Class: Decoder

Inherits:
Object
  • Object
show all
Defined in:
lib/rbencode.rb

Overview

Decoder for a bencoded string

Instance Method Summary collapse

Constructor Details

#initialize(encoded) ⇒ Decoder

Returns a new instance of Decoder.



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# File 'lib/rbencode.rb', line 58

def initialize(encoded)
  @encoded_buffer = encoded.chars
end

Instance Method Details

#decode ⇒ Object 



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# File 'lib/rbencode.rb', line 62

def decode
  type = @encoded_buffer[0]
  if /[\d]/.match? type
    parse_string
  elsif type == 'i'
    parse_int
  elsif type == 'l'
    parse_array
  elsif type == 'd'
    parse_hash
  else
    raise MalformedData
  end
end

#parse_array ⇒ Object 



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# File 'lib/rbencode.rb', line 96

def parse_array
  @encoded_buffer.shift  # drop the l
  array = []
  array.push(decode) while @encoded_buffer[0] != 'e'
  @encoded_buffer.shift  # drop the e
  array
end

#parse_hash ⇒ Object 



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# File 'lib/rbencode.rb', line 104

def parse_hash
  @encoded_buffer.shift  # drop the l
  hash = {}
  while @encoded_buffer[0] != 'e'
    key = decode
    value = decode
    hash[key] = value
  end
  @encoded_buffer.shift  # drop the e
  hash
end

#parse_int ⇒ Object 



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# File 'lib/rbencode.rb', line 88

def parse_int
  @encoded_buffer.shift  # drop the i
  int_chars = []
  int_chars.push(@encoded_buffer.shift) while @encoded_buffer[0] != 'e'
  @encoded_buffer.shift  # drop the e
  int_chars.join.to_i
end

#parse_string ⇒ Object

Raises:



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# File 'lib/rbencode.rb', line 77

def parse_string
  count_chars = []
  count_chars.push(@encoded_buffer.shift) while @encoded_buffer[0] != ':'
  @encoded_buffer.shift  # Drop the colon
  count = count_chars.join.to_i

  raise MalformedData if @encoded_buffer.length < count

  @encoded_buffer.shift(count).join
end