// regular expressions including recordsabstract class Rexp case object ZERO extends Rexpcase object ONE extends Rexpcase class CHAR(c: Char) extends Rexpcase class ALT(r1: Rexp, r2: Rexp) extends Rexp case class SEQ(r1: Rexp, r2: Rexp) extends Rexp case class STAR(r: Rexp) extends Rexp case class SPECIAL(s: String) extends Rexpdef nullable (r: Rexp) : Boolean = r match { case ZERO => false case ONE => true case CHAR(_) => false case ALT(r1, r2) => nullable(r1) || nullable(r2) case SEQ(r1, r2) => nullable(r1) && nullable(r2) case STAR(_) => true}def der(c: Char, r: Rexp) : Rexp = r match { case ZERO => ZERO case ONE => ZERO case CHAR(d) => if (c == d) ONE else ZERO case ALT(r1, r2) => ALT(der(c, r1), der(c, r2)) case SEQ(r1, r2) => if (nullable(r1)) ALT(SEQ(der(c, r1), r2), der(c, r2)) else SEQ(der(c, r1), r2) case STAR(r1) => SEQ(der(c, r1), STAR(r1))}def ders(s: List[Char], r: Rexp) : Rexp = s match { case Nil => r case c::s => ders(s, der(c, r))}def simp(r: Rexp) : Rexp = r match { case ALT(r1, r2) => (simp(r1), simp(r2)) match { case (ZERO, r2s) => r2s case (r1s, ZERO) => r1s case (r1s, r2s) => if (r1s == r2s) r1s else ALT (r1s, r2s) } case SEQ(r1, r2) => (simp(r1), simp(r2)) match { case (ZERO, _) => ZERO case (_, ZERO) => ZERO case (ONE, r2s) => r2s case (r1s, ONE) => r1s case (r1s, r2s) => SEQ(r1s, r2s) } case r => r}def ders_simp(s: List[Char], r: Rexp) : Rexp = s match { case Nil => r case c::s => ders_simp(s, simp(der(c, r)))}// scalatags import $ivy.`com.lihaoyi::scalatags:0.8.2` import scalatags.Text.all._import scalatags.Text._def pp(r: Rexp) : TypedTag[String] = r match { case CHAR(c) => li(code(c.toString)) case ALT(r1, r2) => li(code("+"), ul(pp(r1), pp(r2))) case SEQ(r1, r2) => li(code(raw("·")), ul(pp(r1), pp(r2))) case STAR(r1) => li(code("*"), ul(pp(r1))) case ZERO => li(code("0")) case ONE => li(code("1")) case SPECIAL(s) => li(code(raw(s)))} def mktree(r: Rexp) = ul(cls := "tree")(pp(r))def index(rs: List[Rexp]) = html( head(link(rel := "stylesheet", href := "./style.css")), body(rs.map(mktree)) )/*println(index(List(simple, test, evil2)))val simple = CHAR('a')val test = ALT(CHAR('a'), CHAR('b'))write.over(pwd/"t1.html", index(List(evil2, ders("a".toList, evil2), ders("aa".toList, evil2), ders("aaa".toList, evil2))))*/val evil2 = SEQ(STAR(STAR(CHAR('a'))), CHAR('b'))val r1 = STAR(ALT(SPECIAL("<i>r<sub>1</sub></i>"), SPECIAL("<i>r<sub>2</sub></i>")))val r2 = ALT(SPECIAL("<i>r<sub>1</sub></i>"), STAR(SPECIAL("<i>r<sub>2</sub></i>")))@maindef main(fname: String) = { val content = index(List(r1, r2, evil2)) os.write.over(os.pwd / fname, content)} // scalatags import $ivy.`com.lihaoyi::scalatags:0.8.2` import scalatags.Text.all._import scalatags.Text._def pp(r: Rexp) : TypedTag[String] = r match { case CHAR(c) => li(code(c.toString)) case ALTs(rs) => li(code("+"), ul(rs.map(pp))) case SEQs(rs) => li(code(raw("·")), ul(rs.map(pp))) case STAR(r1) => li(code("*"), ul(pp(r1))) case ZERO => li(code("0")) case ONE => li(code("1")) //case SPECIAL(s) => li(code(raw(s)))} def mktree(r: Rexp) = ul(cls := "tree")(pp(r))def index(rs: List[Rexp]) = html( head(link(rel := "stylesheet", href := "./style.css")), body(rs.map(mktree)) )@maindef main(fname: String) = { val r = ("a" | "ab" | "a") ~ ("c" | "bc") val strs = List("","a","ab","abc") val content = index(strs.map(s => ders(s.toList, r))) os.write.over(os.pwd / fname, content)}