Class: ActiveSupport::Multibyte::Chars

Chars enables you to work transparently with multibyte encodings 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 chars method. Methods which would normally return a String object now return a Chars object so methods can be chained.

  "The Perfect String  ".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".chars.downcase.to_s

The actual operations on the string are delegated to handlers. Theoretically handlers can be implemented for any encoding, but the default handler handles UTF-8. This handler is set during initialization, if you want to use you own handler, you can set it on the Chars class. Look at the UTF8Handler source for an example how to implement your own handler. If you your own handler to work on anything but UTF-8 you probably also want to override Chars#handler.

  ActiveSupport::Multibyte::Chars.handler = MyHandler

Note that a few methods are defined on Chars instead of the handler because they are defined on Object or Kernel and method_missing can‘t catch them.

Methods

<=> =~ acts_like_string? gsub handler handler= method_missing new respond_to? split to_str

External Aliases

string -> to_s

Attributes

string [R]

Public Class methods

handler=(klass)

Set the handler class for the Char objects.

[Source]

     # File vendor/rails/activesupport/lib/active_support/multibyte/chars.rb, line 111
111:     def self.handler=(klass)
112:       @@handler = klass
113:     end

new(str)

Create a new Chars instance.

[Source]

    # File vendor/rails/activesupport/lib/active_support/multibyte/chars.rb, line 58
58:     def initialize(str)
59:       @string = str.respond_to?(:string) ? str.string : str
60:     end

Public Instance methods

<=>(other)

Returns -1, 0 or +1 depending on whether the Chars object is to be sorted before, equal or after the object on the right side of the operation. It accepts any object that implements to_s. See String.<=> for more details.

[Source]

    # File vendor/rails/activesupport/lib/active_support/multibyte/chars.rb, line 65
65:     def <=>(other); @string <=> other.to_s; end

=~(other)

Like String.=~ only it returns the character offset (in codepoints) instead of the byte offset.

[Source]

    # File vendor/rails/activesupport/lib/active_support/multibyte/chars.rb, line 77
77:     def =~(other)
78:       handler.translate_offset(@string, @string =~ other)
79:     end

acts_like_string?()

Enable more predictable duck-typing on String-like classes. See Object#acts_like?.

[Source]

    # File vendor/rails/activesupport/lib/active_support/multibyte/chars.rb, line 53
53:     def acts_like_string?
54:       true
55:     end

gsub(*a, &b)

Gsub works exactly the same as gsub on a normal string.

[Source]

    # File vendor/rails/activesupport/lib/active_support/multibyte/chars.rb, line 74
74:     def gsub(*a, &b); @string.gsub(*a, &b).chars; end

handler()

Returns the proper handler for the contained string depending on $KCODE and the encoding of the string. This method is used internally to always redirect messages to the proper classes depending on the context.

[Source]

     # File vendor/rails/activesupport/lib/active_support/multibyte/chars.rb, line 117
117:     def handler
118:       if utf8_pragma?
119:         @@handler
120:       else
121:         ActiveSupport::Multibyte::Handlers::PassthruHandler
122:       end
123:     end

method_missing(m, *a, &b)

Try to forward all undefined methods to the handler, when a method is not defined on the handler, send it to the contained string. Method_missing is also responsible for making the bang! methods destructive.

[Source]

     # File vendor/rails/activesupport/lib/active_support/multibyte/chars.rb, line 83
 83:     def method_missing(m, *a, &b)
 84:       begin
 85:         # Simulate methods with a ! at the end because we can't touch the enclosed string from the handlers.
 86:         if m.to_s =~ /^(.*)\!$/ && handler.respond_to?($1)
 87:           result = handler.send($1, @string, *a, &b)
 88:           if result == @string
 89:             result = nil
 90:           else
 91:             @string.replace result
 92:           end
 93:         elsif handler.respond_to?(m)
 94:           result = handler.send(m, @string, *a, &b)
 95:         else
 96:           result = @string.send(m, *a, &b)
 97:         end
 98:       rescue Handlers::EncodingError
 99:         @string.replace handler.tidy_bytes(@string)
100:         retry
101:       end
102:       
103:       if result.kind_of?(String)
104:         result.chars
105:       else
106:         result
107:       end
108:     end

respond_to?(method, include_priv = false)

Make duck-typing with String possible

[Source]

    # File vendor/rails/activesupport/lib/active_support/multibyte/chars.rb, line 45
45:     def respond_to?(method, include_priv = false)
46:       super || @string.respond_to?(method, include_priv) ||
47:         handler.respond_to?(method, include_priv) ||
48:         (method.to_s =~ /(.*)!/ && handler.respond_to?($1, include_priv)) ||
49:         false
50:     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.

[Source]

    # File vendor/rails/activesupport/lib/active_support/multibyte/chars.rb, line 69
69:     def split(*args)
70:       @string.split(*args).map { |i| i.chars }
71:     end

to_str()

The magic method to make String and Chars comparable

[Source]

    # File vendor/rails/activesupport/lib/active_support/multibyte/chars.rb, line 38
38:     def to_str
39:       # Using any other ways of overriding the String itself will lead you all the way from infinite loops to
40:       # core dumps. Don't go there.
41:       @string
42:     end

Methods

Included Modules

External Aliases

Attributes

Public Class methods

Public Instance methods