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

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 76
76:       def self.consumes?(string)
77:         # Unpack is a little bit faster than regular expressions.
78:         string.unpack('U*')
79:         true
80:       rescue ArgumentError
81:         false
82:       end

new(string) click to toggle source

Creates a new Chars instance by wrapping string.

    # File lib/active_support/multibyte/chars.rb, line 43
43:         def initialize(string)
44:           @wrapped_string = string
45:           @wrapped_string.force_encoding(Encoding::UTF_8) unless @wrapped_string.frozen?
46:         end

wants?(string) click to toggle source

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

     # File lib/active_support/multibyte/chars.rb, line 100
100:         def self.wants?(string)
101:           $KCODE == 'UTF8' && consumes?(string)
102:         end

Public Instance Methods

+(other) click to toggle source

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

Example:

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

     # File lib/active_support/multibyte/chars.rb, line 108
108:         def +(other)
109:           chars(@wrapped_string + other)
110:         end

<=>(other) click to toggle source

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.

    # File lib/active_support/multibyte/chars.rb, line 93
93:       def <=>(other)
94:         @wrapped_string <=> other.to_s
95:       end

=~(other) click to toggle source

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

Example:

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

     # File lib/active_support/multibyte/chars.rb, line 116
116:         def =~(other)
117:           translate_offset(@wrapped_string =~ other)
118:         end

=~(other) click to toggle source

     # File lib/active_support/multibyte/chars.rb, line 239
239:         def =~(other)
240:           @wrapped_string =~ other
241:         end

[](*args) click to toggle source

Alias for: slice

[]=(*args) click to toggle source

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"

     # File lib/active_support/multibyte/chars.rb, line 266
266:       def []=(*args)
267:         replace_by = args.pop
268:         # Indexed replace with regular expressions already works
269:         if args.first.is_a?(Regexp)
270:           @wrapped_string[*args] = replace_by
271:         else
272:           result = Unicode.u_unpack(@wrapped_string)
273:           if args[0].is_a?(Fixnum)
274:             raise IndexError, "index #{args[0]} out of string" if args[0] >= result.length
275:             min = args[0]
276:             max = args[1].nil? ? min : (min + args[1] - 1)
277:             range = Range.new(min, max)
278:             replace_by = [replace_by].pack('U') if replace_by.is_a?(Fixnum)
279:           elsif args.first.is_a?(Range)
280:             raise RangeError, "#{args[0]} out of range" if args[0].min >= result.length
281:             range = args[0]
282:           else
283:             needle = args[0].to_s
284:             min = index(needle)
285:             max = min + Unicode.u_unpack(needle).length - 1
286:             range = Range.new(min, max)
287:           end
288:           result[range] = Unicode.u_unpack(replace_by)
289:           @wrapped_string.replace(result.pack('U*'))
290:         end
291:       end

acts_like_string?() click to toggle source

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

    # File lib/active_support/multibyte/chars.rb, line 71
71:       def acts_like_string?
72:         true
73:       end

capitalize() click to toggle source

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

Example:

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

     # File lib/active_support/multibyte/chars.rb, line 359
359:       def capitalize
360:         (slice(0) || chars('')).upcase + (slice(1..1) || chars('')).downcase
361:       end

center(integer, padstr=' ') click to toggle source

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  "

     # File lib/active_support/multibyte/chars.rb, line 234
234:         def center(integer, padstr=' ')
235:           justify(integer, :center, padstr)
236:         end

compose() click to toggle source

Performs composition on all the characters.

Example:

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

     # File lib/active_support/multibyte/chars.rb, line 397
397:       def compose
398:         chars(Unicode.compose_codepoints(Unicode.u_unpack(@wrapped_string)).pack('U*'))
399:       end

decompose() click to toggle source

Performs canonical decomposition on all the characters.

Example:

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

     # File lib/active_support/multibyte/chars.rb, line 388
388:       def decompose
389:         chars(Unicode.decompose_codepoints(:canonical, Unicode.u_unpack(@wrapped_string)).pack('U*'))
390:       end

downcase() click to toggle source

Convert characters in the string to lowercase.

Example:

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

     # File lib/active_support/multibyte/chars.rb, line 351
351:       def downcase
352:         chars(Unicode.apply_mapping @wrapped_string, :lowercase_mapping)
353:       end

g_length() click to toggle source

Returns the number of grapheme clusters in the string.

Example:

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

     # File lib/active_support/multibyte/chars.rb, line 406
406:       def g_length
407:         Unicode.g_unpack(@wrapped_string).length
408:       end

include?(other) click to toggle source

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

Example:

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

     # File lib/active_support/multibyte/chars.rb, line 140
140:         def include?(other)
141:           # We have to redefine this method because Enumerable defines it.
142:           @wrapped_string.include?(other)
143:         end

index(needle, offset=0) click to toggle source

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

     # File lib/active_support/multibyte/chars.rb, line 150
150:         def index(needle, offset=0)
151:           wrapped_offset = first(offset).wrapped_string.length
152:           index = @wrapped_string.index(needle, wrapped_offset)
153:           index ? (Unicode.u_unpack(@wrapped_string.slice(0...index)).size) : nil
154:         end

insert(offset, fragment) click to toggle source

Inserts the passed string at specified codepoint offsets.

