Add ActiveSupport::Multibyte. Provides String#chars which lets you deal with strings as a sequence of chars, not of bytes. Closes #6242 [Julian Tarkhanov, Manfred Stienstra & Jan Behrens]

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@5223 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

15 files changed, 1390 insertions, 0 deletions

diff --git a/activesupport/CHANGELOG b/activesupport/CHANGELOG
index 6818f32f55..cf68da71c4 100644
--- a/activesupport/CHANGELOG
+++ b/activesupport/CHANGELOG
@@ -1,5 +1,7 @@
 *SVN*
 
+* Add ActiveSupport::Multibyte.  Provides String#chars which lets you deal with strings as a sequence of chars, not of bytes. Closes #6242 [Julian Tarkhanov, Manfred Stienstra & Jan Behrens]
+
 * Fix issue with #class_inheritable_accessor saving updates to the parent class when initialized with an Array or Hash [mojombo]
 
 * Hash#to_xml supports Bignum and BigDecimal.  #6313 [edibiase]
diff --git a/activesupport/lib/active_support.rb b/activesupport/lib/active_support.rb
index 4289e57865..5504fa8f01 100644
--- a/activesupport/lib/active_support.rb
+++ b/activesupport/lib/active_support.rb
@@ -40,3 +40,5 @@ require 'active_support/option_merger'
 require 'active_support/values/time_zone'
 
 require 'active_support/json'
+
+require 'active_support/multibyte'
diff --git a/activesupport/lib/active_support/core_ext/string.rb b/activesupport/lib/active_support/core_ext/string.rb
index 240e1ff1da..b9f075522f 100644
--- a/activesupport/lib/active_support/core_ext/string.rb
+++ b/activesupport/lib/active_support/core_ext/string.rb
@@ -3,6 +3,7 @@ require File.dirname(__FILE__) + '/string/conversions'
 require File.dirname(__FILE__) + '/string/access'
 require File.dirname(__FILE__) + '/string/starts_ends_with'
 require File.dirname(__FILE__) + '/string/iterators'
+require File.dirname(__FILE__) + '/string/unicode'
 
 class String #:nodoc:
   include ActiveSupport::CoreExtensions::String::Access
@@ -10,4 +11,5 @@ class String #:nodoc:
   include ActiveSupport::CoreExtensions::String::Inflections
   include ActiveSupport::CoreExtensions::String::StartsEndsWith
   include ActiveSupport::CoreExtensions::String::Iterators
+  include ActiveSupport::CoreExtensions::String::Unicode
 end
diff --git a/activesupport/lib/active_support/core_ext/string/unicode.rb b/activesupport/lib/active_support/core_ext/string/unicode.rb
new file mode 100644
index 0000000000..0e4c76fb86
--- /dev/null
+++ b/activesupport/lib/active_support/core_ext/string/unicode.rb
@@ -0,0 +1,42 @@
+module ActiveSupport #:nodoc:
+  module CoreExtensions #:nodoc:
+    module String #:nodoc:
+      # Define methods for handeling unicode data.
+      module Unicode
+        # +chars+ is a Unicode safe proxy for string methods. It creates and returns an instance of the
+        # ActiveSupport::Multibyte::Chars class which encapsulates the original string. A Unicode safe version of all
+        # the String methods are defined on this proxy class. Undefined methods are forwarded to String, so all of the
+        # string overrides can also be called through the +chars+ proxy.
+        #
+        #   name = 'Claus Müller'
+        #   name.reverse #=> "rell??M sualC"
+        #   name.length #=> 13
+        #
+        #   name.chars.reverse.to_s #=> "rellüM sualC"
+        #   name.chars.length #=> 12
+        #   
+        #
+        # All the methods on the chars proxy which normally return a string will return a Chars object. This allows
+        # method chaining on the result of any of these methods.
+        #
+        #   name.chars.reverse.length #=> 12
+        #
+        # The Char object tries to be as interchangeable with String objects as possible: sorting and comparing between
+        # String and Char work like expected. The bang! methods change the internal string representation in the Chars
+        # object. Interoperability problems can be resolved easily with a +to_s+ call.
+        #
+        # For more information about the methods defined on the Chars proxy see ActiveSupport::Multibyte::Chars and
+        # ActiveSupport::Multibyte::Handlers::UTF8Handler
+        def chars
+          ActiveSupport::Multibyte::Chars.new(self)
+        end
+
+        # Returns true if the string has UTF-8 semantics (a String used for purely byte resources is unlikely to have
+        # them), returns false otherwise.
+        def is_utf8?
+          ActiveSupport::Multibyte::Handlers::UTF8Handler.consumes?(self)
+        end
+      end
+    end
+  end
+end
\ No newline at end of file
diff --git a/activesupport/lib/active_support/multibyte.rb b/activesupport/lib/active_support/multibyte.rb
new file mode 100644
index 0000000000..5e518b65f0
--- /dev/null
+++ b/activesupport/lib/active_support/multibyte.rb
@@ -0,0 +1,7 @@
+module ActiveSupport::Multibyte
+  DEFAULT_NORMALIZATION_FORM = :kc
+  NORMALIZATIONS_FORMS = [:c, :kc, :d, :kd]
+  UNICODE_VERSION = '5.0.0'
+end
+
+require 'active_support/multibyte/chars'
\ No newline at end of file
diff --git a/activesupport/lib/active_support/multibyte/chars.rb b/activesupport/lib/active_support/multibyte/chars.rb
new file mode 100644
index 0000000000..a9795de523
--- /dev/null
+++ b/activesupport/lib/active_support/multibyte/chars.rb
@@ -0,0 +1,129 @@
+require 'active_support/multibyte/handlers/utf8_handler'
+require 'active_support/multibyte/handlers/passthru_handler'
+
+# Encapsulates all the functionality related to the Chars proxy.
+module ActiveSupport::Multibyte
+  # Chars enables you to work transparently with multibyte encodings 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 +chars+ method. Methods
+  # which would normally return a String object now return a Chars object so methods can be chained.
+  #
+  #   "The Perfect String  ".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".chars.downcase.to_s
+  #
+  # The actual operations on the string are delegated to handlers. Theoretically handlers can be implemented for
+  # any encoding, but the default handler handles UTF-8. This handler is set during initialization, if you want to
+  # use you own handler, you can set it on the Chars class. Look at the UTF8Handler source for an example how to
+  # implement your own handler. If you your own handler to work on anything but UTF-8 you probably also
+  # want to override Chars#handler.
+  #
+  #   ActiveSupport::Multibyte::Chars.handler = MyHandler
+  #
+  # Note that a few methods are defined on Chars instead of the handler because they are defined on Object or Kernel
+  # and method_missing can't catch them.
+  class Chars
+    
+    attr_reader :string # The contained string
+    alias_method :to_s, :string
+    
+    include Comparable
+    
+    # The magic method to make String and Chars comparable
+    def to_str
+      # Using any other ways of overriding the String itself will lead you all the way from infinite loops to
+      # core dumps. Don't go there.
+      @string
+    end
+    
+    # Create a new Chars instance.
+    def initialize(str)
+      @string = (str.string rescue str)
+    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+. See String.<=>
+    # for more details.
