DuckCorp » CyborgHood

require 'locale'

module HTTPHeaders

# RFC2616 Accept-Language field

# (also used in RFC2798 'preferredLanguage' LDAP attribute type)

class AcceptLanguage

LANG_RANGE_Q_PATTERN="([a-z]{1,8}(-[a-z]{1,8})*(;q=)|\*)"

ACCEPT_LANG_PATTERN="#{LANG_RANGE_Q_PATTERN}( *, *#{LANG_RANGE_Q_PATTERN})*"

attr_reader :sorted_language_list

private :new

def initialize(sorted_language_list)

# if no preference list, then assume that all languages are equally acceptable

@sorted_language_list = sorted_language_list.empty? ? ["*"] : sorted_language_list

end

def self.parse(accept_language_list)

return nil unless accept_language_list =~ Regexp.new(ACCEPT_LANG_PATTERN, Regexp::EXTENDED | Regexp::IGNORECASE)

list = accept_language_list.split(',').collect do |lang_range_q|

lang_range, quality = lang_range_q.split(';')

quality ||= 1

LanguageRange.new(lang_range, quality)

end

new(list.sort)

end

def reduce(available_language_list)

tag_list = available_language_list.collect do |tag|

l_tag = Locale::Object.new(tag)

match = []

@sorted_language_list.each do |lr|

match << lr if lr.range == "*" or

lr.range == l_tag.to_iso3066 or

(lr.range + "-" == l_tag.to_iso3066[0, lr.range.size + 1])

end

match.sort_by {|lr| lr.range.size }

quality = match.empty? ? 0 : match.last.quality

LanguageRange.new(l_tag, quality)

end

acceptable_tag_list = tag_list.select {|lt| lr.quality != 0 }

acceptable_tag_list.sort

end

end

class LanguageRange

include Sortable

attr_reader :quality

def initialize(lang_range, quality)

@l_lang_range = (lang_range.is_a? Locale::Object) ? lang_range : Locale::Object.new(lang_range)

@quality = quality.to_f

end

def range

@l_lang_range.to_iso3066

end

def <=>(lr)

r = self.quality <=> lr.quality

# if quality is equal, then prefer the most specific language range

if r == 0

self.range.size <=> lr.range.size

else

r

end

end

end

end