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
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- Comparable START:includes
| [R] | wrapped_string |
Returns true when the proxy class can handle the string. Returns false otherwise.
Creates a new Chars instance by wrapping string.
Returns true if the Chars class can and should act as a proxy for the string string. Returns false otherwise.
Returns a new Chars object containing the other object concatenated to the string.
Example:
('Café'.mb_chars + ' périferôl').to_s # => "Café périferôl"
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.
Like String#=~ only it returns the character offset (in codepoints) instead of the byte offset.
Example:
'Café périferôl'.mb_chars =~ /ô/ # => 12
Alias for slice
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 activesupport/lib/active_support/multibyte/chars.rb, line 266 266: def []=(*args) 267: replace_by = args.pop 268: # Indexed replace with regular expressions already works 269: if args.first.is_a?(Regexp) 270: @wrapped_string[*args] = replace_by 271: else 272: result = Unicode.u_unpack(@wrapped_string) 273: case args.first 274: when Fixnum 275: raise IndexError, "index #{args[0]} out of string" if args[0] >= result.length 276: min = args[0] 277: max = args[1].nil? ? min : (min + args[1] - 1) 278: range = Range.new(min, max) 279: replace_by = [replace_by].pack('U') if replace_by.is_a?(Fixnum) 280: when Range 281: raise RangeError, "#{args[0]} out of range" if args[0].min >= result.length 282: range = args[0] 283: else 284: needle = args[0].to_s 285: min = index(needle) 286: max = min + Unicode.u_unpack(needle).length - 1 287: range = Range.new(min, max) 288: end 289: result[range] = Unicode.u_unpack(replace_by) 290: @wrapped_string.replace(result.pack('U*')) 291: end 292: end
Enable more predictable duck-typing on String-like classes. See Object#acts_like?.
Converts the first character to uppercase and the remainder to lowercase.
Example:
'über'.mb_chars.capitalize.to_s # => "Über"
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 "
Performs composition on all the characters.
Example:
'é'.length # => 3 'é'.mb_chars.compose.to_s.length # => 2
Performs canonical decomposition on all the characters.
Example:
'é'.length # => 2 'é'.mb_chars.decompose.to_s.length # => 3
Convert characters in the string to lowercase.
Example:
'VĚDA A VÝZKUM'.mb_chars.downcase.to_s # => "věda a výzkum"
Returns the number of grapheme clusters in the string.
Example:
'क्षि'.mb_chars.length # => 4 'क्षि'.mb_chars.g_length # => 3
Returns true if contained string contains other. Returns false otherwise.
Example:
'Café'.mb_chars.include?('é') # => true
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 activesupport/lib/active_support/multibyte/chars.rb, line 150 150: def index(needle, offset=0) 151: wrapped_offset = first(offset).wrapped_string.length 152: index = @wrapped_string.index(needle, wrapped_offset) 153: index ? (Unicode.u_unpack(@wrapped_string.slice(0...index)).size) : nil 154: end
Inserts the passed string at specified codepoint offsets.
Example:
'Café'.mb_chars.insert(4, ' périferôl').to_s # => "Café périferôl"
# File activesupport/lib/active_support/multibyte/chars.rb, line 124 124: def insert(offset, fragment) 125: unpacked = Unicode.u_unpack(@wrapped_string) 126: unless offset > unpacked.length 127: @wrapped_string.replace( 128: Unicode.u_unpack(@wrapped_string).insert(offset, *Unicode.u_unpack(fragment)).pack('U*') 129: ) 130: else 131: raise IndexError, "index #{offset} out of string" 132: end 133: self 134: 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:
'こんにちは'.mb_chars.limit(7).to_s # => "こん"
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 "
Strips entire range of Unicode whitespace from the left of the string.
Forward all undefined methods to the wrapped string.
# File activesupport/lib/active_support/multibyte/chars.rb, line 54 54: def method_missing(method, *args, &block) 55: if method.to_s =~ /!$/ 56: @wrapped_string.__send__(method, *args, &block) 57: self 58: else 59: result = @wrapped_string.__send__(method, *args, &block) 60: result.kind_of?(String) ? chars(result) : result 61: end 62: 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 is ActiveSupport::Multibyte::Unicode.default_normalization_form
Returns the codepoint of the first character in the string.
Example:
'こんにちは'.mb_chars.ord # => 12371
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.
Reverses all characters in the string.
Example:
'Café'.mb_chars.reverse.to_s # => 'éfaC'
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 activesupport/lib/active_support/multibyte/chars.rb, line 163 163: def rindex(needle, offset=nil) 164: offset ||= length 165: wrapped_offset = first(offset).wrapped_string.length 166: index = @wrapped_string.rindex(needle, wrapped_offset) 167: index ? (Unicode.u_unpack(@wrapped_string.slice(0...index)).size) : nil 168: 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"
Strips entire range of Unicode whitespace from the right of the string.
Returns the number of codepoints in the string
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 activesupport/lib/active_support/multibyte/chars.rb, line 307 307: def slice(*args) 308: if args.size > 2 309: raise ArgumentError, "wrong number of arguments (#{args.size} for 1)" # Do as if we were native 310: elsif (args.size == 2 && !(args.first.is_a?(Numeric) || args.first.is_a?(Regexp))) 311: raise TypeError, "cannot convert #{args.first.class} into Integer" # Do as if we were native 312: elsif (args.size == 2 && !args[1].is_a?(Numeric)) 313: raise TypeError, "cannot convert #{args[1].class} into Integer" # Do as if we were native 314: elsif args[0].kind_of? Range 315: cps = Unicode.u_unpack(@wrapped_string).slice(*args) 316: result = cps.nil? ? nil : cps.pack('U*') 317: elsif args[0].kind_of? Regexp 318: result = @wrapped_string.slice(*args) 319: elsif args.size == 1 && args[0].kind_of?(Numeric) 320: character = Unicode.u_unpack(@wrapped_string)[args[0]] 321: result = character && [character].pack('U') 322: else 323: cps = Unicode.u_unpack(@wrapped_string).slice(*args) 324: result = cps && cps.pack('U*') 325: end 326: result && chars(result) 327: end
Strips entire range of Unicode whitespace from the right and left of the string.
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.
Alias for titleize
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"
Convert characters in the string to uppercase.
Example:
'Laurent, où sont les tests ?'.mb_chars.upcase.to_s # => "LAURENT, OÙ SONT LES TESTS ?"