documentation update

[ginac.git] / ginac / expair.h

diff --git a/ginac/expair.h b/ginac/expair.h
index 925db97230ea8f471416b27ccedfe9a1328f6925..a170ae8649ba994b621ebc6ef15d51bde99c528f 100644 (file)
--- a/ginac/expair.h
+++ b/ginac/expair.h
@@ -3,7 +3,7 @@
  *  Definition of expression pairs (building blocks of expairseq). */
 
 /*
- *  GiNaC Copyright (C) 1999-2002 Johannes Gutenberg University Mainz, Germany
+ *  GiNaC Copyright (C) 1999-2003 Johannes Gutenberg University Mainz, Germany
  *
  *  This program is free software; you can redistribute it and/or modify
  *  it under the terms of the GNU General Public License as published by
@@ -102,11 +102,19 @@ public:
        ex coeff;   ///< second member of pair, must be numeric
 };
 
-/** Function objects for insertion into third argument of STL's sort() etc. */
+/** Function object for insertion into third argument of STL's sort() etc. */
 struct expair_is_less : public std::binary_function<expair, expair, bool> {
        bool operator()(const expair &lh, const expair &rh) const { return lh.is_less(rh); }
 };
 
+/** Function object not caring about the numerical coefficients for insertion
+ *  into third argument of STL's sort().  Note that this does not define a
+ *  strict weak ordering since for any symbol x we have neither 3*x<2*x or
+ *  2*x<3*x.  Handle with care! */
+struct expair_rest_is_less : public std::binary_function<expair, expair, bool> {
+       bool operator()(const expair &lh, const expair &rh) const { return (lh.rest.compare(rh.rest)<0); }
+};
+
 struct expair_swap : public std::binary_function<expair, expair, void> {
        void operator()(expair &lh, expair &rh) const { lh.swap(rh); }
 };