Class: Rbkb::Cli::Len

Inherits:
Executable show all
Defined in:
lib/rbkb/cli/len.rb

Overview

len prepends a binary length number in front of its input and outputs raw on STDOUT

Instance Attribute Summary

Attributes inherited from Executable

#argv, #exit_status, #oparse, #opts, #stderr, #stdin, #stdout

Instance Method Summary collapse

Methods inherited from Executable

#bail, #bail_args, #exit, run

Constructor Details

#initialize(*args) ⇒ Len

Returns a new instance of Len.



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# File 'lib/rbkb/cli/len.rb', line 10

def initialize(*args)
  # endianness pair. index 0 is always the default
  @endpair = [:big, :little]

  super(*args) do |this|
    {
      :nudge => 0, 
      :size => 4, 
      :endian => @endpair[0],
    }.each {|k,v| this.opts[k] ||= v}

    yield this if block_given?
  end
end

Instance Method Details

#go(*args) ⇒ Object 



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# File 'lib/rbkb/cli/len.rb', line 64

def go(*args)
  super(*args)
  unless len=@opts[:static]
    len = @opts[:indat].size
    len += @opts[:size] if @opts[:tot]
    len += @opts[:nudge]
  end
  @stdout << len.to_bytes(@opts[:endian], @opts[:size]) << @opts[:indat]
  self.exit(0)
end

#make_parser ⇒ Object 



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# File 'lib/rbkb/cli/len.rb', line 25

def make_parser()
  super()
  add_std_file_opt(:indat)
  arg = @oparse
  arg.banner += " <data | blank for stdin>"

  arg.on("-n", "--nudge INT", Numeric, "Add integer to length") do |n|
    @opts[:nudge] += n
  end

  arg.on("-s", "--size=SIZE", Numeric, 
         "Size of length field in bytes") do |s|
    bail("Size must be greater than 0") unless (@opts[:size] = s) > 0
  end

  arg.on("-x", "--[no-]swap", 
         "Swap endianness. Default=#{@opts[:endian]}") do |x|
    @opts[:endian] = @endpair[(x)? 1 : 0]
  end

  arg.on("-t", "--[no-]total", "Include size word in size") do |t|
    @opts[:tot]=t
  end

  arg.on("-l", "--length=LEN", Numeric, 
         "Ignore all other flags and use static LEN") do |l|
    @opts[:static]=l
  end
end

#parse(*args) ⇒ Object 



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# File 'lib/rbkb/cli/len.rb', line 56

def parse(*args)
  super(*args)
  @opts[:indat] ||= @argv.shift
  parse_catchall()
  @opts[:indat] ||= @stdin.read
end