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 # => #<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
Public Class Methods
Returns true
when the proxy class can handle the string.
Returns false
otherwise.
# File lib/active_support/multibyte/chars.rb, line 79 def self.consumes?(string) string.encoding == Encoding::UTF_8 end
Creates a new Chars instance by wrapping string.
# File 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
Public Instance Methods
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 148 def capitalize (slice(0) || chars("")).upcase + (slice(1..-1) || chars("")).downcase end
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 184 def compose chars(Unicode.compose(@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
# File lib/active_support/multibyte/chars.rb, line 176 def decompose chars(Unicode.decompose(:canonical, @wrapped_string.codepoints.to_a).pack("U*")) end
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 134 def downcase chars Unicode.downcase(@wrapped_string) end
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 192 def grapheme_length Unicode.unpack_graphemes(@wrapped_string).length 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"
# File lib/active_support/multibyte/chars.rb, line 120 def limit(limit) slice(0...translate_offset(limit)) end
Forward all undefined methods to the wrapped string.
# File 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
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 168 def normalize(form = nil) chars(Unicode.normalize(@wrapped_string, form)) 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
.
# File lib/active_support/multibyte/chars.rb, line 73 def respond_to_missing?(method, include_private) @wrapped_string.respond_to?(method, include_private) end
Reverses all characters in the string.
'Café'.mb_chars.reverse.to_s # => 'éfaC'
# File lib/active_support/multibyte/chars.rb, line 111 def reverse chars(Unicode.unpack_graphemes(@wrapped_string).reverse.flatten.pack("U*")) 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'
# File 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 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 88 def split(*args) @wrapped_string.split(*args).map { |i| self.class.new(i) } end
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 141 def swapcase chars Unicode.swapcase(@wrapped_string) 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.
# File lib/active_support/multibyte/chars.rb, line 201 def tidy_bytes(force = false) chars(Unicode.tidy_bytes(@wrapped_string, force)) 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"
# File lib/active_support/multibyte/chars.rb, line 156 def titleize chars(downcase.to_s.gsub(/\b('?\S)/u) { Unicode.upcase($1) }) end
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 127 def upcase chars Unicode.upcase(@wrapped_string) end
Private Instance Methods
# File lib/active_support/multibyte/chars.rb, line 230 def chars(string) self.class.new(string) end
# File lib/active_support/multibyte/chars.rb, line 218 def translate_offset(byte_offset) return nil if byte_offset.nil? return 0 if @wrapped_string == "" begin @wrapped_string.byteslice(0...byte_offset).unpack("U*").length rescue ArgumentError byte_offset -= 1 retry end end