aboutsummaryrefslogtreecommitdiffstats
path: root/activesupport/lib/active_support/multibyte/chars.rb
blob: 019fb2df06aa548db11c64b3960d466581a0d39d (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
# encoding: utf-8
require 'active_support/core_ext/string/access'
require 'active_support/core_ext/string/behavior'

module ActiveSupport #:nodoc:
  module Multibyte #:nodoc:
    # 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
    class Chars
      attr_reader :wrapped_string
      alias to_s wrapped_string
      alias to_str wrapped_string

      if RUBY_VERSION >= "1.9"
        # Creates a new Chars instance by wrapping _string_.
        def initialize(string)
          @wrapped_string = string
          @wrapped_string.force_encoding(Encoding::UTF_8) unless @wrapped_string.frozen?
        end
      else
        def initialize(string) #:nodoc:
          @wrapped_string = string
        end
      end

      # Forward all undefined methods to the wrapped string.
      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 +true+ if _obj_ responds to the given method. Private methods are included in the search
      # only if the optional second parameter evaluates to +true+.
      def respond_to?(method, include_private=false)
        super || @wrapped_string.respond_to?(method, include_private) || false
      end

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

      # Returns +true+ when the proxy class can handle the string. Returns +false+ otherwise.
      def self.consumes?(string)
        # Unpack is a little bit faster than regular expressions.
        string.unpack('U*')
        true
      rescue ArgumentError
        false
      end

      include Comparable

      # 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 <tt>String#<=></tt> for more details.
      def <=>(other)
        @wrapped_string <=> other.to_s
      end

      if RUBY_VERSION < "1.9"
        # Returns +true+ if the Chars class can and should act as a proxy for the string _string_. Returns
        # +false+ otherwise.
        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"
        def +(other)
          chars(@wrapped_string + other)
        end

        # Like <tt>String#=~</tt> only it returns the character offset (in codepoints) instead of the byte offset.
        #
        # Example:
        #   'Café périferôl'.mb_chars =~ /ô/ # => 12
        def =~(other)
          translate_offset(@wrapped_string =~ other)
        end

        # Inserts the passed string at specified codepoint offsets.
        #
        # Example:
        #   'Café'.mb_chars.insert(4, ' périferôl').to_s # => "Café périferôl"
        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

        # Returns +true+ if contained string contains _other_. Returns +false+ otherwise.
        #
        # Example:
        #   'Café'.mb_chars.include?('é') # => true
        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
        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

        # 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
        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

        # Returns the number of codepoints in the string
        def size
          Unicode.u_unpack(@wrapped_string).size
        end
        alias_method :length, :size

        # Strips entire range of Unicode whitespace from the right of the string.
        def rstrip
          chars(@wrapped_string.gsub(Unicode::TRAILERS_PAT, ''))
        end

        # Strips entire range of Unicode whitespace from the left of the string.
        def lstrip
          chars(@wrapped_string.gsub(Unicode::LEADERS_PAT, ''))
        end

        # Strips entire range of Unicode whitespace from the right and left of the string.
        def strip
          rstrip.lstrip
        end

        # Returns the codepoint of the first character in the string.
        #
        # Example:
        #   'こんにちは'.mb_chars.ord # => 12371
        def ord
          Unicode.u_unpack(@wrapped_string)[0]
        end

        # Works just like <tt>String#rjust</tt>, 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"
        def rjust(integer, padstr=' ')
          justify(integer, :right, padstr)
        end

        # Works just like <tt>String#ljust</tt>, 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   "
        def ljust(integer, padstr=' ')
          justify(integer, :left, padstr)
        end

        # Works just like <tt>String#center</tt>, 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  "
        def center(integer, padstr=' ')
          justify(integer, :center, padstr)
        end

      else
        def =~(other)
          @wrapped_string =~ other
        end
      end

      # Works just like <tt>String#split</tt>, 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"]
      def split(*args)
        @wrapped_string.split(*args).map { |i| i.mb_chars }
      end

      # Like <tt>String#[]=</tt>, 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"
      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

      # Reverses all characters in the string.
      #
      # Example:
      #   'Café'.mb_chars.reverse.to_s # => 'éfaC'
      def reverse
        chars(Unicode.g_unpack(@wrapped_string).reverse.flatten.pack('U*'))
      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"
      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
      alias_method :[], :slice

      # 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"
      def limit(limit)
        slice(0...translate_offset(limit))
      end

