Remove expairseq::construct_from_2_ex_via_exvector() member function.
[ginac.git] / ginac / expairseq.cpp
index 296575a8382f770ae26bc714ab9ebb02806bdbe6..11da774902a1d17994674291f674a0a022526482 100644 (file)
@@ -3,7 +3,7 @@
  *  Implementation of sequences of expression pairs. */
 
 /*
- *  GiNaC Copyright (C) 1999-2010 Johannes Gutenberg University Mainz, Germany
+ *  GiNaC Copyright (C) 1999-2015 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
 #include "utils.h"
 #include "hash_seed.h"
 #include "indexed.h"
+#include "compiler.h"
 
 #include <algorithm>
-#if EXPAIRSEQ_USE_HASHTAB
-#include <cmath>
-#endif // EXPAIRSEQ_USE_HASHTAB
 #include <iostream>
 #include <iterator>
+#include <memory>
 #include <stdexcept>
 #include <string>
 
@@ -70,40 +69,10 @@ public:
 // public
 
 expairseq::expairseq() 
-#if EXPAIRSEQ_USE_HASHTAB
-       : hashtabsize(0)
-#endif // EXPAIRSEQ_USE_HASHTAB
 {}
 
 // protected
 
-#if 0
-/** For use by copy ctor and assignment operator. */
-void expairseq::copy(const expairseq &other)
-{
-       seq = other.seq;
-       overall_coeff = other.overall_coeff;
-#if EXPAIRSEQ_USE_HASHTAB
-       // copy hashtab
-       hashtabsize = other.hashtabsize;
-       if (hashtabsize!=0) {
-               hashmask = other.hashmask;
-               hashtab.resize(hashtabsize);
-               epvector::const_iterator osb = other.seq.begin();
-               for (unsigned i=0; i<hashtabsize; ++i) {
-                       hashtab[i].clear();
-                       for (epplist::const_iterator cit=other.hashtab[i].begin();
-                            cit!=other.hashtab[i].end(); ++cit) {
-                               hashtab[i].push_back(seq.begin()+((*cit)-osb));
-                       }
-               }
-       } else {
-               hashtab.clear();
-       }
-#endif // EXPAIRSEQ_USE_HASHTAB
-}
-#endif
-
 //////////
 // other constructors
 //////////
@@ -128,12 +97,11 @@ expairseq::expairseq(const epvector &v, const ex &oc, bool do_index_renaming)
        GINAC_ASSERT(is_canonical());
 }
 
-expairseq::expairseq(std::auto_ptr<epvector> vp, const ex &oc, bool do_index_renaming)
+expairseq::expairseq(epvector && vp, const ex &oc, bool do_index_renaming)
   :  overall_coeff(oc)
 {
-       GINAC_ASSERT(vp.get()!=0);
        GINAC_ASSERT(is_a<numeric>(oc));
-       construct_from_epvector(*vp, do_index_renaming);
+       construct_from_epvector(std::move(vp), do_index_renaming);
        GINAC_ASSERT(is_canonical());
 }
 
@@ -144,12 +112,12 @@ expairseq::expairseq(std::auto_ptr<epvector> vp, const ex &oc, bool do_index_ren
 void expairseq::read_archive(const archive_node &n, lst &sym_lst) 
 {
        inherited::read_archive(n, sym_lst);
-       archive_node::archive_node_cit first = n.find_first("rest");
-       archive_node::archive_node_cit last = n.find_last("coeff");
+       auto first = n.find_first("rest");
+       auto last = n.find_last("coeff");
        ++last;
        seq.reserve((last-first)/2);
 
-       for (archive_node::archive_node_cit loc = first; loc < last;) {
+       for (auto loc = first; loc < last;) {
                ex rest;
                ex coeff;
                n.find_ex_by_loc(loc++, rest, sym_lst);
@@ -166,11 +134,9 @@ void expairseq::read_archive(const archive_node &n, lst &sym_lst)
 void expairseq::archive(archive_node &n) const
 {
        inherited::archive(n);
-       epvector::const_iterator i = seq.begin(), iend = seq.end();
-       while (i != iend) {
-               n.add_ex("rest", i->rest);
-               n.add_ex("coeff", i->coeff);
-               ++i;
+       for (auto & i : seq) {
+               n.add_ex("rest", i.rest);
+               n.add_ex("coeff", i.coeff);
        }
        n.add_ex("overall_coeff", overall_coeff);
 }
@@ -208,59 +174,6 @@ void expairseq::do_print_tree(const print_tree & c, unsigned level) const
                overall_coeff.print(c, level + c.delta_indent);
        }
        c.s << std::string(level + c.delta_indent,' ') << "=====" << std::endl;
-#if EXPAIRSEQ_USE_HASHTAB
-       c.s << std::string(level + c.delta_indent,' ')
-           << "hashtab size " << hashtabsize << std::endl;
-       if (hashtabsize == 0) return;
-#define MAXCOUNT 5
-       unsigned count[MAXCOUNT+1];
-       for (int i=0; i<MAXCOUNT+1; ++i)
-               count[i] = 0;
-       unsigned this_bin_fill;
-       unsigned cum_fill_sq = 0;
-       unsigned cum_fill = 0;
-       for (unsigned i=0; i<hashtabsize; ++i) {
-               this_bin_fill = 0;
-               if (hashtab[i].size() > 0) {
-                       c.s << std::string(level + c.delta_indent, ' ')
-                           << "bin " << i << " with entries ";
-                       for (epplist::const_iterator it=hashtab[i].begin();
-                            it!=hashtab[i].end(); ++it) {
-                               c.s << *it-seq.begin() << " ";
-                               ++this_bin_fill;
-                       }
-                       c.s << std::endl;
-                       cum_fill += this_bin_fill;
-                       cum_fill_sq += this_bin_fill*this_bin_fill;
-               }
-               if (this_bin_fill<MAXCOUNT)
-                       ++count[this_bin_fill];
-               else
-                       ++count[MAXCOUNT];
-       }
-       unsigned fact = 1;
-       double cum_prob = 0;
-       double lambda = (1.0*seq.size()) / hashtabsize;
-       for (int k=0; k<MAXCOUNT; ++k) {
-               if (k>0)
-                       fact *= k;
-               double prob = std::pow(lambda,k)/fact * std::exp(-lambda);
-               cum_prob += prob;
-               c.s << std::string(level + c.delta_indent, ' ') << "bins with " << k << " entries: "
-                   << int(1000.0*count[k]/hashtabsize)/10.0 << "% (expected: "
-                   << int(prob*1000)/10.0 << ")" << std::endl;
-       }
-       c.s << std::string(level + c.delta_indent, ' ') << "bins with more entries: "
-           << int(1000.0*count[MAXCOUNT]/hashtabsize)/10.0 << "% (expected: "
-           << int((1-cum_prob)*1000)/10.0 << ")" << std::endl;
-
-       c.s << std::string(level + c.delta_indent, ' ') << "variance: "
-           << 1.0/hashtabsize*cum_fill_sq-(1.0/hashtabsize*cum_fill)*(1.0/hashtabsize*cum_fill)
-           << std::endl;
-       c.s << std::string(level + c.delta_indent, ' ') << "average fill: "
-           << (1.0*cum_fill)/hashtabsize
-           << " (should be equal to " << (1.0*seq.size())/hashtabsize << ")" << std::endl;
-#endif // EXPAIRSEQ_USE_HASHTAB
 }
 
 bool expairseq::info(unsigned inf) const
@@ -273,8 +186,8 @@ bool expairseq::info(unsigned inf) const
                                return true;
                        else if (flags & status_flags::has_no_indices)
                                return false;
-                       for (epvector::const_iterator i = seq.begin(); i != seq.end(); ++i) {
-                               if (i->rest.info(info_flags::has_indices)) {
+                       for (auto & i : seq) {
+                               if (i.rest.info(info_flags::has_indices)) {
                                        this->setflag(status_flags::has_indices);
                                        this->clearflag(status_flags::has_no_indices);
                                        return true;
@@ -306,46 +219,43 @@ ex expairseq::op(size_t i) const
 
 ex expairseq::map(map_function &f) const
 {
-       std::auto_ptr<epvector> v(new epvector);
-       v->reserve(seq.size()+1);
+       epvector v;
+       v.reserve(seq.size()+1);
 
