class Erubis::PI::TinyEruby

def convert(input)
  src = "_buf = '';"           # preamble
  pos = 0
  input.scan(EMBEDDED_PATTERN) do |lspace, stmt, rspace, indicator, expr|
    match = Regexp.last_match
    len   = match.begin(0) - pos
    text  = input[pos, len]
    pos   = match.end(0)
    #src << " _buf << '" << escape_text(text) << "';"
    text.gsub!(/['\\]/, '\\\\\&')
    src << " _buf << '" << text << "';" unless text.empty?
    if stmt                # <?rb ... ?>
      if lspace && rspace
        src << "#{lspace}#{stmt}#{rspace}"
      else
        src << " _buf << '" << lspace << "';" if lspace
        src << stmt << ";"
        src << " _buf << '" << rspace << "';" if rspace
      end
    else                       # ${...}, $!{...}
      if !indicator
        src << " _buf << " << @escape << "(" << expr << ");"
      elsif indicator == '!'
        src << " _buf << (" << expr << ").to_s;"
      end
    end
  end
  #rest = $' || input                        # ruby1.8
  rest = pos == 0 ? input : input[pos..-1]   # ruby1.9
  #src << " _buf << '" << escape_text(rest) << "';"
  rest.gsub!(/['\\]/, '\\\\\&')
  src << " _buf << '" << rest << "';" unless rest.empty?
  src << "\n_buf.to_s\n"       # postamble
  return src
end

def evaluate(_context=Object.new)
  if _context.is_a?(Hash)
    _obj = Object.new
    _context.each do |k, v| _obj.instance_variable_set("@#{k}", v) end
    _context = _obj
  end
  _context.instance_eval @src
end

def initialize(input=nil, options={})
  @escape  = options[:escape] || 'Erubis::XmlHelper.escape_xml'
  @src = convert(input) if input
end

def result(_binding=TOPLEVEL_BINDING)
  eval @src, _binding
end