+    def <=>(other); @string <=> other.to_s; 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.
+    def split(*args)
+      @string.split(*args).map { |i| i.chars }
+    end
+    
+    # Gsub works exactly the same as gsub on a normal string.
+    def gsub(*a, &b); @string.gsub(*a, &b).chars; end
+    
+    # Like String.=~ only it returns the character offset (in codepoints) instead of the byte offset.
+    def =~(other)
+      handler.translate_offset(@string, @string =~ other)
+    end
+    
+    # Try to forward all undefined methods to the handler, when a method is not defined on the handler, send it to
+    # the contained string. Method_missing is also responsible for making the bang! methods destructive.
+    def method_missing(m, *a, &b)
+      begin
+        # Simulate methods with a ! at the end because we can't touch the enclosed string from the handlers.
+        if m.to_s =~ /^(.*)\!$/
+          result = handler.send($1, @string, *a, &b)
+          if result == @string
+            result = nil
+          else
+            @string.replace result
+          end
+        else
+          result = handler.send(m, @string, *a, &b)
+        end
+      rescue NoMethodError
+        result = @string.send(m, *a, &b)
+      rescue Handlers::EncodingError
+        @string.replace handler.tidy_bytes(@string)
+        retry
+      end
+      
+      if result.kind_of?(String)
+        result.chars
+      else
+        result
+      end
+    end
+    
+    # Set the handler class for the Char objects.
+    def self.handler=(klass)
+      @@handler = klass
+    end
+
+    # Returns the proper handler for the contained string depending on $KCODE and the encoding of the string. This
+    # method is used internally to always redirect messages to the proper classes depending on the context.
+    def handler
+      if utf8_pragma?
+        @@handler
+      else
+        ActiveSupport::Multibyte::Handlers::PassthruHandler
+      end
+    end
+
+    private
+      
+      # +utf8_pragma+ checks if it can send this string to the handlers. It makes sure @string isn't nil and $KCODE is
+      # set to 'UTF8'.
+      def utf8_pragma?
+        !@string.nil? && ($KCODE == 'UTF8')
+      end
+  end
+end
+
+# When we can load the utf8proc library, override normalization with the faster methods
+begin
+  require 'utf8proc_native'
+  require 'active_support/multibyte/handlers/utf8_handler_proc'
+  ActiveSupport::Multibyte::Chars.handler = ActiveSupport::Multibyte::Handlers::UTF8HandlerProc
+rescue LoadError
+  ActiveSupport::Multibyte::Chars.handler = ActiveSupport::Multibyte::Handlers::UTF8Handler
+end
\ No newline at end of file
diff --git a/activesupport/lib/active_support/multibyte/generators/generate_tables.rb b/activesupport/lib/active_support/multibyte/generators/generate_tables.rb
new file mode 100644
index 0000000000..4045b94282
--- /dev/null
+++ b/activesupport/lib/active_support/multibyte/generators/generate_tables.rb
@@ -0,0 +1,141 @@
+#!/usr/bin/env ruby
+begin
+  require File.dirname(__FILE__) + '/../../../active_support'
+rescue IOError
+end
+require 'open-uri'
+require 'tmpdir'
+
+module ActiveSupport::Multibyte::Handlers #:nodoc:
+  class UnicodeDatabase #:nodoc:
+    def self.load
+      [Hash.new(Codepoint.new),[],{},{}]
+    end
+  end
+  
+  class UnicodeTableGenerator #:nodoc:
+    BASE_URI = "http://www.unicode.org/Public/#{ActiveSupport::Multibyte::UNICODE_VERSION}/ucd/"
+    SOURCES = {
+      :codepoints => BASE_URI + 'UnicodeData.txt',
+      :composition_exclusion => BASE_URI + 'CompositionExclusions.txt',
+      :grapheme_break_property => BASE_URI + 'auxiliary/GraphemeBreakProperty.txt'
+    }
+    
+    def initialize
+      @ucd = UnicodeDatabase.new
+      
+      default = Codepoint.new
+      default.combining_class = 0
+      default.uppercase_mapping = 0
+      default.lowercase_mapping = 0
+      @ucd.codepoints = Hash.new(default)
+      
+      @ucd.composition_exclusion = []
+      @ucd.composition_map = {}
+      @ucd.boundary = {}
+    end
+    
+    def parse_codepoints(line)
+      codepoint = Codepoint.new
+      raise "Could not parse input." unless line =~ /^
+        ([0-9A-F]+);        # code
+        ([^;]+);            # name
+        ([A-Z]+);           # general category
+        ([0-9]+);           # canonical combining class
+        ([A-Z]+);           # bidi class
+        (<([A-Z]*)>)?       # decomposition type
+        ((\ ?[0-9A-F]+)*);  # decompomposition mapping
+        ([0-9]*);           # decimal digit
+        ([0-9]*);           # digit
+        ([^;]*);            # numeric
+        ([YN]*);            # bidi mirrored
+        ([^;]*);            # unicode 1.0 name
+        ([^;]*);            # iso comment
+        ([0-9A-F]*);        # simple uppercase mapping
+        ([0-9A-F]*);        # simple lowercase mapping
+        ([0-9A-F]*)$/ix     # simple titlecase mapping
+      codepoint.code              = $1.hex
+      #codepoint.name              = $2
+      #codepoint.category          = $3
+      codepoint.combining_class   = Integer($4)
+      #codepoint.bidi_class        = $5
+      codepoint.decomp_type       = $7
+      codepoint.decomp_mapping    = ($8=='') ? nil : $8.split.collect { |element| element.hex }
+      #codepoint.bidi_mirrored     = ($13=='Y') ? true : false
+      codepoint.uppercase_mapping = ($16=='') ? 0 : $16.hex
+      codepoint.lowercase_mapping = ($17=='') ? 0 : $17.hex
+      #codepoint.titlecase_mapping = ($18=='') ? nil : $18.hex
+      @ucd.codepoints[codepoint.code] = codepoint
+    end
+
+    def parse_grapheme_break_property(line)
+      if line =~ /^([0-9A-F\.]+)\s*;\s*([\w]+)\s*#/
+        type = $2.downcase.intern
+        @ucd.boundary[type] ||= []
+        if $1.include? '..'
+          parts = $1.split '..'