-       epvector::const_iterator cit = seq.begin(), last = seq.end();
-       while (cit != last) {
-               v->push_back(split_ex_to_pair(f(recombine_pair_to_ex(*cit))));
-               ++cit;
-       }
+       for (auto & it : seq)
+               v.push_back(split_ex_to_pair(f(recombine_pair_to_ex(it))));
 
        if (overall_coeff.is_equal(default_overall_coeff()))
-               return thisexpairseq(v, default_overall_coeff(), true);
+               return thisexpairseq(std::move(v), default_overall_coeff(), true);
        else {
                ex newcoeff = f(overall_coeff);
                if(is_a<numeric>(newcoeff))
-                       return thisexpairseq(v, newcoeff, true);
+                       return thisexpairseq(std::move(v), newcoeff, true);
                else {
-                       v->push_back(split_ex_to_pair(newcoeff));
-                       return thisexpairseq(v, default_overall_coeff(), true);
+                       v.push_back(split_ex_to_pair(newcoeff));
+                       return thisexpairseq(std::move(v), default_overall_coeff(), true);
                }
        }
 }
 
 /** Perform coefficient-wise automatic term rewriting rules in this class. */
-ex expairseq::eval(int level) const
+ex expairseq::eval() const
 {
-       if ((level==1) && (flags &status_flags::evaluated))
+       if (flags &status_flags::evaluated)
                return *this;
-       
-       std::auto_ptr<epvector> vp = evalchildren(level);
-       if (vp.get() == 0)
+
+       const epvector evaled = evalchildren();
+       if (!evaled.empty())
+               return dynallocate<expairseq>(std::move(evaled), overall_coeff).setflag(status_flags::evaluated);
+       else
                return this->hold();
-       
-       return (new expairseq(vp, overall_coeff))->setflag(status_flags::dynallocated | status_flags::evaluated);
 }
 
 epvector* conjugateepvector(const epvector&epv)
 {
-       epvector *newepv = 0;
-       for (epvector::const_iterator i=epv.begin(); i!=epv.end(); ++i) {
-               if(newepv) {
+       epvector *newepv = nullptr;
+       for (auto i=epv.begin(); i!=epv.end(); ++i) {
+               if (newepv) {
                        newepv->push_back(i->conjugate());
                        continue;
                }
@@ -365,27 +275,15 @@ epvector* conjugateepvector(const epvector&epv)
 
 ex expairseq::conjugate() const
 {
-       epvector* newepv = conjugateepvector(seq);
+       std::unique_ptr<epvector> newepv(conjugateepvector(seq));
        ex x = overall_coeff.conjugate();
-       if (!newepv && are_ex_trivially_equal(x, overall_coeff)) {
-               return *this;
-       }
-       ex result = thisexpairseq(newepv ? *newepv : seq, x);
        if (newepv) {
-               delete newepv;
+               return thisexpairseq(std::move(*newepv), x);
        }
-       return result;
-}
-
-bool expairseq::is_polynomial(const ex & var) const
-{
-       if (!is_exactly_a<add>(*this) && !is_exactly_a<mul>(*this))
-               return basic::is_polynomial(var);
-       for (epvector::const_iterator i=seq.begin(); i!=seq.end(); ++i) {
-               if (!(i->rest).is_polynomial(var))
-                       return false;
+       if (are_ex_trivially_equal(x, overall_coeff)) {
+               return *this;
        }
-       return true;
+       return thisexpairseq(seq, x);
 }
 
 bool expairseq::match(const ex & pattern, exmap & repl_lst) const
@@ -407,6 +305,12 @@ bool expairseq::match(const ex & pattern, exmap & repl_lst) const
                        }
                }
 
+               // Even if the expression does not match the pattern, some of
+               // its subexpressions could match it. For example, x^5*y^(-1)
+               // does not match the pattern $0^5, but its subexpression x^5
+               // does. So, save repl_lst in order to not add bogus entries.
+               exmap tmp_repl = repl_lst;
+
                // Unfortunately, this is an O(N^2) operation because we can't
                // sort the pattern in a useful way...
 
@@ -422,9 +326,9 @@ bool expairseq::match(const ex & pattern, exmap & repl_lst) const
                        ex p = pattern.op(i);
                        if (has_global_wildcard && p.is_equal(global_wildcard))
                                continue;
-                       exvector::iterator it = ops.begin(), itend = ops.end();
+                       auto it = ops.begin(), itend = ops.end();
                        while (it != itend) {
-                               if (it->match(p, repl_lst)) {
+                               if (it->match(p, tmp_repl)) {
                                        ops.erase(it);
                                        goto found;
                                }
@@ -440,15 +344,21 @@ found:            ;
                        // it has already been matched before, in which case the matches
                        // must be equal)
                        size_t num = ops.size();
-                       std::auto_ptr<epvector> vp(new epvector);
-                       vp->reserve(num);
+                       epvector vp;
+                       vp.reserve(num);
                        for (size_t i=0; i<num; i++)
-                               vp->push_back(split_ex_to_pair(ops[i]));
-                       ex rest = thisexpairseq(vp, default_overall_coeff());
-                       for (exmap::const_iterator it = repl_lst.begin(); it != repl_lst.end(); ++it) {
-                               if (it->first.is_equal(global_wildcard))
-                                       return rest.is_equal(it->second);
+                               vp.push_back(split_ex_to_pair(ops[i]));
+                       ex rest = thisexpairseq(std::move(vp), default_overall_coeff());
+                       for (auto & it : tmp_repl) {
+                               if (it.first.is_equal(global_wildcard)) {
+                                       if (rest.is_equal(it.second)) {
+                                               repl_lst = tmp_repl;
+                                               return true;
+                                       }
+                                       return false;
+                               }
                        }
+                       repl_lst = tmp_repl;
                        repl_lst[global_wildcard] = rest;
                        return true;
 
@@ -456,7 +366,11 @@ found:             ;
 
                        // No global wildcard, then the match fails if there are any
                        // unmatched terms left
-                       return ops.empty();
+                       if (ops.empty()) {
+                               repl_lst = tmp_repl;
+                               return true;
+                       }
+                       return false;
                }
        }
        return inherited::match(pattern, repl_lst);
@@ -464,9 +378,9 @@ found:              ;
 
 ex expairseq::subs(const exmap & m, unsigned options) const
 {
-       std::auto_ptr<epvector> vp = subschildren(m, options);
-       if (vp.get())
-               return ex_to<basic>(thisexpairseq(vp, overall_coeff, true));
+       epvector subsed = subschildren(m, options);
+       if (!subsed.empty())
+               return ex_to<basic>(thisexpairseq(std::move(subsed), overall_coeff, (options & subs_options::no_index_renaming) == 0));
        else if ((options & subs_options::algebraic) && is_exactly_a<mul>(*this))
                return static_cast<const mul *>(this)->algebraic_subs_mul(m, options);
        else
@@ -491,54 +405,17 @@ int expairseq::compare_same_type(const basic &other) const
        if (cmpval!=0)
                return cmpval;
        
