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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 #:nodoc:
# 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
# Make duck-typing with String possible
def respond_to?(method)
super || @string.respond_to?(method) || handler.respond_to?(method) ||
(method.to_s =~ /(.*)!/ && handler.respond_to?($1)) || false
end
# Create a new Chars instance.
def initialize(str)
@string = str.respond_to?(:string) ? str.string : str
end
# Returns -1, 0 or +1 depending on whether the Chars object is to be sorted before, equal or after the
# object on the right side of the operation. It accepts any object that implements +to_s+. See String.<=>
# for more details.
def <=>(other); @string <=> other.to_s; end
# Works just like String#split, with the exception that the items in the resulting list are Chars
# instances instead of String. This makes chaining methods easier.
def split(*args)
@string.split(*args).map { |i| i.chars }
end
# Gsub works exactly the same as gsub on a normal string.
def gsub(*a, &b); @string.gsub(*a, &b).chars; end
# Like String.=~ only it returns the character offset (in codepoints) instead of the byte offset.
def =~(other)
handler.translate_offset(@string, @string =~ other)
end
# Try to forward all undefined methods to the handler, when a method is not defined on the handler, send it to
# the contained string. Method_missing is also responsible for making the bang! methods destructive.
def method_missing(m, *a, &b)
begin
# Simulate methods with a ! at the end because we can't touch the enclosed string from the handlers.
if m.to_s =~ /^(.*)\!$/ && handler.respond_to?($1)
result = handler.send($1, @string, *a, &b)
if result == @string
result = nil
else
@string.replace result
end
elsif handler.respond_to?(m)
result = handler.send(m, @string, *a, &b)
else
result = @string.send(m, *a, &b)
end
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
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