Class: ActiveSupport::Multibyte::Chars

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

Overview

:nodoc: 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

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(string) ⇒ Chars

:nodoc:



43
44
45
46
 
# File 'lib/active_support/multibyte/chars.rb', line 43

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.



54
55
56
57
58
59
60
61
62
 
# File 'lib/active_support/multibyte/chars.rb', line 54

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

Instance Attribute Details

#wrapped_string ⇒ Object (readonly) Also known as: to_s, to_str

Returns the value of attribute wrapped_string.



37
38
39
 
# File 'lib/active_support/multibyte/chars.rb', line 37

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) 


76
77
78
79
80
81
82
 
# File 'lib/active_support/multibyte/chars.rb', line 76

def self.consumes?(string)
  # Unpack is a little bit faster than regular expressions.
  string.unpack('U*')
  true
rescue ArgumentError
  false
end

.wants?(string) ⇒ Boolean

Returns true if the Chars class can and should act as a proxy for the string string. Returns false otherwise.

Returns:

  • (Boolean) 


100
101
102
 
# File 'lib/active_support/multibyte/chars.rb', line 100

def self.wants?(string)
  $KCODE == 'UTF8' && consumes?(string)
end

Instance Method Details

#+(other) ⇒ Object

Returns a new Chars object containing the other object concatenated to the string.

Example:

('Café'.mb_chars + ' périferôl').to_s # => "Café périferôl"



108
109
110
 
# File 'lib/active_support/multibyte/chars.rb', line 108

def +(other)
  chars(@wrapped_string + other)
end

#<=>(other) ⇒ Object

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:

'é'.mb_chars <=> 'ü'.mb_chars # => -1

See String#<=> for more details.



93
94
95
 
# File 'lib/active_support/multibyte/chars.rb', line 93

def <=>(other)
  @wrapped_string <=> other.to_s
end

#=~(other) ⇒ Object

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

Example:

'Café périferôl'.mb_chars =~ /ô/ # => 12



116
117
118
 
# File 'lib/active_support/multibyte/chars.rb', line 116

def =~(other)
  translate_offset(@wrapped_string =~ other)
end

#[]=(*args) ⇒ Object

Like String#[]=, except instead of byte offsets you specify character offsets.

Example:

s = "Müller"
s.mb_chars[2] = "e" # Replace character with offset 2
s
# => "Müeler"

s = "Müller"
s.mb_chars[1, 2] = "ö" # Replace 2 characters at character offset 1
s
# => "Möler"



266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
 
# File 'lib/active_support/multibyte/chars.rb', line 266

def []=(*args)
  replace_by = args.pop
  # Indexed replace with regular expressions already works
  if args.first.is_a?(Regexp)
    @wrapped_string[*args] = replace_by
  else
    result = Unicode.u_unpack(@wrapped_string)
    case args.first
      when Fixnum
        raise IndexError, "index #{args[0]} out of string" if args[0] >= result.length
        min = args[0]
        max = args[1].nil? ? min : (min + args[1] - 1)
        range = Range.new(min, max)
        replace_by = [replace_by].pack('U') if replace_by.is_a?(Fixnum)
      when Range
        raise RangeError, "#{args[0]} out of range" if args[0].min >= result.length
        range = args[0]
      else
        needle = args[0].to_s
        min = index(needle)
        max = min + Unicode.u_unpack(needle).length - 1
        range = Range.new(min, max)
    end
    result[range] = Unicode.u_unpack(replace_by)
    @wrapped_string.replace(result.pack('U*'))
  end
end

#acts_like_string? ⇒ Boolean

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

Returns:

  • (Boolean) 


71
72
73
 
# File 'lib/active_support/multibyte/chars.rb', line 71

def acts_like_string?
  true
end

#capitalize ⇒ Object

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

Example:

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



359
360
361
 
# File 'lib/active_support/multibyte/chars.rb', line 359

def capitalize
  (slice(0) || chars('')).upcase + (slice(1..-1) || chars('')).downcase
end

#center(integer, padstr = ' ') ⇒ Object

Works just like String#center, only integer specifies characters instead of bytes.

Example:

"¾ cup".mb_chars.center(8).to_s
# => " ¾ cup  "

"¾ cup".mb_chars.center(8, " ").to_s # Use non-breaking whitespace
# => " ¾ cup  "



234
235
236
 
# File 'lib/active_support/multibyte/chars.rb', line 234

def center(integer, padstr=' ')
  justify(integer, :center, padstr)
end

#compose ⇒ Object

Performs composition on all the characters.