-#if EXPAIRSEQ_USE_HASHTAB
-       GINAC_ASSERT(hashtabsize==o.hashtabsize);
-       if (hashtabsize==0) {
-#endif // EXPAIRSEQ_USE_HASHTAB
-               epvector::const_iterator cit1 = seq.begin();
-               epvector::const_iterator cit2 = o.seq.begin();
-               epvector::const_iterator last1 = seq.end();
-               epvector::const_iterator last2 = o.seq.end();
-               
-               for (; (cit1!=last1)&&(cit2!=last2); ++cit1, ++cit2) {
-                       cmpval = (*cit1).compare(*cit2);
-                       if (cmpval!=0) return cmpval;
-               }
+       auto cit1 = seq.begin(), last1 = seq.end();
+       auto cit2 = o.seq.begin(), last2 = o.seq.end();
+       for (; (cit1!=last1) && (cit2!=last2); ++cit1, ++cit2) {
+               cmpval = (*cit1).compare(*cit2);
+               if (cmpval!=0) return cmpval;
+       }
                
-               GINAC_ASSERT(cit1==last1);
-               GINAC_ASSERT(cit2==last2);
+       GINAC_ASSERT(cit1==last1);
+       GINAC_ASSERT(cit2==last2);
                
-               return 0;
-#if EXPAIRSEQ_USE_HASHTAB
-       }
-       
-       // compare number of elements in each hashtab entry
-       for (unsigned i=0; i<hashtabsize; ++i) {
-               unsigned cursize=hashtab[i].size();
-               if (cursize != o.hashtab[i].size())
-                       return (cursize < o.hashtab[i].size()) ? -1 : 1;
-       }
-       
-       // compare individual (sorted) hashtab entries
-       for (unsigned i=0; i<hashtabsize; ++i) {
-               unsigned sz = hashtab[i].size();
-               if (sz>0) {
-                       const epplist &eppl1 = hashtab[i];
-                       const epplist &eppl2 = o.hashtab[i];
-                       epplist::const_iterator it1 = eppl1.begin();
-                       epplist::const_iterator it2 = eppl2.begin();
-                       while (it1!=eppl1.end()) {
-                               cmpval = (*(*it1)).compare(*(*it2));
-                               if (cmpval!=0)
-                                       return cmpval;
-                               ++it1;
-                               ++it2;
-                       }
-               }
-       }
-       
-       return 0; // equal
-#endif // EXPAIRSEQ_USE_HASHTAB
+       return 0;
 }
 
 bool expairseq::is_equal_same_type(const basic &other) const
@@ -553,56 +430,14 @@ bool expairseq::is_equal_same_type(const basic &other) const
        if (!overall_coeff.is_equal(o.overall_coeff))
                return false;
        
-#if EXPAIRSEQ_USE_HASHTAB
-       // compare number of elements in each hashtab entry
-       if (hashtabsize!=o.hashtabsize) {
-               std::cout << "this:" << std::endl;
-               print(print_tree(std::cout));
-               std::cout << "other:" << std::endl;
-               other.print(print_tree(std::cout));
-       }
-               
-       GINAC_ASSERT(hashtabsize==o.hashtabsize);
-       
-       if (hashtabsize==0) {
-#endif // EXPAIRSEQ_USE_HASHTAB
-               epvector::const_iterator cit1 = seq.begin();
-               epvector::const_iterator cit2 = o.seq.begin();
-               epvector::const_iterator last1 = seq.end();
-               
-               while (cit1!=last1) {
-                       if (!(*cit1).is_equal(*cit2)) return false;
-                       ++cit1;
-                       ++cit2;
-               }
-               
-               return true;
-#if EXPAIRSEQ_USE_HASHTAB
-       }
-       
-       for (unsigned i=0; i<hashtabsize; ++i) {
-               if (hashtab[i].size() != o.hashtab[i].size())
+       auto cit2 = o.seq.begin();
+       for (auto & cit1 : seq) {
+               if (!cit1.is_equal(*cit2))
                        return false;
+               ++cit2;
        }
 
-       // compare individual sorted hashtab entries
-       for (unsigned i=0; i<hashtabsize; ++i) {
-               unsigned sz = hashtab[i].size();
-               if (sz>0) {
-                       const epplist &eppl1 = hashtab[i];
-                       const epplist &eppl2 = o.hashtab[i];
-                       epplist::const_iterator it1 = eppl1.begin();
-                       epplist::const_iterator it2 = eppl2.begin();
-                       while (it1!=eppl1.end()) {
-                               if (!(*(*it1)).is_equal(*(*it2))) return false;
-                               ++it1;
-                               ++it2;
-                       }
-               }
-       }
-       
        return true;
-#endif // EXPAIRSEQ_USE_HASHTAB
 }
 
 unsigned expairseq::return_type() const
@@ -613,16 +448,10 @@ unsigned expairseq::return_type() const
 unsigned expairseq::calchash() const
 {
        unsigned v = make_hash_seed(typeid(*this));
-       epvector::const_iterator i = seq.begin();
-       const epvector::const_iterator end = seq.end();
-       while (i != end) {
-               v ^= i->rest.gethash();
-#if !EXPAIRSEQ_USE_HASHTAB
-               // rotation spoils commutativity!
+       for (auto & i : seq) {
+               v ^= i.rest.gethash();
                v = rotate_left(v);
-               v ^= i->coeff.gethash();
-#endif // !EXPAIRSEQ_USE_HASHTAB
-               ++i;
+               v ^= i.coeff.gethash();
        }
 
        v ^= overall_coeff.gethash();
@@ -638,13 +467,11 @@ unsigned expairseq::calchash() const
 
 ex expairseq::expand(unsigned options) const
 {
-       std::auto_ptr<epvector> vp = expandchildren(options);
-       if (vp.get())
-               return thisexpairseq(vp, overall_coeff);
-       else {
-               // The terms have not changed, so it is safe to declare this expanded
-               return (options == 0) ? setflag(status_flags::expanded) : *this;
+       epvector expanded = expandchildren(options);
+       if (!expanded.empty()) {
+               return thisexpairseq(std::move(expanded), overall_coeff);
        }
+       return (options == 0) ? setflag(status_flags::expanded) : *this;
 }
 
 //////////
@@ -658,7 +485,7 @@ ex expairseq::expand(unsigned options) const
  *  has (at least) two possible different semantics but we want to inherit
  *  methods thus avoiding code duplication.  Sometimes a method in expairseq
  *  has to create a new one of the same semantics, which cannot be done by a
- *  ctor because the name (add, mul,...) is unknown on the expaiseq level.  In
+ *  ctor because the name (add, mul,...) is unknown on the expairseq level.  In
  *  order for this trick to work a derived class must of course override this
  *  definition. */
 ex expairseq::thisexpairseq(const epvector &v, const ex &oc, bool do_index_renaming) const
@@ -666,9 +493,9 @@ ex expairseq::thisexpairseq(const epvector &v, const ex &oc, bool do_index_renam
        return expairseq(v, oc, do_index_renaming);
 }
 
-ex expairseq::thisexpairseq(std::auto_ptr<epvector> vp, const ex &oc, bool do_index_renaming) const
+ex expairseq::thisexpairseq(epvector && vp, const ex &oc, bool do_index_renaming) const
 {
-       return expairseq(vp, oc, do_index_renaming);
+       return expairseq(std::move(vp), oc, do_index_renaming);
 }
 
 void expairseq::printpair(const print_context & c, const expair & p, unsigned upper_precedence) const
@@ -686,8 +513,8 @@ void expairseq::printseq(const print_context & c, char delim,
 {
        if (this_precedence <= upper_precedence)
                c.s << "(";
-       epvector::const_iterator it, it_last = seq.end() - 1;
-       for (it=seq.begin(); it!=it_last; ++it) {
+       auto it = seq.begin(), it_last = seq.end() - 1;
+       for (; it!=it_last; ++it) {
                printpair(c, *it, this_precedence);
                c.s << delim;
        }
@@ -733,14 +560,11 @@ expair expairseq::combine_pair_with_coeff_to_pair(const expair &p,
  *  @see expairseq::split_ex_to_pair() */
 ex expairseq::recombine_pair_to_ex(const expair &p) const
 {
-       return lst(p.rest,p.coeff);
+       return lst{p.rest, p.coeff};
 }
 
 bool expairseq::expair_needs_further_processing(epp it)
 {
-#if EXPAIRSEQ_USE_HASHTAB
-       //#  error "FIXME: expair_needs_further_processing not yet implemented for hashtabs, sorry. A.F."
-#endif // EXPAIRSEQ_USE_HASHTAB
        return false;
 }
 
