diff --git a/src/Pure/General/symbol.scala b/src/Pure/General/symbol.scala
--- a/src/Pure/General/symbol.scala
+++ b/src/Pure/General/symbol.scala
@@ -1,668 +1,669 @@
 /*  Title:      Pure/General/symbol.scala
     Author:     Makarius
 
 Isabelle text symbols.
 */
 
 package isabelle
 
 
 import scala.collection.mutable
 import scala.util.matching.Regex
 import scala.annotation.tailrec
 
 
 object Symbol
 {
   type Symbol = String
 
   // counting Isabelle symbols, starting from 1
   type Offset = Text.Offset
   type Range = Text.Range
 
 
   /* spaces */
 
   val space_char = ' '
   val space = " "
 
   private val static_spaces = space * 4000
 
   def spaces(n: Int): String =
   {
     require(n >= 0, "negative spaces")
     if (n < static_spaces.length) static_spaces.substring(0, n)
     else space * n
   }
 
 
   /* ASCII characters */
 
   def is_ascii_printable(c: Char): Boolean = space_char <= c && c <= '~'
 
   def is_ascii_letter(c: Char): Boolean = 'A' <= c && c <= 'Z' || 'a' <= c && c <= 'z'
 
   def is_ascii_digit(c: Char): Boolean = '0' <= c && c <= '9'
 
   def is_ascii_hex(c: Char): Boolean =
     '0' <= c && c <= '9' || 'A' <= c && c <= 'F' || 'a' <= c && c <= 'f'
 
   def is_ascii_quasi(c: Char): Boolean = c == '_' || c == '\''
 
   def is_ascii_blank(c: Char): Boolean = " \t\n\u000b\f\r".contains(c)
 
   def is_ascii_line_terminator(c: Char): Boolean = "\r\n".contains(c)
 
   def is_ascii_letdig(c: Char): Boolean =
     is_ascii_letter(c) || is_ascii_digit(c) || is_ascii_quasi(c)
 
   def is_ascii_identifier(s: String): Boolean =
     s.length > 0 && is_ascii_letter(s(0)) && s.forall(is_ascii_letdig)
 
   def ascii(c: Char): Symbol =
   {
     if (c > 127) error("Non-ASCII character: " + quote(c.toString))
     else char_symbols(c.toInt)
   }
 
   def is_ascii(s: Symbol): Boolean = s.length == 1 && s(0) < 128
 
 
   /* symbol matching */
 
-  private val symbol_total = new Regex("""(?xs)
-    [\ud800-\udbff][\udc00-\udfff] | \r\n | \\ < \^? ([A-Za-z][A-Za-z0-9_']*)? >? | .""")
+  private val symbol_total =
+    new Regex("(?xs) [\ud800-\udbff][\udc00-\udfff] " +
+      """ | \r\n | \\ < \^? ([A-Za-z][A-Za-z0-9_']*)? >? | .""")
 
   private def is_plain(c: Char): Boolean =
     !(c == '\r' || c == '\\' || Character.isHighSurrogate(c))
 
   def is_malformed(s: Symbol): Boolean =
     s.length match {
       case 1 =>
         val c = s(0)
         Character.isHighSurrogate(c) || Character.isLowSurrogate(c) || c == '\ufffd'
       case 2 =>
         val c1 = s(0)
         val c2 = s(1)
         !(c1 == '\r' && c2 == '\n' || Character.isSurrogatePair(c1, c2))
       case _ => !s.endsWith(">") || s == "\\<>" || s == "\\<^>"
     }
 
   def is_newline(s: Symbol): Boolean =
     s == "\n" || s == "\r" || s == "\r\n"
 
   class Matcher(text: CharSequence)
   {
     private val matcher = symbol_total.pattern.matcher(text)
     def apply(start: Int, end: Int): Int =
     {
       require(0 <= start && start < end && end <= text.length, "bad matcher range")
       if (is_plain(text.charAt(start))) 1
       else {
         matcher.region(start, end).lookingAt
         matcher.group.length
       }
     }
   }
 
