Class | ActiveSupport::Multibyte::Chars
In: | lib/active_support/multibyte/chars.rb
Parent: | Object

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

### Methods

+ <=> =~ [] []= acts_like_string? capitalize center compose compose_codepoints consumes? decompose decompose_codepoints downcase g_length g_pack g_unpack in_char_class? include? index insert length ljust lstrip method_missing new normalize ord reorder_characters respond_to? reverse rjust rstrip size slice slice! split strip tidy_bytes tidy_bytes u_unpack upcase wants?

### Included Modules

Comparable

### Constants

HANGUL_SBASE | = | 0xAC00 |  | Hangul character boundaries and properties
HANGUL_LBASE | = | 0x1100
HANGUL_VBASE | = | 0x1161
HANGUL_TBASE | = | 0x11A7
HANGUL_LCOUNT | = | 19
HANGUL_VCOUNT | = | 21
HANGUL_TCOUNT | = | 28
HANGUL_NCOUNT | = | HANGUL_VCOUNT * HANGUL_TCOUNT
HANGUL_SCOUNT | = | 11172
HANGUL_SLAST | = | HANGUL_SBASE + HANGUL_SCOUNT
HANGUL_JAMO_FIRST | = | 0x1100
HANGUL_JAMO_LAST | = | 0x11FF
UNICODE_WHITESPACE | = | [ (0x0009..0x000D).to_a, # White_Space # Cc [5] <control-0009>..<control-000D> 0x0020, # White_Space # Zs SPACE 0x0085, # White_Space # Cc <control-0085> 0x00A0, # White_Space # Zs NO-BREAK SPACE 0x1680, # White_Space # Zs OGHAM SPACE MARK 0x180E, # White_Space # Zs MONGOLIAN VOWEL SEPARATOR (0x2000..0x200A).to_a, # White_Space # Zs [11] EN QUAD..HAIR SPACE 0x2028, # White_Space # Zl LINE SEPARATOR 0x2029, # White_Space # Zp PARAGRAPH SEPARATOR 0x202F, # White_Space # Zs NARROW NO-BREAK SPACE 0x205F, # White_Space # Zs MEDIUM MATHEMATICAL SPACE 0x3000, # White_Space # Zs IDEOGRAPHIC SPACE ].flatten.freeze |  | All the unicode whitespace
UNICODE_LEADERS_AND_TRAILERS | = | UNICODE_WHITESPACE + [65279] |  | BOM (byte order mark) can also be seen as whitespace, it‘s a non-rendering character used to distinguish between little and big endian. This is not an issue in utf-8, so it must be ignored.
UNICODE_TRAILERS_PAT | = | /(#{codepoints_to_pattern(UNICODE_LEADERS_AND_TRAILERS)})+\Z/
UNICODE_LEADERS_PAT | = | /\A(#{codepoints_to_pattern(UNICODE_LEADERS_AND_TRAILERS)})+/
UTF8_PAT | = | /\A(?: [\x00-\x7f] | [\xc2-\xdf] [\x80-\xbf] | \xe0 [\xa0-\xbf] [\x80-\xbf] | [\xe1-\xef] [\x80-\xbf] [\x80-\xbf] | \xf0 [\x90-\xbf] [\x80-\xbf] [\x80-\xbf] | [\xf1-\xf3] [\x80-\xbf] [\x80-\xbf] [\x80-\xbf] | \xf4 [\x80-\x8f] [\x80-\xbf] [\x80-\xbf] )*\z/xn |  | Borrowed from the Kconv library by Shinji KONO - (also as seen on the W3C site)

### External Aliases

wrapped_string | -> | to_s
wrapped_string | -> | to_str

### Attributes

wrapped_string | [R] |

### Public Class methods

compose_codepoints(codepoints)

Compose decomposed characters to the composed form.

consumes?(string)

Returns `true` when the proxy class can handle the string. Returns `false` otherwise.

decompose_codepoints(type, codepoints)

Decompose composed characters to the decomposed form.

g_pack(unpacked)

Reverse operation of g_unpack.

Example:

      Chars.g_pack(Chars.g_unpack('क्षि')) #=> 'क्षि'

g_unpack(string)

Unpack the string at grapheme boundaries. Returns a list of character lists.

Example:

      Chars.g_unpack('क्षि') #=> [[2325, 2381], [2359], [2367]]
      Chars.g_unpack('Café') #=> [[67], [97], [102], [233]]

in_char_class?(codepoint, classes)

Detect whether the codepoint is in a certain character class. Returns `true` when it‘s in the specified character class and `false` otherwise. Valid character classes are: `:cr`, `:lf`, `:l`, `:v`, `:lv`, `:lvt` and `:t`.