@@ -775,77 +599,28 @@ bool expairseq::can_make_flat(const expair &p) const
 // non-virtual functions in this class
 //////////
 
-void expairseq::construct_from_2_ex_via_exvector(const ex &lh, const ex &rh)
-{
-       exvector v;
-       v.reserve(2);
-       v.push_back(lh);
-       v.push_back(rh);
-       construct_from_exvector(v);
-#if EXPAIRSEQ_USE_HASHTAB
-       GINAC_ASSERT((hashtabsize==0)||(hashtabsize>=minhashtabsize));
-       GINAC_ASSERT(hashtabsize==calc_hashtabsize(seq.size()));
-#endif // EXPAIRSEQ_USE_HASHTAB
-}
-
 void expairseq::construct_from_2_ex(const ex &lh, const ex &rh)
 {
        if (typeid(ex_to<basic>(lh)) == typeid(*this)) {
                if (typeid(ex_to<basic>(rh)) == typeid(*this)) {
-#if EXPAIRSEQ_USE_HASHTAB
-                       unsigned totalsize = ex_to<expairseq>(lh).seq.size() +
-                                            ex_to<expairseq>(rh).seq.size();
-                       if (calc_hashtabsize(totalsize)!=0) {
-                               construct_from_2_ex_via_exvector(lh,rh);
-                       } else {
-#endif // EXPAIRSEQ_USE_HASHTAB
-                               if (is_a<mul>(lh) && lh.info(info_flags::has_indices) && 
-                                       rh.info(info_flags::has_indices)) {
-                                       ex newrh=rename_dummy_indices_uniquely(lh, rh);
-                                       construct_from_2_expairseq(ex_to<expairseq>(lh),
-                                                                  ex_to<expairseq>(newrh));
-                               }
-                               else
-                                       construct_from_2_expairseq(ex_to<expairseq>(lh),
-                                                                  ex_to<expairseq>(rh));
-#if EXPAIRSEQ_USE_HASHTAB
+                       if (is_a<mul>(lh) && lh.info(info_flags::has_indices) && 
+                               rh.info(info_flags::has_indices)) {
+                               ex newrh=rename_dummy_indices_uniquely(lh, rh);
+                               construct_from_2_expairseq(ex_to<expairseq>(lh),
+                                                          ex_to<expairseq>(newrh));
                        }
-#endif // EXPAIRSEQ_USE_HASHTAB
+                       else
+                               construct_from_2_expairseq(ex_to<expairseq>(lh),
+                                                          ex_to<expairseq>(rh));
                        return;
                } else {
-#if EXPAIRSEQ_USE_HASHTAB
-                       unsigned totalsize = ex_to<expairseq>(lh).seq.size()+1;
-                       if (calc_hashtabsize(totalsize)!=0) {
-                               construct_from_2_ex_via_exvector(lh, rh);
-                       } else {
-#endif // EXPAIRSEQ_USE_HASHTAB
-                               construct_from_expairseq_ex(ex_to<expairseq>(lh), rh);
-#if EXPAIRSEQ_USE_HASHTAB
-                       }
-#endif // EXPAIRSEQ_USE_HASHTAB
+                       construct_from_expairseq_ex(ex_to<expairseq>(lh), rh);
                        return;
                }
        } else if (typeid(ex_to<basic>(rh)) == typeid(*this)) {
-#if EXPAIRSEQ_USE_HASHTAB
-               unsigned totalsize=ex_to<expairseq>(rh).seq.size()+1;
-               if (calc_hashtabsize(totalsize)!=0) {
-                       construct_from_2_ex_via_exvector(lh,rh);
-               } else {
-#endif // EXPAIRSEQ_USE_HASHTAB
-                       construct_from_expairseq_ex(ex_to<expairseq>(rh),lh);
-#if EXPAIRSEQ_USE_HASHTAB
-               }
-#endif // EXPAIRSEQ_USE_HASHTAB
-               return;
-       }
-       
-#if EXPAIRSEQ_USE_HASHTAB
-       if (calc_hashtabsize(2)!=0) {
-               construct_from_2_ex_via_exvector(lh,rh);
+               construct_from_expairseq_ex(ex_to<expairseq>(rh),lh);
                return;
        }
-       hashtabsize = 0;
-#endif // EXPAIRSEQ_USE_HASHTAB
        
        if (is_exactly_a<numeric>(lh)) {
                if (is_exactly_a<numeric>(rh)) {
@@ -886,15 +661,13 @@ void expairseq::construct_from_2_ex(const ex &lh, const ex &rh)
 }
 
 void expairseq::construct_from_2_expairseq(const expairseq &s1,
-                                                                                  const expairseq &s2)
+                                           const expairseq &s2)
 {
        combine_overall_coeff(s1.overall_coeff);
        combine_overall_coeff(s2.overall_coeff);
 
-       epvector::const_iterator first1 = s1.seq.begin();
-       epvector::const_iterator last1 = s1.seq.end();
-       epvector::const_iterator first2 = s2.seq.begin();
-       epvector::const_iterator last2 = s2.seq.end();
+       auto first1 = s1.seq.begin(), last1 = s1.seq.end();
+       auto first2 = s2.seq.begin(), last2 = s2.seq.end();
 
        seq.reserve(s1.seq.size()+s2.seq.size());
 
@@ -934,14 +707,14 @@ void expairseq::construct_from_2_expairseq(const expairseq &s1,
        }
        
        if (needs_further_processing) {
-               epvector v = seq;
-               seq.clear();
-               construct_from_epvector(v);
+               // Clear seq and start over.
+               epvector v = std::move(seq);
+               construct_from_epvector(std::move(v));
        }
 }
 
 void expairseq::construct_from_expairseq_ex(const expairseq &s,
-                                                                                       const ex &e)
+                                            const ex &e)
 {
        combine_overall_coeff(s.overall_coeff);
        if (is_exactly_a<numeric>(e)) {
@@ -950,8 +723,7 @@ void expairseq::construct_from_expairseq_ex(const expairseq &s,
                return;
        }
        
-       epvector::const_iterator first = s.seq.begin();
-       epvector::const_iterator last = s.seq.end();
+       auto first = s.seq.begin(), last = s.seq.end();
        expair p = split_ex_to_pair(e);
        
        seq.reserve(s.seq.size()+1);
@@ -996,9 +768,9 @@ void expairseq::construct_from_expairseq_ex(const expairseq &s,
        }
 
        if (needs_further_processing) {
-               epvector v = seq;
-               seq.clear();
-               construct_from_epvector(v);
+               // Clear seq and start over.
+               epvector v = std::move(seq);
+               construct_from_epvector(std::move(v));
        }
 }
 