      # Convert characters in the string to uppercase.
      #
      # Example:
      #   'Laurent, où sont les tests ?'.mb_chars.upcase.to_s # => "LAURENT, OÙ SONT LES TESTS ?"
      def upcase
        chars(Unicode.apply_mapping @wrapped_string, :uppercase_mapping)
      end

      # Convert characters in the string to lowercase.
      #
      # Example:
      #   'VĚDA A VÝZKUM'.mb_chars.downcase.to_s # => "věda a výzkum"
      def downcase
        chars(Unicode.apply_mapping @wrapped_string, :lowercase_mapping)
      end

      # Converts the first character to uppercase and the remainder to lowercase.
      #
      # Example:
      #  'über'.mb_chars.capitalize.to_s # => "Über"
      def capitalize
        (slice(0) || chars('')).upcase + (slice(1..-1) || chars('')).downcase
      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"
      def titleize
        chars(downcase.to_s.gsub(/\b('?[\S])/u) { Unicode.apply_mapping $1, :uppercase_mapping })
      end
      alias_method :titlecase, :titleize

      # Returns the KC normalization of the string by default. NFKC is considered the best normalization form for
      # passing strings to databases and validations.
      #
      # * <tt>form</tt> - The form you want to normalize in. Should be one of the following:
      #   <tt>:c</tt>, <tt>:kc</tt>, <tt>:d</tt>, or <tt>:kd</tt>. Default is
      #   ActiveSupport::Multibyte::Unicode.default_normalization_form
      def normalize(form = nil)
        chars(Unicode.normalize(@wrapped_string, form))
      end

      # Performs canonical decomposition on all the characters.
      #
      # Example:
      #   'é'.length                         # => 2
      #   'é'.mb_chars.decompose.to_s.length # => 3
      def decompose
        chars(Unicode.decompose_codepoints(:canonical, Unicode.u_unpack(@wrapped_string)).pack('U*'))
      end

      # Performs composition on all the characters.
      #
      # Example:
      #   'é'.length                       # => 3
      #   'é'.mb_chars.compose.to_s.length # => 2
      def compose
        chars(Unicode.compose_codepoints(Unicode.u_unpack(@wrapped_string)).pack('U*'))
      end

      # Returns the number of grapheme clusters in the string.
      #
      # Example:
      #   'क्षि'.mb_chars.length   # => 4
      #   'क्षि'.mb_chars.g_length # => 3
      def g_length
        Unicode.g_unpack(@wrapped_string).length
      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.
      def tidy_bytes(force = false)
        chars(Unicode.tidy_bytes(@wrapped_string, force))
      end

       %w(capitalize downcase lstrip reverse rstrip slice strip tidy_bytes upcase).each do |method|
        # Only define a corresponding bang method for methods defined in the proxy; On 1.9 the proxy will
        # exclude lstrip!, rstrip! and strip! because they are already work as expected on multibyte strings.
        if public_method_defined?(method)
          define_method("#{method}!") do |*args|
            @wrapped_string = send(args.nil? ? method : method, *args).to_s
            self
          end
        end
      end

      protected

        def translate_offset(byte_offset) #:nodoc:
          return nil if byte_offset.nil?
          return 0   if @wrapped_string == ''

          if @wrapped_string.respond_to?(:force_encoding)
            @wrapped_string = @wrapped_string.dup.force_encoding(Encoding::ASCII_8BIT)
          end

          begin
            @wrapped_string[0...byte_offset].unpack('U*').length
          rescue ArgumentError => e
            byte_offset -= 1
            retry
          end
        end

        def justify(integer, way, padstr=' ') #:nodoc:
          raise ArgumentError, "zero width padding" if padstr.length == 0
          padsize = integer - size
          padsize = padsize > 0 ? padsize : 0
          case way
          when :right
            result = @wrapped_string.dup.insert(0, padding(padsize, padstr))
          when :left
            result = @wrapped_string.dup.insert(-1, padding(padsize, padstr))
          when :center
            lpad = padding((padsize / 2.0).floor, padstr)
            rpad = padding((padsize / 2.0).ceil, padstr)
            result = @wrapped_string.dup.insert(0, lpad).insert(-1, rpad)
          end
          chars(result)
        end

        def padding(padsize, padstr=' ') #:nodoc:
          if padsize != 0
            chars(padstr * ((padsize / Unicode.u_unpack(padstr).size) + 1)).slice(0, padsize)
          else
            ''
          end
        end

        def chars(string) #:nodoc:
          self.class.new(string)
        end
    end
  end
end