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
- +
- <=>
- =~
- []=
- acts_like_string?
- capitalize
- center
- compose
- consumes?
- decompose
- downcase
- g_length
- include?
- index
- insert
- limit
- ljust
- lstrip
- method_missing
- new
- normalize
- ord
- respond_to?
- reverse
- rindex
- rjust
- rstrip
- size
- slice
- split
- strip
- tidy_bytes
- titleize
- upcase
- wants?
- Comparable
[R] | wrapped_string | |
[R] | to_s | |
[R] | to_str |
Returns true when the proxy class can handle the string. Returns false otherwise.
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# File activesupport/lib/active_support/multibyte/chars.rb, line 75 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.
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# File activesupport/lib/active_support/multibyte/chars.rb, line 42 def initialize(string) @wrapped_string = string @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.
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# File activesupport/lib/active_support/multibyte/chars.rb, line 99 def self.wants?(string) $KCODE == 'UTF8' && consumes?(string) end
Returns a new Chars object containing the other object concatenated to the string.
Example:
('Café'.mb_chars + ' périferôl').to_s # => "Café périferôl"
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# File activesupport/lib/active_support/multibyte/chars.rb, line 107 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.
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# File activesupport/lib/active_support/multibyte/chars.rb, line 92 def <=>(other) @wrapped_string <=> other.to_s end
Like String#=~ only it returns the character offset (in codepoints) instead of the byte offset.
Example:
'Café périferôl'.mb_chars =~ /ô/ # => 12
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# File activesupport/lib/active_support/multibyte/chars.rb, line 115 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"
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# File activesupport/lib/active_support/multibyte/chars.rb, line 265 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?(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 + 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?.
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# File activesupport/lib/active_support/multibyte/chars.rb, line 70 def acts_like_string? true end
Converts the first character to uppercase and the remainder to lowercase.
Example:
'über'.mb_chars.capitalize.to_s # => "Über"
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# File activesupport/lib/active_support/multibyte/chars.rb, line 358 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:
"¾ cup".mb_chars.center(8).to_s # => " ¾ cup " "¾ cup".mb_chars.center(8, " ").to_s # Use non-breaking whitespace # => " ¾ cup "
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# File activesupport/lib/active_support/multibyte/chars.rb, line 233 def center(integer, padstr=' ') justify(integer, :center, padstr) end
Performs composition on all the characters.
Example:
'é'.length # => 3 'é'.mb_chars.compose.to_s.length # => 2
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# File activesupport/lib/active_support/multibyte/chars.rb, line 396 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 'é'.mb_chars.decompose.to_s.length # => 3
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# File activesupport/lib/active_support/multibyte/chars.rb, line 387 def decompose chars(Unicode.decompose_codepoints(:canonical, Unicode.u_unpack(@wrapped_string)).pack('U*')) end
Convert characters in the string to lowercase.
Example:
'VĚDA A VÝZKUM'.mb_chars.downcase.to_s # => "věda a výzkum"
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# File activesupport/lib/active_support/multibyte/chars.rb, line 350 def downcase chars(Unicode.apply_mapping @wrapped_string, :lowercase_mapping) end
Returns the number of grapheme clusters in the string.
Example:
'क्षि'.mb_chars.length # => 4 'क्षि'.mb_chars.g_length # => 3
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# File activesupport/lib/active_support/multibyte/chars.rb, line 405 def g_length Unicode.g_unpack(@wrapped_string).length end
Returns true if contained string contains other. Returns false otherwise.
Example:
'Café'.mb_chars.include?('é') # => true
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# File activesupport/lib/active_support/multibyte/chars.rb, line 139 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:
'Café périferôl'.mb_chars.index('ô') # => 12 'Café périferôl'.mb_chars.index(/\w/u) # => 0
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# File activesupport/lib/active_support/multibyte/chars.rb, line 149 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:
'Café'.mb_chars.insert(4, ' périferôl').to_s # => "Café périferôl"
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# File activesupport/lib/active_support/multibyte/chars.rb, line 123 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"
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# File activesupport/lib/active_support/multibyte/chars.rb, line 334 def limit(limit) slice(0...translate_offset(limit)) end
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 "
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# File activesupport/lib/active_support/multibyte/chars.rb, line 220 def ljust(integer, padstr=' ') justify(integer, :left, padstr) end
Strips entire range of Unicode whitespace from the left of the string.
