CSV::StreamBuf

Buffered stream.

EXAMPLE 1 – an IO.

class MyBuf < StreamBuf
  # Do initialize myself before a super class.  Super class might call my
  # method 'read'. (Could be awful for C++ user. :-)
  def initialize(s)
    @s = s
    super()
  end

  # define my own 'read' method.
  # CAUTION: Returning nil means EnfOfStream.
  def read(size)
    @s.read(size)
  end

  # release buffers. in Ruby which has GC, you do not have to call this...
  def terminate
    @s = nil
    super()
  end
end

buf = MyBuf.new(STDIN)
my_str = ''
p buf[0, 0]               # => '' (null string)
p buf[0]                  # => 97 (char code of 'a')
p buf[0, 1]               # => 'a'
my_str = buf[0, 5]
p my_str                  # => 'abcde' (5 chars)
p buf[0, 6]               # => "abcde\n" (6 chars)
p buf[0, 7]               # => "abcde\n" (6 chars)
p buf.drop(3)             # => 3 (dropped chars)
p buf.get(0, 2)           # => 'de' (2 chars)
p buf.is_eos?             # => false (is not EOS here)
p buf.drop(5)             # => 3 (dropped chars)
p buf.is_eos?             # => true (is EOS here)
p buf[0]                  # => nil (is EOS here)

EXAMPLE 2 – String.

This is a conceptual example.  No pros with this.

class StrBuf < StreamBuf
  def initialize(s)
    @str = s
    @idx = 0
    super()
  end

  def read(size)
    str = @str[@idx, size]
    @idx += str.size
    str
  end
end