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
Public Class Methods
Returns true
when the proxy class can handle the string. Returns false
otherwise.
# File lib/mail/multibyte/chars.rb, line 76 def self.consumes?(string) # Unpack is a little bit faster than regular expressions. string.unpack('U*') true rescue ArgumentError false end
Creates a new Chars
instance by wrapping string.
# File lib/mail/multibyte/chars.rb, line 43 def initialize(string) @wrapped_string = string.dup @wrapped_string.force_encoding(Encoding::UTF_8) unless @wrapped_string.frozen? end
Returns true
if the Chars
class can and should act as a proxy for the string string. Returns false
otherwise.
# File lib/mail/multibyte/chars.rb, line 100 def self.wants?(string) $KCODE == 'UTF8' && consumes?(string) end
Public Instance Methods
Returns a new Chars
object containing the other object concatenated to the string.
Example:
(Mail::Multibyte.mb_chars('Café') + ' périferôl').to_s # => "Café périferôl"
# File lib/mail/multibyte/chars.rb, line 108 def +(other) chars(@wrapped_string + other) end
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 93 def <=>(other) @wrapped_string <=> other.to_s end
Like String#=~
only it returns the character offset (in codepoints) instead of the byte offset.
Example:
Mail::Multibyte.mb_chars('Café périferôl') =~ /ô/ # => 12
# File lib/mail/multibyte/chars.rb, line 116 def =~(other) translate_offset(@wrapped_string =~ other) end
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 266 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
Enable more predictable duck-typing on String-like classes. See Object#acts_like?.
# File lib/mail/multibyte/chars.rb, line 71 def acts_like_string? true end
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 359 def capitalize (slice(0) || chars('')).upcase + (slice(1..-1) || chars('')).downcase end
Works just like String#center
, only integer specifies characters instead of bytes.
Example:
Mail::Multibyte.mb_chars("¾ cup").center(8).to_s # => " ¾ cup " Mail::Multibyte.mb_chars("¾ cup").center(8, " ").to_s # Use non-breaking whitespace # => " ¾ cup "
# File lib/mail/multibyte/chars.rb, line 234 def center(integer, padstr=' ') justify(integer, :center, padstr) end
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 397 def compose chars(Unicode.compose_codepoints(Unicode.u_unpack(@wrapped_string)).pack('U*')) end
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 388 def decompose chars(Unicode.decompose_codepoints(:canonical, Unicode.u_unpack(@wrapped_string)).pack('U*')) end
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 351 def downcase chars(Unicode.apply_mapping(@wrapped_string, :lowercase_mapping)) end
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 406 def g_length Unicode.g_unpack(@wrapped_string).length end
Returns true
if contained string contains other. Returns false
otherwise.
Example:
Mail::Multibyte.mb_chars('Café').include?('é') # => true
# File lib/mail/multibyte/chars.rb, line 140 def include?(other) # We have to redefine this method because Enumerable defines it. @wrapped_string.include?(other) end
Returns the position needle in the string, counting in codepoints. Returns nil
if needle isn’t found.
Example:
Mail::Multibyte.mb_chars('Café périferôl').index('ô') # => 12 Mail::Multibyte.mb_chars('Café périferôl').index(/\w/u) # => 0
# File lib/mail/multibyte/chars.rb, line 150 def index(needle, offset=0) wrapped_offset = first(offset).wrapped_string.length index = @wrapped_string.index(needle, wrapped_offset) index ? (Unicode.u_unpack(@wrapped_string.slice(0...index)).size) : nil end
Inserts the passed string at specified codepoint offsets.
Example:
Mail::Multibyte.mb_chars('Café').insert(4, ' périferôl').to_s # => "Café périferôl"
# File lib/mail/multibyte/chars.rb, line 124 def insert(offset, fragment) unpacked = Unicode.u_unpack(@wrapped_string) unless offset > unpacked.length @wrapped_string.replace( Unicode.u_unpack(@wrapped_string).insert(offset, *Unicode.u_unpack(fragment)).pack('U*') ) else raise IndexError, "index #{offset} out of string" end self end
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/mail/multibyte/chars.rb, line 335 def limit(limit) slice(0...translate_offset(limit)) end
Works just like String#ljust
, only integer specifies characters instead of bytes.