 
   /* iterator */
 
   private val char_symbols: Array[Symbol] =
     (0 until 256).iterator.map(i => new String(Array(i.toChar))).toArray
 
   def iterator(text: CharSequence): Iterator[Symbol] =
     new Iterator[Symbol]
     {
       private val matcher = new Matcher(text)
       private var i = 0
       def hasNext: Boolean = i < text.length
       def next(): Symbol =
       {
         val n = matcher(i, text.length)
         val s =
           if (n == 0) ""
           else if (n == 1) {
             val c = text.charAt(i)
             if (c < char_symbols.length) char_symbols(c)
             else text.subSequence(i, i + n).toString
           }
           else text.subSequence(i, i + n).toString
         i += n
         s
       }
     }
 
   def explode(text: CharSequence): List[Symbol] = iterator(text).toList
 
   def length(text: CharSequence): Int = iterator(text).length
 
   def trim_blanks(text: CharSequence): String =
     Library.trim(is_blank, explode(text)).mkString
 
   def all_blank(str: String): Boolean =
     iterator(str).forall(is_blank)
 
   def trim_blank_lines(text: String): String =
     cat_lines(split_lines(text).dropWhile(all_blank).reverse.dropWhile(all_blank).reverse)
 
 
   /* decoding offsets */
 
   object Index
   {
     private sealed case class Entry(chr: Int, sym: Int)
 
     val empty: Index = new Index(Nil)
 
     def apply(text: CharSequence): Index =
     {
       val matcher = new Matcher(text)
       val buf = new mutable.ListBuffer[Entry]
       var chr = 0
       var sym = 0
       while (chr < text.length) {
         val n = matcher(chr, text.length)
         chr += n
         sym += 1
         if (n > 1) buf += Entry(chr, sym)
       }
       if (buf.isEmpty) empty else new Index(buf.toList)
     }
   }
 
   final class Index private(entries: List[Index.Entry])
   {
     private val hash: Int = entries.hashCode
     private val index: Array[Index.Entry] = entries.toArray
 
     def decode(symbol_offset: Offset): Text.Offset =
     {
       val sym = symbol_offset - 1
       val end = index.length
       @tailrec def bisect(a: Int, b: Int): Int =
       {
         if (a < b) {
           val c = (a + b) / 2
           if (sym < index(c).sym) bisect(a, c)
           else if (c + 1 == end || sym < index(c + 1).sym) c
           else bisect(c + 1, b)
         }
         else -1
       }
       val i = bisect(0, end)
       if (i < 0) sym
       else index(i).chr + sym - index(i).sym
     }
     def decode(symbol_range: Range): Text.Range = symbol_range.map(decode)
 
     override def hashCode: Int = hash
     override def equals(that: Any): Boolean =
       that match {
         case other: Index => index.sameElements(other.index)
         case _ => false
       }
   }
 
 
   /* symbolic text chunks -- without actual text */
 
   object Text_Chunk
   {
     sealed abstract class Name
     case object Default extends Name
     case class Id(id: Document_ID.Generic) extends Name
     case class File(name: String) extends Name
 
     def apply(text: CharSequence): Text_Chunk =
       new Text_Chunk(Text.Range(0, text.length), Index(text))
   }
 
   final class Text_Chunk private(val range: Text.Range, private val index: Index)
   {
     override def hashCode: Int = (range, index).hashCode
     override def equals(that: Any): Boolean =
       that match {
         case other: Text_Chunk =>
           range == other.range &&
           index == other.index
         case _ => false
       }
 
     override def toString: String = "Text_Chunk" + range.toString
 
     def decode(symbol_offset: Offset): Text.Offset = index.decode(symbol_offset)
     def decode(symbol_range: Range): Text.Range = index.decode(symbol_range)
     def incorporate(symbol_range: Range): Option[Text.Range] =
     {
       def in(r: Range): Option[Text.Range] =
         range.try_restrict(decode(r)) match {
           case Some(r1) if !r1.is_singularity => Some(r1)
           case _ => None
         }
      in(symbol_range) orElse in(symbol_range - 1)
     }
   }
 
 
   /* recoding text */
 
   private class Recoder(list: List[(String, String)])
   {
     private val (min, max) =
     {
       var min = '\uffff'
       var max = '\u0000'
       for ((x, _) <- list) {
         val c = x(0)
         if (c < min) min = c
         if (c > max) max = c
       }
       (min, max)
     }
     private val table =
     {
       var tab = Map[String, String]()
       for ((x, y) <- list) {
         tab.get(x) match {
           case None => tab += (x -> y)
           case Some(z) =>
             error("Duplicate symbol mapping of " + quote(x) + " to " + quote(y) + " vs. " + quote(z))
         }
       }
       tab
     }
     def recode(text: String): String =
     {
       val len = text.length
       val matcher = symbol_total.pattern.matcher(text)
       val result = new StringBuilder(len)
       var i = 0
       while (i < len) {
         val c = text(i)
         if (min <= c && c <= max) {
           matcher.region(i, len).lookingAt
           val x = matcher.group
           result.append(table.getOrElse(x, x))
           i = matcher.end
         }
         else { result.append(c); i += 1 }
       }
       result.toString
     }
   }
 