+          @ucd.boundary[type] << (parts[0].hex..parts[1].hex)
+        else
+          @ucd.boundary[type] << $1.hex
+        end
+      end
+    end
+    
+    def parse_composition_exclusion(line)
+      if line =~ /^([0-9A-F]+)/i
+        @ucd.composition_exclusion << $1.hex
+      end
+    end
+    
+    def create_composition_map
+      @ucd.codepoints.each do |_, cp|
+        if !cp.nil? and cp.combining_class == 0 and cp.decomp_type.nil? and !cp.decomp_mapping.nil? and cp.decomp_mapping.length == 2 and @ucd[cp.decomp_mapping[0]].combining_class == 0 and !@ucd.composition_exclusion.include?(cp.code)
+          @ucd.composition_map[cp.decomp_mapping[0]] ||= {}
+          @ucd.composition_map[cp.decomp_mapping[0]][cp.decomp_mapping[1]] = cp.code
+        end
+      end
+    end
+
+    def normalize_boundary_map
+      @ucd.boundary.each do |k,v|
+        if [:lf, :cr].include? k
+          @ucd.boundary[k] = v[0]
+        end
+      end
+    end
+  
+    def parse
+      SOURCES.each do |type, url|
+        filename =  File.join(Dir.tmpdir, "#{url.split('/').last}")
+        unless File.exist?(filename)
+          $stderr.puts "Downloading #{url.split('/').last}"
+          File.open(filename, 'wb') do |target|
+            open(url) do |source|
+              source.each_line { |line| target.write line }
+            end
+          end
+        end
+        File.open(filename) do |file|
+          file.each_line { |line| send "parse_#{type}".intern, line }
+        end        
+      end
+      create_composition_map
+      normalize_boundary_map
+    end
+    
+    def dump_to(filename)
+      File.open(filename, 'wb') do |f|
+        f.write Marshal.dump([@ucd.codepoints, @ucd.composition_exclusion, @ucd.composition_map, @ucd.boundary])
+      end
+    end
+  end
+end
+
+if __FILE__ == $0
+  filename = ActiveSupport::Multibyte::Handlers::UnicodeDatabase.filename
+  generator = ActiveSupport::Multibyte::Handlers::UnicodeTableGenerator.new
+  generator.parse
+  print "Writing to: #{filename}"
+  generator.dump_to filename
+  puts " (#{File.size(filename)} bytes)"
+end
diff --git a/activesupport/lib/active_support/multibyte/handlers/passthru_handler.rb b/activesupport/lib/active_support/multibyte/handlers/passthru_handler.rb
new file mode 100644
index 0000000000..b28e345585
--- /dev/null
+++ b/activesupport/lib/active_support/multibyte/handlers/passthru_handler.rb
@@ -0,0 +1,9 @@
+# Chars uses this handler when $KCODE is not set to 'UTF8'. Because this handler doesn't define any methods all call
+# will be forwarded to String.
+class ActiveSupport::Multibyte::Handlers::PassthruHandler
+  
+  # Return the original byteoffset
+  def self.translate_offset(string, byte_offset) #:nodoc:
+    byte_offset
+  end
+end
\ No newline at end of file
diff --git a/activesupport/lib/active_support/multibyte/handlers/utf8_handler.rb b/activesupport/lib/active_support/multibyte/handlers/utf8_handler.rb
new file mode 100644
index 0000000000..0928209d85
--- /dev/null
+++ b/activesupport/lib/active_support/multibyte/handlers/utf8_handler.rb
@@ -0,0 +1,447 @@
+# Contains all the handlers and helper classes
+module ActiveSupport::Multibyte::Handlers
+  class EncodingError < ArgumentError; end
+  
+  class Codepoint #:nodoc:
+    attr_accessor :code, :combining_class, :decomp_type, :decomp_mapping, :uppercase_mapping, :lowercase_mapping
+  end
+  
+  class UnicodeDatabase #:nodoc:
+    attr_accessor :codepoints, :composition_exclusion, :composition_map, :boundary
+    
+    # Creates a new UnicodeDatabase instance and loads the database.
+    def initialize
+      begin
+        @codepoints, @composition_exclusion, @composition_map, @boundary = self.class.load
+      rescue Exception => e
+          raise IOError.new("Couldn't load the unicode tables for UTF8Handler (#{e.message}), handler is unusable")
+      end
+      @codepoints ||= Hash.new(Codepoint.new)
+      @composition_exclusion ||= []
+      @composition_map ||= {}
+      @boundary ||= {}
+      
+      # Redefine the === method so we can write shorter rules for grapheme cluster breaks
+      @boundary.each do |k,_|
+        @boundary[k].instance_eval do
+          def ===(other)
+            detect { |i| i === other } ? true : false
+          end
+        end if @boundary[k].kind_of?(Array)
+      end
+    end
+    
+    # Shortcut to ucd.codepoints[]
+    def [](index); @codepoints[index]; end
+    
+    # Returns the directory in which the data files are stored
+    def self.dirname
+      File.dirname(__FILE__) + '/../../values/'
+    end
+    
+    # Returns the filename for the data file for this version
+    def self.filename
+      File.expand_path File.join(dirname, "unicode_tables-#{VERSION}.dat")
+    end
+    
+    # Loads the unicode database and returns all the internal objects of UnicodeDatabase
+    def self.load
+      begin
+        return load_file(filename)
+      rescue Exception
+        # If we can't load our own version, try the rest
+        Dir["#{dirname}/*.dat"].sort.each do |dat|
+          begin
+            return load_file(dat)
+          rescue Exception
+          end
+        end
+      end
+      raise IOError.new("Can't load a marshal file for your version of Ruby")
+    end
+    
+    def self.load_file(filename)
+      File.open(self.filename, 'rb') { |f| Marshal.load f.read }
+    end
+  end
+  
+  # UTF8Handler implements Unicode aware operations for strings, these operations will be used by the Chars
+  # proxy when $KCODE is set to 'UTF8'.
+  class UTF8Handler
+    # Hangul character boundaries and properties
+    HANGUL_SBASE = 0xAC00
+    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
+    
+    # All the unicode whitespace
+    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
+    
+    # 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_LEADERS_AND_TRAILERS = UNICODE_WHITESPACE + [65279] # ZERO-WIDTH NO-BREAK SPACE aka BOM
+    
+    # Borrowed from the Kconv library by Shinji KONO - (also as seen on the W3C site)
+     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
+    
+    # Returns a regular expression pattern that matches the passed Unicode codepoints
+    def self.codepoints_to_pattern(array_of_codepoints) #:nodoc:
+      array_of_codepoints.collect{ |e| [e].pack 'U*' }.join('|') 
+    end
+    UNICODE_TRAILERS_PAT = /(#{codepoints_to_pattern(UNICODE_LEADERS_AND_TRAILERS)})+\Z/
+    UNICODE_LEADERS_PAT = /\A(#{codepoints_to_pattern(UNICODE_LEADERS_AND_TRAILERS)})+/
+    
+    class << self
+      
+      # ///
+      # /// BEGIN String method overrides
+      # ///
+      
+      # Inserts the passed string at specified codepoint offsets
+      def insert(str, offset, fragment)
+        str.replace(
+          u_unpack(str).insert(
+            offset,
+            u_unpack(fragment)
+          ).flatten.pack('U*')
+        )
+      end
+      
+      # Returns the position of the passed argument in the string, counting in codepoints
+      def index(str, *args)
+        bidx = str.index(*args)
+        bidx ? (u_unpack(str.slice(0...bidx)).size) : nil
+      end
+      
+      # Does Unicode-aware rstrip
+      def rstrip(str)
+        str.gsub(UNICODE_TRAILERS_PAT, '')
+      end
+      
+      # Does Unicode-aware lstrip
+      def lstrip(str)
+        str.gsub(UNICODE_LEADERS_PAT, '')
+      end
+      
+      # Removed leading and trailing whitespace
+      def strip(str)
+        str.gsub(UNICODE_LEADERS_PAT, '').gsub(UNICODE_TRAILERS_PAT, '')
+      end
+      
+      # Returns the number of codepoints in the string
+      def size(str)
+        u_unpack(str).size
+      end
+      alias_method :length, :size
+      
+      # Reverses codepoints in the string.
