incomplete XML parser / Scala の parser combinator で XML の構文解析器を作ったが，まだ不完全

parse-xml.scala

import scala.util.parsing.combinator._

abstract class XML
case class Element(name: String, attributes: Map[String, String], contents: Seq[XML]) extends XML
case class Letter(c: Char) extends XML
case class CDATA(text: String) extends XML
case class CharEntity(c: Char) extends XML
case class Entity(c: Char) extends XML
case class Comment(text: String) extends XML

object parseXML extends RegexParsers {
  def name = "[a-zA-Z]+".r
  def value = """'(.*?)'|"(.*?)"""".r
  def attribute = name~"="~value ^^ {
    case x~"="~y => (x, y)
  }
  def startTag = "<"~>name~rep(attribute)<~">" ^^ {
    case x~y => (x, Map() ++ y)
  }
  def emptyTag = "<"~>name~rep(attribute)<~"/>" ^^ {
    case x~y => Element(x, Map() ++ y, Seq())
  }
  def endTag = "</"~>name<~">"
  def element: Parser[Element] = startTag~rep(content)~endTag ^^ {
    case (name, attribs)~contents~_ => Element(name, attribs, contents)
  }
  def content = (
      element
    | letter^^{s: String => Letter(s.charAt(0))}
    | cdata
    | charEntity
  )
  def letter = "[^&<>]".r
  def charEntity = "&#"~>"[0-9a-fA-F]+".r<~";" ^^ {hex: String => CharEntity(Integer.parseInt(hex, 16).toChar)}
  def cdata = "<![CDATA["~>"""[^\]]*""".r<~"]]>" ^^ { CDATA(_) }

  def apply(source: String) = println(parseAll(content, source))

  def main(args: Array[String]) {
    println("input: " + args(0))
    println(apply(args(0)))
  }
}