edge badge

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
C
D
G
L
M
N
R
S
T
U
Included Modules
Attributes
[R] to_s
[R] to_str
[R] wrapped_string
Class Public methods
consumes?(string)

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

# File activesupport/lib/active_support/multibyte/chars.rb, line 75
def self.consumes?(string)
  string.encoding == Encoding::UTF_8
end
new(string)

Creates a new Chars instance by wrapping string.

# File activesupport/lib/active_support/multibyte/chars.rb, line 51
def initialize(string)
  @wrapped_string = string
  @wrapped_string.force_encoding(Encoding::UTF_8) unless @wrapped_string.frozen?
end
Instance Public methods
capitalize()

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

'über'.mb_chars.capitalize.to_s # => "Über"
# File activesupport/lib/active_support/multibyte/chars.rb, line 134
def capitalize
  (slice(0) || chars('')).upcase + (slice(1..-1) || chars('')).downcase
end
compose()

Performs composition on all the characters.

'é'.length                       # => 3
'é'.mb_chars.compose.to_s.length # => 2
# File activesupport/lib/active_support/multibyte/chars.rb, line 170
def compose
  chars(Unicode.compose(@wrapped_string.codepoints.to_a).pack('U*'))
end
decompose()

Performs canonical decomposition on all the characters.

'é'.length                         # => 2
'é'.mb_chars.decompose.to_s.length # => 3
# File activesupport/lib/active_support/multibyte/chars.rb, line 162
def decompose
  chars(Unicode.decompose(:canonical, @wrapped_string.codepoints.to_a).pack('U*'))
end
downcase()

Converts characters in the string to lowercase.

'VĚDA A VÝZKUM'.mb_chars.downcase.to_s # => "věda a výzkum"
# File activesupport/lib/active_support/multibyte/chars.rb, line 120
def downcase
  chars Unicode.downcase(@wrapped_string)
end
grapheme_length()

Returns the number of grapheme clusters in the string.

'क्षि'.mb_chars.length   # => 4
'क्षि'.mb_chars.grapheme_length # => 3
# File activesupport/lib/active_support/multibyte/chars.rb, line 178
def grapheme_length
  Unicode.unpack_graphemes(@wrapped_string).length
end
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"
# File activesupport/lib/active_support/multibyte/chars.rb, line 106
def limit(limit)
  slice(0...translate_offset(limit))
end
method_missing(method, *args, &block)

Forward all undefined methods to the wrapped string.

# File activesupport/lib/active_support/multibyte/chars.rb, line 57
def method_missing(method, *args, &block)
  result = @wrapped_string.__send__(method, *args, &block)
  if method.to_s =~ /!$/
    self if result
  else
    result.kind_of?(String) ? chars(result) : result
  end
end
normalize(form = nil)

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

# File activesupport/lib/active_support/multibyte/chars.rb, line 154
def normalize(form = nil)
  chars(Unicode.normalize(@wrapped_string, form))
end
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.

# File activesupport/lib/active_support/multibyte/chars.rb, line 69
def respond_to_missing?(method, include_private)
  @wrapped_string.respond_to?(method, include_private)
end
reverse()

Reverses all characters in the string.

'Café'.mb_chars.reverse.to_s # => 'éfaC'
# File activesupport/lib/active_support/multibyte/chars.rb, line 97
def reverse
  chars(Unicode.unpack_graphemes(@wrapped_string).reverse.flatten.pack('U*'))
end
slice!(*args)

Works like like String#slice!, but returns an instance of Chars, or nil if the string was not modified.

# File activesupport/lib/active_support/multibyte/chars.rb, line 90
def slice!(*args)
  chars(@wrapped_string.slice!(*args))
end
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"]
# File activesupport/lib/active_support/multibyte/chars.rb, line 84
def split(*args)
  @wrapped_string.split(*args).map { |i| self.class.new(i) }
end
swapcase()

Converts characters in the string to the opposite case.

'El Cañón".mb_chars.swapcase.to_s # => "eL cAÑÓN"
# File activesupport/lib/active_support/multibyte/chars.rb, line 127
def swapcase
  chars Unicode.swapcase(@wrapped_string)
end
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.

# File activesupport/lib/active_support/multibyte/chars.rb, line 187
def tidy_bytes(force = false)
  chars(Unicode.tidy_bytes(@wrapped_string, force))
end
titlecase()
Alias for: titleize
titleize()

Capitalizes the first letter of every word, when possible.

"ÉL QUE SE ENTERÓ".mb_chars.titleize    # => "Él Que Se Enteró"
"日本語".mb_chars.titleize                 # => "日本語"
Also aliased as: titlecase
# File activesupport/lib/active_support/multibyte/chars.rb, line 142
def titleize
  chars(downcase.to_s.gsub(/\b('?\S)/u) { Unicode.upcase($1)})
end
upcase()

Converts characters in the string to uppercase.

'Laurent, où sont les tests ?'.mb_chars.upcase.to_s # => "LAURENT, OÙ SONT LES TESTS ?"
# File activesupport/lib/active_support/multibyte/chars.rb, line 113
def upcase
  chars Unicode.upcase(@wrapped_string)
end