# File activesupport/lib/active_support/multibyte/handlers/utf8_handler.rb, line 158
      def []=(str, *args)
        replace_by = args.pop
        # Indexed replace with regular expressions already works
        return str[*args] = replace_by if args.first.is_a?(Regexp)
        result = u_unpack(str)
        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(str, needle)
          max = min + length(needle) - 1
          range = Range.new(min, max)
        end
        result[range] = u_unpack(replace_by)
        str.replace(result.pack('U*'))
      end

# File activesupport/lib/active_support/multibyte/handlers/utf8_handler.rb, line 274
      def capitalize(str)
        upcase(slice(str, 0..0)) + downcase(slice(str, 1..-1) || '')
      end

# File activesupport/lib/active_support/multibyte/handlers/utf8_handler.rb, line 217
      def center(str, integer, padstr=' ')
        justify(str, integer, :center, padstr)
      end

# File activesupport/lib/active_support/multibyte/handlers/utf8_handler.rb, line 310
      def compose(str)
        compose_codepoints u_unpack(str).pack('U*')
      end

# File activesupport/lib/active_support/multibyte/handlers/utf8_handler.rb, line 340
      def consumes?(str)
        # Unpack is a little bit faster than regular expressions
        begin
          str.unpack('U*')
          true
        rescue ArgumentError
          false
        end
      end

# File activesupport/lib/active_support/multibyte/handlers/utf8_handler.rb, line 305
      def decompose(str)
        decompose_codepoints(:canonical, u_unpack(str)).pack('U*')
      end

# File activesupport/lib/active_support/multibyte/handlers/utf8_handler.rb, line 271
      def downcase(str); to_case :lowercase_mapping, str; end

# File activesupport/lib/active_support/multibyte/handlers/utf8_handler.rb, line 352
      def g_length(str)
        g_unpack(str).length
      end

# File activesupport/lib/active_support/multibyte/handlers/utf8_handler.rb, line 139
      def index(str, *args)
        bidx = str.index(*args)
        bidx ? (u_unpack(str.slice(0...bidx)).size) : nil
      end

# File activesupport/lib/active_support/multibyte/handlers/utf8_handler.rb, line 129
      def insert(str, offset, fragment)
        str.replace(
          u_unpack(str).insert(
            offset,
            u_unpack(fragment)
          ).flatten.pack('U*')
        )
      end

# File activesupport/lib/active_support/multibyte/handlers/utf8_handler.rb, line 204
      def ljust(str, integer, padstr=' ')
        justify(str, integer, :left, padstr)
      end

# File activesupport/lib/active_support/multibyte/handlers/utf8_handler.rb, line 227
      def lstrip(str)
        str.gsub(UNICODE_LEADERS_PAT, '')
      end

# File activesupport/lib/active_support/multibyte/handlers/utf8_handler.rb, line 287
      def normalize(str, form=ActiveSupport::Multibyte::DEFAULT_NORMALIZATION_FORM)
        # See http://www.unicode.org/reports/tr15, Table 1
        codepoints = u_unpack(str)
        case form
          when :d
            reorder_characters(decompose_codepoints(:canonical, codepoints))
          when :c
            compose_codepoints reorder_characters(decompose_codepoints(:canonical, codepoints))
          when :kd
            reorder_characters(decompose_codepoints(:compatability, codepoints))
          when :kc
            compose_codepoints reorder_characters(decompose_codepoints(:compatability, codepoints))
          else
            raise ArgumentError, "#{form} is not a valid normalization variant", caller
        end.pack('U*')
      end

# File activesupport/lib/active_support/multibyte/handlers/utf8_handler.rb, line 243
      def reverse(str)
        u_unpack(str).reverse.pack('U*')
      end

# File activesupport/lib/active_support/multibyte/handlers/utf8_handler.rb, line 191
      def rjust(str, integer, padstr=' ')
        justify(str, integer, :right, padstr)
      end

# File activesupport/lib/active_support/multibyte/handlers/utf8_handler.rb, line 222
      def rstrip(str)
        str.gsub(UNICODE_TRAILERS_PAT, '')
      end

# File activesupport/lib/active_support/multibyte/handlers/utf8_handler.rb, line 237
      def size(str)
        u_unpack(str).size
      end

