Class: ActiveSupport::Multibyte::Chars

Inherits:
Object
  • Object
show all
Includes:
Comparable
Defined in:
activesupport/lib/active_support/multibyte/chars.rb

Overview

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
# => #<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

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(string) ⇒ Chars

Creates a new Chars instance by wrapping string.


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# 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

Dynamic Method Handling

This class handles dynamic methods through the method_missing method

#method_missing(method, *args, &block) ⇒ Object

Forward all undefined methods to the wrapped string.


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# File 'activesupport/lib/active_support/multibyte/chars.rb', line 61

def method_missing(method, *args, &block)
  result = @wrapped_string.__send__(method, *args, &block)
  if method.end_with?("!")
    self if result
  else
    result.kind_of?(String) ? chars(result) : result
  end
end

Instance Attribute Details

#wrapped_stringObject (readonly) Also known as: to_s, to_str

Returns the value of attribute wrapped_string


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# File 'activesupport/lib/active_support/multibyte/chars.rb', line 48

def wrapped_string
  @wrapped_string
end

Class Method Details

.consumes?(string) ⇒ Boolean

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

Returns:

  • (Boolean)

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# File 'activesupport/lib/active_support/multibyte/chars.rb', line 79

def self.consumes?(string)
  ActiveSupport::Deprecation.warn(<<-MSG.squish)
    ActiveSupport::Multibyte::Chars.consumes? is deprecated and will be
    removed from Rails 6.1. Use string.is_utf8? instead.
  MSG

  string.encoding == Encoding::UTF_8
end

Instance Method Details

#as_json(options = nil) ⇒ Object

:nodoc:


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# File 'activesupport/lib/active_support/multibyte/chars.rb', line 199

def as_json(options = nil) #:nodoc:
  to_s.as_json(options)
end

#composeObject

Performs composition on all the characters.

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

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# File 'activesupport/lib/active_support/multibyte/chars.rb', line 178

def compose
  chars(Unicode.compose(@wrapped_string.codepoints.to_a).pack("U*"))
end

#decomposeObject

Performs canonical decomposition on all the characters.

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

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# File 'activesupport/lib/active_support/multibyte/chars.rb', line 170

def decompose
  chars(Unicode.decompose(:canonical, @wrapped_string.codepoints.to_a).pack("U*"))
end

#grapheme_lengthObject

Returns the number of grapheme clusters in the string.

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

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# File 'activesupport/lib/active_support/multibyte/chars.rb', line 186

def grapheme_length
  @wrapped_string.scan(/\X/).length
end

#limit(limit) ⇒ Object

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"

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# File 'activesupport/lib/active_support/multibyte/chars.rb', line 125

def limit(limit)
  chars(@wrapped_string.truncate_bytes(limit, omission: nil))
end

#normalize(form = nil) ⇒ Object

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


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# File 'activesupport/lib/active_support/multibyte/chars.rb', line 145

def normalize(form = nil)
  form ||= Unicode.default_normalization_form

  # See https://www.unicode.org/reports/tr15, Table 1
  if alias_form = Unicode::NORMALIZATION_FORM_ALIASES[form]
    ActiveSupport::Deprecation.warn(<<-MSG.squish)
      ActiveSupport::Multibyte::Chars#normalize is deprecated and will be
      removed from Rails 6.1. Use #unicode_normalize(:#{alias_form}) instead.
    MSG

    send(:unicode_normalize, alias_form)
  else
    ActiveSupport::Deprecation.warn(<<-MSG.squish)
      ActiveSupport::Multibyte::Chars#normalize is deprecated and will be
      removed from Rails 6.1. Use #unicode_normalize instead.
    MSG

    raise ArgumentError, "#{form} is not a valid normalization variant", caller
  end
end

#respond_to_missing?(method, include_private) ⇒ Boolean

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.

Returns:

  • (Boolean)

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# 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

#reverseObject

Reverses all characters in the string.

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

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# File 'activesupport/lib/active_support/multibyte/chars.rb', line 116

def reverse
  chars(@wrapped_string.scan(/\X/).reverse.join)
end

#slice!(*args) ⇒ Object

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'

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# File 'activesupport/lib/active_support/multibyte/chars.rb', line 106

def slice!(*args)
  string_sliced = @wrapped_string.slice!(*args)
  if string_sliced
    chars(string_sliced)
  end
end

#split(*args) ⇒ Object

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"]

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# File 'activesupport/lib/active_support/multibyte/chars.rb', line 93

def split(*args)
  @wrapped_string.split(*args).map { |i| self.class.new(i) }
end

#tidy_bytes(force = false) ⇒ Object

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.


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# File 'activesupport/lib/active_support/multibyte/chars.rb', line 195

def tidy_bytes(force = false)
  chars(Unicode.tidy_bytes(@wrapped_string, force))
end

#titleizeObject Also known as: titlecase

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"

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# File 'activesupport/lib/active_support/multibyte/chars.rb', line 133

def titleize
  chars(downcase.to_s.gsub(/\b('?\S)/u) { $1.upcase })
end