class I18n::Backend::Transliterator::HashTransliterator

rule.
A transliterator which accepts a Hash of characters as its translation

def add(hash)

Add transliteration rules to the approximations hash. 
def add(hash)
  hash.each do |key, value|
    approximations[key.to_s] = value.to_s
  end
end

def add_default_approximations 

def add_default_approximations
  DEFAULT_APPROXIMATIONS.each do |key, value|
    approximations[key] = value
  end
end

def approximations 

def approximations
  @approximations ||= {}
end

def initialize(rule = nil) 

def initialize(rule = nil)
  @rule = rule
  add_default_approximations
  add rule if rule
end

def transliterate(string, replacement = nil) 

def transliterate(string, replacement = nil)
  replacement ||= DEFAULT_REPLACEMENT_CHAR
  string.gsub(/[^\x00-\x7f]/u) do |char|
    approximations[char] || replacement
  end
end