUT_RECORD_SEPARATOR)
  ret_val = gets(a_sep_string)
  raise EOFError unless ret_val
  ret_val
end

def readlines(a_sep_string = $INPUT_RECORD_SEPARATOR)
  ret_val = []
  each_line(a_sep_string) { |line| ret_val << line }
  ret_val
end

def ungetc(byte)
  @output_buffer = byte.chr + @output_buffer
end