 
 
   /** symbol interpretation **/
 
   val ARGUMENT_CARTOUCHE = "cartouche"
   val ARGUMENT_SPACE_CARTOUCHE = "space_cartouche"
 
   private lazy val symbols =
   {
     val contents =
       for (path <- Path.split(Isabelle_System.getenv("ISABELLE_SYMBOLS")) if path.is_file)
         yield (File.read(path))
     new Interpretation(cat_lines(contents))
   }
 
   private class Interpretation(symbols_spec: String)
   {
     /* read symbols */
 
     private val No_Decl = new Regex("""(?xs) ^\s* (?: \#.* )? $ """)
     private val Key = new Regex("""(?xs) (.+): """)
 
     private def read_decl(decl: String): (Symbol, Properties.T) =
     {
       def err() = error("Bad symbol declaration: " + decl)
 
       def read_props(props: List[String]): Properties.T =
       {
         props match {
           case Nil => Nil
           case _ :: Nil => err()
           case Key(x) :: y :: rest => (x -> y.replace('\u2423', ' ')) :: read_props(rest)
           case _ => err()
         }
       }
       decl.split("\\s+").toList match {
         case sym :: props if sym.length > 1 && !is_malformed(sym) =>
           (sym, read_props(props))
         case _ => err()
       }
     }
 
     private val symbols: List[(Symbol, Properties.T)] =
       (((List.empty[(Symbol, Properties.T)], Set.empty[Symbol]) /:
           split_lines(symbols_spec).reverse)
         { case (res, No_Decl()) => res
           case ((list, known), decl) =>
             val (sym, props) = read_decl(decl)
             if (known(sym)) (list, known)
             else ((sym, props) :: list, known + sym)
         })._1
 
 
     /* basic properties */
 
     val properties: Map[Symbol, Properties.T] = Map(symbols: _*)
 
     val names: Map[Symbol, (String, String)] =
     {
       val Name = new Regex("""\\<\^?([A-Za-z][A-Za-z0-9_']*)>""")
       val Argument = new Properties.String("argument")
       def argument(sym: Symbol, props: Properties.T): String =
         props match {
           case Argument(arg) =>
             if (arg == ARGUMENT_CARTOUCHE || arg == ARGUMENT_SPACE_CARTOUCHE) arg
             else error("Bad argument: " + quote(arg) + " for symbol " + quote(sym))
           case _ => ""
         }
       Map((for ((sym @ Name(a), props) <- symbols) yield sym -> (a, argument(sym, props))): _*)
     }
 
     val groups: List[(String, List[Symbol])] =
       symbols.flatMap({ case (sym, props) =>
         val gs = for (("group", g) <- props) yield g
         if (gs.isEmpty) List(sym -> "unsorted") else gs.map(sym -> _)
       }).groupBy(_._2).toList.map({ case (group, list) => (group, list.map(_._1)) })
         .sortBy(_._1)
 
     val abbrevs: Multi_Map[Symbol, String] =
       Multi_Map((
         for {
           (sym, props) <- symbols
           ("abbrev", a) <- props.reverse
         } yield sym -> a): _*)
 
     val codes: List[(Symbol, Int)] =
     {
       val Code = new Properties.String("code")
       for {
         (sym, props) <- symbols
         code <-
           props match {
             case Code(s) =>
               try { Some(Integer.decode(s).intValue) }
               catch { case _: NumberFormatException => error("Bad code for symbol " + sym) }
             case _ => None
           }
       } yield {
         if (code < 128) error("Illegal ASCII code for symbol " + sym)
         else (sym, code)
       }
     }
 