@@ -1006,56 +778,56 @@ void expairseq::construct_from_exvector(const exvector &v)
 {
        // simplifications: +(a,+(b,c),d) -> +(a,b,c,d) (associativity)
        //                  +(d,b,c,a) -> +(a,b,c,d) (canonicalization)
-       //                  +(...,x,*(x,c1),*(x,c2)) -> +(...,*(x,1+c1+c2)) (c1, c2 numeric())
+       //                  +(...,x,*(x,c1),*(x,c2)) -> +(...,*(x,1+c1+c2)) (c1, c2 numeric)
        //                  (same for (+,*) -> (*,^)
 
        make_flat(v);
-#if EXPAIRSEQ_USE_HASHTAB
-       combine_same_terms();
-#else
        canonicalize();
        combine_same_terms_sorted_seq();
-#endif // EXPAIRSEQ_USE_HASHTAB
 }
 
 void expairseq::construct_from_epvector(const epvector &v, bool do_index_renaming)
 {
        // simplifications: +(a,+(b,c),d) -> +(a,b,c,d) (associativity)
        //                  +(d,b,c,a) -> +(a,b,c,d) (canonicalization)
-       //                  +(...,x,*(x,c1),*(x,c2)) -> +(...,*(x,1+c1+c2)) (c1, c2 numeric())
-       //                  (same for (+,*) -> (*,^)
+       //                  +(...,x,*(x,c1),*(x,c2)) -> +(...,*(x,1+c1+c2)) (c1, c2 numeric)
+       //                  same for (+,*) -> (*,^)
 
        make_flat(v, do_index_renaming);
-#if EXPAIRSEQ_USE_HASHTAB
-       combine_same_terms();
-#else
        canonicalize();
        combine_same_terms_sorted_seq();
-#endif // EXPAIRSEQ_USE_HASHTAB
+}
+
+void expairseq::construct_from_epvector(epvector &&v, bool do_index_renaming)
+{
+       // simplifications: +(a,+(b,c),d) -> +(a,b,c,d) (associativity)
+       //                  +(d,b,c,a) -> +(a,b,c,d) (canonicalization)
+       //                  +(...,x,*(x,c1),*(x,c2)) -> +(...,*(x,1+c1+c2)) (c1, c2 numeric)
+       //                  same for (+,*) -> (*,^)
+
+       make_flat(std::move(v), do_index_renaming);
+       canonicalize();
+       combine_same_terms_sorted_seq();
 }
 
 /** Combine this expairseq with argument exvector.
  *  It cares for associativity as well as for special handling of numerics. */
 void expairseq::make_flat(const exvector &v)
 {
-       exvector::const_iterator cit;
-       
        // count number of operands which are of same expairseq derived type
        // and their cumulative number of operands
        int nexpairseqs = 0;
        int noperands = 0;
        bool do_idx_rename = false;
        
-       cit = v.begin();
-       while (cit!=v.end()) {
-               if (typeid(ex_to<basic>(*cit)) == typeid(*this)) {
+       for (auto & cit : v) {
+               if (typeid(ex_to<basic>(cit)) == typeid(*this)) {
                        ++nexpairseqs;
-                       noperands += ex_to<expairseq>(*cit).seq.size();
+                       noperands += ex_to<expairseq>(cit).seq.size();
                }
                if (is_a<mul>(*this) && (!do_idx_rename) &&
-                               cit->info(info_flags::has_indices))
+                   cit.info(info_flags::has_indices))
                        do_idx_rename = true;
-               ++cit;
        }
        
        // reserve seq and coeffseq which will hold all operands
@@ -1063,26 +835,22 @@ void expairseq::make_flat(const exvector &v)
        
        // copy elements and split off numerical part
        make_flat_inserter mf(v, do_idx_rename);
-       cit = v.begin();
-       while (cit!=v.end()) {
-               if (typeid(ex_to<basic>(*cit)) == typeid(*this)) {
-                       ex newfactor = mf.handle_factor(*cit, _ex1);
+       for (auto & cit : v) {
+               if (typeid(ex_to<basic>(cit)) == typeid(*this)) {
+                       ex newfactor = mf.handle_factor(cit, _ex1);
                        const expairseq &subseqref = ex_to<expairseq>(newfactor);
                        combine_overall_coeff(subseqref.overall_coeff);
-                       epvector::const_iterator cit_s = subseqref.seq.begin();
-                       while (cit_s!=subseqref.seq.end()) {
-                               seq.push_back(*cit_s);
-                               ++cit_s;
+                       for (auto & cit_s : subseqref.seq) {
+                               seq.push_back(cit_s);
                        }
                } else {
-                       if (is_exactly_a<numeric>(*cit))
-                               combine_overall_coeff(*cit);
+                       if (is_exactly_a<numeric>(cit))
+                               combine_overall_coeff(cit);
                        else {
-                               ex newfactor = mf.handle_factor(*cit, _ex1);
+                               ex newfactor = mf.handle_factor(cit, _ex1);
                                seq.push_back(split_ex_to_pair(newfactor));
                        }
                }
-               ++cit;
        }
 }
 
@@ -1090,24 +858,20 @@ void expairseq::make_flat(const exvector &v)
  *  It cares for associativity as well as for special handling of numerics. */
 void expairseq::make_flat(const epvector &v, bool do_index_renaming)
 {
-       epvector::const_iterator cit;
-       
        // count number of operands which are of same expairseq derived type
        // and their cumulative number of operands
        int nexpairseqs = 0;
        int noperands = 0;
        bool really_need_rename_inds = false;
        
-       cit = v.begin();
-       while (cit!=v.end()) {
-               if (typeid(ex_to<basic>(cit->rest)) == typeid(*this)) {
+       for (auto & cit : v) {
+               if (typeid(ex_to<basic>(cit.rest)) == typeid(*this)) {
                        ++nexpairseqs;
-                       noperands += ex_to<expairseq>(cit->rest).seq.size();
+                       noperands += ex_to<expairseq>(cit.rest).seq.size();
                }
                if ((!really_need_rename_inds) && is_a<mul>(*this) &&
-                               cit->rest.info(info_flags::has_indices))
+                   cit.rest.info(info_flags::has_indices))
                        really_need_rename_inds = true;
-               ++cit;
        }
        do_index_renaming = do_index_renaming && really_need_rename_inds;
        
@@ -1116,35 +880,29 @@ void expairseq::make_flat(const epvector &v, bool do_index_renaming)
        make_flat_inserter mf(v, do_index_renaming);
        
        // copy elements and split off numerical part
-       cit = v.begin();
-       while (cit!=v.end()) {
-               if ((typeid(ex_to<basic>(cit->rest)) == typeid(*this)) &&
-                   this->can_make_flat(*cit)) {
-                       ex newrest = mf.handle_factor(cit->rest, cit->coeff);
+       for (auto & cit : v) {
+               if (typeid(ex_to<basic>(cit.rest)) == typeid(*this) &&
+                   this->can_make_flat(cit)) {
+                       ex newrest = mf.handle_factor(cit.rest, cit.coeff);
                        const expairseq &subseqref = ex_to<expairseq>(newrest);
                        combine_overall_coeff(ex_to<numeric>(subseqref.overall_coeff),
-                                                           ex_to<numeric>(cit->coeff));
-                       epvector::const_iterator cit_s = subseqref.seq.begin();
-                       while (cit_s!=subseqref.seq.end()) {
-                               seq.push_back(expair(cit_s->rest,
-                                                    ex_to<numeric>(cit_s->coeff).mul_dyn(ex_to<numeric>(cit->coeff))));
-                               //seq.push_back(combine_pair_with_coeff_to_pair(*cit_s,
-                               //                                              (*cit).coeff));
-                               ++cit_s;
+                                             ex_to<numeric>(cit.coeff));
+                       for (auto & cit_s : subseqref.seq) {
+                               seq.push_back(expair(cit_s.rest,
+                                                    ex_to<numeric>(cit_s.coeff).mul_dyn(ex_to<numeric>(cit.coeff))));
                        }
                } else {
-                       if (cit->is_canonical_numeric())
-                               combine_overall_coeff(mf.handle_factor(cit->rest, _ex1));
+                       if (cit.is_canonical_numeric())
+                               combine_overall_coeff(mf.handle_factor(cit.rest, _ex1));
                        else {
-                               ex rest = cit->rest;
-                               ex newrest = mf.handle_factor(rest, cit->coeff);
+                               ex rest = cit.rest;
+                               ex newrest = mf.handle_factor(rest, cit.coeff);
                                if (are_ex_trivially_equal(newrest, rest))
-                                       seq.push_back(*cit);
+                                       seq.push_back(cit);
                                else
-                                       seq.push_back(expair(newrest, cit->coeff));
+                                       seq.push_back(expair(newrest, cit.coeff));
                        }
                }
-               ++cit;
        }
 }
 
