Class: BERT::Encode

Inherits:
Object
  • Object
show all
Includes:
Types
Defined in:
lib/bert/encode.rb

Constant Summary

Constants included from Types

Types::ATOM, Types::BIN, Types::FLOAT, Types::FUN, Types::INT, Types::LARGE_BIGNUM, Types::LARGE_TUPLE, Types::LIST, Types::MAGIC, Types::MAX_INT, Types::MIN_INT, Types::NEW_FUN, Types::NIL, Types::SMALL_BIGNUM, Types::SMALL_INT, Types::SMALL_TUPLE, Types::STRING

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(out) ⇒ Encode

Returns a new instance of Encode.



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# File 'lib/bert/encode.rb', line 7

def initialize(out)
  self.out = out
end

Instance Attribute Details

#out ⇒ Object

Returns the value of attribute out.



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# File 'lib/bert/encode.rb', line 5

def out
  @out
end

Class Method Details

.encode(data) ⇒ Object 



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# File 'lib/bert/encode.rb', line 11

def self.encode(data)
  io = StringIO.new
  self.new(io).write_any(data)
  io.string
end

Instance Method Details

#write_1(byte) ⇒ Object 



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# File 'lib/bert/encode.rb', line 35

def write_1(byte)
  out.write([byte].pack("C"))
end

#write_2(short) ⇒ Object 



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# File 'lib/bert/encode.rb', line 39

def write_2(short)
  out.write([short].pack("n"))
end

#write_4(long) ⇒ Object 



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# File 'lib/bert/encode.rb', line 43

def write_4(long)
  out.write([long].pack("N"))
end

#write_any(obj) ⇒ Object 



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# File 'lib/bert/encode.rb', line 17

def write_any obj
  write_1 MAGIC
  write_any_raw obj
end

#write_any_raw(obj) ⇒ Object 



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# File 'lib/bert/encode.rb', line 22

def write_any_raw obj
  case obj
    when Symbol then write_symbol(obj)
    when Fixnum, Bignum then write_fixnum(obj)
    when Float then write_float(obj)
    when Tuple then write_tuple(obj)
    when Array then write_list(obj)
    when String then write_binary(obj)
    else
      fail(obj)
  end
end

#write_bignum(num) ⇒ Object 



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# File 'lib/bert/encode.rb', line 80

def write_bignum(num)
  if num.is_a?(Bignum)
    n = num.size
  else
    n = (num.to_s(2).size / 8.0).ceil
  end
  if n <= 256
    write_1 SMALL_BIGNUM
    write_1 n
    write_bignum_guts(num)
  else
    write_1 LARGE_BIGNUM
    write_4 n
    write_bignum_guts(num)
  end
end

#write_bignum_guts(num) ⇒ Object 



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# File 'lib/bert/encode.rb', line 97

def write_bignum_guts(num)
  write_1 (num >= 0 ? 0 : 1)
  num = num.abs
  while num != 0
    rem = num % 256
    write_1 rem
    num = num >> 8
  end
end

#write_binary(data) ⇒ Object 



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# File 'lib/bert/encode.rb', line 130

def write_binary(data)
  write_1 BIN
  write_4 data.length
  write_string data
end

#write_boolean(bool) ⇒ Object 



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# File 'lib/bert/encode.rb', line 51

def write_boolean(bool)
  write_symbol(bool.to_s.to_sym)
end

#write_fixnum(num) ⇒ Object 



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# File 'lib/bert/encode.rb', line 63

def write_fixnum(num)
  if num >= 0 && num < 256
    write_1 SMALL_INT
    write_1 num
  elsif num <= MAX_INT && num >= MIN_INT
    write_1 INT
    write_4 num
  else
    write_bignum num
  end
end

#write_float(float) ⇒ Object 



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# File 'lib/bert/encode.rb', line 75

def write_float(float)
  write_1 FLOAT
  write_string format("%15.15e", float).ljust(31, "\000")
end

#write_list(data) ⇒ Object 



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# File 'lib/bert/encode.rb', line 121

def write_list(data)
  fail(data) unless data.is_a? Array
  write_1 NIL and return if data.empty?
  write_1 LIST
  write_4 data.length
  data.each{|e| write_any_raw e }
  write_1 NIL
end

#write_string(string) ⇒ Object 



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# File 'lib/bert/encode.rb', line 47

def write_string(string)
  out.write(string)
end

#write_symbol(sym) ⇒ Object 



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# File 'lib/bert/encode.rb', line 55

def write_symbol(sym)
  fail(sym) unless sym.is_a?(Symbol)
  data = sym.to_s
  write_1 ATOM
  write_2 data.length
  write_string data
end

#write_tuple(data) ⇒ Object 



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# File 'lib/bert/encode.rb', line 107

def write_tuple(data)
  fail(data) unless data.is_a? Array

  if data.length < 256
    write_1 SMALL_TUPLE
    write_1 data.length
  else
    write_1 LARGE_TUPLE
    write_4 data.length
  end

  data.each { |e| write_any_raw e }
end