 
     /* recoding */
 
     private val (decoder, encoder) =
     {
       val mapping =
         for ((sym, code) <- codes) yield (sym, new String(Character.toChars(code)))
       (new Recoder(mapping), new Recoder(for ((x, y) <- mapping) yield (y, x)))
     }
 
     def decode(text: String): String = decoder.recode(text)
     def encode(text: String): String = encoder.recode(text)
 
     private def recode_set(elems: String*): Set[String] =
     {
       val content = elems.toList
       Set((content ::: content.map(decode)): _*)
     }
 
     private def recode_map[A](elems: (String, A)*): Map[String, A] =
     {
       val content = elems.toList
       Map((content ::: content.map({ case (sym, a) => (decode(sym), a) })): _*)
     }
 
 
     /* user fonts */
 
     private val Font = new Properties.String("font")
     val fonts: Map[Symbol, String] =
       recode_map((for ((sym, Font(font)) <- symbols) yield sym -> font): _*)
 
     val font_names: List[String] = Set(fonts.toList.map(_._2): _*).toList
     val font_index: Map[String, Int] = Map((font_names zip font_names.indices.toList): _*)
 
 
     /* classification */
 
     val letters: Set[String] = recode_set(
       "A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M",
       "N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z",
       "a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m",
       "n", "o", "p", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z",
 
       "\\<A>", "\\<B>", "\\<C>", "\\<D>", "\\<E>", "\\<F>", "\\<G>",
       "\\<H>", "\\<I>", "\\<J>", "\\<K>", "\\<L>", "\\<M>", "\\<N>",
       "\\<O>", "\\<P>", "\\<Q>", "\\<R>", "\\<S>", "\\<T>", "\\<U>",
       "\\<V>", "\\<W>", "\\<X>", "\\<Y>", "\\<Z>", "\\<a>", "\\<b>",
       "\\<c>", "\\<d>", "\\<e>", "\\<f>", "\\<g>", "\\<h>", "\\<i>",
       "\\<j>", "\\<k>", "\\<l>", "\\<m>", "\\<n>", "\\<o>", "\\<p>",
       "\\<q>", "\\<r>", "\\<s>", "\\<t>", "\\<u>", "\\<v>", "\\<w>",
       "\\<x>", "\\<y>", "\\<z>",
 
       "\\<AA>", "\\<BB>", "\\<CC>", "\\<DD>", "\\<EE>", "\\<FF>",
       "\\<GG>", "\\<HH>", "\\<II>", "\\<JJ>", "\\<KK>", "\\<LL>",
       "\\<MM>", "\\<NN>", "\\<OO>", "\\<PP>", "\\<QQ>", "\\<RR>",
       "\\<SS>", "\\<TT>", "\\<UU>", "\\<VV>", "\\<WW>", "\\<XX>",
       "\\<YY>", "\\<ZZ>", "\\<aa>", "\\<bb>", "\\<cc>", "\\<dd>",
       "\\<ee>", "\\<ff>", "\\<gg>", "\\<hh>", "\\<ii>", "\\<jj>",
       "\\<kk>", "\\<ll>", "\\<mm>", "\\<nn>", "\\<oo>", "\\<pp>",
       "\\<qq>", "\\<rr>", "\\<ss>", "\\<tt>", "\\<uu>", "\\<vv>",
       "\\<ww>", "\\<xx>", "\\<yy>", "\\<zz>",
 
       "\\<alpha>", "\\<beta>", "\\<gamma>", "\\<delta>", "\\<epsilon>",
       "\\<zeta>", "\\<eta>", "\\<theta>", "\\<iota>", "\\<kappa>",
       "\\<mu>", "\\<nu>", "\\<xi>", "\\<pi>", "\\<rho>", "\\<sigma>",
       "\\<tau>", "\\<upsilon>", "\\<phi>", "\\<chi>", "\\<psi>",
       "\\<omega>", "\\<Gamma>", "\\<Delta>", "\\<Theta>", "\\<Lambda>",
       "\\<Xi>", "\\<Pi>", "\\<Sigma>", "\\<Upsilon>", "\\<Phi>",
       "\\<Psi>", "\\<Omega>")
 
     val blanks: Set[String] = recode_set(space, "\t", "\n", "\u000B", "\f", "\r", "\r\n")
 
     val sym_chars =
       Set("!", "#", "$", "%", "&", "*", "+", "-", "/", "<", "=", ">", "?", "@", "^", "_", "|", "~")
 
     val symbolic: Set[String] = recode_set((for {(sym, _) <- symbols; if raw_symbolic(sym)} yield sym): _*)
 
