module Pluralizr

A module that takes a single word and returns the pluralized version of that word. It attempts to take into account various rules—like, handling words that end in ‘y’ where the ‘y’ is preceded by a vowel or consonant (i.e., day -> days versus baby -> babies)—as well as words of French, Greek and Latin origins.

Constants

EXCEPTIONS_LIST: List of words that are exceptions to the rules in the RULES constant variable hash.
IRREGULAR_WORDS: List of words whose plural form doesn’t adhere to a rule in the RULES hash, but instead, often mutates the original word. For example, mouse => mice. Or, foot => feet.
PLURAL_ONLY_WORDS: List of words that only have a plural form. There is no singular form of the word. For example, the word tweezers has no singular form. The word tweezer is actually a verb and not a noun.
RULES: Hash containing the various rules for specific word endings in the English language.
SINGULAR_AND_PLURAL_FORMS_ARE_THE_SAME: List of words whose plural form is the same as its singular form. For example, deer is used in both singular and plural contexts.
VERSION: Current gem version.

Public Class Methods

pluralize(word) click to toggle source

Pluralizes the object passed in or returns an error if an exception is raised.

Parameters:¶ ↑

word: The object passed in.

Returns:¶ ↑

Either an error message, if any exceptions are raised via Pluralizr.check_for_errors method, or the appropriate plural version of the word passed into the method.

# File lib/pluralizr.rb, line 25
def self.pluralize(word)

  check_for_errors(word)

  case
  when word.is_irregular? then return IRREGULAR_WORDS[word]
  when word.has_same_singular_and_plural_form? || word.only_has_plural_form?
    return word
  when word.ends_with_vowel_and_y_or_o? || word.ends_with_double_vowel_and_f?
    return word.insert(-1, 's')
  else
    RULES.each do |rule, props| 
      return find_plural_of(word, props) if word.end_with?(rule)
    end
  end
  return find_plural_of(word, RULES['default'])
end

Protected Class Methods

check_for_errors(word) click to toggle source

Checks if word passed into the Pluralizr.pluralize method raises any errors. Currently, the following errors are checked: Pluralizr::InvalidTypeError, Pluralizr::InvalidStringError, and Pluralizr::TooManyWordsError.

Parameters:¶ ↑

word: A String representing the original word passed in.

Returns:¶ ↑

An error message and backtrace if an error is raised.

# File lib/pluralizr.rb, line 115
def self.check_for_errors(word)
  raise InvalidTypeError   if !word.is_a? String
  raise InvalidStringError if word.match(/^[\d\W_]/)
  raise TooManyWordsError  if !word.match(/^[a-z]+$/i)
end

convert_ending_of(word, with_ending, offset) click to toggle source

Converts the word passed into the Pluralizr.pluralize method into its plural form.

Parameters:¶ ↑

word: A String representing the original word passed in.
with_ending: A String representing the word’s plural form ending.
offset: An Integer representing the number of letters to remove from the end of the original word, before appending the plural form ending.

Returns:¶ ↑

A string representing the pluralized form of the original word passed in.

# File lib/pluralizr.rb, line 136
def self.convert_ending_of(word, with_ending, offset)
  word[0..offset].insert(-1, with_ending)
end

find_plural_of(word, props) click to toggle source

Determines which implementation method to use based on several factors: whether or not the rule from the RULES hash matching the word being passed in has an exceptions list and, if so, whether the word is on that list or not.

Parameters:¶ ↑

word: A String representing the original word passed in.
props: A hash value representing the properties of the rule,

from the RULES hash, matching the word passed in.

Returns:¶ ↑

The pluralized form of the original word passed in.

# File lib/pluralizr.rb, line 94
def self.find_plural_of(word, props)
  if !props[:has_exception_list]
    convert_ending_of(word, props[:with_ending], props[:offset])
  elsif EXCEPTIONS_LIST.include?(word)
    EXCEPTIONS_LIST[word]
  else
    convert_ending_of(word, props[:with_ending], props[:offset])
  end
end

Public Instance Methods

ends_with_double_vowel_and_f?() click to toggle source

Returns true if the word (the caller) ends in a double vowel plus ‘f’. For example, proof or handkerchief.

# File lib/pluralizr.rb, line 54
def ends_with_double_vowel_and_f?
  self.match(/[aeiouy]+[f]$/i)
end

ends_with_vowel_and_y_or_o?() click to toggle source

Returns true if the word (the caller) ends in a vowel plus either a ‘y’ or an ‘o’. For example, day and valley or stereo and tattoo.

# File lib/pluralizr.rb, line 47
def ends_with_vowel_and_y_or_o?
  self.match(/[aeiouy][oy]$/i)
end

has_same_singular_and_plural_form?() click to toggle source

Returns true if the word (the caller) is found in the SINGULAR_AND_PLURAL_FORMS_ARE_THE_SAME hash.

# File lib/pluralizr.rb, line 75
def has_same_singular_and_plural_form?
  SINGULAR_AND_PLURAL_FORMS_ARE_THE_SAME.include?(self)
end

is_irregular?() click to toggle source

Returns true if the word (the caller) is found in the IRREGULAR_WORDS hash.

# File lib/pluralizr.rb, line 61
def is_irregular?
  IRREGULAR_WORDS.include?(self)
end

only_has_plural_form?() click to toggle source

Returns true if the word (the caller) is found in the PLURAL_ONLY_WORDS hash.

# File lib/pluralizr.rb, line 68
def only_has_plural_form?
  PLURAL_ONLY_WORDS.include?(self)
end