+      def reverse(str)
+        u_unpack(str).reverse.pack('U*')
+      end
+      
+      # Implements Unicode-aware slice with codepoints. Slicing on one point returns the codepoints for that
+      # character.
+      def slice(str, *args)
+        if (args.size == 2 && args.first.is_a?(Range))
+          raise TypeError, 'cannot convert Range 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[0].kind_of? Numeric
+          u_unpack(str)[args[0]]
+        else
+          str.slice(*args)
+        end
+      end
+      alias_method :[], :slice
+      
+      # Convert characters in the string to uppercase
+      def upcase(str); to_case :uppercase_mapping, str; end
+      
+      # Convert characters in the string to lowercase
+      def downcase(str); to_case :lowercase_mapping, str; end
+      
+      # Returns a copy of +str+ with the first character converted to uppercase and the remainder to lowercase
+      def capitalize(str)
+        upcase(slice(str, 0..0)) + downcase(slice(str, 1..-1) || '')
+      end
+      
+      # ///
+      # /// Extra String methods for unicode operations
+      # ///
+      
+      # Returns the KC normalization of the string by default. NFKC is considered the best normalization form for
+      # passing strings to databases and validations.
+      #
+      # * <tt>str</tt>: The string to perform normalization on.
+      # * <tt>form</tt>: The form you want to normalize in. Should be one of the following: :c, :kc, :d or :kd.
+      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
+      
+      # Perform decomposition on the characters in the string
+      def decompose(str)
+        decompose_codepoints(:canonical, u_unpack(str)).pack('U*')
+      end
+      
+      # Perform composition on the characters in the string
+      def compose(str)
+        compose_codepoints u_unpack(str).pack('U*')
+      end
+      
+      # ///
+      # /// BEGIN Helper methods for unicode operation
+      # ///
+      
+      # Used to translate an offset from bytes to characters, for instance one received from a regular expression match
+      def translate_offset(str, byte_offset)
+        return 0 if str == ''
+        return nil if byte_offset.nil?
+        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
+      
+      # Checks if the string is valid UTF8.
+      def consumes?(str)
+        # Unpack is a little bit faster than regular expressions
+        begin
+          str.unpack('U*')
+          true
+        rescue ArgumentError
+          false
+        end
+      end
+      
+      # Returns the number of grapheme clusters in the string. This method is very likely to be moved or renamed
+      # in future versions.
+      def g_length(str)
+        g_unpack(str).length
+      end
+      
+      # Strips all the non-utf-8 bytes from the string resulting in a valid utf-8 string
+      def tidy_bytes(str)
+        str.split(//u).reject { |c| !UTF8_PAT.match(c) }.join
+      end
+      
+      protected
+      
+      # Detect whether the codepoint is in a certain character class. Primarily used by the
+      # grapheme cluster support.
+      def in_char_class?(codepoint, classes)
+        classes.detect { |c| UCD.boundary[c] === codepoint } ? true : false
+      end
+      
+      # Unpack the string at codepoints boundaries
+      def u_unpack(str)
+        begin
+          str.unpack 'U*'
+        rescue ArgumentError
+          raise EncodingError.new('malformed UTF-8 character')
+        end
+      end
+      
+      # Unpack the string at grapheme boundaries instead of codepoint boundaries
+      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
+      
+      # Reverse operation of g_unpack
+      def g_pack(unpacked)
+        unpacked.flatten
+      end
+      
+      # Convert characters to a different case
+      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
+      
+      # Re-order codepoints so the string becomes canonical
+      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
+      
+      # Decompose composed characters to the decomposed form
+      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
+      
+      # Compose decomposed characters to the composed form
+      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
+      
+      # UniCode Database
+      UCD = UnicodeDatabase.new
+    end
+  end
+end
\ No newline at end of file
diff --git a/activesupport/lib/active_support/multibyte/handlers/utf8_handler_proc.rb b/activesupport/lib/active_support/multibyte/handlers/utf8_handler_proc.rb
new file mode 100644
index 0000000000..f551af6cc7
--- /dev/null
+++ b/activesupport/lib/active_support/multibyte/handlers/utf8_handler_proc.rb
@@ -0,0 +1,44 @@
+# Methods in this handler call functions in the utf8proc ruby extension. These are significantly faster than the
+# pure ruby versions. Chars automatically uses this handler when it can load the utf8proc extension. For
+# documentation on handler methods see UTF8Handler.
+class ActiveSupport::Multibyte::Handlers::UTF8HandlerProc < ActiveSupport::Multibyte::Handlers::UTF8Handler
+  
+  class << self
+    def normalize(str, form=ActiveSupport::Multibyte::DEFAULT_NORMALIZATION_FORM) #:nodoc:
+      codepoints = str.unpack('U*')
+      case form
+        when :d
+          utf8map(str, :stable)
+        when :c
+          utf8map(str, :stable, :compose)
+        when :kd
+          utf8map(str, :stable, :compat)
+        when :kc
+          utf8map(str, :stable, :compose, :compat)
+        else
+          raise ArgumentError, "#{form} is not a valid normalization variant", caller
+      end
+    end
+    
+    def decompose(str) #:nodoc:
+      utf8map(str, :stable)
+    end
+    
+    def downcase(str) #:nodoc:c
+      utf8map(str, :casefold)
+    end
+    
+    protected
+    
+    def utf8map(str, *option_array) #:nodoc:
+      options = 0
+      option_array.each do |option|
+        flag = Utf8Proc::Options[option]
+        raise ArgumentError, "Unknown argument given to utf8map." unless
+          flag
+        options |= flag
+      end
+      return Utf8Proc::utf8map(str, options)
+    end
+  end
+end
diff --git a/activesupport/lib/active_support/values/unicode_tables-1.8.4.dat b/activesupport/lib/active_support/values/unicode_tables-1.8.4.dat
new file mode 100644
index 0000000000..13a081388a
--- /dev/null
+++ b/activesupport/lib/active_support/values/unicode_tables-1.8.4.dat
diff --git a/activesupport/lib/active_support/values/unicode_tables-1.8.5.dat b/activesupport/lib/active_support/values/unicode_tables-1.8.5.dat
new file mode 100644
index 0000000000..7b96885f32
--- /dev/null
+++ b/activesupport/lib/active_support/values/unicode_tables-1.8.5.dat
diff --git a/activesupport/test/multibyte_chars_test.rb b/activesupport/test/multibyte_chars_test.rb
new file mode 100644
index 0000000000..e5ad9d26ee
--- /dev/null
+++ b/activesupport/test/multibyte_chars_test.rb
@@ -0,0 +1,163 @@
+require File.dirname(__FILE__) + '/abstract_unit'
+
+$KCODE = 'UTF8'
+
+class CharsTest < Test::Unit::TestCase
+  
+  def setup
+    @s = {
+      :utf8 => "Abcd Блå ffi блa  埋",
+      :ascii => "asci ias c iia s",
+      :bytes => "\270\236\010\210\245"
+    }
+  end
+  
+  def test_sanity
+    @s.each do |t, s|
+      assert s.respond_to?(:chars), "All string should have the chars method (#{t})"
+      assert s.respond_to?(:to_s), "All string should have the to_s method (#{t})"
+      assert_kind_of ActiveSupport::Multibyte::Chars, s.chars, "#chars should return an instance of Chars (#{t})"
+    end
+  end
+  
+  def test_comparability
+    @s.each do |t, s|
+      assert_equal s, s.chars.to_s, "Chars#to_s should return enclosed string unchanged"
+    end
+    assert_nothing_raised do
+      assert_equal "a", "a", "Normal string comparisons should be unaffected"
+      assert_not_equal "a", "b", "Normal string comparisons should be unaffected"
+      assert_not_equal "a".chars, "b".chars, "Chars objects should be comparable"
+      assert_equal "a".chars, "A".downcase.chars, "Chars objects should be comparable to each other"
+      assert_equal "a".chars, "A".downcase, "Chars objects should be comparable to strings coming from elsewhere"
+    end
+    
+    assert !@s[:utf8].eql?(@s[:utf8].chars), "Strict comparison is not supported"
+    assert_equal @s[:utf8], @s[:utf8].chars, "Chars should be compared by their enclosed string"
+
+    other_string = @s[:utf8].dup
+    assert_equal other_string, @s[:utf8].chars, "Chars should be compared by their enclosed string"
+    assert_equal other_string.chars, @s[:utf8].chars, "Chars should be compared by their enclosed string"
+    
+    strings = ['builder'.chars, 'armor'.chars, 'zebra'.chars]
+    strings.sort!
