module MotionSupport::Inflector

The Inflector transforms words from singular to plural, class names to table names, modularized class names to ones without, and class names to foreign keys. The default inflections for pluralization, singularization, and uncountable words are kept in inflections.rb.

Public Class Methods

camelize(term, uppercase_first_letter = true) click to toggle source

By default, camelize converts strings to UpperCamelCase. If the argument to camelize is set to :lower then camelize produces lowerCamelCase.

camelize will also convert '/' to '::' which is useful for converting paths to namespaces.

'active_model'.camelize                # => "ActiveModel"
'active_model'.camelize(:lower)        # => "activeModel"
'active_model/errors'.camelize         # => "ActiveModel::Errors"
'active_model/errors'.camelize(:lower) # => "activeModel::Errors"

As a rule of thumb you can think of camelize as the inverse of underscore, though there are cases where that does not hold:

'SSLError'.underscore.camelize # => "SslError"
# File lib/motion-support/inflector/methods.rb, line 48
def camelize(term, uppercase_first_letter = true)
  string = term.to_s
  if uppercase_first_letter
    string = string.sub(/^[a-z\d]*/) { |match| inflections.acronyms[match] || match.capitalize }
  else
    string = string.sub(/^(?:#{inflections.acronym_regex}(?=\b|[A-Z_])|\w)/) { |match| match.downcase }
  end
  string.gsub(/(?:_|(\/))([a-z\d]*)/i) { "#{$1}#{inflections.acronyms[$2] || $2.capitalize}" }.gsub('/', '::')
end
classify(table_name) click to toggle source

Create a class name from a plural table name like Rails does for table names to models. Note that this returns a string and not a Class (To convert to an actual class follow classify with constantize).

'egg_and_hams'.classify # => "EggAndHam"
'posts'.classify        # => "Post"

Singular names are not handled correctly:

'business'.classify     # => "Busines"
# File lib/motion-support/inflector/methods.rb, line 130
def classify(table_name)
  # strip out any leading schema name
  camelize(singularize(table_name.to_s.sub(/.*\./, '')))
end
constantize(camel_cased_word) click to toggle source

Tries to find a constant with the name specified in the argument string.

'Module'.constantize     # => Module
'Test::Unit'.constantize # => Test::Unit

The name is assumed to be the one of a top-level constant, no matter whether it starts with “::” or not. No lexical context is taken into account:

C = 'outside'
module M
  C = 'inside'
  C               # => 'inside'
  'C'.constantize # => 'outside', same as ::C
end

NameError is raised when the name is not in CamelCase or the constant is unknown.

# File lib/motion-support/inflector/methods.rb, line 199
def constantize(camel_cased_word)
  names = camel_cased_word.split('::')
  names.shift if names.empty? || names.first.empty?

  names.inject(Object) do |constant, name|
    if constant == Object
      constant.const_get(name)
    else
      candidate = constant.const_get(name)
      next candidate if constant.const_defined?(name, false)
      next candidate unless Object.const_defined?(name)

      # Go down the ancestors to check it it's owned
      # directly before we reach Object or the end of ancestors.
      constant = constant.ancestors.inject do |const, ancestor|
        break const    if ancestor == Object
        break ancestor if ancestor.const_defined?(name, false)
        const
      end

      # owner is in Object, so raise
      constant.const_get(name, false)
    end
  end
end
dasherize(underscored_word) click to toggle source

Replaces underscores with dashes in the string.

'puni_puni'.dasherize # => "puni-puni"
# File lib/motion-support/inflector/methods.rb, line 138
def dasherize(underscored_word)
  underscored_word.gsub('_', '-')
end
deconstantize(path) click to toggle source

Removes the rightmost segment from the constant expression in the string.

'Net::HTTP'.deconstantize   # => "Net"
'::Net::HTTP'.deconstantize # => "::Net"
'String'.deconstantize      # => ""
'::String'.deconstantize    # => ""
''.deconstantize            # => ""

See also demodulize.

# File lib/motion-support/inflector/methods.rb, line 166
def deconstantize(path)
  path.to_s[0...(path.rindex('::') || 0)] # implementation based on the one in facets' Module#spacename
end
demodulize(path) click to toggle source

Removes the module part from the expression in the string.