Example:
Mail::Multibyte.mb_chars("¾ cup").rjust(8).to_s # => "¾ cup " Mail::Multibyte.mb_chars("¾ cup").rjust(8, " ").to_s # Use non-breaking whitespace # => "¾ cup "
# File lib/mail/multibyte/chars.rb, line 221 def ljust(integer, padstr=' ') justify(integer, :left, padstr) end
Strips entire range of Unicode
whitespace from the left of the string.
# File lib/mail/multibyte/chars.rb, line 182 def lstrip chars(@wrapped_string.gsub(Unicode::LEADERS_PAT, '')) end
Forward all undefined methods to the wrapped string.
# File lib/mail/multibyte/chars.rb, line 54 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
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 isMail::Multibyte::Unicode.default_normalization_form
# File lib/mail/multibyte/chars.rb, line 379 def normalize(form = nil) chars(Unicode.normalize(@wrapped_string, form)) end
Returns the codepoint of the first character in the string.
Example:
Mail::Multibyte.mb_chars('こんにちは').ord # => 12371
# File lib/mail/multibyte/chars.rb, line 195 def ord Unicode.u_unpack(@wrapped_string)[0] end
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/mail/multibyte/chars.rb, line 66 def respond_to?(method, include_private=false) super || @wrapped_string.respond_to?(method, include_private) || false end
Reverses all characters in the string.
Example:
Mail::Multibyte.mb_chars('Café').reverse.to_s # => 'éfaC'
# File lib/mail/multibyte/chars.rb, line 297 def reverse chars(Unicode.g_unpack(@wrapped_string).reverse.flatten.pack('U*')) end
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:
Mail::Multibyte.mb_chars('Café périferôl').rindex('é') # => 6 Mail::Multibyte.mb_chars('Café périferôl').rindex(/\w/u) # => 13
# File lib/mail/multibyte/chars.rb, line 163 def rindex(needle, offset=nil) offset ||= length wrapped_offset = first(offset).wrapped_string.length index = @wrapped_string.rindex(needle, wrapped_offset) index ? (Unicode.u_unpack(@wrapped_string.slice(0...index)).size) : nil end
Works just like String#rjust
, only integer specifies characters instead of bytes.
Example:
Mail::Multibyte.mb_chars("¾ cup").rjust(8).to_s # => " ¾ cup" Mail::Multibyte.mb_chars("¾ cup").rjust(8, " ").to_s # Use non-breaking whitespace # => " ¾ cup"
# File lib/mail/multibyte/chars.rb, line 208 def rjust(integer, padstr=' ') justify(integer, :right, padstr) end
Strips entire range of Unicode
whitespace from the right of the string.
# File lib/mail/multibyte/chars.rb, line 177 def rstrip chars(@wrapped_string.gsub(Unicode::TRAILERS_PAT, '')) end
Returns the number of codepoints in the string
# File lib/mail/multibyte/chars.rb, line 171 def size Unicode.u_unpack(@wrapped_string).size end
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 306 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
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 249 def split(*args) @wrapped_string.split(*args).map { |i| i.mb_chars } end
Strips entire range of Unicode
whitespace from the right and left of the string.
# File lib/mail/multibyte/chars.rb, line 187 def strip rstrip.lstrip end
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 413 def tidy_bytes(force = false) chars(Unicode.tidy_bytes(@wrapped_string, force)) end
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 368 def titleize chars(downcase.to_s.gsub(/\b('?\S)/u) { Unicode.apply_mapping $1, :uppercase_mapping }) end
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 343 def upcase chars(Unicode.apply_mapping(@wrapped_string, :uppercase_mapping)) end