gistfile1.rb

class HtmlTag < Parslet::Parser
  root(:tag)
  rule(:tag) do
    ( open_tag | close_tag | self_closing_tag ).as(:html_tag)
  end

  rule(:self_closing_tag) { str("<") >> tag_name >> attributes? >> (spaces? >> str("/")) >> str(">") }
  rule(:open_tag) { str("<") >> tag_name >> attributes? >> str(">") }
  rule(:close_tag) { str("</") >> tag_name >> str(">") }

  rule(:tag_name) { match("[A-Za-z_:]") >> name_char.repeat }

  rule(:attributes?) { attribute.repeat }

  rule(:attribute) do
    spaces >> attribute_name >> (str("=") >> attribute_value).maybe
  end
  rule(:attribute_name) { match("[A-Za-z_:]") >> name_char.repeat(1) }
  rule(:attribute_value) { (str('"') >> match('[^"]').repeat >> str('"') | str("'") >> match("[^']").repeat >> str("'") ) }

  rule(:name_char) { match("[\-A-Za-z0-9._:?]") }
  rule(:space) { match("[ \t]") }
  rule(:spaces) { space.repeat(1) }
  rule(:spaces?) { space.repeat }
end