Class ActiveSupport::Multibyte::Chars
In: lib/active_support/multibyte/chars.rb
Parent: Object

Chars enables you to work transparently with UTF-8 encoding in the Ruby String class without having extensive knowledge about the encoding. A Chars object accepts a string upon initialization and proxies String methods in an encoding safe manner. All the normal String methods are also implemented on the proxy.

String methods are proxied through the Chars object, and can be accessed through the mb_chars method. Methods which would normally return a String object now return a Chars object so methods can be chained.

  "The Perfect String  ".mb_chars.downcase.strip.normalize # => "the perfect string"

Chars objects are perfectly interchangeable with String objects as long as no explicit class checks are made. If certain methods do explicitly check the class, call to_s before you pass chars objects to them.

  bad.explicit_checking_method "T".mb_chars.downcase.to_s

The default Chars implementation assumes that the encoding of the string is UTF-8, if you want to handle different encodings you can write your own multibyte string handler and configure it through ActiveSupport::Multibyte.proxy_class.

  class CharsForUTF32
    def size
      @wrapped_string.size / 4
    end

    def self.accepts?(string)
      string.length % 4 == 0
    end
  end

  ActiveSupport::Multibyte.proxy_class = CharsForUTF32

Methods

+   <=>   =~   =~   []   []=   acts_like_string?   capitalize   center   compose   consumes?   decompose   downcase   g_length   include?   index   insert   limit   ljust   lstrip   method_missing   new   normalize   ord   respond_to?   reverse   rindex   rjust   rstrip   size   slice   split   strip   tidy_bytes   titlecase   titleize   upcase   wants?  

Included Modules

Comparable

External Aliases

wrapped_string -> to_s
wrapped_string -> to_str

Attributes

wrapped_string  [R] 

Public Class methods

Returns true when the proxy class can handle the string. Returns false otherwise.

Creates a new Chars instance by wrapping string.

Returns true if the Chars class can and should act as a proxy for the string string. Returns false otherwise.

Public Instance methods

Returns a new Chars object containing the other object concatenated to the string.

Example:

  ('Café'.mb_chars + ' périferôl').to_s # => "Café périferôl"

Returns -1, 0, or 1, depending on whether the Chars object is to be sorted before, equal or after the object on the right side of the operation. It accepts any object that implements to_s:

  'é'.mb_chars <=> 'ü'.mb_chars # => -1

See String#<=> for more details.

Like String#=~ only it returns the character offset (in codepoints) instead of the byte offset.

Example:

  'Café périferôl'.mb_chars =~ /ô/ # => 12
[](*args)

Alias for slice

Like String#[]=, except instead of byte offsets you specify character offsets.

Example:

  s = "Müller"
  s.mb_chars[2] = "e" # Replace character with offset 2
  s
  # => "Müeler"

  s = "Müller"
  s.mb_chars[1, 2] = "ö" # Replace 2 characters at character offset 1
  s
  # => "Möler"

Enable more predictable duck-typing on String-like classes. See Object#acts_like?.

Converts the first character to uppercase and the remainder to lowercase.

Example:

 'über'.mb_chars.capitalize.to_s # => "Über"

Works just like String#center, only integer specifies characters instead of bytes.

Example:

  "¾ cup".mb_chars.center(8).to_s
  # => " ¾ cup  "

  "¾ cup".mb_chars.center(8, " ").to_s # Use non-breaking whitespace
  # => " ¾ cup  "

Performs composition on all the characters.

Example:

  'é'.length                       # => 3
  'é'.mb_chars.compose.to_s.length # => 2

Performs canonical decomposition on all the characters.

Example:

  'é'.length                         # => 2
  'é'.mb_chars.decompose.to_s.length # => 3

Convert characters in the string to lowercase.

Example:

  'VĚDA A VÝZKUM'.mb_chars.downcase.to_s # => "věda a výzkum"

Returns the number of grapheme clusters in the string.

Example:

  'क्षि'.mb_chars.length   # => 4
  'क्षि'.mb_chars.g_length # => 3

Returns true if contained string contains other. Returns false otherwise.

Example:

  'Café'.mb_chars.include?('é') # => true

Returns the position needle in the string, counting in codepoints. Returns nil if needle isn‘t found.

Example:

  'Café périferôl'.mb_chars.index('ô')   # => 12
  'Café périferôl'.mb_chars.index(/\w/u) # => 0

Inserts the passed string at specified codepoint offsets.

Example:

  'Café'.mb_chars.insert(4, ' périferôl').to_s # => "Café périferôl"

Limit the byte size of the string to a number of bytes without breaking characters. Usable when the storage for a string is limited for some reason.

Example:

  'こんにちは'.mb_chars.limit(7).to_s # => "こん"

Works just like String#ljust, only integer specifies characters instead of bytes.

Example:

  "¾ cup".mb_chars.rjust(8).to_s
  # => "¾ cup   "

  "¾ cup".mb_chars.rjust(8, " ").to_s # Use non-breaking whitespace
  # => "¾ cup   "

Strips entire range of Unicode whitespace from the left of the string.

Forward all undefined methods to the wrapped string.

Returns the KC normalization of the string by default. NFKC is considered the best normalization form for passing strings to databases and validations.

  • form - The form you want to normalize in. Should be one of the following: :c, :kc, :d, or :kd. Default is ActiveSupport::Multibyte::Unicode.default_normalization_form

Returns the codepoint of the first character in the string.

Example:

  'こんにちは'.mb_chars.ord # => 12371

Returns true if obj responds to the given method. Private methods are included in the search only if the optional second parameter evaluates to true.

Reverses all characters in the string.

Example:

  'Café'.mb_chars.reverse.to_s # => 'éfaC'

Returns the position needle in the string, counting in codepoints, searching backward from offset or the end of the string. Returns nil if needle isn‘t found.

Example:

  'Café périferôl'.mb_chars.rindex('é')   # => 6
  'Café périferôl'.mb_chars.rindex(/\w/u) # => 13

Works just like String#rjust, only integer specifies characters instead of bytes.

Example:

  "¾ cup".mb_chars.rjust(8).to_s
  # => "   ¾ cup"

  "¾ cup".mb_chars.rjust(8, " ").to_s # Use non-breaking whitespace
  # => "   ¾ cup"

Strips entire range of Unicode whitespace from the right of the string.

Returns the number of codepoints in the string

Implements Unicode-aware slice with codepoints. Slicing on one point returns the codepoints for that character.

Example:

  'こんにちは'.mb_chars.slice(2..3).to_s # => "にち"

Works just like String#split, with the exception that the items in the resulting list are Chars instances instead of String. This makes chaining methods easier.

Example:

  'Café périferôl'.mb_chars.split(/é/).map { |part| part.upcase.to_s } # => ["CAF", " P", "RIFERÔL"]

Strips entire range of Unicode whitespace from the right and left of the string.

Replaces all ISO-8859-1 or CP1252 characters by their UTF-8 equivalent resulting in a valid UTF-8 string.

Passing true will forcibly tidy all bytes, assuming that the string‘s encoding is entirely CP1252 or ISO-8859-1.

titlecase()

Alias for titleize

Capitalizes the first letter of every word, when possible.

Example:

  "ÉL QUE SE ENTERÓ".mb_chars.titleize    # => "Él Que Se Enteró"
  "日本語".mb_chars.titleize                 # => "日本語"

Convert characters in the string to uppercase.

Example:

  'Laurent, où sont les tests ?'.mb_chars.upcase.to_s # => "LAURENT, OÙ SONT LES TESTS ?"

[Validate]