Example:

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



397
398
399
 
# File 'lib/active_support/multibyte/chars.rb', line 397

def compose
  chars(Unicode.compose_codepoints(Unicode.u_unpack(@wrapped_string)).pack('U*'))
end

#decompose ⇒ Object

Performs canonical decomposition on all the characters.

Example:

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



388
389
390
 
# File 'lib/active_support/multibyte/chars.rb', line 388

def decompose
  chars(Unicode.decompose_codepoints(:canonical, Unicode.u_unpack(@wrapped_string)).pack('U*'))
end

#downcase ⇒ Object

Convert characters in the string to lowercase.

Example:

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



351
352
353
 
# File 'lib/active_support/multibyte/chars.rb', line 351

def downcase
  chars(Unicode.apply_mapping @wrapped_string, :lowercase_mapping)
end

#g_length ⇒ Object

Returns the number of grapheme clusters in the string.

Example:

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



406
407
408
 
# File 'lib/active_support/multibyte/chars.rb', line 406

def g_length
  Unicode.g_unpack(@wrapped_string).length
end

#include?(other) ⇒ Boolean

Returns true if contained string contains other. Returns false otherwise.

Example:

'Café'.mb_chars.include?('é') # => true

Returns:

  • (Boolean) 


140
141
142
143
 
# File 'lib/active_support/multibyte/chars.rb', line 140

def include?(other)
  # We have to redefine this method because Enumerable defines it.
  @wrapped_string.include?(other)
end

#index(needle, offset = 0) ⇒ Object

Returns the position needle in the string, counting in codepoints. Returns nil if needle isn’t found.

Example:

'Café périferôl'.mb_chars.index('ô')   # => 12
'Café périferôl'.mb_chars.index(/\w/u) # => 0



150
151
152
153
154
 
# File 'lib/active_support/multibyte/chars.rb', line 150

def index(needle, offset=0)
  wrapped_offset = first(offset).wrapped_string.length
  index = @wrapped_string.index(needle, wrapped_offset)
  index ? (Unicode.u_unpack(@wrapped_string.slice(0...index)).size) : nil
end

#insert(offset, fragment) ⇒ Object

Inserts the passed string at specified codepoint offsets.

Example:

'Café'.mb_chars.insert(4, ' périferôl').to_s # => "Café périferôl"



124
125
126
127
128
129
130
131
132
133
134
 
# File 'lib/active_support/multibyte/chars.rb', line 124

def insert(offset, fragment)
  unpacked = Unicode.u_unpack(@wrapped_string)
  unless offset > unpacked.length
    @wrapped_string.replace(
        Unicode.u_unpack(@wrapped_string).insert(offset, *Unicode.u_unpack(fragment)).pack('U*')
    )
  else
    raise IndexError, "index #{offset} out of string"
  end
  self
end

#limit(limit) ⇒ Object

Limit 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.

Example:

'こんにちは'.mb_chars.limit(7).to_s # => "こん"



335
336
337
 
# File 'lib/active_support/multibyte/chars.rb', line 335

def limit(limit)
  slice(0...translate_offset(limit))
end

#ljust(integer, padstr = ' ') ⇒ Object

Works just like String#ljust, only integer specifies characters instead of bytes.

Example:

"¾ cup".mb_chars.rjust(8).to_s
# => "¾ cup   "

"¾ cup".mb_chars.rjust(8, " ").to_s # Use non-breaking whitespace
# => "¾ cup   "



221
222
223
 
# File 'lib/active_support/multibyte/chars.rb', line 221

def ljust(integer, padstr=' ')
  justify(integer, :left, padstr)
end

#lstrip ⇒ Object

Strips entire range of Unicode whitespace from the left of the string.



182
183
184
 
# File 'lib/active_support/multibyte/chars.rb', line 182

def lstrip
  chars(@wrapped_string.gsub(Unicode::LEADERS_PAT, ''))
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



379
380
381
 
# File 'lib/active_support/multibyte/chars.rb', line 379

def normalize(form = nil)
  chars(Unicode.normalize(@wrapped_string, form))
end

#ord ⇒ Object

Returns the codepoint of the first character in the string.

Example:

'こんにちは'.mb_chars.ord # => 12371



195
196
197
 
# File 'lib/active_support/multibyte/chars.rb', line 195

def ord
  Unicode.u_unpack(@wrapped_string)[0]
end

#respond_to?(method, include_private = false) ⇒ 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) 


66
67
68
 
# File 'lib/active_support/multibyte/chars.rb', line 66

def respond_to?(method, include_private=false)
  super || @wrapped_string.respond_to?(method, include_private)
end

#reverse ⇒ Object

Reverses all characters in the string.