@@ -1165,10 +923,10 @@ void expairseq::combine_same_terms_sorted_seq()
 
        bool needs_further_processing = false;
 
-       epvector::iterator itin1 = seq.begin();
-       epvector::iterator itin2 = itin1+1;
-       epvector::iterator itout = itin1;
-       epvector::iterator last = seq.end();
+       auto itin1 = seq.begin();
+       auto itin2 = itin1 + 1;
+       auto itout = itin1;
+       auto last = seq.end();
        // must_copy will be set to true the first time some combination is 
        // possible from then on the sequence has changed and must be compacted
        bool must_copy = false;
@@ -1198,321 +956,12 @@ void expairseq::combine_same_terms_sorted_seq()
                seq.erase(itout,last);
 
        if (needs_further_processing) {
-               epvector v = seq;
-               seq.clear();
-               construct_from_epvector(v);
-       }
-}
-
-#if EXPAIRSEQ_USE_HASHTAB
-
-unsigned expairseq::calc_hashtabsize(unsigned sz) const
-{
-       unsigned size;
-       unsigned nearest_power_of_2 = 1 << log2(sz);
-       // if (nearest_power_of_2 < maxhashtabsize/hashtabfactor) {
-       //  size = nearest_power_of_2*hashtabfactor;
-       size = nearest_power_of_2/hashtabfactor;
-       if (size<minhashtabsize)
-               return 0;
-
-       // hashtabsize must be a power of 2
-       GINAC_ASSERT((1U << log2(size))==size);
-       return size;
-}
-
-unsigned expairseq::calc_hashindex(const ex &e) const
-{
-       // calculate hashindex
-       unsigned hashindex;
-       if (is_a<numeric>(e)) {
-               hashindex = hashmask;
-       } else {
-               hashindex = e.gethash() & hashmask;
-               // last hashtab entry is reserved for numerics
-               if (hashindex==hashmask) hashindex = 0;
-       }
-       GINAC_ASSERT((hashindex<hashtabsize)||(hashtabsize==0));
-       return hashindex;
-}
-
-void expairseq::shrink_hashtab()
-{
-       unsigned new_hashtabsize;
-       while (hashtabsize!=(new_hashtabsize=calc_hashtabsize(seq.size()))) {
-               GINAC_ASSERT(new_hashtabsize<hashtabsize);
-               if (new_hashtabsize==0) {
-                       hashtab.clear();
-                       hashtabsize = 0;
-                       canonicalize();
-                       return;
-               }
-               
-               // shrink by a factor of 2
-               unsigned half_hashtabsize = hashtabsize/2;
-               for (unsigned i=0; i<half_hashtabsize-1; ++i)
-                       hashtab[i].merge(hashtab[i+half_hashtabsize],epp_is_less());
-               // special treatment for numeric hashes
-               hashtab[0].merge(hashtab[half_hashtabsize-1],epp_is_less());
-               hashtab[half_hashtabsize-1] = hashtab[hashtabsize-1];
-               hashtab.resize(half_hashtabsize);
-               hashtabsize = half_hashtabsize;
-               hashmask = hashtabsize-1;
-       }
-}
-
-void expairseq::remove_hashtab_entry(epvector::const_iterator element)
-{
-       if (hashtabsize==0)
-               return; // nothing to do
-       
-       // calculate hashindex of element to be deleted
-       unsigned hashindex = calc_hashindex((*element).rest);
-
-       // find it in hashtab and remove it
-       epplist &eppl = hashtab[hashindex];
-       epplist::iterator epplit = eppl.begin();
-       bool erased = false;
-       while (epplit!=eppl.end()) {
-               if (*epplit == element) {
-                       eppl.erase(epplit);
-                       erased = true;
-                       break;
-               }
-               ++epplit;
-       }
-       if (!erased) {
-               std::cout << "tried to erase " << element-seq.begin() << std::endl;
-               std::cout << "size " << seq.end()-seq.begin() << std::endl;
-
-               unsigned hashindex = calc_hashindex(element->rest);
-               epplist &eppl = hashtab[hashindex];
-               epplist::iterator epplit = eppl.begin();
-               bool erased = false;
-               while (epplit!=eppl.end()) {
-                       if (*epplit == element) {
-                               eppl.erase(epplit);
-                               erased = true;
-                               break;
-                       }
-                       ++epplit;
-               }
-               GINAC_ASSERT(erased);
-       }
-       GINAC_ASSERT(erased);
-}
-
-void expairseq::move_hashtab_entry(epvector::const_iterator oldpos,
-                                   epvector::iterator newpos)
-{
-       GINAC_ASSERT(hashtabsize!=0);
-       
-       // calculate hashindex of element which was moved
-       unsigned hashindex=calc_hashindex((*newpos).rest);
-
-       // find it in hashtab and modify it
-       epplist &eppl = hashtab[hashindex];
-       epplist::iterator epplit = eppl.begin();
-       while (epplit!=eppl.end()) {
-               if (*epplit == oldpos) {
-                       *epplit = newpos;
-                       break;
-               }
-               ++epplit;
-       }
-       GINAC_ASSERT(epplit!=eppl.end());
-}
-
-void expairseq::sorted_insert(epplist &eppl, epvector::const_iterator elem)
-{
-       epplist::const_iterator current = eppl.begin();
-       while ((current!=eppl.end()) && ((*current)->is_less(*elem))) {
-               ++current;
-       }
-       eppl.insert(current,elem);
-}    
-
-void expairseq::build_hashtab_and_combine(epvector::iterator &first_numeric,
-                                          epvector::iterator &last_non_zero,
-                                          std::vector<bool> &touched,
-                                          unsigned &number_of_zeroes)
-{
-       epp current = seq.begin();
-
-       while (current!=first_numeric) {
-               if (is_exactly_a<numeric>(current->rest)) {
-                       --first_numeric;
-                       iter_swap(current,first_numeric);
-               } else {
-                       // calculate hashindex
-                       unsigned currenthashindex = calc_hashindex(current->rest);
-
-                       // test if there is already a matching expair in the hashtab-list
-                       epplist &eppl=hashtab[currenthashindex];
-                       epplist::iterator epplit = eppl.begin();
-                       while (epplit!=eppl.end()) {
-                               if (current->rest.is_equal((*epplit)->rest))
-                                       break;
-                               ++epplit;
-                       }
-                       if (epplit==eppl.end()) {
-                               // no matching expair found, append this to end of list
-                               sorted_insert(eppl,current);
-                               ++current;
-                       } else {
-                               // epplit points to a matching expair, combine it with current
-                               (*epplit)->coeff = ex_to<numeric>((*epplit)->coeff).
-                                                  add_dyn(ex_to<numeric>(current->coeff));
-                               
-                               // move obsolete current expair to end by swapping with last_non_zero element
-                               // if this was a numeric, it is swapped with the expair before first_numeric 
-                               iter_swap(current,last_non_zero);
-                               --first_numeric;
-                               if (first_numeric!=last_non_zero) iter_swap(first_numeric,current);
-                               --last_non_zero;
-                               ++number_of_zeroes;
-                               // test if combined term has coeff 0 and can be removed is done later
-                               touched[(*epplit)-seq.begin()] = true;
-                       }
-               }
-       }
-}
-
-void expairseq::drop_coeff_0_terms(epvector::iterator &first_numeric,
-                                   epvector::iterator &last_non_zero,
-                                   std::vector<bool> &touched,
-                                   unsigned &number_of_zeroes)
-{
-       // move terms with coeff 0 to end and remove them from hashtab
-       // check only those elements which have been touched
-       epp current = seq.begin();
-       size_t i = 0;
-       while (current!=first_numeric) {
-               if (!touched[i]) {
-                       ++current;
-                       ++i;
-               } else if (!ex_to<numeric>((*current).coeff).is_zero()) {
-                       ++current;
-                       ++i;
-               } else {
-                       remove_hashtab_entry(current);
-                       
-                       // move element to the end, unless it is already at the end
-                       if (current!=last_non_zero) {
-                               iter_swap(current,last_non_zero);
-                               --first_numeric;
-                               bool numeric_swapped = first_numeric!=last_non_zero;
-                               if (numeric_swapped)
-                                       iter_swap(first_numeric,current);
-                               epvector::iterator changed_entry;
-
-                               if (numeric_swapped)
-                                       changed_entry = first_numeric;
-                               else
-                                       changed_entry = last_non_zero;
-                               
-                               --last_non_zero;
-                               ++number_of_zeroes;
-
-                               if (first_numeric!=current) {
-
-                                       // change entry in hashtab which referred to first_numeric or last_non_zero to current
-                                       move_hashtab_entry(changed_entry,current);
-                                       touched[current-seq.begin()] = touched[changed_entry-seq.begin()];
-                               }
-                       } else {
-                               --first_numeric;
-                               --last_non_zero;
-                               ++number_of_zeroes;
-                       }
-               }
-       }
-       GINAC_ASSERT(i==current-seq.begin());
-}
-
-/** True if one of the coeffs vanishes, otherwise false.
- *  This would be an invariant violation, so this should only be used for
- *  debugging purposes. */
-bool expairseq::has_coeff_0() const
-{
-       epvector::const_iterator i = seq.begin(), end = seq.end();
-       while (i != end) {
-               if (i->coeff.is_zero())
-                       return true;
-               ++i;
+               // Clear seq and start over.
+               epvector v = std::move(seq);
+               construct_from_epvector(std::move(v));
        }
-       return false;
-}
-
-void expairseq::add_numerics_to_hashtab(epvector::iterator first_numeric,
-                                                                               epvector::const_iterator last_non_zero)
-{
-       if (first_numeric == seq.end()) return; // no numerics
-       
-       epvector::const_iterator current = first_numeric, last = last_non_zero + 1;
-       while (current != last) {
-               sorted_insert(hashtab[hashmask], current);
-               ++current;
-       }
-}
-
-void expairseq::combine_same_terms()
-{
-       // combine same terms, drop term with coeff 0, move numerics to end
-       
-       // calculate size of hashtab
-       hashtabsize = calc_hashtabsize(seq.size());
-       
-       // hashtabsize is a power of 2
-       hashmask = hashtabsize-1;
-       
-       // allocate hashtab
-       hashtab.clear();
-       hashtab.resize(hashtabsize);
-       
-       if (hashtabsize==0) {
-               canonicalize();
-               combine_same_terms_sorted_seq();
-               GINAC_ASSERT(!has_coeff_0());
-               return;
-       }
-       
-       // iterate through seq, move numerics to end,
-       // fill hashtab and combine same terms
-       epvector::iterator first_numeric = seq.end();
-       epvector::iterator last_non_zero = seq.end()-1;
-       
-       size_t num = seq.size();
-       std::vector<bool> touched(num);
-       
-       unsigned number_of_zeroes = 0;
-       
-       GINAC_ASSERT(!has_coeff_0());
-       build_hashtab_and_combine(first_numeric,last_non_zero,touched,number_of_zeroes);
-       
-       // there should not be any terms with coeff 0 from the beginning,
-       // so it should be safe to skip this step
-       if (number_of_zeroes!=0) {
-               drop_coeff_0_terms(first_numeric,last_non_zero,touched,number_of_zeroes);
-       }
-       
-       add_numerics_to_hashtab(first_numeric,last_non_zero);
-       
-       // pop zero elements
-       for (unsigned i=0; i<number_of_zeroes; ++i) {
-               seq.pop_back();
-       }
-       
-       // shrink hashtabsize to calculated value
-       GINAC_ASSERT(!has_coeff_0());
-       
-       shrink_hashtab();
-       
-       GINAC_ASSERT(!has_coeff_0());
 }
 