'ActiveRecord::CoreExtensions::String::Inflections'.demodulize # => "Inflections"
'Inflections'.demodulize                                       # => "Inflections"

See also deconstantize.

# File lib/motion-support/inflector/methods.rb, line 148
def demodulize(path)
  path = path.to_s
  if i = path.rindex('::')
    path[(i+2)..-1]
  else
    path
  end
end
foreign_key(class_name, separate_class_name_and_id_with_underscore = true) click to toggle source

Creates a foreign key name from a class name. separate_class_name_and_id_with_underscore sets whether the method should put '_' between the name and 'id'.

'Message'.foreign_key        # => "message_id"
'Message'.foreign_key(false) # => "messageid"
'Admin::Post'.foreign_key    # => "post_id"
# File lib/motion-support/inflector/methods.rb, line 177
def foreign_key(class_name, separate_class_name_and_id_with_underscore = true)
  underscore(demodulize(class_name)) + (separate_class_name_and_id_with_underscore ? "_id" : "id")
end
humanize(lower_case_and_underscored_word) click to toggle source

Capitalizes the first word and turns underscores into spaces and strips a trailing “_id”, if any. Like titleize, this is meant for creating pretty output.

'employee_salary'.humanize # => "Employee salary"
'author_id'.humanize       # => "Author"
# File lib/motion-support/inflector/methods.rb, line 86
def humanize(lower_case_and_underscored_word)
  result = lower_case_and_underscored_word.to_s.dup
  inflections.humans.each { |(rule, replacement)| break if result.sub!(rule, replacement) }
  result.gsub!(/_id$/, "")
  result.gsub!('_', ' ')
  result.gsub(/([a-z\d]*)/i) { |match|
    "#{inflections.acronyms[match] || match.downcase}"
  }.gsub(/^\w/) { |match| match.upcase }
end
inflections() { |instance| ... } click to toggle source

Yields a singleton instance of Inflector::Inflections so you can specify additional inflector rules.

MotionSupport::Inflector.inflections do |inflect|
  inflect.uncountable 'rails'
end
# File lib/motion-support/inflector/inflections.rb, line 230
def inflections(&block)
  if block_given?
    yield Inflections.instance
  else
    Inflections.instance
  end
end
ordinal(number) click to toggle source

Returns the suffix that should be added to a number to denote the position in an ordered sequence such as 1st, 2nd, 3rd, 4th.

ordinal(1)     # => "st"
ordinal(2)     # => "nd"
ordinal(1002)  # => "nd"
ordinal(1003)  # => "rd"
ordinal(-11)   # => "th"
ordinal(-1021) # => "st"
# File lib/motion-support/inflector/methods.rb, line 265
def ordinal(number)
  abs_number = number.to_i.abs

  if (11..13).include?(abs_number % 100)
    "th"
  else
    case abs_number % 10
    when 1; "st"
    when 2; "nd"
    when 3; "rd"
    else    "th"
    end
  end
end
ordinalize(number) click to toggle source

Turns a number into an ordinal string used to denote the position in an ordered sequence such as 1st, 2nd, 3rd, 4th.

ordinalize(1)     # => "1st"
ordinalize(2)     # => "2nd"
ordinalize(1002)  # => "1002nd"
ordinalize(1003)  # => "1003rd"
ordinalize(-11)   # => "-11th"
ordinalize(-1021) # => "-1021st"
# File lib/motion-support/inflector/methods.rb, line 289
def ordinalize(number)
  "#{number}#{ordinal(number)}"
end
pluralize(word) click to toggle source

Returns the plural form of the word in the string.

'post'.pluralize             # => "posts"
'octopus'.pluralize          # => "octopi"
'sheep'.pluralize            # => "sheep"
'words'.pluralize            # => "words"
'CamelOctopus'.pluralize     # => "CamelOctopi"
# File lib/motion-support/inflector/methods.rb, line 16
def pluralize(word)
  apply_inflections(word, inflections.plurals)
end
safe_constantize(camel_cased_word) click to toggle source

Tries to find a constant with the name specified in the argument string.

