lib/multibases/base16.rb
# frozen_string_literal: true
require 'multibases/byte_array'
require 'multibases/ord_table'
module Multibases
class Base16
def inspect
'[Multibases::Base16 ' \
"alphabet=\"#{@table.alphabet}\"" \
"#{@table.strict? ? ' strict' : ''}" \
']'
end
# RFC 4648 implementation
def self.encode(plain)
plain = plain.pack('C*') if plain.is_a?(Array)
# plain.each_byte.map do |byte| byte.to_s(16) end.join
EncodedByteArray.new(
plain.unpack1('H*').bytes,
encoding: Encoding::US_ASCII
)
end
def self.decode(packed)
packed = packed.pack('C*') if packed.is_a?(Array)
# packed.scan(/../).map { |x| x.hex.chr }.join
DecodedByteArray.new(Array(String(packed)).pack('H*').bytes)
end
class Table < OrdTable
def self.from(alphabet, **opts)
alphabet = alphabet.bytes if alphabet.respond_to?(:bytes)
alphabet.map!(&:ord)
new(alphabet, **opts)
end
def initialize(ords, **opts)
ords = ords.uniq
if ords.length < 16 || ords.length > 17
# Allow 17 for stale padding that does nothing
raise ArgumentError,
'Expected alphabet to contain 16 exactly. Actual: ' \
"#{ords.length} characters."
end
super ords, **opts
end
end
def initialize(alphabet, strict: false, encoding: nil)
@table = Table.from(alphabet, strict: strict, encoding: encoding)
end
def encode(plain)
encoded = Multibases::Base16.encode(plain)
return encoded if default?
encoded.transcode(
Default.table_ords(force_strict: @table.strict?),
table_ords,
encoding: @table.encoding
)
end
def decode(encoded)
return DecodedByteArray::EMPTY if encoded.empty?
unless encoded.is_a?(Array)
encoded = encoded.force_encoding(@table.encoding).bytes
end
unless decodable?(encoded)
raise ArgumentError, "'#{encoded}' contains unknown characters'"
end
unless default?
encoded = ByteArray.new(encoded).transcode(
table_ords,
Default.table_ords(force_strict: @table.strict?),
encoding: Encoding::US_ASCII
)
end
Multibases::Base16.decode(encoded)
end
def default?
eql?(Default)
end
def eql?(other)
other.is_a?(Base16) && other.instance_variable_get(:@table) == @table
end
alias == eql?
def decodable?(encoded)
(encoded.uniq - @table.tr_ords).length.zero?
end
def table_ords(force_strict: nil)
@table.tr_ords(force_strict: force_strict)
end
Default = Base16.new('0123456789abcdef')
end
end