-#endif // EXPAIRSEQ_USE_HASHTAB
-
 /** Check if this expairseq is in sorted (canonical) form.  Useful mainly for
  *  debugging or in assertions since being sorted is an invariance. */
 bool expairseq::is_canonical() const
@@ -1520,12 +969,8 @@ bool expairseq::is_canonical() const
        if (seq.size() <= 1)
                return 1;
        
-#if EXPAIRSEQ_USE_HASHTAB
-       if (hashtabsize > 0) return 1; // not canoncalized
-#endif // EXPAIRSEQ_USE_HASHTAB
-       
-       epvector::const_iterator it = seq.begin(), itend = seq.end();
-       epvector::const_iterator it_last = it;
+       auto it = seq.begin(), itend = seq.end();
+       auto it_last = it;
        for (++it; it!=itend; it_last=it, ++it) {
                if (!(it_last->is_less(*it) || it_last->is_equal(*it))) {
                        if (!is_exactly_a<numeric>(it_last->rest) ||
@@ -1551,111 +996,87 @@ bool expairseq::is_canonical() const
        return 1;
 }
 
-
 /** Member-wise expand the expairs in this sequence.
  *
  *  @see expairseq::expand()
- *  @return pointer to epvector containing expanded pairs or zero pointer,
- *  if no members were changed. */
-std::auto_ptr<epvector> expairseq::expandchildren(unsigned options) const
+ *  @return epvector containing expanded pairs, empty if no members
+ *    had to be changed. */
+epvector expairseq::expandchildren(unsigned options) const
 {
-       const epvector::const_iterator last = seq.end();
-       epvector::const_iterator cit = seq.begin();
+       auto cit = seq.begin(), last = seq.end();
        while (cit!=last) {
-               const ex &expanded_ex = cit->rest.expand(options);
+               const ex expanded_ex = cit->rest.expand(options);
                if (!are_ex_trivially_equal(cit->rest,expanded_ex)) {
                        
                        // something changed, copy seq, eval and return it
-                       std::auto_ptr<epvector> s(new epvector);
-                       s->reserve(seq.size());
+                       epvector s;
+                       s.reserve(seq.size());
                        
                        // copy parts of seq which are known not to have changed
-                       epvector::const_iterator cit2 = seq.begin();
-                       while (cit2!=cit) {
-                               s->push_back(*cit2);
-                               ++cit2;
-                       }
+                       s.insert(s.begin(), seq.begin(), cit);
 
                        // copy first changed element
-                       s->push_back(combine_ex_with_coeff_to_pair(expanded_ex,
-                                                                  cit2->coeff));
-                       ++cit2;
+                       s.push_back(expair(expanded_ex, cit->coeff));
+                       ++cit;
 
                        // copy rest
-                       while (cit2!=last) {
-                               s->push_back(combine_ex_with_coeff_to_pair(cit2->rest.expand(options),
-                                                                          cit2->coeff));
-                               ++cit2;
+                       while (cit != last) {
+                               s.push_back(expair(cit->rest.expand(options), cit->coeff));
+                               ++cit;
                        }
                        return s;
                }
+
                ++cit;
        }
        
-       return std::auto_ptr<epvector>(0); // signalling nothing has changed
+       return epvector(); // empty signalling nothing has changed
 }
 