+    assert_equal ['armor', 'builder', 'zebra'], strings, "Chars should be sortable based on their enclosed string"
+
+    # This leads to a StackLevelTooDeep exception if the comparison is not wired properly
+    assert_raise(NameError) do
+      Chars
+    end
+  end
+  
+  def test_utf8?
+    assert @s[:utf8].is_utf8?, "UTF-8 strings are UTF-8"
+    assert @s[:ascii].is_utf8?, "All ASCII strings are also valid UTF-8"
+    assert !@s[:bytes].is_utf8?, "This bytestring isn't UTF-8"
+  end
+  
+  # The test for the following methods are defined here because they can only be defined on the Chars class for
+  # various reasons 
+  
+  def test_gsub
+    assert_equal 'éxa', 'éda'.chars.gsub(/d/, 'x')
+    with_kcode('none') do
+      assert_equal 'éxa', 'éda'.chars.gsub(/d/, 'x')
+    end
+  end
+  
+  def test_split
+    word = "efficient"
+    chars = ["e", "ffi", "c", "i", "e", "n", "t"]
+    assert_equal chars, word.split(//)
+    assert_equal chars, word.chars.split(//)
+    assert_kind_of ActiveSupport::Multibyte::Chars, word.chars.split(//).first, "Split should return Chars instances"
+  end
+  
+  def test_regexp
+    with_kcode('none') do
+      assert_equal 12, (@s[:utf8].chars =~ /ffi/),
+        "Regex matching should be bypassed to String"
+    end
+    with_kcode('UTF8') do
+      assert_equal 9, (@s[:utf8].chars =~ /ffi/),
+        "Regex matching should be unicode aware"
+    end
+  end
+  
+  def test_pragma
+    with_kcode('UTF8') do
+      assert " ".chars.send(:utf8_pragma?), "UTF8 pragma should be on because KCODE is UTF8"
+    end
+    with_kcode('none') do
+      assert !" ".chars.send(:utf8_pragma?), "UTF8 pragma should be off"
+    end
+  end
+  
+  def test_handler_setting
+    handler = ''.chars.handler
+    
+    ActiveSupport::Multibyte::Chars.handler = :first
+    assert_equal :first, ''.chars.handler
+    ActiveSupport::Multibyte::Chars.handler = :second
+    assert_equal :second, ''.chars.handler
+    assert_raise(NoMethodError) do
+      ''.chars.handler.split
+    end
+    
+    ActiveSupport::Multibyte::Chars.handler = handler
+  end
+  
+  def test_method_chaining
+    assert_kind_of ActiveSupport::Multibyte::Chars, ''.chars.downcase
+    assert_kind_of ActiveSupport::Multibyte::Chars, ''.chars.strip, "Strip should return a Chars object"
+    assert_kind_of ActiveSupport::Multibyte::Chars, ''.chars.downcase.strip, "The Chars object should be " +
+        "forwarded down the call path for chaining"
+    assert_equal 'foo', "  FOO   ".chars.normalize.downcase.strip, "The Chars that results from the " +
+      " operations should be comparable to the string value of the result"
+  end
+  
+  def test_passthrough_on_kcode
+    # The easiest way to check if the passthrough is in place is through #size
+    with_kcode('nonce') do
+      assert_equal 26, @s[:utf8].chars.size
+    end
+    with_kcode('UTF8') do
+      assert_equal 17, @s[:utf8].chars.size
+    end
+  end
+    
+  def test_destructiveness  
+    # Note that we're testing the destructiveness here and not the correct behaviour of the methods
+    str = 'ac'
+    str.chars.insert(1, 'b')
+    assert_equal 'abc', str, 'Insert should be destructive for a string'
+    
+    str = 'ac'
+    str.chars.reverse!
+    assert_equal 'ca', str, 'reverse! should be destructive for a string'
+  end
+  
+  def test_resilience
+    assert_nothing_raised do
+      assert_equal 1, @s[:bytes].chars.size, "There's only one valid utf-8 byte in the string"
+    end
+    assert_nothing_raised do
+      assert_equal "\010", @s[:bytes].chars.reverse, "There's only one valid utf-8 byte in the string"
+    end
+    assert_nothing_raised do
+      @s[:bytes].chars.reverse!
