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
# => #<ActiveSupport::Multibyte::Chars:0x007fdc434ccc10 @wrapped_string="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

Included Modules

  • Comparable

Attributes

[R] to_s
[R] to_str
[R] wrapped_string

Class Public methods

new(string)

Creates a new Chars instance by wrapping string.

📝 Source code 
# File activesupport/lib/active_support/multibyte/chars.rb, line 55
      def initialize(string)
        @wrapped_string = string
        @wrapped_string.force_encoding(Encoding::UTF_8) unless @wrapped_string.frozen?
      end
🔎 See on GitHub

Instance Public methods

compose()

Performs composition on all the characters.

'é'.length                       # => 3
'é'.mb_chars.compose.to_s.length # => 2
📝 Source code 
# File activesupport/lib/active_support/multibyte/chars.rb, line 139
      def compose
        chars(Unicode.compose(@wrapped_string.codepoints.to_a).pack("U*"))
      end
🔎 See on GitHub

decompose()

Performs canonical decomposition on all the characters.

'é'.length                         # => 2
'é'.mb_chars.decompose.to_s.length # => 3
📝 Source code 
# File activesupport/lib/active_support/multibyte/chars.rb, line 131
      def decompose
        chars(Unicode.decompose(:canonical, @wrapped_string.codepoints.to_a).pack("U*"))
      end
🔎 See on GitHub

grapheme_length()

Returns the number of grapheme clusters in the string.

'क्षि'.mb_chars.length   # => 4
'क्षि'.mb_chars.grapheme_length # => 3
📝 Source code 
# File activesupport/lib/active_support/multibyte/chars.rb, line 147
      def grapheme_length
        @wrapped_string.scan(/\X/).length
      end
🔎 See on GitHub

limit(limit)

Limits 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.

'こんにちは'.mb_chars.limit(7).to_s # => "こん"
📝 Source code 
# File activesupport/lib/active_support/multibyte/chars.rb, line 114
      def limit(limit)
        chars(@wrapped_string.truncate_bytes(limit, omission: nil))
      end
🔎 See on GitHub

method_missing(method, *args, &block)

Forward all undefined methods to the wrapped string.

📝 Source code 
# File activesupport/lib/active_support/multibyte/chars.rb, line 61
      def method_missing(method, *args, &block)
        result = @wrapped_string.__send__(method, *args, &block)
        if method.end_with?("!")
          self if result
        else
          result.kind_of?(String) ? chars(result) : result
        end
      end
🔎 See on GitHub

respond_to_missing?(method, include_private)

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.

📝 Source code 
# File activesupport/lib/active_support/multibyte/chars.rb, line 73
      def respond_to_missing?(method, include_private)
        @wrapped_string.respond_to?(method, include_private)
      end
🔎 See on GitHub

reverse()

Reverses all characters in the string.

'Café'.mb_chars.reverse.to_s # => 'éfaC'
📝 Source code 
# File activesupport/lib/active_support/multibyte/chars.rb, line 105
      def reverse
        chars(@wrapped_string.scan(/\X/).reverse.join)
      end
🔎 See on GitHub

slice!(*args)

Works like String#slice!, but returns an instance of Chars, or nil if the string was not modified. The string will not be modified if the range given is out of bounds

string = 'Welcome'
string.mb_chars.slice!(3)    # => #<ActiveSupport::Multibyte::Chars:0x000000038109b8 @wrapped_string="c">
string # => 'Welome'
string.mb_chars.slice!(0..3) # => #<ActiveSupport::Multibyte::Chars:0x00000002eb80a0 @wrapped_string="Welo">
string # => 'me'
📝 Source code 
# File activesupport/lib/active_support/multibyte/chars.rb, line 95
      def slice!(*args)
        string_sliced = @wrapped_string.slice!(*args)
        if string_sliced
          chars(string_sliced)
        end
      end
🔎 See on GitHub

split(*args)

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.

'Café périferôl'.mb_chars.split(/é/).map { |part| part.upcase.to_s } # => ["CAF", " P", "RIFERÔL"]
📝 Source code 
# File activesupport/lib/active_support/multibyte/chars.rb, line 82
      def split(*args)
        @wrapped_string.split(*args).map { |i| self.class.new(i) }
      end
🔎 See on GitHub

tidy_bytes(force = false)

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.

📝 Source code 
# File activesupport/lib/active_support/multibyte/chars.rb, line 156
      def tidy_bytes(force = false)
        chars(Unicode.tidy_bytes(@wrapped_string, force))
      end
🔎 See on GitHub

titlecase()

Alias for: titleize

titleize()

Capitalizes the first letter of every word, when possible.

"ÉL QUE SE ENTERÓ".mb_chars.titleize.to_s    # => "Él Que Se Enteró"
"日本語".mb_chars.titleize.to_s               # => "日本語"
Also aliased as: titlecase
📝 Source code 
# File activesupport/lib/active_support/multibyte/chars.rb, line 122
      def titleize
        chars(downcase.to_s.gsub(/\b('?\S)/u) { $1.upcase })
      end
🔎 See on GitHub