Example:

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

     # File lib/active_support/multibyte/chars.rb, line 124
124:         def insert(offset, fragment)
125:           unpacked = Unicode.u_unpack(@wrapped_string)
126:           unless offset > unpacked.length
127:             @wrapped_string.replace(
128:               Unicode.u_unpack(@wrapped_string).insert(offset, *Unicode.u_unpack(fragment)).pack('U*')
129:             )
130:           else
131:             raise IndexError, "index #{offset} out of string"
132:           end
133:           self
134:         end

limit(limit) click to toggle source

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:

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

     # File lib/active_support/multibyte/chars.rb, line 335
335:       def limit(limit)
336:         slice(0...translate_offset(limit))
337:       end

ljust(integer, padstr=' ') click to toggle source

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   "

     # File lib/active_support/multibyte/chars.rb, line 221
221:         def ljust(integer, padstr=' ')
222:           justify(integer, :left, padstr)
223:         end

lstrip() click to toggle source

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

     # File lib/active_support/multibyte/chars.rb, line 182
182:         def lstrip
183:           chars(@wrapped_string.gsub(Unicode::LEADERS_PAT, ''))
184:         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 54
54:       def method_missing(method, *args, &block)
55:         if method.to_s =~ /!$/
56:           @wrapped_string.__send__(method, *args, &block)
57:           self
58:         else
59:           result = @wrapped_string.__send__(method, *args, &block)
60:           result.kind_of?(String) ? chars(result) : result
61:         end
62:       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 379
379:       def normalize(form = nil)
380:         chars(Unicode.normalize(@wrapped_string, form))
381:       end

ord() click to toggle source

Returns the codepoint of the first character in the string.

Example:

  'こんにちは'.mb_chars.ord # => 12371

     # File lib/active_support/multibyte/chars.rb, line 195
195:         def ord
196:           Unicode.u_unpack(@wrapped_string)[0]
197:         end

respond_to?(method, include_private=false) 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 66
66:       def respond_to?(method, include_private=false)
67:         super || @wrapped_string.respond_to?(method, include_private) || false
68:       end

reverse() click to toggle source

Reverses all characters in the string.

Example:

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

     # File lib/active_support/multibyte/chars.rb, line 297
297:       def reverse
298:         chars(Unicode.g_unpack(@wrapped_string).reverse.flatten.pack('U*'))
299:       end

rindex(needle, offset=nil) click to toggle source

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

     # File lib/active_support/multibyte/chars.rb, line 163
163:         def rindex(needle, offset=nil)
164:           offset ||= length
165:           wrapped_offset = first(offset).wrapped_string.length
166:           index = @wrapped_string.rindex(needle, wrapped_offset)
167:           index ? (Unicode.u_unpack(@wrapped_string.slice(0...index)).size) : nil
168:         end

rjust(integer, padstr=' ') click to toggle source

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"

     # File lib/active_support/multibyte/chars.rb, line 208
208:         def rjust(integer, padstr=' ')
209:           justify(integer, :right, padstr)
210:         end

rstrip() click to toggle source

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

     # File lib/active_support/multibyte/chars.rb, line 177
177:         def rstrip
178:           chars(@wrapped_string.gsub(Unicode::TRAILERS_PAT, ''))
179:         end

size() click to toggle source

Returns the number of codepoints in the string

     # File lib/active_support/multibyte/chars.rb, line 171
171:         def size
172:           Unicode.u_unpack(@wrapped_string).size
173:         end

slice(*args) click to toggle source

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"

     # File lib/active_support/multibyte/chars.rb, line 306
306:       def slice(*args)
307:         if args.size > 2
308:           raise ArgumentError, "wrong number of arguments (#{args.size} for 1)" # Do as if we were native
309:         elsif (args.size == 2 && !(args.first.is_a?(Numeric) || args.first.is_a?(Regexp)))
310:           raise TypeError, "cannot convert #{args.first.class} into Integer" # Do as if we were native
311:         elsif (args.size == 2 && !args[1].is_a?(Numeric))
312:           raise TypeError, "cannot convert #{args[1].class} into Integer" # Do as if we were native
313:         elsif args[0].kind_of? Range
314:           cps = Unicode.u_unpack(@wrapped_string).slice(*args)
315:           result = cps.nil? ? nil : cps.pack('U*')
316:         elsif args[0].kind_of? Regexp
317:           result = @wrapped_string.slice(*args)
318:         elsif args.size == 1 && args[0].kind_of?(Numeric)
319:           character = Unicode.u_unpack(@wrapped_string)[args[0]]
320:           result = character && [character].pack('U')
321:         else
322:           cps = Unicode.u_unpack(@wrapped_string).slice(*args)
323:           result = cps && cps.pack('U*')
324:         end
325:         result && chars(result)
326:       end

Also aliased as: []

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.

Example:

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

     # File lib/active_support/multibyte/chars.rb, line 249
249:       def split(*args)
250:         @wrapped_string.split(*args).map { |i| i.mb_chars }
251:       end

strip() click to toggle source

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

     # File lib/active_support/multibyte/chars.rb, line 187
187:         def strip
188:           rstrip.lstrip
189:         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 413
413:       def tidy_bytes(force = false)
414:         chars(Unicode.tidy_bytes(@wrapped_string, force))
415:       end

titlecase() click to toggle source

Alias for: titleize

titleize() click to toggle source

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"

     # File lib/active_support/multibyte/chars.rb, line 368
368:       def titleize
369:         chars(downcase.to_s.gsub(/\b('?[\S])/) { Unicode.apply_mapping $1, :uppercase_mapping })
370:       end

Also aliased as: titlecase

upcase() click to toggle source

Convert characters in the string to uppercase.

Example:

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

     # File lib/active_support/multibyte/chars.rb, line 343
343:       def upcase
344:         chars(Unicode.apply_mapping @wrapped_string, :uppercase_mapping)
345:       end

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ActiveSupport::Multibyte::Chars

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