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_charsmethod. 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_sbefore 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
Methods
#
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Included Modules
Constants
HANGUL_SBASE = 0xAC00
 

Hangul character boundaries and properties

HANGUL_LBASE = 0x1100
 
HANGUL_VBASE = 0x1161
 
HANGUL_TBASE = 0x11A7
 
HANGUL_LCOUNT = 19
 
HANGUL_VCOUNT = 21
 
HANGUL_TCOUNT = 28
 
HANGUL_NCOUNT = HANGUL_VCOUNT * HANGUL_TCOUNT
 
HANGUL_SCOUNT = 11172
 
HANGUL_SLAST = HANGUL_SBASE + HANGUL_SCOUNT
 
HANGUL_JAMO_FIRST = 0x1100
 
HANGUL_JAMO_LAST = 0x11FF
 
UNICODE_WHITESPACE = [ (0x0009..0x000D).to_a, # White_Space # Cc [5] <control-0009>..<control-000D> 0x0020, # White_Space # Zs SPACE 0x0085, # White_Space # Cc <control-0085> 0x00A0, # White_Space # Zs NO-BREAK SPACE 0x1680, # White_Space # Zs OGHAM SPACE MARK 0x180E, # White_Space # Zs MONGOLIAN VOWEL SEPARATOR (0x2000..0x200A).to_a, # White_Space # Zs [11] EN QUAD..HAIR SPACE 0x2028, # White_Space # Zl LINE SEPARATOR 0x2029, # White_Space # Zp PARAGRAPH SEPARATOR 0x202F, # White_Space # Zs NARROW NO-BREAK SPACE 0x205F, # White_Space # Zs MEDIUM MATHEMATICAL SPACE 0x3000, # White_Space # Zs IDEOGRAPHIC SPACE ].flatten.freeze
 

All the unicode whitespace

UNICODE_LEADERS_AND_TRAILERS = UNICODE_WHITESPACE + [65279]
 

BOM (byte order mark) can also be seen as whitespace, it's a non-rendering character used to distinguish between little and big endian. This is not an issue in utf-8, so it must be ignored.

UNICODE_TRAILERS_PAT = /(#{codepoints_to_pattern(UNICODE_LEADERS_AND_TRAILERS)})+\Z/
 
UNICODE_LEADERS_PAT = /\A(#{codepoints_to_pattern(UNICODE_LEADERS_AND_TRAILERS)})+/
 
UTF8_PAT = ActiveSupport::Multibyte::VALID_CHARACTER['UTF-8']
 
Attributes
[R] to_s
[R] to_str
[R] wrapped_string
Class Public methods
compose_codepoints(codepoints)

Compose decomposed characters to the composed form.

# File activesupport/lib/active_support/multibyte/chars.rb, line 576
def compose_codepoints(codepoints)
  pos = 0
  eoa = codepoints.length - 1
  starter_pos = 0
  starter_char = codepoints[0]
  previous_combining_class = -1
  while pos < eoa
    pos += 1
    lindex = starter_char - HANGUL_LBASE
    # -- Hangul
    if 0 <= lindex and lindex < HANGUL_LCOUNT
      vindex = codepoints[starter_pos+1] - HANGUL_VBASE rescue vindex = -1
      if 0 <= vindex and vindex < HANGUL_VCOUNT
        tindex = codepoints[starter_pos+2] - HANGUL_TBASE rescue tindex = -1
        if 0 <= tindex and tindex < HANGUL_TCOUNT
          j = starter_pos + 2
          eoa -= 2
        else
          tindex = 0
          j = starter_pos + 1
          eoa -= 1
        end
        codepoints[starter_pos..j] = (lindex * HANGUL_VCOUNT + vindex) * HANGUL_TCOUNT + tindex + HANGUL_SBASE
      end
      starter_pos += 1
      starter_char = codepoints[starter_pos]
    # -- Other characters
    else
      current_char = codepoints[pos]
      current = UCD.codepoints[current_char]
      if current.combining_class > previous_combining_class
        if ref = UCD.composition_map[starter_char]
          composition = ref[current_char]
        else
          composition = nil
        end
        unless composition.nil?
          codepoints[starter_pos] = composition
          starter_char = composition
          codepoints.delete_at pos
          eoa -= 1
          pos -= 1
          previous_combining_class = -1
        else
          previous_combining_class = current.combining_class
        end
      else
        previous_combining_class = current.combining_class
      end
      if current.combining_class == 0
        starter_pos = pos
        starter_char = codepoints[pos]
      end
    end
  end
  codepoints
end
consumes?(string)

Returns truewhen the proxy class can handle the string. Returns falseotherwise.