'Module'.safe_constantize     # => Module
'Test::Unit'.safe_constantize # => Test::Unit

The name is assumed to be the one of a top-level constant, no matter whether it starts with “::” or not. No lexical context is taken into account:

C = 'outside'
module M
  C = 'inside'
  C                    # => 'inside'
  'C'.safe_constantize # => 'outside', same as ::C
end

nil is returned when the name is not in CamelCase or the constant (or part of it) is unknown.

'blargle'.safe_constantize  # => nil
'UnknownModule'.safe_constantize  # => nil
'UnknownModule::Foo::Bar'.safe_constantize  # => nil
# File lib/motion-support/inflector/methods.rb, line 247
def safe_constantize(camel_cased_word)
  constantize(camel_cased_word)
rescue NameError => e
  raise unless e.message =~ /(uninitialized constant|wrong constant name) #{const_regexp(camel_cased_word)}$/ ||
    e.name.to_s == camel_cased_word.to_s
rescue ArgumentError => e
  raise unless e.message =~ /not missing constant #{const_regexp(camel_cased_word)}\!$/
end
singularize(word) click to toggle source

The reverse of pluralize, returns the singular form of a word in a string.

'posts'.singularize            # => "post"
'octopi'.singularize           # => "octopus"
'sheep'.singularize            # => "sheep"
'word'.singularize             # => "word"
'CamelOctopi'.singularize      # => "CamelOctopus"
# File lib/motion-support/inflector/methods.rb, line 28
def singularize(word)
  apply_inflections(word, inflections.singulars)
end
tableize(class_name) click to toggle source

Create the name of a table like Rails does for models to table names. This method uses the pluralize method on the last word in the string.

'RawScaledScorer'.tableize # => "raw_scaled_scorers"
'egg_and_ham'.tableize     # => "egg_and_hams"
'fancyCategory'.tableize   # => "fancy_categories"
# File lib/motion-support/inflector/methods.rb, line 116
def tableize(class_name)
  pluralize(underscore(class_name))
end
titleize(word) click to toggle source

Capitalizes all the words and replaces some characters in the string to create a nicer looking title. titleize is meant for creating pretty output. It is not used in the Rails internals.

titleize is also aliased as titlecase.

'man from the boondocks'.titleize   # => "Man From The Boondocks"
'x-men: the last stand'.titleize    # => "X Men: The Last Stand"
'TheManWithoutAPast'.titleize       # => "The Man Without A Past"
'raiders_of_the_lost_ark'.titleize  # => "Raiders Of The Lost Ark"
# File lib/motion-support/inflector/methods.rb, line 106
def titleize(word)
  humanize(underscore(word)).gsub(/\b(?<!['’`])[a-z]/) { |match| match.capitalize }
end
underscore(camel_cased_word) click to toggle source

Makes an underscored, lowercase form from the expression in the string.

Changes '::' to '/' to convert namespaces to paths.

'ActiveModel'.underscore         # => "active_model"
'ActiveModel::Errors'.underscore # => "active_model/errors"

As a rule of thumb you can think of underscore as the inverse of camelize, though there are cases where that does not hold:

'SSLError'.underscore.camelize # => "SslError"
# File lib/motion-support/inflector/methods.rb, line 69
def underscore(camel_cased_word)
  word = camel_cased_word.to_s.dup
  word.gsub!('::', '/')
  word.gsub!(/(?:([A-Za-z\d])|^)(#{inflections.acronym_regex})(?=\b|[^a-z])/) { "#{$1}#{$1 && '_'}#{$2.downcase}" }
  word.gsub!(/([A-Z\d]+)([A-Z][a-z])/,'\1_\2')
  word.gsub!(/([a-z\d])([A-Z])/,'\1_\2')
  word.gsub!("-", "_")
  word.downcase!
  word
end

Private Class Methods

apply_inflections(word, rules) click to toggle source

Applies inflection rules for singularize and pluralize.

apply_inflections('post', inflections.plurals)    # => "posts"
apply_inflections('posts', inflections.singulars) # => "post"
# File lib/motion-support/inflector/methods.rb, line 310
def apply_inflections(word, rules)
  result = word.to_s.dup

  if word.empty? || inflections.uncountables.include?(result.downcase[/\b\w+\Z/])
    result
  else
    rules.each { |(rule, replacement)| break if result.sub!(rule, replacement) }
    result
  end
end