 
     /* misc symbols */
 
     val newline_decoded = decode(newline)
     val comment_decoded = decode(comment)
     val cancel_decoded = decode(cancel)
     val latex_decoded = decode(latex)
     val marker_decoded = decode(marker)
     val open_decoded = decode(open)
     val close_decoded = decode(close)
 
 
     /* control symbols */
 
     val control_decoded: Set[Symbol] =
       Set((for ((sym, _) <- symbols if sym.startsWith("\\<^")) yield decode(sym)): _*)
 
     val sub_decoded = decode(sub)
     val sup_decoded = decode(sup)
     val bold_decoded = decode(bold)
     val emph_decoded = decode(emph)
     val bsub_decoded = decode(bsub)
     val esub_decoded = decode(esub)
     val bsup_decoded = decode(bsup)
     val esup_decoded = decode(esup)
   }
 
 
   /* tables */
 
   def properties: Map[Symbol, Properties.T] = symbols.properties
   def names: Map[Symbol, (String, String)] = symbols.names
   def groups: List[(String, List[Symbol])] = symbols.groups
   def abbrevs: Multi_Map[Symbol, String] = symbols.abbrevs
   def codes: List[(Symbol, Int)] = symbols.codes
   def groups_code: List[(String, List[Symbol])] =
   {
     val has_code = codes.iterator.map(_._1).toSet
     groups.flatMap({ case (group, symbols) =>
       val symbols1 = symbols.filter(has_code)
       if (symbols1.isEmpty) None else Some((group, symbols1))
     })
   }
 
   lazy val is_code: Int => Boolean = codes.map(_._2).toSet
   def decode(text: String): String = symbols.decode(text)
   def encode(text: String): String = symbols.encode(text)
 
   def decode_yxml(text: String, cache: XML.Cache = XML.Cache.none): XML.Body =
     YXML.parse_body(decode(text), cache = cache)
 
   def decode_yxml_failsafe(text: String, cache: XML.Cache = XML.Cache.none): XML.Body =
     YXML.parse_body_failsafe(decode(text), cache = cache)
 
   def encode_yxml(body: XML.Body): String = encode(YXML.string_of_body(body))
 
   def decode_strict(text: String): String =
   {
     val decoded = decode(text)
     if (encode(decoded) == text) decoded
     else {
       val bad = new mutable.ListBuffer[Symbol]
       for (s <- iterator(text) if encode(decode(s)) != s && !bad.contains(s))
         bad += s
       error("Bad Unicode symbols in text: " + commas_quote(bad))
     }
   }
 
   def output(unicode_symbols: Boolean, text: String): String =
     if (unicode_symbols) Symbol.decode(text) else Symbol.encode(text)
 
   def fonts: Map[Symbol, String] = symbols.fonts
   def font_names: List[String] = symbols.font_names
   def font_index: Map[String, Int] = symbols.font_index
   def lookup_font(sym: Symbol): Option[Int] = symbols.fonts.get(sym).map(font_index(_))
 
 
   /* classification */
 
   def is_letter(sym: Symbol): Boolean = symbols.letters.contains(sym)
   def is_digit(sym: Symbol): Boolean = sym.length == 1 && '0' <= sym(0) && sym(0) <= '9'
   def is_quasi(sym: Symbol): Boolean = sym == "_" || sym == "'"
   def is_letdig(sym: Symbol): Boolean = is_letter(sym) || is_digit(sym) || is_quasi(sym)
   def is_blank(sym: Symbol): Boolean = symbols.blanks.contains(sym)
 
 
   /* symbolic newline */
 
   val newline: Symbol = "\\<newline>"
   def newline_decoded: Symbol = symbols.newline_decoded
 
   def print_newlines(str: String): String =
     if (str.contains('\n'))
       (for (s <- iterator(str)) yield { if (s == "\n") newline_decoded else s }).mkString
     else str
 
 
   /* formal comments */
 
   val comment: Symbol = "\\<comment>"
   val cancel: Symbol = "\\<^cancel>"
   val latex: Symbol = "\\<^latex>"
   val marker: Symbol = "\\<^marker>"
 
   def comment_decoded: Symbol = symbols.comment_decoded
   def cancel_decoded: Symbol = symbols.cancel_decoded
   def latex_decoded: Symbol = symbols.latex_decoded
   def marker_decoded: Symbol = symbols.marker_decoded
 
