src/Pure/General/linear_set.scala
2017-04-04 ago tuned signature;
2016-10-24 ago discontinued unused / untested distinction of separate PIDE modules;
2015-01-08 ago tuned;
2014-04-22 ago accomodate scala-2.11.0: evade somewhat erratic fix of ImmutableSetFactory in Scala/bfa70315d72d;
2014-02-20 ago tuned imports;
2012-08-10 ago clarified Linear_Set.next/prev: check definedness;
2012-08-10 ago tuned;
2012-08-09 ago refined recover_spans: take visible range into account, reparse and trim results -- to improve editing experience wrt. unbalanced quotations etc.;
2012-08-09 ago tuned signature;
2012-08-09 ago more direct Linear_Set.reverse, swapping orientation of the graph;
2012-02-27 ago prefer final ADTs -- prevent ooddities;
2012-02-26 ago more PIDE modules;
2012-02-23 ago streamlined abstract datatype, eliminating odd representation class;
2012-02-23 ago tuned;
2011-05-12 ago minor adaption for scala-2.9.0.final;
2010-08-22 ago tuned;
2010-08-17 ago added functor Linear_Set, based on former adhoc structures in document.ML;
2010-08-13 ago added get_after convenience;
2010-05-29 ago avoid :\ which is not tail-recursive and tends to overflow the tiny JVM stack, which is not resizable at runtime;
2010-05-24 ago renamed "rev" to "reverse" following usual Scala conventions;
2010-05-22 ago added rev_iterator;
2010-05-10 ago adapted to scala-2.8.0.RC2;
2010-03-29 ago adapted to Scala 2.8.0 Beta1 -- with notable changes to scala.collection;
2010-01-10 ago elements with start entry;
2010-01-10 ago tuned;
2009-09-16 ago tuned;
2009-09-16 ago added append_after (tuned version of former insert_after of Seq);
2009-09-15 ago double linking for improved performance of "prev";
2009-09-01 ago misc cleanup and internal reorganization;
2009-09-01 ago added linear_set.scala from http://isabelle.in.tum.de/repos/isabelle-jedit/rev/d567692f9717