# File activesupport/lib/active_support/multibyte/chars.rb, line 122
def self.consumes?(string)
  # Unpack is a little bit faster than regular expressions.
  string.unpack('U*')
  true
rescue ArgumentError
  false
end
decompose_codepoints(type, codepoints)

Decompose composed characters to the decomposed form.

# File activesupport/lib/active_support/multibyte/chars.rb, line 555
def decompose_codepoints(type, codepoints)
  codepoints.inject([]) do |decomposed, cp|
    # if it's a hangul syllable starter character
    if HANGUL_SBASE <= cp and cp < HANGUL_SLAST
      sindex = cp - HANGUL_SBASE
      ncp = [] # new codepoints
      ncp << HANGUL_LBASE + sindex / HANGUL_NCOUNT
      ncp << HANGUL_VBASE + (sindex % HANGUL_NCOUNT) / HANGUL_TCOUNT
      tindex = sindex % HANGUL_TCOUNT
      ncp << (HANGUL_TBASE + tindex) unless tindex == 0
      decomposed.concat ncp
    # if the codepoint is decomposable in with the current decomposition type
    elsif (ncp = UCD.codepoints[cp].decomp_mapping) and (!UCD.codepoints[cp].decomp_type || type == :compatability)
      decomposed.concat decompose_codepoints(type, ncp.dup)
    else
      decomposed << cp
    end
  end
end
g_pack(unpacked)

Reverse operation of g_unpack.

Example:

Chars.g_pack(Chars.g_unpack('क्षि')) #=> 'क्षि'
# File activesupport/lib/active_support/multibyte/chars.rb, line 526
def g_pack(unpacked)
  (unpacked.flatten).pack('U*')
end
g_unpack(string)

Unpack the string at grapheme boundaries. Returns a list of character lists.

Example:

Chars.g_unpack('क्षि') #=> [[2325, 2381], [2359], [2367]]
Chars.g_unpack('Café') #=> [[67], [97], [102], [233]]
# File activesupport/lib/active_support/multibyte/chars.rb, line 492
def g_unpack(string)
  codepoints = u_unpack(string)
  unpacked = []
  pos = 0
  marker = 0
  eoc = codepoints.length
  while(pos < eoc)
    pos += 1
    previous = codepoints[pos-1]
    current = codepoints[pos]
    if (
        # CR X LF
        one = ( previous == UCD.boundary[:cr] and current == UCD.boundary[:lf] ) or
        # L X (L|V|LV|LVT)
        two = ( UCD.boundary[:l] === previous and in_char_class?(current, [:l,:v,:lv,:lvt]) ) or
        # (LV|V) X (V|T)
        three = ( in_char_class?(previous, [:lv,:v]) and in_char_class?(current, [:v,:t]) ) or
        # (LVT|T) X (T)
        four = ( in_char_class?(previous, [:lvt,:t]) and UCD.boundary[:t] === current ) or
        # X Extend
        five = (UCD.boundary[:extend] === current)
      )
    else
      unpacked << codepoints[marker..pos-1]
      marker = pos
    end
  end
  unpacked
end
in_char_class?(codepoint, classes)

Detect whether the codepoint is in a certain character class. Returns truewhen it's in the specified character class and falseotherwise. Valid character classes are: :cr, :lf, :l, :v, :lv, :lvtand :t.

Primarily used by the grapheme cluster support.

# File activesupport/lib/active_support/multibyte/chars.rb, line 483
def in_char_class?(codepoint, classes)
  classes.detect { |c| UCD.boundary[c] === codepoint } ? true : false
end
new(string)

Creates a new Chars instance by wrapping string.

# File activesupport/lib/active_support/multibyte/chars.rb, line 83
def initialize(string)
  @wrapped_string = string
  @wrapped_string.force_encoding(Encoding::UTF_8) unless @wrapped_string.frozen?
end
reorder_characters(codepoints)

Re-order codepoints so the string becomes canonical.