# File activesupport/lib/active_support/multibyte/handlers/utf8_handler.rb, line 249
      def slice(str, *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 = u_unpack(str).slice(*args)
          cps.nil? ? nil : cps.pack('U*')
        elsif args.size == 1 && args[0].kind_of?(Numeric)
          u_unpack(str)[args[0]]
        else
          u_unpack(str).slice(*args).pack('U*')
        end
      end

# File activesupport/lib/active_support/multibyte/handlers/utf8_handler.rb, line 232
      def strip(str)
        str.gsub(UNICODE_LEADERS_PAT, '').gsub(UNICODE_TRAILERS_PAT, '')
      end

# File activesupport/lib/active_support/multibyte/handlers/utf8_handler.rb, line 357
      def tidy_bytes(str)
        str.split(//u).map do |c|
          if !UTF8_PAT.match(c)
            n = c.unpack('C')[0]
            n < 128 ? n.chr :
            n < 160 ? [UCD.cp1252[n] || n].pack('U') :
            n < 192 ? "\xC2" + n.chr : "\xC3" + (n-64).chr
          else
            c
          end
        end.join
      end

# File activesupport/lib/active_support/multibyte/handlers/utf8_handler.rb, line 319
      def translate_offset(str, byte_offset)
        return nil if byte_offset.nil?
        return 0 if str == ''
        chunk = str[0..byte_offset]
        begin
          begin
            chunk.unpack('U*').length - 1
          rescue ArgumentError => e
            chunk = str[0..(byte_offset+=1)]
            # Stop retrying at the end of the string
            raise e unless byte_offset < chunk.length 
            # We damaged a character, retry
            retry
          end
        # Catch the ArgumentError so we can throw our own
        rescue ArgumentError 
          raise EncodingError.new('malformed UTF-8 character')
        end
      end

# File activesupport/lib/active_support/multibyte/handlers/utf8_handler.rb, line 268
      def upcase(str); to_case :uppercase_mapping, str; end

# File activesupport/lib/active_support/multibyte/handlers/utf8_handler.rb, line 501
      def compose_codepoints(codepoints)
        pos = 0
        eoa = codepoints.length - 1
        starter_pos = 0
        starter_char = codepoints[0]
        previous_combining_class = -1
        while pos < eoa
          pos += 1
          lindex = starter_char - HANGUL_LBASE
          # -- Hangul
          if 0 <= lindex and lindex < HANGUL_LCOUNT
            vindex = codepoints[starter_pos+1] - HANGUL_VBASE rescue vindex = -1
            if 0 <= vindex and vindex < HANGUL_VCOUNT
              tindex = codepoints[starter_pos+2] - HANGUL_TBASE rescue tindex = -1
              if 0 <= tindex and tindex < HANGUL_TCOUNT
                j = starter_pos + 2
                eoa -= 2
              else
                tindex = 0
                j = starter_pos + 1
                eoa -= 1
              end
              codepoints[starter_pos..j] = (lindex * HANGUL_VCOUNT + vindex) * HANGUL_TCOUNT + tindex + HANGUL_SBASE
            end
            starter_pos += 1
            starter_char = codepoints[starter_pos]
          # -- Other characters
          else
            current_char = codepoints[pos]
            current = UCD[current_char]
            if current.combining_class > previous_combining_class
              if ref = UCD.composition_map[starter_char]
                composition = ref[current_char]
              else
                composition = nil
              end
              unless composition.nil?
                codepoints[starter_pos] = composition
                starter_char = composition
                codepoints.delete_at pos
                eoa -= 1
                pos -= 1
                previous_combining_class = -1
              else
                previous_combining_class = current.combining_class
              end
            else
              previous_combining_class = current.combining_class
            end
            if current.combining_class == 0
              starter_pos = pos
              starter_char = codepoints[pos]
            end
          end
        end
        codepoints
      end

