class CodeRay::Tokens

def split_into_parts *sizes

of source strings. The Diff encoder uses it for inline highlighting.
This method is used by @Scanner#tokenize@ when called with an Array

betweem them.
part closes all opened tokens. This is useful to insert tokens
the text size specified by the parameter. In addition, each
The result will be an Array of Tokens objects. The parts have

Split the tokens into parts of the given +sizes+. 
def split_into_parts *sizes
  return Array.new(sizes.size) { Tokens.new } if size == 2 && first == ''
  parts = []
  opened = []
  content = nil
  part = Tokens.new
  part_size = 0
  size = sizes.first
  i = 0
  for item in self
    case content
    when nil
      content = item
    when String
      if size && part_size + content.size > size  # token must be cut
        if part_size < size  # some part of the token goes into this part
          content = content.dup  # content may no be safe to change
          part << content.slice!(0, size - part_size) << item
        end
        # close all open groups and lines...
        closing = opened.reverse.flatten.map do |content_or_kind|
          case content_or_kind
          when :begin_group
            :end_group
          when :begin_line
            :end_line
          else
            content_or_kind
          end
        end
        part.concat closing
        begin
          parts << part
          part = Tokens.new
          size = sizes[i += 1]
        end until size.nil? || size > 0
        # ...and open them again.
        part.concat opened.flatten
        part_size = 0
        redo unless content.empty?
      else
        part << content << item
        part_size += content.size
      end
      content = nil
    when Symbol
      case content
      when :begin_group, :begin_line
        opened << [content, item]
      when :end_group, :end_line
        opened.pop
      else
        raise ArgumentError, 'Unknown token action: %p, kind = %p' % [content, item]
      end
      part << content << item
      content = nil
    else
      raise ArgumentError, 'Token input junk: %p, kind = %p' % [content, item]
    end
  end
  parts << part
  parts << Tokens.new while parts.size < sizes.size
  parts
end