module BinData::BasePrimitive::CheckValuePlugin

def check_value(current_value)
  expected = eval_parameter(:check_value, :value => current_value)
  if not expected
    raise ValidityError,
          "value '#{current_value}' not as expected for #{debug_name}"
  elsif current_value != expected and expected != true
    raise ValidityError,
          "value is '#{current_value}' but " +
          "expected '#{expected}' for #{debug_name}"
  end
end

def do_read(io) #:nodoc:
  super(io)
  check_value(snapshot)
end