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class ActiveSupport::Multibyte::Chars

Parent:
Object
Included modules:

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
# => #<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

Attributes

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

Public Class Methods

consumes?(string) Show source
# File activesupport/lib/active_support/multibyte/chars.rb, line 79
def self.consumes?(string)
  string.encoding == Encoding::UTF_8
end

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

new(string) Show source
# 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

Creates a new Chars instance by wrapping string.

Public Instance Methods

capitalize() Show source
# File activesupport/lib/active_support/multibyte/chars.rb, line 148
def capitalize
  (slice(0) || chars("")).upcase + (slice(1..-1) || chars("")).downcase
end

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

'über'.mb_chars.capitalize.to_s # => "Über"
compose() Show source
# File activesupport/lib/active_support/multibyte/chars.rb, line 184
def compose
  chars(Unicode.compose(@wrapped_string.codepoints.to_a).pack("U*"))
end

Performs composition on all the characters.

'é'.length                       # => 3
'é'.mb_chars.compose.to_s.length # => 2
decompose() Show source
# File activesupport/lib/active_support/multibyte/chars.rb, line 176
def decompose
  chars(Unicode.decompose(:canonical, @wrapped_string.codepoints.to_a).pack("U*"))
end

Performs canonical decomposition on all the characters.

'é'.length                         # => 2
'é'.mb_chars.decompose.to_s.length # => 3
downcase() Show source
# File activesupport/lib/active_support/multibyte/chars.rb, line 134
def downcase
  chars Unicode.downcase(@wrapped_string)
end

Converts characters in the string to lowercase.

'VĚDA A VÝZKUM'.mb_chars.downcase.to_s # => "věda a výzkum"
grapheme_length() Show source
# File activesupport/lib/active_support/multibyte/chars.rb, line 192
def grapheme_length
  Unicode.unpack_graphemes(@wrapped_string).length
end

Returns the number of grapheme clusters in the string.

'क्षि'.mb_chars.length   # => 4
'क्षि'.mb_chars.grapheme_length # => 3
limit(limit) Show source
# File activesupport/lib/active_support/multibyte/chars.rb, line 120
def limit(limit)
  slice(0...translate_offset(limit))
end

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"
method_missing(method, *args, &block) Show source
# File activesupport/lib/active_support/multibyte/chars.rb, line 61
def method_missing(method, *args, &block)
  result = @wrapped_string.__send__(method, *args, &block)
  if /!$/.match?(method)
    self if result
  else
    result.kind_of?(String) ? chars(result) : result
  end
end

Forward all undefined methods to the wrapped string.

normalize(form = nil) Show source
# File activesupport/lib/active_support/multibyte/chars.rb, line 168
def normalize(form = nil)
  chars(Unicode.normalize(@wrapped_string, form))
end

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

respond_to_missing?(method, include_private) Show source
# 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

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.

reverse() Show source
# File activesupport/lib/active_support/multibyte/chars.rb, line 111
def reverse
  chars(Unicode.unpack_graphemes(@wrapped_string).reverse.flatten.pack("U*"))
end

Reverses all characters in the string.

'Café'.mb_chars.reverse.to_s # => 'éfaC'
slice!(*args) Show source
# File activesupport/lib/active_support/multibyte/chars.rb, line 101
def slice!(*args)
  string_sliced = @wrapped_string.slice!(*args)
  if string_sliced
    chars(string_sliced)
  end
end

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'
split(*args) Show source
# File activesupport/lib/active_support/multibyte/chars.rb, line 88
def split(*args)
  @wrapped_string.split(*args).map { |i| self.class.new(i) }
end

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"]
swapcase() Show source
# File activesupport/lib/active_support/multibyte/chars.rb, line 141
def swapcase
  chars Unicode.swapcase(@wrapped_string)
end

Converts characters in the string to the opposite case.

'El Cañón'.mb_chars.swapcase.to_s # => "eL cAÑÓN"
tidy_bytes(force = false) Show source
# File activesupport/lib/active_support/multibyte/chars.rb, line 201
def tidy_bytes(force = false)
  chars(Unicode.tidy_bytes(@wrapped_string, force))
end

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
titleize() Show source
# File activesupport/lib/active_support/multibyte/chars.rb, line 156
def titleize
  chars(downcase.to_s.gsub(/\b('?\S)/u) { Unicode.upcase($1) })
end

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
upcase() Show source
# File activesupport/lib/active_support/multibyte/chars.rb, line 127
def upcase
  chars Unicode.upcase(@wrapped_string)
end

Converts characters in the string to uppercase.

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

© 2004–2018 David Heinemeier Hansson
Licensed under the MIT License.