Example:

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



298
299
300
 
# File 'lib/active_support/multibyte/chars.rb', line 298

def reverse
  chars(Unicode.g_unpack(@wrapped_string).reverse.flatten.pack('U*'))
end

#rindex(needle, offset = nil) ⇒ Object

Returns the position needle in the string, counting in codepoints, searching backward from offset or the end of the string. Returns nil if needle isn’t found.

Example:

'Café périferôl'.mb_chars.rindex('é')   # => 6
'Café périferôl'.mb_chars.rindex(/\w/u) # => 13



163
164
165
166
167
168
 
# File 'lib/active_support/multibyte/chars.rb', line 163

def rindex(needle, offset=nil)
  offset ||= length
  wrapped_offset = first(offset).wrapped_string.length
  index = @wrapped_string.rindex(needle, wrapped_offset)
  index ? (Unicode.u_unpack(@wrapped_string.slice(0...index)).size) : nil
end

#rjust(integer, padstr = ' ') ⇒ Object

Works just like String#rjust, only integer specifies characters instead of bytes.

Example:

"¾ cup".mb_chars.rjust(8).to_s
# => "   ¾ cup"

"¾ cup".mb_chars.rjust(8, " ").to_s # Use non-breaking whitespace
# => "   ¾ cup"



208
209
210
 
# File 'lib/active_support/multibyte/chars.rb', line 208

def rjust(integer, padstr=' ')
  justify(integer, :right, padstr)
end

#rstrip ⇒ Object

Strips entire range of Unicode whitespace from the right of the string.



177
178
179
 
# File 'lib/active_support/multibyte/chars.rb', line 177

def rstrip
  chars(@wrapped_string.gsub(Unicode::TRAILERS_PAT, ''))
end

#size ⇒ Object Also known as: length

Returns the number of codepoints in the string



171
172
173
 
# File 'lib/active_support/multibyte/chars.rb', line 171

def size
  Unicode.u_unpack(@wrapped_string).size
end

#slice(*args) ⇒ Object Also known as: []

Implements Unicode-aware slice with codepoints. Slicing on one point returns the codepoints for that character.

Example:

'こんにちは'.mb_chars.slice(2..3).to_s # => "にち"



307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
 
# File 'lib/active_support/multibyte/chars.rb', line 307

def slice(*args)
  if args.size > 2
    raise ArgumentError, "wrong number of arguments (#{args.size} for 1)" # Do as if we were native
  elsif (args.size == 2 && !(args.first.is_a?(Numeric) || args.first.is_a?(Regexp)))
    raise TypeError, "cannot convert #{args.first.class} into Integer" # Do as if we were native
  elsif (args.size == 2 && !args[1].is_a?(Numeric))
    raise TypeError, "cannot convert #{args[1].class} into Integer" # Do as if we were native
  elsif args[0].kind_of? Range
    cps = Unicode.u_unpack(@wrapped_string).slice(*args)
    result = cps.nil? ? nil : cps.pack('U*')
  elsif args[0].kind_of? Regexp
    result = @wrapped_string.slice(*args)
  elsif args.size == 1 && args[0].kind_of?(Numeric)
    character = Unicode.u_unpack(@wrapped_string)[args[0]]
    result = character && [character].pack('U')
  else
    cps = Unicode.u_unpack(@wrapped_string).slice(*args)
    result = cps && cps.pack('U*')
  end
  result && chars(result)
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.

Example:

'Café périferôl'.mb_chars.split(/é/).map { |part| part.upcase.to_s } # => ["CAF", " P", "RIFERÔL"]



249
250
251
 
# File 'lib/active_support/multibyte/chars.rb', line 249

def split(*args)
  @wrapped_string.split(*args).map { |i| i.mb_chars }
end

#strip ⇒ Object

Strips entire range of Unicode whitespace from the right and left of the string.



187
188
189
 
# File 'lib/active_support/multibyte/chars.rb', line 187

def strip
  rstrip.lstrip
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.



413
414
415
 
# File 'lib/active_support/multibyte/chars.rb', line 413

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

#titleize ⇒ Object Also known as: titlecase

Capitalizes the first letter of every word, when possible.

Example:

"ÉL QUE SE ENTERÓ".mb_chars.titleize    # => "Él Que Se Enteró"
"日本語".mb_chars.titleize                 # => "日本語"



368
369
370
 
# File 'lib/active_support/multibyte/chars.rb', line 368

def titleize
  chars(downcase.to_s.gsub(/\b('?[\S])/u) { Unicode.apply_mapping $1, :uppercase_mapping })
end

#upcase ⇒ Object

Convert characters in the string to uppercase.

Example:

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



343
344
345
 
# File 'lib/active_support/multibyte/chars.rb', line 343

def upcase
  chars(Unicode.apply_mapping @wrapped_string, :uppercase_mapping)
end