+      assert_equal "\010", @s[:bytes], "There's only one valid utf-8 byte in the string"
+    end
+  end
+  
+  protected
+
+  def with_kcode(kcode)
+    old_kcode, $KCODE = $KCODE, kcode
+    begin
+      yield
+    ensure
+      $KCODE = old_kcode
+    end
+  end
+end
diff --git a/activesupport/test/multibyte_conformance.rb b/activesupport/test/multibyte_conformance.rb
new file mode 100644
index 0000000000..dfd77bd6e1
--- /dev/null
+++ b/activesupport/test/multibyte_conformance.rb
@@ -0,0 +1,141 @@
+require File.dirname(__FILE__) + '/abstract_unit'
+require 'open-uri'
+
+$KCODE = 'UTF8'
+UNIDATA_URL = "http://www.unicode.org/Public/#{ActiveSupport::Multibyte::UNICODE_VERSION}/ucd"
+UNIDATA_FILE = '/NormalizationTest.txt'
+CACHE_DIR = File.dirname(__FILE__) + '/cache'
+
+class Downloader
+  def self.download(from, to)
+    unless File.exist?(to)
+      $stderr.puts "Downloading #{from} to #{to}"
+      unless File.exists?(File.dirname(to))
+        system "mkdir -p #{File.dirname(to)}"
+      end
+      open(from) do |source|
+        File.open(to, 'w') do |target|
+          source.each_line do |l|
+            target.write l
+          end
+        end
+       end
+     end
+  end
+end
+
+class String
+  # Unicode Inspect returns the codepoints of the string in hex
+  def ui
+    "#{self} " + ("[%s]" % unpack("U*").map{|cp| cp.to_s(16) }.join(' '))
+  end unless ''.respond_to?(:ui)
+end
+
+Dir.mkdir(CACHE_DIR) unless File.exists?(CACHE_DIR)
+Downloader.download(UNIDATA_URL + UNIDATA_FILE, CACHE_DIR + UNIDATA_FILE)
+
+module ConformanceTest
+  def test_normalizations_C
+    each_line_of_norm_tests do |*cols|
+      col1, col2, col3, col4, col5, comment = *cols
+      
+      # CONFORMANCE:
+      # 1. The following invariants must be true for all conformant implementations
+      #
+      #    NFC
+      #      c2 ==  NFC(c1) ==  NFC(c2) ==  NFC(c3)
+      assert_equal col2.ui, @handler.normalize(col1, :c).ui, "Form C - Col 2 has to be NFC(1) - #{comment}"
+      assert_equal col2.ui, @handler.normalize(col2, :c).ui, "Form C - Col 2 has to be NFC(2) - #{comment}"
+      assert_equal col2.ui, @handler.normalize(col3, :c).ui, "Form C - Col 2 has to be NFC(3) - #{comment}"
+      #
+      #      c4 ==  NFC(c4) ==  NFC(c5)
+      assert_equal col4.ui, @handler.normalize(col4, :c).ui, "Form C - Col 4 has to be C(4) - #{comment}"
+      assert_equal col4.ui, @handler.normalize(col5, :c).ui, "Form C - Col 4 has to be C(5) - #{comment}"
+    end
+  end
+  
+  def test_normalizations_D
+    each_line_of_norm_tests do |*cols|
+      col1, col2, col3, col4, col5, comment = *cols
+      #
+      #    NFD
+      #      c3 ==  NFD(c1) ==  NFD(c2) ==  NFD(c3)
+      assert_equal col3.ui, @handler.normalize(col1, :d).ui, "Form D - Col 3 has to be NFD(1) - #{comment}"
+      assert_equal col3.ui, @handler.normalize(col2, :d).ui, "Form D - Col 3 has to be NFD(2) - #{comment}"
+      assert_equal col3.ui, @handler.normalize(col3, :d).ui, "Form D - Col 3 has to be NFD(3) - #{comment}"
+      #      c5 ==  NFD(c4) ==  NFD(c5)
+      assert_equal col5.ui, @handler.normalize(col4, :d).ui, "Form D - Col 5 has to be NFD(4) - #{comment}"
+      assert_equal col5.ui, @handler.normalize(col5, :d).ui, "Form D - Col 5 has to be NFD(5) - #{comment}"
+    end
+  end
+  
+  def test_normalizations_KC
+    each_line_of_norm_tests do | *cols |
+      col1, col2, col3, col4, col5, comment = *cols  
+      #
+      #    NFKC
+      #      c4 == NFKC(c1) == NFKC(c2) == NFKC(c3) == NFKC(c4) == NFKC(c5)
+      assert_equal col4.ui, @handler.normalize(col1, :kc).ui, "Form D - Col 4 has to be NFKC(1) - #{comment}"
+      assert_equal col4.ui, @handler.normalize(col2, :kc).ui, "Form D - Col 4 has to be NFKC(2) - #{comment}"
+      assert_equal col4.ui, @handler.normalize(col3, :kc).ui, "Form D - Col 4 has to be NFKC(3) - #{comment}"
+      assert_equal col4.ui, @handler.normalize(col4, :kc).ui, "Form D - Col 4 has to be NFKC(4) - #{comment}"
+      assert_equal col4.ui, @handler.normalize(col5, :kc).ui, "Form D - Col 4 has to be NFKC(5) - #{comment}"
+    end
+  end
+  
+  def test_normalizations_KD
+    each_line_of_norm_tests do | *cols |
+      col1, col2, col3, col4, col5, comment = *cols  
+      #
+      #    NFKD
+      #      c5 == NFKD(c1) == NFKD(c2) == NFKD(c3) == NFKD(c4) == NFKD(c5)
+      assert_equal col5.ui, @handler.normalize(col1, :kd).ui, "Form KD - Col 5 has to be NFKD(1) - #{comment}"
+      assert_equal col5.ui, @handler.normalize(col2, :kd).ui, "Form KD - Col 5 has to be NFKD(2) - #{comment}"
+      assert_equal col5.ui, @handler.normalize(col3, :kd).ui, "Form KD - Col 5 has to be NFKD(3) - #{comment}"
+      assert_equal col5.ui, @handler.normalize(col4, :kd).ui, "Form KD - Col 5 has to be NFKD(4) - #{comment}"
+      assert_equal col5.ui, @handler.normalize(col5, :kd).ui, "Form KD - Col 5 has to be NFKD(5) - #{comment}"
+    end
+  end
+  
+  protected
+    def each_line_of_norm_tests(&block)
+      lines = 0
+      max_test_lines = 0 # Don't limit below 38, because that's the header of the testfile
+      File.open(File.dirname(__FILE__) + '/cache' + UNIDATA_FILE, 'r') do | f |
+        until f.eof? || (max_test_lines > 38 and lines > max_test_lines)
+          lines += 1
+          line = f.gets.chomp!
+          next if (line.empty? || line =~ /^\#/)      
+          
+          cols, comment = line.split("#")
+          cols = cols.split(";").map{|e| e.strip}.reject{|e| e.empty? }
+          next unless cols.length == 5
+          
+          # codepoints are in hex in the test suite, pack wants them as integers
+          cols.map!{|c| c.split.map{|codepoint| codepoint.to_i(16)}.pack("U*") }
+          cols << comment
+          
+          yield(*cols)
+        end
+      end
+    end
+end
+
+begin
+  require_library_or_gem('utf8proc_native')
+  require 'active_record/multibyte/handlers/utf8_handler_proc'
+  class ConformanceTestProc < Test::Unit::TestCase
+    include ConformanceTest
+    def setup
+      @handler = ::ActiveSupport::Multibyte::Handlers::UTF8HandlerProc
+    end
+  end
+rescue LoadError
+end
+
+class ConformanceTestPure < Test::Unit::TestCase
+  include ConformanceTest
+  def setup
+    @handler = ::ActiveSupport::Multibyte::Handlers::UTF8Handler
+  end
+end
\ No newline at end of file
diff --git a/activesupport/test/multibyte_handler_test.rb b/activesupport/test/multibyte_handler_test.rb
new file mode 100644
index 0000000000..08291c1212
--- /dev/null
+++ b/activesupport/test/multibyte_handler_test.rb
@@ -0,0 +1,261 @@
+require File.dirname(__FILE__) + '/abstract_unit'
+
+$KCODE = 'UTF8'
+
+class String
+  # Unicode Inspect returns the codepoints of the string in hex
+  def ui
+    "#{self} " + ("[%s]" % unpack("U*").map{|cp| cp.to_s(16) }.join(' '))
+  end unless ''.respond_to?(:ui)
+end
+
+module UTF8HandlingTest
+  
+  def common_setup
+    # This is an ASCII string with some russian strings and a ligature. It's nicely calibrated, because
+    # slicing it at some specific bytes will kill your characters if you use standard Ruby routines.
