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

Constants

HANGUL_JAMO_FIRST
HANGUL_JAMO_LAST
HANGUL_LBASE
HANGUL_LCOUNT
HANGUL_NCOUNT
HANGUL_SBASE: Hangul character boundaries and properties
HANGUL_SCOUNT
HANGUL_SLAST
HANGUL_TBASE
HANGUL_TCOUNT
HANGUL_VBASE
HANGUL_VCOUNT
UNICODE_LEADERS_AND_TRAILERS: 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_LEADERS_PAT
UNICODE_TRAILERS_PAT
UNICODE_WHITESPACE: All the unicode whitespace
UTF8_PAT

Attributes

to_s[R]

to_str[R]

wrapped_string[R]

Public Class Methods

compose_codepoints(codepoints) click to toggle source

Compose decomposed characters to the composed form.

# File 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) 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 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) click to toggle source

Decompose composed characters to the decomposed form.

# File 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) click to toggle source

Reverse operation of g_unpack.

Example:

Chars.g_pack(Chars.g_unpack('क्षि')) #=> 'क्षि'

# File lib/active_support/multibyte/chars.rb, line 526
def g_pack(unpacked)
  (unpacked.flatten).pack('U*')
end

g_unpack(string) click to toggle source

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 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) click to toggle source

Detect whether the codepoint is in a certain character class. Returns true when it’s in the specified character class and false otherwise. Valid character classes are: :cr, :lf, :l, :v, :lv, :lvt and :t.

Primarily used by the grapheme cluster support.

# File 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) click to toggle source

Creates a new Chars instance by wrapping string.

# File 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) click to toggle source

Re-order codepoints so the string becomes canonical.

# File 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) click to toggle source

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

# File 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) click to toggle source

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 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) 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 117
def self.wants?(string)
  $KCODE == 'UTF8' && consumes?(string)
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 146
def +(other)
  self << other
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. See String#<=> for more details.

Example:

'é'.mb_chars <=> 'ü'.mb_chars #=> -1

# File lib/active_support/multibyte/chars.rb, line 138
def <=>(other)
  @wrapped_string <=> other.to_s
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 154
def =~(other)
  translate_offset(@wrapped_string =~ other)
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 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?() 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 111
def acts_like_string?
  true
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 392
def capitalize
  (slice(0) || chars('')).upcase + (slice(1..-1) || chars('')).downcase
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 292
def center(integer, padstr=' ')
  justify(integer, :center, padstr)
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 434
def compose
  chars(self.class.compose_codepoints(self.class.u_unpack(@wrapped_string)).pack('U*'))
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 425
def decompose
  chars(self.class.decompose_codepoints(:canonical, self.class.u_unpack(@wrapped_string)).pack('U*'))
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 384
def downcase
  apply_mapping :lowercase_mapping
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 443
def g_length
  self.class.g_unpack(@wrapped_string).length
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 187
def include?(other)
  # We have to redefine this method because Enumerable defines it.
  @wrapped_string.include?(other)
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 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) 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 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() click to toggle source

Alias for: size

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 279
def ljust(integer, padstr=' ')
  justify(integer, :left, padstr)
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 302
def lstrip
  chars(@wrapped_string.gsub(UNICODE_LEADERS_PAT, ''))
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 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) 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.

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 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() 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 368
def ord
  self.class.u_unpack(@wrapped_string)[0]
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 106
def respond_to?(method, include_private=false)
  super || @wrapped_string.respond_to?(method, include_private) || false
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 321
def reverse
  chars(self.class.g_unpack(@wrapped_string).reverse.flatten.pack('U*'))
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 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=' ') 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 266
def rjust(integer, padstr=' ')
  justify(integer, :right, padstr)
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 297
def rstrip
  chars(@wrapped_string.gsub(UNICODE_TRAILERS_PAT, ''))
end

size() click to toggle source

Returns the number of codepoints in the string

# File lib/active_support/multibyte/chars.rb, line 312
def size
  self.class.u_unpack(@wrapped_string).size
end

Also aliased as: length

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 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

Also aliased as: []

slice!(*args) click to toggle source

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 lib/active_support/multibyte/chars.rb, line 358
def slice!(*args)
  slice = self[*args]
  self[*args] = ''
  slice
end

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 163
def split(*args)
  @wrapped_string.split(*args).map { |i| i.mb_chars }
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 307
def strip
  rstrip.lstrip
end

tidy_bytes() click to toggle source

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

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

upcase() click to toggle source

Convert characters in the string to uppercase.

Example:

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

# File lib/active_support/multibyte/chars.rb, line 376
def upcase
  apply_mapping :uppercase_mapping
end

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ActiveSupport::Multibyte::Chars

Constants

Attributes

Public Class Methods

Public Instance Methods