# File activesupport/lib/active_support/multibyte/chars.rb, line 539
def reorder_characters(codepoints)
  length = codepoints.length- 1
  pos = 0
  while pos < length do
    cp1, cp2 = UCD.codepoints[codepoints[pos]], UCD.codepoints[codepoints[pos+1]]
    if (cp1.combining_class > cp2.combining_class) && (cp2.combining_class > 0)
      codepoints[pos..pos+1] = cp2.code, cp1.code
      pos += (pos > 0 ? -1 : 1)
    else
      pos += 1
    end
  end
  codepoints
end
tidy_bytes(string)

Replaces all ISO-8859-1 or CP1252 characters by their UTF-8 equivalent resulting in a valid UTF-8 string.

# File activesupport/lib/active_support/multibyte/chars.rb, line 635
def tidy_bytes(string)
  string.split(//).map do |c|
    c.force_encoding(Encoding::ASCII) if c.respond_to?(:force_encoding)
    if !ActiveSupport::Multibyte::VALID_CHARACTER['UTF-8'].match(c)
      n = c.unpack('C')[0]
      n < 128 ? n.chr :
      n < 160 ? [UCD.cp1252[n] || n].pack('U') :
      n < 192 ? "\xC2" + n.chr : "\xC3" + (n-64).chr
    else
      c
    end
  end.join
end
u_unpack(string)

Unpack the string at codepoints boundaries. Raises an EncodingError when the encoding of the string isn't valid UTF-8.

Example:

Chars.u_unpack('Café') #=> [67, 97, 102, 233]
# File activesupport/lib/active_support/multibyte/chars.rb, line 470
def u_unpack(string)
  begin
    string.unpack 'U*'
  rescue ArgumentError
    raise EncodingError, 'malformed UTF-8 character'
  end
end
wants?(string)

Returns trueif the Chars class can and should act as a proxy for the string string. Returns falseotherwise.

# File activesupport/lib/active_support/multibyte/chars.rb, line 117
def self.wants?(string)
  $KCODE == 'UTF8' && consumes?(string)
end
Instance Public methods
+(other)

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

Example:

('Café'.mb_chars + ' périferôl').to_s #=> "Café périferôl"
# File activesupport/lib/active_support/multibyte/chars.rb, line 146
def +(other)
  self << other
end
<=>(other)

Returns -1, 0or +1depending 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.

Example:

'é'.mb_chars <=> 'ü'.mb_chars #=> -1
# File activesupport/lib/active_support/multibyte/chars.rb, line 138
def <=>(other)
  @wrapped_string <=> other.to_s
end
=~(other)

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

Example:

'Café périferôl'.mb_chars =~ /ô/ #=> 12
# File activesupport/lib/active_support/multibyte/chars.rb, line 154
def =~(other)
  translate_offset(@wrapped_string =~ other)
end
[](*args)
[]=(*args)

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 activesupport/lib/active_support/multibyte/chars.rb, line 230
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 = self.class.u_unpack(@wrapped_string)
    if args[0].is_a?(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)
    elsif args.first.is_a?(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 + self.class.u_unpack(needle).length - 1
      range = Range.new(min, max)
    end
    result[range] = self.class.u_unpack(replace_by)
    @wrapped_string.replace(result.pack('U*'))
  end
end
acts_like_string?()

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

# File activesupport/lib/active_support/multibyte/chars.rb, line 111
def acts_like_string?
  true
end
capitalize()

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

Example:

'über'.mb_chars.capitalize.to_s #=> "Über"
# File activesupport/lib/active_support/multibyte/chars.rb, line 392
def capitalize
  (slice(0) || chars('')).upcase + (slice(1..-1) || chars('')).downcase
end
center(integer, padstr=' ')

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 activesupport/lib/active_support/multibyte/chars.rb, line 292
def center(integer, padstr=' ')
  justify(integer, :center, padstr)
end
compose()

Performs composition on all the characters.

Example:

'é'.length #=> 3
'é'.mb_chars.compose.to_s.length #=> 2
# File activesupport/lib/active_support/multibyte/chars.rb, line 434
def compose
  chars(self.class.compose_codepoints(self.class.u_unpack(@wrapped_string)).pack('U*'))
end
decompose()

Performs canonical decomposition on all the characters.