 
   /* cartouches */
 
   val open: Symbol = "\\<open>"
   val close: Symbol = "\\<close>"
 
   def open_decoded: Symbol = symbols.open_decoded
   def close_decoded: Symbol = symbols.close_decoded
 
   def is_open(sym: Symbol): Boolean = sym == open_decoded || sym == open
   def is_close(sym: Symbol): Boolean = sym == close_decoded || sym == close
 
   def cartouche(s: String): String = open + s + close
   def cartouche_decoded(s: String): String = open_decoded + s + close_decoded
 
 
   /* symbols for symbolic identifiers */
 
   private def raw_symbolic(sym: Symbol): Boolean =
     sym.startsWith("\\<") && sym.endsWith(">") && !sym.startsWith("\\<^")
 
   def is_symbolic(sym: Symbol): Boolean =
     !is_open(sym) && !is_close(sym) && (raw_symbolic(sym) || symbols.symbolic.contains(sym))
 
   def is_symbolic_char(sym: Symbol): Boolean = symbols.sym_chars.contains(sym)
 
 
   /* control symbols */
 
   val control_prefix = "\\<^"
   val control_suffix = ">"
 
   def control_name(sym: Symbol): Option[String] =
     if (is_control_encoded(sym))
       Some(sym.substring(control_prefix.length, sym.length - control_suffix.length))
     else None
 
   def is_control_encoded(sym: Symbol): Boolean =
     sym.startsWith(control_prefix) && sym.endsWith(control_suffix)
 
   def is_control(sym: Symbol): Boolean =
     is_control_encoded(sym) || symbols.control_decoded.contains(sym)
 
   def is_controllable(sym: Symbol): Boolean =
     !is_blank(sym) && !is_control(sym) && !is_open(sym) && !is_close(sym) &&
     !is_malformed(sym) && sym != "\""
 
   val sub: Symbol = "\\<^sub>"
   val sup: Symbol = "\\<^sup>"
   val bold: Symbol = "\\<^bold>"
   val emph: Symbol = "\\<^emph>"
   val bsub: Symbol = "\\<^bsub>"
   val esub: Symbol = "\\<^esub>"
   val bsup: Symbol = "\\<^bsup>"
   val esup: Symbol = "\\<^esup>"
 
   def sub_decoded: Symbol = symbols.sub_decoded
   def sup_decoded: Symbol = symbols.sup_decoded
   def bold_decoded: Symbol = symbols.bold_decoded
   def emph_decoded: Symbol = symbols.emph_decoded
   def bsub_decoded: Symbol = symbols.bsub_decoded
   def esub_decoded: Symbol = symbols.esub_decoded
   def bsup_decoded: Symbol = symbols.bsup_decoded
   def esup_decoded: Symbol = symbols.esup_decoded
 
 
   /* metric */
 
   def is_printable(sym: Symbol): Boolean =
     if (is_ascii(sym)) is_ascii_printable(sym(0))
     else !is_control(sym)
 
   object Metric extends Pretty.Metric
   {
     val unit = 1.0
     def apply(str: String): Double =
       (for (s <- iterator(str)) yield {
         val sym = encode(s)
         if (sym.startsWith("\\<long") || sym.startsWith("\\<Long")) 2
         else if (is_printable(sym)) 1
         else 0
       }).sum
   }
 }
diff --git a/src/Pure/library.scala b/src/Pure/library.scala
--- a/src/Pure/library.scala
+++ b/src/Pure/library.scala
@@ -1,299 +1,299 @@
 /*  Title:      Pure/library.scala
     Author:     Makarius
 
 Basic library.
 */
 
 package isabelle
 
 
 import scala.annotation.tailrec
 import scala.collection.mutable
 import scala.util.matching.Regex
 
 
 object Library
 {
   /* resource management */
 
   def using[A <: AutoCloseable, B](a: A)(f: A => B): B =
   {
     try { f(a) }
     finally { if (a != null) a.close() }
   }
 
 
   /* integers */
 
   private val small_int = 10000
   private lazy val small_int_table =
   {
     val array = new Array[String](small_int)
     for (i <- 0 until small_int) array(i) = i.toString
     array
   }
 
   def is_small_int(s: String): Boolean =
   {
     val len = s.length
     1 <= len && len <= 4 &&
     s.forall(c => '0' <= c && c <= '9') &&
     (len == 1 || s(0) != '0')
   }
 
   def signed_string_of_long(i: Long): String =
     if (0 <= i && i < small_int) small_int_table(i.toInt)
     else i.toString
 
   def signed_string_of_int(i: Int): String =
     if (0 <= i && i < small_int) small_int_table(i)
     else i.toString
 