# File activesupport/lib/active_support/multibyte/handlers/utf8_handler.rb, line 480
      def decompose_codepoints(type, codepoints)
        codepoints.inject([]) do |decomposed, cp|
          # if it's a hangul syllable starter character
          if HANGUL_SBASE <= cp and cp < HANGUL_SLAST
            sindex = cp - HANGUL_SBASE
            ncp = [] # new codepoints
            ncp << HANGUL_LBASE + sindex / HANGUL_NCOUNT
            ncp << HANGUL_VBASE + (sindex % HANGUL_NCOUNT) / HANGUL_TCOUNT
            tindex = sindex % HANGUL_TCOUNT
            ncp << (HANGUL_TBASE + tindex) unless tindex == 0
            decomposed.concat ncp
          # if the codepoint is decomposable in with the current decomposition type
          elsif (ncp = UCD[cp].decomp_mapping) and (!UCD[cp].decomp_type || type == :compatability)
            decomposed.concat decompose_codepoints(type, ncp.dup)
          else
            decomposed << cp
          end
        end
      end

# File activesupport/lib/active_support/multibyte/handlers/utf8_handler.rb, line 419
      def g_pack(unpacked)
        unpacked.flatten
      end

# File activesupport/lib/active_support/multibyte/handlers/utf8_handler.rb, line 388
      def g_unpack(str)
        codepoints = u_unpack(str)
        unpacked = []
        pos = 0
        marker = 0
        eoc = codepoints.length
        while(pos < eoc)
          pos += 1
          previous = codepoints[pos-1]
          current = codepoints[pos]
          if (
              # CR X LF
              one = ( previous == UCD.boundary[:cr] and current == UCD.boundary[:lf] ) or
              # L X (L|V|LV|LVT)
              two = ( UCD.boundary[:l] === previous and in_char_class?(current, [:l,:v,:lv,:lvt]) ) or
              # (LV|V) X (V|T)
              three = ( in_char_class?(previous, [:lv,:v]) and in_char_class?(current, [:v,:t]) ) or
              # (LVT|T) X (T)
              four = ( in_char_class?(previous, [:lvt,:t]) and UCD.boundary[:t] === current ) or
              # X Extend
              five = (UCD.boundary[:extend] === current)
            )
          else
            unpacked << codepoints[marker..pos-1]
            marker = pos
          end
        end 
        unpacked
      end

# File activesupport/lib/active_support/multibyte/handlers/utf8_handler.rb, line 374
      def in_char_class?(codepoint, classes)
        classes.detect { |c| UCD.boundary[c] === codepoint } ? true : false
      end

# File activesupport/lib/active_support/multibyte/handlers/utf8_handler.rb, line 425
      def justify(str, integer, way, padstr=' ')
        raise ArgumentError, "zero width padding" if padstr.length == 0
        padsize = integer - size(str)
        padsize = padsize > 0 ? padsize : 0
        case way
        when :right
          str.dup.insert(0, padding(padsize, padstr))
        when :left
          str.dup.insert(-1, padding(padsize, padstr))
        when :center
          lpad = padding((padsize / 2.0).floor, padstr)
          rpad = padding((padsize / 2.0).ceil, padstr)
          str.dup.insert(0, lpad).insert(-1, rpad)
        end
      end

# File activesupport/lib/active_support/multibyte/handlers/utf8_handler.rb, line 442
      def padding(padsize, padstr=' ')
        if padsize != 0
          slice(padstr * ((padsize / size(padstr)) + 1), 0, padsize)
        else
          ''
        end
      end

# File activesupport/lib/active_support/multibyte/handlers/utf8_handler.rb, line 464
      def reorder_characters(codepoints)
        length = codepoints.length- 1
        pos = 0
        while pos < length do
          cp1, cp2 = UCD[codepoints[pos]], UCD[codepoints[pos+1]]
          if (cp1.combining_class > cp2.combining_class) && (cp2.combining_class > 0)
            codepoints[pos..pos+1] = cp2.code, cp1.code
            pos += (pos > 0 ? -1 : 1)
          else
            pos += 1
          end
        end
        codepoints
      end

# File activesupport/lib/active_support/multibyte/handlers/utf8_handler.rb, line 451
      def to_case(way, str)
        u_unpack(str).map do |codepoint|
          cp = UCD[codepoint] 
          unless cp.nil?
            ncp = cp.send(way)
            ncp > 0 ? ncp : codepoint
          else
            codepoint
          end
        end.pack('U*')
      end

# File activesupport/lib/active_support/multibyte/handlers/utf8_handler.rb, line 379
      def u_unpack(str)
        begin
          str.unpack 'U*'
        rescue ArgumentError
          raise EncodingError.new('malformed UTF-8 character')
        end
      end