Example:

'é'.length #=> 2
'é'.mb_chars.decompose.to_s.length #=> 3
# File activesupport/lib/active_support/multibyte/chars.rb, line 425
def decompose
  chars(self.class.decompose_codepoints(:canonical, self.class.u_unpack(@wrapped_string)).pack('U*'))
end
downcase()

Convert characters in the string to lowercase.

Example:

'VĚDA A VÝZKUM'.mb_chars.downcase.to_s #=> "věda a výzkum"
# File activesupport/lib/active_support/multibyte/chars.rb, line 384
def downcase
  apply_mapping :lowercase_mapping
end
g_length()

Returns the number of grapheme clusters in the string.

Example:

'क्षि'.mb_chars.length #=> 4
'क्षि'.mb_chars.g_length #=> 3
# File activesupport/lib/active_support/multibyte/chars.rb, line 443
def g_length
  self.class.g_unpack(@wrapped_string).length
end
include?(other)

Returns trueif contained string contains other. Returns falseotherwise.

Example:

'Café'.mb_chars.include?('é') #=> true
# File activesupport/lib/active_support/multibyte/chars.rb, line 187
def include?(other)
  # We have to redefine this method because Enumerable defines it.
  @wrapped_string.include?(other)
end
index(needle, offset=0)

Returns the position needlein the string, counting in codepoints. Returns nilif needleisn't found.

Example:

'Café périferôl'.mb_chars.index('ô') #=> 12
'Café périferôl'.mb_chars.index(/\w/) #=> 0
# File activesupport/lib/active_support/multibyte/chars.rb, line 197
def index(needle, offset=0)
  wrapped_offset = self.first(offset).wrapped_string.length
  index = @wrapped_string.index(needle, wrapped_offset)
  index ? (self.class.u_unpack(@wrapped_string.slice(0...index)).size) : nil
end
insert(offset, fragment)

Inserts the passed string at specified codepoint offsets.

Example:

'Café'.mb_chars.insert(4, ' périferôl').to_s #=> "Café périferôl"
# File activesupport/lib/active_support/multibyte/chars.rb, line 171
def insert(offset, fragment)
  unpacked = self.class.u_unpack(@wrapped_string)
  unless offset > unpacked.length
    @wrapped_string.replace(
      self.class.u_unpack(@wrapped_string).insert(offset, *self.class.u_unpack(fragment)).pack('U*')
    )
  else
    raise IndexError, "index #{offset} out of string"
  end
  self
end
length()
ljust(integer, padstr=' ')

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 activesupport/lib/active_support/multibyte/chars.rb, line 279
def ljust(integer, padstr=' ')
  justify(integer, :left, padstr)
end
lstrip()

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

# File activesupport/lib/active_support/multibyte/chars.rb, line 302
def lstrip
  chars(@wrapped_string.gsub(UNICODE_LEADERS_PAT, ''))
end
method_missing(method, *args, &block)

Forward all undefined methods to the wrapped string.

# File activesupport/lib/active_support/multibyte/chars.rb, line 94
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
normalize(form=ActiveSupport::Multibyte.default_normalization_form)

Returns the KC normalization of the string by default. NFKC is considered the best normalization form for passing strings to databases and validations.

  • str- The string to perform normalization on.

  • form- The form you want to normalize in. Should be one of the following: :c, :kc, :d, or :kd. Default is ActiveSupport::Multibyte.default_normalization_form

# File activesupport/lib/active_support/multibyte/chars.rb, line 403
def normalize(form=ActiveSupport::Multibyte.default_normalization_form)
  # See http://www.unicode.org/reports/tr15, Table 1
  codepoints = self.class.u_unpack(@wrapped_string)
  chars(case form
    when :d
      self.class.reorder_characters(self.class.decompose_codepoints(:canonical, codepoints))
    when :c
      self.class.compose_codepoints(self.class.reorder_characters(self.class.decompose_codepoints(:canonical, codepoints)))
    when :kd
      self.class.reorder_characters(self.class.decompose_codepoints(:compatability, codepoints))
    when :kc
      self.class.compose_codepoints(self.class.reorder_characters(self.class.decompose_codepoints(:compatability, codepoints)))
    else
      raise ArgumentError, "#{form} is not a valid normalization variant", caller
  end.pack('U*'))
end
ord()

Returns the codepoint of the first character in the string.

