class ActiveSupport::Multibyte::Chars - activesupport-4.2.3 Documentation

# class ActiveSupport::Multibyte::Chars

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

### Attributes

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

### Public Class Methods

consumes?(string) click to toggle source

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

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

new(string) click to toggle source

Creates a new Chars instance by wrapping string.

    # File 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

### Public Instance Methods

capitalize() click to toggle source

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

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

    # File lib/active_support/multibyte/chars.rb, line 134
    def capitalize
      (slice(0) || chars('')).upcase + (slice(1..-1) || chars('')).downcase
    end

compose() click to toggle source

Performs composition on all the characters.

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

    # File lib/active_support/multibyte/chars.rb, line 170
    def compose
      chars(Unicode.compose(@wrapped_string.codepoints.to_a).pack('U*'))
    end

decompose() click to toggle source

Performs canonical decomposition on all the characters.

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

    # File lib/active_support/multibyte/chars.rb, line 162
    def decompose
      chars(Unicode.decompose(:canonical, @wrapped_string.codepoints.to_a).pack('U*'))
    end

downcase() click to toggle source

Converts characters in the string to lowercase.

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

    # File lib/active_support/multibyte/chars.rb, line 120
    def downcase
      chars Unicode.downcase(@wrapped_string)
    end

grapheme_length() click to toggle source

Returns the number of grapheme clusters in the string.

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

    # File lib/active_support/multibyte/chars.rb, line 178
    def grapheme_length
      Unicode.unpack_graphemes(@wrapped_string).length
    end

limit(limit) click to toggle source

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 lib/active_support/multibyte/chars.rb, line 106
    def limit(limit)
      slice(0...translate_offset(limit))
    end

method_missing(method, *args, &block) click to toggle source

Forward all undefined methods to the wrapped string.

    # File 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) click to toggle source

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

    # File 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) click to toggle source

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

reverse() click to toggle source

Reverses all characters in the string.

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

    # File lib/active_support/multibyte/chars.rb, line 97
    def reverse
      chars(Unicode.unpack_graphemes(@wrapped_string).reverse.flatten.pack('U*'))
    end

slice!(*args) click to toggle source

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

    # File lib/active_support/multibyte/chars.rb, line 90
    def slice!(*args)
      chars(@wrapped_string.slice!(*args))
    end

split(*args) click to toggle source

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 lib/active_support/multibyte/chars.rb, line 84
    def split(*args)
      @wrapped_string.split(*args).map { |i| self.class.new(i) }
    end

swapcase() click to toggle source

Converts characters in the string to the opposite case.

    'El Cañón".mb_chars.swapcase.to_s # => "eL cAÑÓN"

    # File lib/active_support/multibyte/chars.rb, line 127
    def swapcase
      chars Unicode.swapcase(@wrapped_string)
    end

tidy_bytes(force = false) click to toggle source

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 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() click to toggle source

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"

    # File lib/active_support/multibyte/chars.rb, line 142
    def titleize
      chars(downcase.to_s.gsub(/\b('?\S)/u) { Unicode.upcase($1)})
    end

Also aliased as: titlecase
upcase() click to toggle source

Converts characters in the string to uppercase.

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

    # File lib/active_support/multibyte/chars.rb, line 113
    def upcase
      chars Unicode.upcase(@wrapped_string)
    end