 
   /* separated chunks */
 
   def separate[A](s: A, list: List[A]): List[A] =
   {
     val result = new mutable.ListBuffer[A]
     var first = true
     for (x <- list) {
       if (first) {
         first = false
         result += x
       }
       else {
         result += s
         result += x
       }
     }
     result.toList
   }
 
   def separated_chunks(sep: Char => Boolean, source: CharSequence): Iterator[CharSequence] =
     new Iterator[CharSequence] {
       private val end = source.length
       private def next_chunk(i: Int): Option[(CharSequence, Int)] =
       {
         if (i < end) {
           var j = i; do j += 1 while (j < end && !sep(source.charAt(j)))
           Some((source.subSequence(i + 1, j), j))
         }
         else None
       }
       private var state: Option[(CharSequence, Int)] = if (end == 0) None else next_chunk(-1)
 
       def hasNext: Boolean = state.isDefined
       def next(): CharSequence =
         state match {
           case Some((s, i)) => state = next_chunk(i); s
           case None => Iterator.empty.next()
         }
     }
 
   def space_explode(sep: Char, str: String): List[String] =
     separated_chunks(_ == sep, str).map(_.toString).toList
 
 
   /* lines */
 
   def terminate_lines(lines: TraversableOnce[String]): String = lines.mkString("", "\n", "\n")
 
   def cat_lines(lines: TraversableOnce[String]): String = lines.mkString("\n")
 
   def split_lines(str: String): List[String] = space_explode('\n', str)
 
   def prefix_lines(prfx: String, str: String): String =
     if (str == "") str else cat_lines(split_lines(str).map(prfx + _))
 
   def first_line(source: CharSequence): String =
   {
     val lines = separated_chunks(_ == '\n', source)
     if (lines.hasNext) lines.next().toString
     else ""
   }
 
   def trim_line(s: String): String =
     if (s.endsWith("\r\n")) s.substring(0, s.length - 2)
     else if (s.endsWith("\r") || s.endsWith("\n")) s.substring(0, s.length - 1)
     else s
 
   def trim_split_lines(s: String): List[String] =
     split_lines(trim_line(s)).map(trim_line)
 
   def encode_lines(s: String): String = s.replace('\n', '\u000b')
   def decode_lines(s: String): String = s.replace('\u000b', '\n')
 
 
   /* strings */
 
   def cat_strings0(strs: TraversableOnce[String]): String = strs.mkString("\u0000")
   def split_strings0(str: String): List[String] = space_explode('\u0000', str)
 
   def make_string(f: StringBuilder => Unit): String =
   {
     val s = new StringBuilder
     f(s)
     s.toString
   }
 
   def try_unprefix(prfx: String, s: String): Option[String] =
     if (s.startsWith(prfx)) Some(s.substring(prfx.length)) else None
 
   def try_unsuffix(sffx: String, s: String): Option[String] =
     if (s.endsWith(sffx)) Some(s.substring(0, s.length - sffx.length)) else None
 
   def perhaps_unprefix(prfx: String, s: String): String = try_unprefix(prfx, s) getOrElse s
   def perhaps_unsuffix(sffx: String, s: String): String = try_unsuffix(sffx, s) getOrElse s
 
   def isolate_substring(s: String): String = new String(s.toCharArray)
 
   def strip_ansi_color(s: String): String =
-    s.replaceAll("""\u001b\[\d+m""", "")
+    s.replaceAll("\u001b\\[\\d+m", "")
 
 
   /* quote */
 
   def single_quote(s: String): String = "'" + s + "'"
 
   def quote(s: String): String = "\"" + s + "\""
 
   def try_unquote(s: String): Option[String] =
     if (s.startsWith("\"") && s.endsWith("\"")) Some(s.substring(1, s.length - 1))
     else None
 
   def perhaps_unquote(s: String): String = try_unquote(s) getOrElse s
 
   def commas(ss: Iterable[String]): String = ss.iterator.mkString(", ")
   def commas_quote(ss: Iterable[String]): String = ss.iterator.map(quote).mkString(", ")
 