 
 /** Member-wise evaluate the expairs in this sequence.
  *
  *  @see expairseq::eval()
- *  @return pointer to epvector containing evaluated pairs or zero pointer,
- *  if no members were changed. */
-std::auto_ptr<epvector> expairseq::evalchildren(int level) const
+ *  @return epvector containing evaluated pairs, empty if no members
+ *    had to be changed. */
+epvector expairseq::evalchildren() const
 {
-       // returns a NULL pointer if nothing had to be evaluated
-       // returns a pointer to a newly created epvector otherwise
-       // (which has to be deleted somewhere else)
-
-       if (level==1)
-               return std::auto_ptr<epvector>(0);
-       
-       if (level == -max_recursion_level)
-               throw(std::runtime_error("max recursion level reached"));
-       
-       --level;
-       epvector::const_iterator last = seq.end();
-       epvector::const_iterator cit = seq.begin();
+       auto cit = seq.begin(), last = seq.end();
        while (cit!=last) {
-               const ex &evaled_ex = cit->rest.eval(level);
-               if (!are_ex_trivially_equal(cit->rest,evaled_ex)) {
-                       
-                       // something changed, copy seq, eval and return it
-                       std::auto_ptr<epvector> s(new epvector);
-                       s->reserve(seq.size());
-                       
+               const expair evaled_pair = combine_ex_with_coeff_to_pair(cit->rest, cit->coeff);
+               if (unlikely(!evaled_pair.is_equal(*cit))) {
+
+                       // something changed: copy seq, eval and return it
+                       epvector s;
+                       s.reserve(seq.size());
+
                        // copy parts of seq which are known not to have changed
-                       epvector::const_iterator cit2=seq.begin();
-                       while (cit2!=cit) {
-                               s->push_back(*cit2);
-                               ++cit2;
-                       }
+                       s.insert(s.begin(), seq.begin(), cit);
 
                        // copy first changed element
-                       s->push_back(combine_ex_with_coeff_to_pair(evaled_ex,
-                                                                  cit2->coeff));
-                       ++cit2;
+                       s.push_back(evaled_pair);
+                       ++cit;
 
                        // copy rest
-                       while (cit2!=last) {
-                               s->push_back(combine_ex_with_coeff_to_pair(cit2->rest.eval(level),
-                                                                          cit2->coeff));
-                               ++cit2;
+                       while (cit != last) {
+                               s.push_back(combine_ex_with_coeff_to_pair(cit->rest, cit->coeff));
+                               ++cit;
                        }
                        return s;
                }
+
                ++cit;
        }
-       
-       return std::auto_ptr<epvector>(0); // signalling nothing has changed
+
+       return epvector(); // signalling nothing has changed
 }
 
 /** Member-wise substitute in this sequence.
  *
  *  @see expairseq::subs()
- *  @return pointer to epvector containing pairs after application of subs,
- *    or NULL pointer if no members were changed. */
-std::auto_ptr<epvector> expairseq::subschildren(const exmap & m, unsigned options) const
+ *  @return epvector containing expanded pairs, empty if no members
+ *    had to be changed. */
+epvector expairseq::subschildren(const exmap & m, unsigned options) const
 {
        // When any of the objects to be substituted is a product or power
        // we have to recombine the pairs because the numeric coefficients may
@@ -1663,8 +1084,8 @@ std::auto_ptr<epvector> expairseq::subschildren(const exmap & m, unsigned option
        if (!(options & (subs_options::pattern_is_product | subs_options::pattern_is_not_product))) {
 
                // Search the list of substitutions and cache our findings
-               for (exmap::const_iterator it = m.begin(); it != m.end(); ++it) {
-                       if (is_exactly_a<mul>(it->first) || is_exactly_a<power>(it->first)) {
+               for (auto & it : m) {
+                       if (is_exactly_a<mul>(it.first) || is_exactly_a<power>(it.first)) {
                                options |= subs_options::pattern_is_product;
                                break;
                        }
@@ -1676,27 +1097,27 @@ std::auto_ptr<epvector> expairseq::subschildren(const exmap & m, unsigned option
        if (options & subs_options::pattern_is_product) {
 
                // Substitute in the recombined pairs
-               epvector::const_iterator cit = seq.begin(), last = seq.end();
+               auto cit = seq.begin(), last = seq.end();
                while (cit != last) {
 
                        const ex &orig_ex = recombine_pair_to_ex(*cit);
                        const ex &subsed_ex = orig_ex.subs(m, options);
                        if (!are_ex_trivially_equal(orig_ex, subsed_ex)) {
 
-                               // Something changed, copy seq, subs and return it
-                               std::auto_ptr<epvector> s(new epvector);
-                               s->reserve(seq.size());
+                               // Something changed: copy seq, subs and return it
+                               epvector s;
+                               s.reserve(seq.size());
 
                                // Copy parts of seq which are known not to have changed
-                               s->insert(s->begin(), seq.begin(), cit);
+                               s.insert(s.begin(), seq.begin(), cit);
 
                                // Copy first changed element
-                               s->push_back(split_ex_to_pair(subsed_ex));
+                               s.push_back(split_ex_to_pair(subsed_ex));
                                ++cit;
 
                                // Copy rest
                                while (cit != last) {
-                                       s->push_back(split_ex_to_pair(recombine_pair_to_ex(*cit).subs(m, options)));
+                                       s.push_back(split_ex_to_pair(recombine_pair_to_ex(*cit).subs(m, options)));
                                        ++cit;
                                }
                                return s;
@@ -1708,26 +1129,27 @@ std::auto_ptr<epvector> expairseq::subschildren(const exmap & m, unsigned option
        } else {
 
                // Substitute only in the "rest" part of the pairs
-               epvector::const_iterator cit = seq.begin(), last = seq.end();
+               auto cit = seq.begin(), last = seq.end();
                while (cit != last) {
 
-                       const ex &subsed_ex = cit->rest.subs(m, options);
-                       if (!are_ex_trivially_equal(cit->rest, subsed_ex)) {
+                       const ex subsed_rest = cit->rest.subs(m, options);
+                       const expair subsed_pair = combine_ex_with_coeff_to_pair(subsed_rest, cit->coeff);
+                       if (!subsed_pair.is_equal(*cit)) {
                        
-                               // Something changed, copy seq, subs and return it
-                               std::auto_ptr<epvector> s(new epvector);
-                               s->reserve(seq.size());
+                               // Something changed: copy seq, subs and return it
+                               epvector s;
+                               s.reserve(seq.size());
 
                                // Copy parts of seq which are known not to have changed
-                               s->insert(s->begin(), seq.begin(), cit);
+                               s.insert(s.begin(), seq.begin(), cit);
                        
                                // Copy first changed element
-                               s->push_back(combine_ex_with_coeff_to_pair(subsed_ex, cit->coeff));
+                               s.push_back(subsed_pair);
                                ++cit;
 
                                // Copy rest
                                while (cit != last) {
-                                       s->push_back(combine_ex_with_coeff_to_pair(cit->rest.subs(m, options), cit->coeff));
+                                       s.push_back(combine_ex_with_coeff_to_pair(cit->rest.subs(m, options), cit->coeff));
                                        ++cit;
                                }
                                return s;
@@ -1738,17 +1160,11 @@ std::auto_ptr<epvector> expairseq::subschildren(const exmap & m, unsigned option
        }
        
        // Nothing has changed
-       return std::auto_ptr<epvector>(0);
+       return epvector();
 }
 
 //////////
 // static member variables
 //////////
 
-#if EXPAIRSEQ_USE_HASHTAB
-unsigned expairseq::maxhashtabsize = 0x4000000U;
-unsigned expairseq::minhashtabsize = 0x1000U;
-unsigned expairseq::hashtabfactor = 1;
-#endif // EXPAIRSEQ_USE_HASHTAB
-
 } // namespace GiNaC