Primarily used by the grapheme cluster support.

new(string)

Creates a new Chars instance by wrapping string.

reorder_characters(codepoints)

Re-order codepoints so the string becomes canonical.

tidy_bytes(string)

Replaces all ISO-8859-1 or CP1252 characters by their UTF-8 equivalent resulting in a valid UTF-8 string.

u_unpack(string)

Unpack the string at codepoints boundaries. Raises an EncodingError when the encoding of the string isn‘t valid UTF-8.

Example:

      Chars.u_unpack('Café') #=> [67, 97, 102, 233]

wants?(string)

Returns `true` if the Chars class can and should act as a proxy for the string string. Returns `false` otherwise.

### Public Instance methods

+(other)

Returns a new Chars object containing the other object concatenated to the string.

Example:

      ('Café'.mb_chars + ' périferôl').to_s #=> "Café périferôl"

<=>(other)

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`. See `String#<=>` for more details.

Example:

      'é'.mb_chars <=> 'ü'.mb_chars #=> -1

=~(other)

Like `String#=~` only it returns the character offset (in codepoints) instead of the byte offset.

Example:

      'Café périferôl'.mb_chars =~ /ô/ #=> 12

[](*args)

Alias for slice

[]=(*args)

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"

acts_like_string?()

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

capitalize()

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

Example:

     'über'.mb_chars.capitalize.to_s #=> "Über"

center(integer, padstr=' ')

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  "

compose()

Performs composition on all the characters.

Example:

      'é'.length #=> 3
      'é'.mb_chars.compose.to_s.length #=> 2

decompose()

Performs canonical decomposition on all the characters.

Example:

      'é'.length #=> 2
      'é'.mb_chars.decompose.to_s.length #=> 3

downcase()

Convert characters in the string to lowercase.

Example:

      'VĚDA A VÝZKUM'.mb_chars.downcase.to_s #=> "věda a výzkum"

g_length()

Returns the number of grapheme clusters in the string.

Example:

      'क्षि'.mb_chars.length #=> 4
      'क्षि'.mb_chars.g_length #=> 3

include?(other)

Returns `true` if contained string contains other. Returns `false` otherwise.

Example:

      'Café'.mb_chars.include?('é') #=> true

index(needle, offset=0)

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

insert(offset, fragment)

Inserts the passed string at specified codepoint offsets.

Example:

      'Café'.mb_chars.insert(4, ' périferôl').to_s #=> "Café périferôl"

length()

Alias for size

ljust(integer, padstr=' ')

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   "

lstrip()

Strips entire range of Unicode whitespace from the left of the string.

method_missing(method, *args, &block)

Forward all undefined methods to the wrapped string.

normalize(form=ActiveSupport::Multibyte.default_normalization_form)

Returns the KC normalization of the string by default. NFKC is considered the best normalization form for passing strings to databases and validations.

- `str` - The string to perform normalization on.
- `form` - The form you want to normalize in. Should be one of the following: `:c`, `:kc`, `:d`, or `:kd`. Default is ActiveSupport::Multibyte.default_normalization_form

ord()

Returns the codepoint of the first character in the string.

Example:

      'こんにちは'.mb_chars.ord #=> 12371

respond_to?(method, include_private=false)

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`.

reverse()

Reverses all characters in the string.

Example:

      'Café'.mb_chars.reverse.to_s #=> 'éfaC'

rjust(integer, padstr=' ')

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"

rstrip()

Strips entire range of Unicode whitespace from the right of the string.

size()

Returns the number of codepoints in the string

slice(*args)

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"

slice!(*args)

Like `String#slice!`, except instead of byte offsets you specify character offsets.

Example:

      s = 'こんにちは'
      s.mb_chars.slice!(2..3).to_s #=> "にち"
      s #=> "こんは"

split(*args)

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"]

strip()

Strips entire range of Unicode whitespace from the right and left of the string.

tidy_bytes()

Replaces all ISO-8859-1 or CP1252 characters by their UTF-8 equivalent resulting in a valid UTF-8 string.

upcase()

Convert characters in the string to uppercase.

Example:

      'Laurent, òu sont les tests?'.mb_chars.upcase.to_s #=> "LAURENT, ÒU SONT LES TESTS?"

[Validate]