 
   /* CharSequence */
 
   class Reverse(text: CharSequence, start: Int, end: Int) extends CharSequence
   {
     require(0 <= start && start <= end && end <= text.length, "bad reverse range")
 
     def this(text: CharSequence) = this(text, 0, text.length)
 
     def length: Int = end - start
     def charAt(i: Int): Char = text.charAt(end - i - 1)
 
     def subSequence(i: Int, j: Int): CharSequence =
       if (0 <= i && i <= j && j <= length) new Reverse(text, end - j, end - i)
       else throw new IndexOutOfBoundsException
 
     override def toString: String =
     {
       val buf = new StringBuilder(length)
       for (i <- 0 until length)
         buf.append(charAt(i))
       buf.toString
     }
   }
 
   class Line_Termination(text: CharSequence) extends CharSequence
   {
     def length: Int = text.length + 1
     def charAt(i: Int): Char = if (i == text.length) '\n' else text.charAt(i)
     def subSequence(i: Int, j: Int): CharSequence =
       if (j == text.length + 1) new Line_Termination(text.subSequence(i, j - 1))
       else text.subSequence(i, j)
     override def toString: String = text.toString + "\n"
   }
 
 
   /* regular expressions */
 
   def make_regex(s: String): Option[Regex] =
     try { Some(new Regex(s)) } catch { case ERROR(_) => None }
 
   def is_regex_meta(c: Char): Boolean = """()[]{}\^$|?*+.<>-=!""".contains(c)
 
   def escape_regex(s: String): String =
     if (s.exists(is_regex_meta)) {
       (for (c <- s.iterator)
        yield { if (is_regex_meta(c)) "\\" + c.toString else c.toString }).mkString
     }
     else s
 
 
   /* lists */
 
   def take_prefix[A](pred: A => Boolean, xs: List[A]): (List[A], List[A]) =
     (xs.takeWhile(pred), xs.dropWhile(pred))
 
   def take_suffix[A](pred: A => Boolean, xs: List[A]): (List[A], List[A]) =
   {
     val rev_xs = xs.reverse
     (rev_xs.dropWhile(pred).reverse, rev_xs.takeWhile(pred).reverse)
   }
 
   def trim[A](pred: A => Boolean, xs: List[A]): List[A] =
     take_suffix(pred, take_prefix(pred, xs)._2)._1
 
   def member[A, B](xs: List[A])(x: B): Boolean = xs.contains(x)
   def insert[A](x: A)(xs: List[A]): List[A] = if (xs.contains(x)) xs else x :: xs
   def remove[A, B](x: B)(xs: List[A]): List[A] = if (member(xs)(x)) xs.filterNot(_ == x) else xs
   def update[A](x: A)(xs: List[A]): List[A] = x :: remove(x)(xs)
 
   def merge[A](xs: List[A], ys: List[A]): List[A] =
     if (xs.eq(ys)) xs
     else if (xs.isEmpty) ys
     else ys.foldRight(xs)(Library.insert(_)(_))
 
   def distinct[A](xs: List[A], eq: (A, A) => Boolean = (x: A, y: A) => x == y): List[A] =
   {
     val result = new mutable.ListBuffer[A]
     xs.foreach(x => if (!result.exists(y => eq(x, y))) result += x)
     result.toList
   }
 
   def duplicates[A](lst: List[A], eq: (A, A) => Boolean = (x: A, y: A) => x == y): List[A] =
   {
     val result = new mutable.ListBuffer[A]
     @tailrec def dups(rest: List[A]): Unit =
       rest match {
         case Nil =>
         case x :: xs =>
           if (!result.exists(y => eq(x, y)) && xs.exists(y => eq(x, y))) result += x
           dups(xs)
       }
     dups(lst)
     result.toList
   }
 
   def replicate[A](n: Int, a: A): List[A] =
     if (n < 0) throw new IllegalArgumentException
     else if (n == 0) Nil
     else {
       val res = new mutable.ListBuffer[A]
       (1 to n).foreach(_ => res += a)
       res.toList
     }
 
 
   /* proper values */
 
   def proper_string(s: String): Option[String] =
     if (s == null || s == "") None else Some(s)
 
   def proper_list[A](list: List[A]): Option[List[A]] =
     if (list == null || list.isEmpty) None else Some(list)
 
 
   /* reflection */
 
   def is_subclass[A, B](a: Class[A], b: Class[B]): Boolean =
   {
     import scala.language.existentials
     @tailrec def subclass(c: Class[_]): Boolean =
     {
       c == b ||
         {
           val d = c.getSuperclass
           d != null && subclass(d)
         }
     }
     subclass(a)
   }
 }