# by activesupport/lib/active_support/inflector.rb

@@singular = []

def add_singular(rule, replace)
  @@singular << [rule, replace]
end

add_singular(/s$/i, '')
add_singular(/(n)ews$/i, '\1ews')
add_singular(/([ti])a$/i, '\1um')
add_singular(/((a)naly|(b)a|(d)iagno|(p)arenthe|(p)rogno|(s)ynop|(t)he)ses$/i, '\1\2sis')
add_singular(/(^analy)ses$/i, '\1sis')
add_singular(/([^f])ves$/i, '\1fe')
add_singular(/(hive)s$/i, '\1')
add_singular(/(tive)s$/i, '\1')
add_singular(/([lr])ves$/i, '\1f')
add_singular(/([^aeiouy]|qu)ies$/i, '\1y')
add_singular(/(s)eries$/i, '\1eries')
add_singular(/(m)ovies$/i, '\1ovie')
add_singular(/(x|ch|ss|sh)es$/i, '\1')
add_singular(/([m|l])ice$/i, '\1ouse')
add_singular(/(bus)es$/i, '\1')
add_singular(/(o)es$/i, '\1')
add_singular(/(shoe)s$/i, '\1')
add_singular(/(cris|ax|test)es$/i, '\1is')
add_singular(/(octop|vir)i$/i, '\1us')
add_singular(/(alias|status)es$/i, '\1')
add_singular(/^(ox)en/i, '\1')
add_singular(/(vert|ind)ices$/i, '\1ex')
add_singular(/(matr)ices$/i, '\1ix')
add_singular(/(quiz)zes$/i, '\1')

# The reverse of +pluralize+, returns the singular form of a word in a string.
#
# Examples:
#   "posts".singularize            # => "post"
#   "octopi".singularize           # => "octopus"
#   "sheep".singluarize            # => "sheep"
#   "word".singluarize             # => "word"
#   "the blue mailmen".singularize # => "the blue mailman"
#   "CamelOctopi".singularize      # => "CamelOctopus"
def singularize(word)
  result = word.to_s.dup
  @@singular.each { |(rule, replacement)| break if result.gsub!(rule, replacement) }
  result
end