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# File activesupport/lib/active_support/multibyte/chars.rb, line 181 def lstrip chars(@wrapped_string.gsub(Unicode::LEADERS_PAT, '')) end
Forward all undefined methods to the wrapped string.
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# File activesupport/lib/active_support/multibyte/chars.rb, line 53 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.
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form - The form you want to normalize in. Should be one of the following: :c, :kc, :d, or :kd. Default is ActiveSupport::Multibyte::Unicode.default_normalization_form
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# File activesupport/lib/active_support/multibyte/chars.rb, line 378 def normalize(form = nil) chars(Unicode.normalize(@wrapped_string, form)) end
Returns the codepoint of the first character in the string.
Example:
'こんにちは'.mb_chars.ord # => 12371
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# File activesupport/lib/active_support/multibyte/chars.rb, line 194 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.
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# File activesupport/lib/active_support/multibyte/chars.rb, line 65 def respond_to?(method, include_private=false) super || @wrapped_string.respond_to?(method, include_private) || false end
Reverses all characters in the string.
Example:
'Café'.mb_chars.reverse.to_s # => 'éfaC'
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# File activesupport/lib/active_support/multibyte/chars.rb, line 296 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:
'Café périferôl'.mb_chars.rindex('é') # => 6 'Café périferôl'.mb_chars.rindex(/\w/u) # => 13
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# File activesupport/lib/active_support/multibyte/chars.rb, line 162 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:
"¾ cup".mb_chars.rjust(8).to_s # => " ¾ cup" "¾ cup".mb_chars.rjust(8, " ").to_s # Use non-breaking whitespace # => " ¾ cup"
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# File activesupport/lib/active_support/multibyte/chars.rb, line 207 def rjust(integer, padstr=' ') justify(integer, :right, padstr) end
Strips entire range of Unicode whitespace from the right of the string.
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# File activesupport/lib/active_support/multibyte/chars.rb, line 176 def rstrip chars(@wrapped_string.gsub(Unicode::TRAILERS_PAT, '')) end
Returns the number of codepoints in the string
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# File activesupport/lib/active_support/multibyte/chars.rb, line 170 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:
'こんにちは'.mb_chars.slice(2..3).to_s # => "にち"
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# File activesupport/lib/active_support/multibyte/chars.rb, line 305 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:
'Café périferôl'.mb_chars.split(/é/).map { |part| part.upcase.to_s } # => ["CAF", " P", "RIFERÔL"]
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# File activesupport/lib/active_support/multibyte/chars.rb, line 248 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.
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# File activesupport/lib/active_support/multibyte/chars.rb, line 186 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.
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# File activesupport/lib/active_support/multibyte/chars.rb, line 412 def tidy_bytes(force = false) chars(Unicode.tidy_bytes(@wrapped_string, force)) end
Capitalizes the first letter of every word, when possible.
Example:
"ÉL QUE SE ENTERÓ".mb_chars.titleize # => "Él Que Se Enteró" "日本語".mb_chars.titleize # => "日本語"
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# File activesupport/lib/active_support/multibyte/chars.rb, line 367 def titleize chars(downcase.to_s.gsub(/\b('?[\S])/) { Unicode.apply_mapping $1, :uppercase_mapping }) end
Convert characters in the string to uppercase.
Example:
'Laurent, où sont les tests ?'.mb_chars.upcase.to_s # => "LAURENT, OÙ SONT LES TESTS ?"
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# File activesupport/lib/active_support/multibyte/chars.rb, line 342 def upcase chars(Unicode.apply_mapping @wrapped_string, :uppercase_mapping) end