class Mail::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 Mail::Multibyte.proxy_class.

class CharsForUTF32
  def size
    @wrapped_string.size / 4
  end

  def self.accepts?(string)
    string.length % 4 == 0
  end
end

Mail::Multibyte.proxy_class = CharsForUTF32

Attributes

to_s[R]
to_str[R]
wrapped_string[R]

Public Class Methods

new(string) click to toggle source

Creates a new Chars instance by wrapping string.

# File lib/mail/multibyte/chars.rb, line 42
def initialize(string)
  @wrapped_string = string.dup
  @wrapped_string.force_encoding(Encoding::UTF_8) unless @wrapped_string.frozen?
end

Public Instance Methods

<=>(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/mail/multibyte/chars.rb, line 78
def <=>(other)
  @wrapped_string <=> other.to_s
end
=~(other) click to toggle source
# File lib/mail/multibyte/chars.rb, line 82
def =~(other)
  @wrapped_string =~ other
end
[](*args)
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/mail/multibyte/chars.rb, line 108
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)
    if args[0].is_a?(Integer)
      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?(Integer)
    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 + 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?() click to toggle source

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

# File lib/mail/multibyte/chars.rb, line 65
def acts_like_string?
  true
end
capitalize() click to toggle source

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

Example:

Mail::Multibyte.mb_chars('über').capitalize.to_s # => "Über"
# File lib/mail/multibyte/chars.rb, line 201
def capitalize
  (slice(0) || chars('')).upcase + (slice(1..-1) || chars('')).downcase
end
compose() click to toggle source

Performs composition on all the characters.

Example:

'é'.length                       # => 3
Mail::Multibyte.mb_chars('é').compose.to_s.length # => 2
# File lib/mail/multibyte/chars.rb, line 239
def compose
  chars(Unicode.compose_codepoints(Unicode.u_unpack(@wrapped_string)).pack('U*'))
end
decompose() click to toggle source

Performs canonical decomposition on all the characters.

Example:

'é'.length                         # => 2
Mail::Multibyte.mb_chars('é').decompose.to_s.length # => 3
# File lib/mail/multibyte/chars.rb, line 230
def decompose
  chars(Unicode.decompose_codepoints(:canonical, Unicode.u_unpack(@wrapped_string)).pack('U*'))
end
downcase() click to toggle source

Convert characters in the string to lowercase.

Example:

Mail::Multibyte.mb_chars('VĚDA A VÝZKUM').downcase.to_s # => "věda a výzkum"
# File lib/mail/multibyte/chars.rb, line 193
def downcase
  chars(Unicode.apply_mapping(@wrapped_string, :lowercase_mapping))
end
g_length() click to toggle source

Returns the number of grapheme clusters in the string.

Example:

Mail::Multibyte.mb_chars('क्षि').length   # => 4
Mail::Multibyte.mb_chars('क्षि').g_length # => 3
# File lib/mail/multibyte/chars.rb, line 248
def g_length
  Unicode.g_unpack(@wrapped_string).length
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) # => "こん"
# File lib/mail/multibyte/chars.rb, line 177
def limit(limit)
  slice(0...translate_offset(limit))
end
method_missing(method, *args, &block) click to toggle source

Forward all undefined methods to the wrapped string.

# File lib/mail/multibyte/chars.rb, line 48
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 = 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.

# File lib/mail/multibyte/chars.rb, line 221
def normalize(form = nil)
  chars(Unicode.normalize(@wrapped_string, form))
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.

Calls superclass method
# File lib/mail/multibyte/chars.rb, line 60
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:

Mail::Multibyte.mb_chars('Café').reverse.to_s # => 'éfaC'
# File lib/mail/multibyte/chars.rb, line 139
def reverse
  chars(Unicode.g_unpack(@wrapped_string).reverse.flatten.pack('U*'))
end
slice(*args) click to toggle source

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

Example:

Mail::Multibyte.mb_chars('こんにちは').slice(2..3).to_s # => "にち"
# File lib/mail/multibyte/chars.rb, line 148
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
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:

Mail::Multibyte.mb_chars('Café périferôl').split(/é/).map { |part| part.upcase.to_s } # => ["CAF", " P", "RIFERÔL"]
# File lib/mail/multibyte/chars.rb, line 91
def split(*args)
  @wrapped_string.split(*args).map { |i| i.mb_chars }
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/mail/multibyte/chars.rb, line 255
def tidy_bytes(force = false)
  chars(Unicode.tidy_bytes(@wrapped_string, force))
end
titlecase()
Alias for: titleize
titleize() click to toggle source

Capitalizes the first letter of every word, when possible.

Example:

Mail::Multibyte.mb_chars("ÉL QUE SE ENTERÓ").titleize    # => "Él Que Se Enteró"
Mail::Multibyte.mb_chars("日本語").titleize                 # => "日本語"
# File lib/mail/multibyte/chars.rb, line 210
def titleize
  chars(downcase.to_s.gsub(/\b('?\S)/u) { Unicode.apply_mapping $1, :uppercase_mapping })
end
Also aliased as: titlecase
upcase() click to toggle source

Convert characters in the string to uppercase.

Example:

Mail::Multibyte.mb_chars('Laurent, où sont les tests ?').upcase.to_s # => "LAURENT, OÙ SONT LES TESTS ?"
# File lib/mail/multibyte/chars.rb, line 185
def upcase
  chars(Unicode.apply_mapping(@wrapped_string, :uppercase_mapping))
end