+    # It has both capital and standard letters, so that we can test case conversions easily.
+    # It has 26 charactes and 28 when the ligature gets split during normalization.
+    @string =     "Abcd Блå ffi бла бла бла бла"
+    @string_kd =  "Abcd Блå ffi бла бла бла бла"
+    @string_kc =  "Abcd Блå ffi бла бла бла бла"
+    @string_c =   "Abcd Блå ffi бла бла бла бла"
+    @string_d =   "Abcd Блå ffi бла бла бла бла"
+    @bytestring = "\270\236\010\210\245" # Not UTF-8
+    
+    # Characters from the character classes as described in UAX #29
+    @character_from_class = {
+      :l => 0x1100, :v => 0x1160, :t => 0x11A8, :lv => 0xAC00, :lvt => 0xAC01, :cr => 0x000D, :lf => 0x000A,
+      :extend => 0x094D, :n => 0x64
+    }
+  end
+  
+  def test_utf8_recognition
+    assert ActiveSupport::Multibyte::Handlers::UTF8Handler.consumes?(@string),
+      "Should recognize as a valid UTF-8 string"
+    assert !ActiveSupport::Multibyte::Handlers::UTF8Handler.consumes?(@bytestring), "This is bytestring, not UTF-8"
+  end
+  
+  def test_simple_normalization
+    # Normalization of DEVANAGARI LETTER QA breaks when composition exclusion isn't used correctly
+    assert_equal [0x915, 0x93c].pack('U*').ui, [0x915, 0x93c].pack('U*').chars.normalize(:c).to_s.ui
+    
+    null_byte_str = "Test\0test"
+    
+    assert_equal '', @handler.normalize(''), "Empty string should not break things"
+    assert_equal null_byte_str.ui, @handler.normalize(null_byte_str, :kc).ui, "Null byte should remain"
+    assert_equal null_byte_str.ui, @handler.normalize(null_byte_str, :c).ui, "Null byte should remain" 
+    assert_equal null_byte_str.ui, @handler.normalize(null_byte_str, :d).ui, "Null byte should remain"
+    assert_equal null_byte_str.ui, @handler.normalize(null_byte_str, :kd).ui, "Null byte should remain"
+    assert_equal null_byte_str.ui, @handler.decompose(null_byte_str).ui, "Null byte should remain"
+    assert_equal null_byte_str.ui, @handler.compose(null_byte_str).ui, "Null byte should remain" 
+    
+    comp_str = [
+      44,  # LATIN CAPITAL LETTER D
+      307, # COMBINING DOT ABOVE
+      328, # COMBINING OGONEK
+      323 # COMBINING DOT BELOW
+    ].pack("U*")
+    norm_str_KC = [44,105,106,328,323].pack("U*")
+    norm_str_C = [44,307,328,323].pack("U*")
+    norm_str_D = [44,307,110,780,78,769].pack("U*")
+    norm_str_KD = [44,105,106,110,780,78,769].pack("U*")
+    
+    assert_equal norm_str_KC.ui, @handler.normalize(comp_str, :kc).ui, "Should normalize KC"
+    assert_equal norm_str_C.ui, @handler.normalize(comp_str, :c).ui, "Should normalize C"
+    assert_equal norm_str_D.ui, @handler.normalize(comp_str, :d).ui, "Should normalize D"
+    assert_equal norm_str_KD.ui, @handler.normalize(comp_str, :kd).ui, "Should normalize KD"
+    
+    assert_raise(ActiveSupport::Multibyte::Handlers::EncodingError) { @handler.normalize(@bytestring) }
+  end
+  
+  # Test for the Public Review Issue #29, bad explaination of composition might lead to a
+  # bad implementation: http://www.unicode.org/review/pr-29.html
+  def test_normalization_C_pri_29
+    [
+      [0x0B47, 0x0300, 0x0B3E],
+      [0x1100, 0x0300, 0x1161]
+    ].map { |c| c.pack('U*') }.each do |c|
+      assert_equal c.ui, @handler.normalize(c, :c).ui, "Composition is implemented incorrectly"
+    end
+  end
+  
+  def test_casefolding
+    simple_str = "abCdef"
+    simple_str_upcase = "ABCDEF"
+    simple_str_downcase = "abcdef"
+    
+    assert_equal '', @handler.downcase(@handler.upcase('')), "Empty string should not break things"
+    assert_equal simple_str_upcase, @handler.upcase(simple_str), "should upcase properly"
+    assert_equal simple_str_downcase, @handler.downcase(simple_str), "should downcase properly"
+    assert_equal simple_str_downcase, @handler.downcase(@handler.upcase(simple_str_downcase)), "upcase and downcase should be mirrors"
+    
+    rus_str = "аБвгд\0f"
+    rus_str_upcase = "АБВГД\0F"
+    rus_str_downcase = "абвгд\0f"
+    assert_equal rus_str_upcase, @handler.upcase(rus_str), "should upcase properly honoring null-byte"
+    assert_equal rus_str_downcase, @handler.downcase(rus_str), "should downcase properly honoring null-byte"
+    
+    jap_str = "の埋め込み化対応はほぼ完成"
+    assert_equal jap_str, @handler.upcase(jap_str), "Japanse has no upcase, should remain unchanged"
+    assert_equal jap_str, @handler.downcase(jap_str), "Japanse has no downcase, should remain unchanged"
+    
+    assert_raise(ActiveSupport::Multibyte::Handlers::EncodingError) { @handler.upcase(@bytestring) }
+  end
+  
+  def test_capitalize
+    { 'аБвг аБвг' => 'Абвг абвг',
+      'аБвг АБВГ' => 'Абвг абвг',
+      'АБВГ АБВГ' => 'Абвг абвг',
+      '' => '' }.each do |f,t|
+        assert_equal t, @handler.capitalize(f), "Capitalize should work as expected"
+    end
+    assert_raise(ActiveSupport::Multibyte::Handlers::EncodingError) { @handler.capitalize(@bytestring) }
+  end
+  
+  def test_translate_offset
+    str = "Блaå" # [2, 2, 1, 2] bytes
+    assert_equal 0, @handler.translate_offset('', 0), "Offset for an empty string makes no sense, return 0"
+    assert_equal 0, @handler.translate_offset(str, 0), "First character, first byte"
+    assert_equal 0, @handler.translate_offset(str, 1), "First character, second byte"
+    assert_equal 1, @handler.translate_offset(str, 2), "Second character, third byte"
+    assert_equal 1, @handler.translate_offset(str, 3), "Second character, fourth byte"
+    assert_equal 2, @handler.translate_offset(str, 4), "Third character, fifth byte"
+    assert_equal 3, @handler.translate_offset(str, 5), "Fourth character, sixth byte"
+    assert_equal 3, @handler.translate_offset(str, 6), "Fourth character, seventh byte"
+    assert_raise(ActiveSupport::Multibyte::Handlers::EncodingError) { @handler.translate_offset(@bytestring, 3) }
+  end
+  
+  def test_insert
+    assert_equal '', @handler.insert('', 0, ''), "Empty string should not break things"
+    assert_equal "Abcd Блå ffiБУМ бла бла бла бла", @handler.insert(@string, 10, "БУМ"), 
+      "Text should be inserted at right codepoints"
+    assert_equal "Abcd Блå ffiБУМ бла бла бла бла", @string, "Insert should be destructive"