Example:

'こんにちは'.mb_chars.ord #=> 12371
# File activesupport/lib/active_support/multibyte/chars.rb, line 368
def ord
  self.class.u_unpack(@wrapped_string)[0]
end
respond_to?(method, include_private=false)

Returns trueif objresponds to the given method. Private methods are included in the search only if the optional second parameter evaluates to true.

# File activesupport/lib/active_support/multibyte/chars.rb, line 106
def respond_to?(method, include_private=false)
  super || @wrapped_string.respond_to?(method, include_private) || false
end
reverse()

Reverses all characters in the string.

Example:

'Café'.mb_chars.reverse.to_s #=> 'éfaC'
# File activesupport/lib/active_support/multibyte/chars.rb, line 321
def reverse
  chars(self.class.g_unpack(@wrapped_string).reverse.flatten.pack('U*'))
end
rindex(needle, offset=nil)

Returns the position needlein the string, counting in codepoints, searching backward from offsetor the end of the string. Returns nilif needleisn't found.

Example:

'Café périferôl'.mb_chars.rindex('é') #=> 6
'Café périferôl'.mb_chars.rindex(/\w/) #=> 13
# File activesupport/lib/active_support/multibyte/chars.rb, line 210
def rindex(needle, offset=nil)
  offset ||= length
  wrapped_offset = self.first(offset).wrapped_string.length
  index = @wrapped_string.rindex(needle, wrapped_offset)
  index ? (self.class.u_unpack(@wrapped_string.slice(0...index)).size) : nil
end
rjust(integer, padstr=' ')

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 activesupport/lib/active_support/multibyte/chars.rb, line 266
def rjust(integer, padstr=' ')
  justify(integer, :right, padstr)
end
rstrip()

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

# File activesupport/lib/active_support/multibyte/chars.rb, line 297
def rstrip
  chars(@wrapped_string.gsub(UNICODE_TRAILERS_PAT, ''))
end
size()

Returns the number of codepoints in the string

Also aliased as: length
# File activesupport/lib/active_support/multibyte/chars.rb, line 312
def size
  self.class.u_unpack(@wrapped_string).size
end
slice(*args)

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"
Also aliased as: []
# File activesupport/lib/active_support/multibyte/chars.rb, line 330
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 = self.class.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 = self.class.u_unpack(@wrapped_string)[args[0]]
    result = character.nil? ? nil : [character].pack('U')
  else
    result = self.class.u_unpack(@wrapped_string).slice(*args).pack('U*')
  end
  result.nil? ? nil : chars(result)
end
slice!(*args)

Like String#slice!, except instead of byte offsets you specify character offsets.

Example:

s = 'こんにちは'
s.mb_chars.slice!(2..3).to_s #=> "にち"
s #=> "こんは"
# File activesupport/lib/active_support/multibyte/chars.rb, line 358
def slice!(*args)
  slice = self[*args]
  self[*args] = ''
  slice
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.

Example:

'Café périferôl'.mb_chars.split(/é/).map { |part| part.upcase.to_s } #=> ["CAF", " P", "RIFERÔL"]
# File activesupport/lib/active_support/multibyte/chars.rb, line 163
def split(*args)
  @wrapped_string.split(*args).map { |i| i.mb_chars }
end
strip()

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

# File activesupport/lib/active_support/multibyte/chars.rb, line 307
def strip
  rstrip.lstrip
end
tidy_bytes()

Replaces all ISO-8859-1 or CP1252 characters by their UTF-8 equivalent resulting in a valid UTF-8 string.

# File activesupport/lib/active_support/multibyte/chars.rb, line 448
def tidy_bytes
  chars(self.class.tidy_bytes(@wrapped_string))
end
upcase()

Convert characters in the string to uppercase.

Example:

'Laurent, òu sont les tests?'.mb_chars.upcase.to_s #=> "LAURENT, ÒU SONT LES TESTS?"
# File activesupport/lib/active_support/multibyte/chars.rb, line 376
def upcase
  apply_mapping :uppercase_mapping
end