class RDoc::Markup::AttributeManager

def add_html(tag, name)
  @html_tags[tag.downcase] = RDoc::Markup::Attribute.bitmap_for name
end

def add_special(pattern, name)
  @special[pattern] = RDoc::Markup::Attribute.bitmap_for name
end

def add_word_pair(start, stop, name)
  raise ArgumentError, "Word flags may not start with '<'" if
    start[0,1] == '<'
  bitmap = RDoc::Markup::Attribute.bitmap_for name
  if start == stop then
    @matching_word_pairs[start] = bitmap
  else
    pattern = /(#{Regexp.escape start})(\S+)(#{Regexp.escape stop})/
    @word_pair_map[pattern] = bitmap
  end
  @protectable << start[0,1]
  @protectable.uniq!
end

def attribute(turn_on, turn_off)
  RDoc::Markup::AttrChanger.new turn_on, turn_off
end

def change_attribute(current, new)
  diff = current ^ new
  attribute(new & diff, current & diff)
end

def changed_attribute_by_name(current_set, new_set)
  current = new = 0
  current_set.each do |name|
    current |= RDoc::Markup::Attribute.bitmap_for(name)
  end
  new_set.each do |name|
    new |= RDoc::Markup::Attribute.bitmap_for(name)
  end
  change_attribute(current, new)
end

def convert_attrs(str, attrs)
  # first do matching ones
  tags = @matching_word_pairs.keys.join("")
  re = /(^|\W)([#{tags}])([#:\\]?[\w.\/-]+?\S?)\2(\W|$)/
  1 while str.gsub!(re) do
    attr = @matching_word_pairs[$2]
    attrs.set_attrs($`.length + $1.length + $2.length, $3.length, attr)
    $1 + NULL * $2.length + $3 + NULL * $2.length + $4
  end
  # then non-matching
  unless @word_pair_map.empty? then
    @word_pair_map.each do |regexp, attr|
      str.gsub!(regexp) {
        attrs.set_attrs($`.length + $1.length, $2.length, attr)
        NULL * $1.length + $2 + NULL * $3.length
      }
    end
  end
end

def convert_html(str, attrs)
  tags = @html_tags.keys.join '|'
  1 while str.gsub!(/<(#{tags})>(.*?)<\/\1>/i) {
    attr = @html_tags[$1.downcase]
    html_length = $1.length + 2
    seq = NULL * html_length
    attrs.set_attrs($`.length + html_length, $2.length, attr)
    seq + $2 + seq + NULL
  }
end

def convert_specials(str, attrs)
  unless @special.empty?
    @special.each do |regexp, attr|
      str.scan(regexp) do
        attrs.set_attrs($`.length, $&.length,
                        attr | RDoc::Markup::Attribute::SPECIAL)
      end
    end
  end
end

def copy_string(start_pos, end_pos)
  res = @str[start_pos...end_pos]
  res.gsub!(/\000/, '')
  res
end

def display_attributes
  puts
  puts @str.tr(NULL, "!")
  bit = 1
  16.times do |bno|
    line = ""
    @str.length.times do |i|
      if (@attrs[i] & bit) == 0
        line << " "
      else
        if bno.zero?
          line << "S"
        else
          line << ("%d" % (bno+1))
        end
      end
    end
    puts(line) unless line =~ /^ *$/
    bit <<= 1
  end
end

def flow(str)
  @str = str
  mask_protected_sequences
  @attrs = RDoc::Markup::AttrSpan.new @str.length
  convert_attrs    @str, @attrs
  convert_html     @str, @attrs
  convert_specials @str, @attrs
  unmask_protected_sequences
  split_into_flow
end

def initialize
  @html_tags = {}
  @matching_word_pairs = {}
  @protectable = %w[<\\]
  @special = {}
  @word_pair_map = {}
  add_word_pair "*", "*", :BOLD
  add_word_pair "_", "_", :EM
  add_word_pair "+", "+", :TT
  add_html "em", :EM
  add_html "i",  :EM
  add_html "b",  :BOLD
  add_html "tt",   :TT
  add_html "code", :TT
end

def mask_protected_sequences
  @str.gsub!(/\\([#{Regexp.escape @protectable.join('')}])/,
             "\\1#{PROTECT_ATTR}")
end

def split_into_flow
  res = []
  current_attr = 0
  str = ""
  str_len = @str.length
  # skip leading invisible text
  i = 0
  i += 1 while i < str_len and @str[i].chr == "\0"
  start_pos = i
  # then scan the string, chunking it on attribute changes
  while i < str_len
    new_attr = @attrs[i]
    if new_attr != current_attr
      if i > start_pos
        res << copy_string(start_pos, i)
        start_pos = i
      end
      res << change_attribute(current_attr, new_attr)
      current_attr = new_attr
      if (current_attr & RDoc::Markup::Attribute::SPECIAL) != 0 then
        i += 1 while
          i < str_len and (@attrs[i] & RDoc::Markup::Attribute::SPECIAL) != 0
        res << RDoc::Markup::Special.new(current_attr,
                                         copy_string(start_pos, i))
        start_pos = i
        next
      end
    end
    # move on, skipping any invisible characters
    begin
      i += 1
    end while i < str_len and @str[i].chr == "\0"
  end
  # tidy up trailing text
  if start_pos < str_len
    res << copy_string(start_pos, str_len)
  end
  # and reset to all attributes off
  res << change_attribute(current_attr, 0) if current_attr != 0
  res
end

def unmask_protected_sequences
  @str.gsub!(/(.)#{PROTECT_ATTR}/, "\\1\000")
end