+    assert_raise(ActiveSupport::Multibyte::Handlers::EncodingError) do
+      @handler.insert(@bytestring, 2, "\210")
+    end
+  end
+  
+  def test_reverse
+    str = "wБлåa \n"
+    rev = "\n aåлБw"
+    assert_equal '', @handler.reverse(''), "Empty string shouldn't change"
+    assert_equal rev.ui, @handler.reverse(str).ui, "Should reverse properly"
+    assert_raise(ActiveSupport::Multibyte::Handlers::EncodingError) { @handler.reverse(@bytestring) }
+  end
+  
+  def test_size
+    assert_equal 0, @handler.size(''), "Empty string has size 0"
+    assert_equal 26, @handler.size(@string), "String length should be 26"
+    assert_equal 26, @handler.length(@string), "String length method should be properly aliased"
+    assert_raise(ActiveSupport::Multibyte::Handlers::EncodingError) { @handler.size(@bytestring) }
+  end
+  
+  def test_slice
+    assert_equal 0x41, @handler.slice(@string, 0), "Singular characters should return codepoints"
+    assert_equal 0xE5, @handler.slice(@string, 7), "Singular characters should return codepoints"
+    assert_equal nil, @handler.slice('', -1..1), "Broken range should return nil"
+    assert_equal '', @handler.slice('', 0..10), "Empty string should not break things"
+    assert_equal "d Блå ffi", @handler.slice(@string, 3..9), "Unicode characters have to be returned"
+    assert_equal " Блå ffi ", @handler.slice(@string, 4..10), "Unicode characters have to be returned"
+    assert_equal "", @handler.slice(@string, 7..6), "Range is empty, should return an empty string"
+    assert_raise(ActiveSupport::Multibyte::Handlers::EncodingError) { @handler.slice(@bytestring, 2..3) }
+  end
+  
+  def test_grapheme_cluster_length
+    assert_equal 0, @handler.g_length(''), "String should count 0 grapheme clusters"
+    assert_equal 2, @handler.g_length([0x0924, 0x094D, 0x0930].pack('U*')), "String should count 2 grapheme clusters"
+    assert_equal 1, @handler.g_length(string_from_classes(%w(cr lf))), "Don't cut between CR and LF"
+    assert_equal 1, @handler.g_length(string_from_classes(%w(l l))), "Don't cut between L"
+    assert_equal 1, @handler.g_length(string_from_classes(%w(l v))), "Don't cut between L and V"
+    assert_equal 1, @handler.g_length(string_from_classes(%w(l lv))), "Don't cut between L and LV"
+    assert_equal 1, @handler.g_length(string_from_classes(%w(l lvt))), "Don't cut between L and LVT"
+    assert_equal 1, @handler.g_length(string_from_classes(%w(lv v))), "Don't cut between LV and V"
+    assert_equal 1, @handler.g_length(string_from_classes(%w(lv t))), "Don't cut between LV and T"
+    assert_equal 1, @handler.g_length(string_from_classes(%w(v v))), "Don't cut between V and V"
+    assert_equal 1, @handler.g_length(string_from_classes(%w(v t))), "Don't cut between V and T"
+    assert_equal 1, @handler.g_length(string_from_classes(%w(lvt t))), "Don't cut between LVT and T"
+    assert_equal 1, @handler.g_length(string_from_classes(%w(t t))), "Don't cut between T and T"
+    assert_equal 1, @handler.g_length(string_from_classes(%w(n extend))), "Don't cut before Extend"
+    assert_equal 2, @handler.g_length(string_from_classes(%w(n n))), "Cut between normal characters"
+    assert_equal 3, @handler.g_length(string_from_classes(%w(n cr lf n))), "Don't cut between CR and LF"
+    assert_equal 2, @handler.g_length(string_from_classes(%w(n l v t))), "Don't cut between L, V and T"
+    assert_raise(ActiveSupport::Multibyte::Handlers::EncodingError) { @handler.g_length(@bytestring) }
+  end
+  
+  def test_index
+     s = "Καλημέρα κόσμε!"
+     assert_equal 0, @handler.index('', ''), "The empty string is always found at the beginning of the string"
+     assert_equal 0, @handler.index('haystack', ''), "The empty string is always found at the beginning of the string"
+     assert_equal 0, @handler.index(s, 'Κ'), "Greek K is at 0"
+     assert_equal 1, @handler.index(s, 'α'), "Greek Alpha is at 1"
+     
+     assert_equal nil, @handler.index(@bytestring, 'a')
+     assert_raise(ActiveSupport::Multibyte::Handlers::EncodingError) { @handler.index(@bytestring, "\010") }
+  end
+  
+  def test_strip
+    # A unicode aware version of strip should strip all 26 types of whitespace. This includes the NO BREAK SPACE
+    # aka BOM (byte order mark). The byte order mark has no place in UTF-8 because it's used to detect LE and BE.
+    b = "\n" + [
+      32, # SPACE
+      8195, # EM SPACE
+      8199, # FIGURE SPACE,
+      8201, # THIN SPACE
+      8202, # HAIR SPACE
+      65279, # NO BREAK SPACE (ZW)
+    ].pack('U*')
+    m = "word блин\n\n\n  word"
+    e = [
+    65279, # NO BREAK SPACE (ZW)
+    8201, # THIN SPACE
+    8199, # FIGURE SPACE,      
+    32, # SPACE
+    ].pack('U*')
+    string = b+m+e
+    
+    assert_equal '', @handler.strip(''), "Empty string should stay empty"
+    assert_equal m+e, @handler.lstrip(string), "Whitespace should be gone on the left"
+    assert_equal b+m, @handler.rstrip(string), "Whitespace should be gone on the right"
+    assert_equal m, @handler.strip(string), "Whitespace should be stripped on both sides"
+    
+    bs = "\n   #{@bytestring} \n\n"
+    assert_equal @bytestring, @handler.strip(bs), "Invalid unicode strings should still strip"
+  end
+  
+  def test_tidy_bytes
+    assert_equal "\010", @handler.tidy_bytes(@bytestring)
+    assert_equal "a\010a", @handler.tidy_bytes('a' + @bytestring + 'a')
+    assert_nothing_raised { @handler.tidy_bytes(@bytestring).unpack('U*') }
+  end
+  
+  protected
+  
+  def string_from_classes(classes)
+    classes.collect do |k|
+      @character_from_class[k.intern]
+    end.pack('U*')
+  end
+end
+
+
+begin
+  require_library_or_gem('utf8proc_native')
+  require 'active_record/multibyte/handlers/utf8_handler_proc'
+  class UTF8HandlingTestProc < Test::Unit::TestCase
+    include UTF8HandlingTest
+    def setup
+      common_setup
+      @handler = ::ActiveSupport::Multibyte::Handlers::UTF8HandlerProc
+    end
+  end
+rescue LoadError
+end
+
+class UTF8HandlingTestPure < Test::Unit::TestCase
+  include UTF8HandlingTest
+  def setup
+    common_setup
+    @handler = ::ActiveSupport::Multibyte::Handlers::UTF8Handler
+  end
+end
\ No newline at end of file