62 lines
1.7 KiB
Ruby
62 lines
1.7 KiB
Ruby
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require 'bit-struct/char-field'
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class BitStruct
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# Class for char fields that can be accessed with values like
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# "xxx.xxx.xxx.xxx", where each xxx is up to 3 decimal digits representing a
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# single octet. The original string-based accessors are still available with
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# the <tt>_chars</tt> suffix.
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#
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# Declared with BitStruct.octets.
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class OctetField < BitStruct::CharField
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# Used in describe.
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def self.class_name
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@class_name ||= "octets"
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end
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SEPARATOR = "."
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FORMAT = "%d"
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BASE = 10
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def add_accessors_to(cl, attr = name) # :nodoc:
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attr_chars = "#{attr}_chars"
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super(cl, attr_chars)
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sep = self.class::SEPARATOR
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base = self.class::BASE
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fmt = self.class::FORMAT
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cl.class_eval do
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define_method attr do ||
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ary = []
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send(attr_chars).each_byte do |c|
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ary << fmt % c
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end
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ary.join(sep)
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end
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old_writer = "#{attr_chars}="
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define_method "#{attr}=" do |val|
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data = val.split(sep).map{|s|s.to_i(base)}.pack("c*")
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send(old_writer, data)
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end
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end
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end
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end
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class << self
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# Define an octet string field in the current subclass of BitStruct,
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# with the given _name_ and _length_ (in bits). Trailing nulls are
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# not considered part of the string. The field is accessed using
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# period-separated decimal digits.
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#
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# If a class is provided, use it for the Field class.
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# If a string is provided, use it for the display_name.
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# If a hash is provided, use it for options.
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#
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def octets(name, length, *rest)
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opts = parse_options(rest, name, OctetField)
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add_field(name, length, opts)
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end
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end
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end
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