Class: Mail::Multibyte::Chars

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

Overview

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

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(string) ⇒ Chars

Creates a new Chars instance by wrapping string.



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# 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

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.



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# 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

Instance Attribute Details

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

Returns the value of attribute wrapped_string.



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# File 'lib/mail/multibyte/chars.rb', line 37

def wrapped_string
  @wrapped_string
end

Instance Method Details

#<=>(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.



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# File 'lib/mail/multibyte/chars.rb', line 78

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

#=~(other) ⇒ Object 



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# File 'lib/mail/multibyte/chars.rb', line 82

def =~(other)
  @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"



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# 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? ⇒ Boolean

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

Returns:

  • (Boolean) 


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# File 'lib/mail/multibyte/chars.rb', line 65

def acts_like_string?
  true
end

#capitalize ⇒ Object

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

Example:

Mail::Multibyte.mb_chars('über').capitalize.to_s # => "Über"



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# File 'lib/mail/multibyte/chars.rb', line 201

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

#compose ⇒ Object

Performs composition on all the characters.

Example:

'é'.length                       # => 3
Mail::Multibyte.mb_chars('é').compose.to_s.length # => 2



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# File 'lib/mail/multibyte/chars.rb', line 239

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
Mail::Multibyte.mb_chars('é').decompose.to_s.length # => 3



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# File 'lib/mail/multibyte/chars.rb', line 230

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:

Mail::Multibyte.mb_chars('VĚDA A VÝZKUM').downcase.to_s # => "věda a výzkum"



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# File 'lib/mail/multibyte/chars.rb', line 193

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

#g_length ⇒ Object

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



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# File 'lib/mail/multibyte/chars.rb', line 248

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

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



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# File 'lib/mail/multibyte/chars.rb', line 177

def limit(limit)
  slice(0...translate_offset(limit))
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 Mail::Multibyte::Unicode.default_normalization_form



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# 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) ⇒ 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) 


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# 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 ⇒ Object

Reverses all characters in the string.

Example:

Mail::Multibyte.mb_chars('Café').reverse.to_s # => 'éfaC'



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# File 'lib/mail/multibyte/chars.rb', line 139

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

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

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"



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# 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

#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:

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



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# 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) ⇒ 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.



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# File 'lib/mail/multibyte/chars.rb', line 255

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:

Mail::Multibyte.mb_chars("ÉL QUE SE ENTERÓ").titleize    # => "Él Que Se Enteró"
Mail::Multibyte.mb_chars("日本語").titleize                 # => "日本語"



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# 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

#upcase ⇒ Object

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 ?"



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# File 'lib/mail/multibyte/chars.rb', line 185

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