/*

Cadabra: a field-theory motivated computer algebra system.
Copyright (C) 2001-2014  Kasper Peeters <kasper.peeters@phi-sci.com>

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 the Free Software Foundation, either version 3 of the
License, or (at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
General Public License for more details.

You should have received a copy of the GNU General Public License
	along with this program.  If not, see <http://www.gnu.org/licenses/>.

*/

#include "Storage.hh"
#include "Combinatorics.hh"
#include "Exceptions.hh"
#include <iomanip>
#include <sstream>
#include <locale>
#include <codecvt>

#include <boost/functional/hash.hpp>

//#define DEBUG 1

namespace cadabra {

	nset_t    name_set;
	rset_t    rat_set;

	long to_long(multiplier_t mul)
		{
		return mul.get_num().get_si();
		}

	double to_double(multiplier_t mul)
		{
		return mul.get_d();
		}

	std::string to_string(long num)
		{
		std::ostringstream str;
		str << num;
		return str.str();
		}

	// Expression constructor/destructor members.

	Ex::Ex()
		: tree<str_node>(), state_(result_t::l_no_action)
		{
		}

	Ex::Ex(tree<str_node>::iterator it)
		: tree<str_node>(it), state_(result_t::l_no_action)
		{
		}

	Ex::Ex(const str_node& x)
		: tree<str_node>(x), state_(result_t::l_no_action)
		{
		}

	Ex::Ex(const Ex& other)
		: std::enable_shared_from_this<Ex>(other), tree<str_node>(other), state_(result_t::l_no_action)
		{
		//	std::cout << "Ex copy constructor" << std::endl;
		}

	Ex::Ex(const std::string& str)
		: state_(result_t::l_no_action)
		{
		set_head(str_node(str));
		}

	Ex::Ex(int val)
		: state_(result_t::l_no_action)
		{
		set_head(str_node("1"));
		multiply(begin()->multiplier, val);
		}

	Ex::result_t Ex::state() const
		{
		return state_;
		}

	void Ex::update_state(Ex::result_t newstate)
		{
		switch(newstate) {
			case Ex::result_t::l_error:
				state_=newstate;
				break;
			case Ex::result_t::l_applied:
				if(state_!=Ex::result_t::l_error)
					state_=newstate;
				break;
			default:
				break;
			}
		}

	void Ex::reset_state()
		{
		state_=Ex::result_t::l_checkpointed;
		}

	bool Ex::changed_state()
		{
		bool ret=false;
		if(state_==result_t::l_checkpointed || state_==result_t::l_applied) ret=true;
		state_=result_t::l_no_action;
		return ret;
		}

	bool Ex::is_rational() const
		{
		if(begin()!=end())
			if(begin()->is_rational())
				return true;
		return false;
		}

	multiplier_t Ex::to_rational() const
		{
		if(!is_rational())
			throw InternalError("Called to_rational() on non-rational Ex");
		return *(begin()->multiplier);
		}

	bool Ex::is_integer() const
		{
		if(begin()!=end())
			if(begin()->is_integer())
				return true;
		return false;
		}

	long Ex::to_integer() const
		{
		if(!is_integer())
			throw InternalError("Called to_integer() on non-integer Ex");
		return to_long(*(begin()->multiplier));
		}

	std::ostream& Ex::print_python(std::ostream& str, Ex::iterator it)
		{
		std::string name(*(*it).name);
		std::string res;
		if(*it->multiplier!=1)
			str << *it->multiplier;

		for(unsigned int i=0; i<name.size(); ++i) {
			if(name[i]=='#')       res+="\\#";
			//		else if(name[i]=='\\') res+="\\backslash{}";
			else                   res+=name[i];
			}
		str << res;

		Ex::sibling_iterator beg=it.begin();
		Ex::sibling_iterator fin=it.end();
		str_node::bracket_t    current_bracket=str_node::b_invalid;
		str_node::parent_rel_t current_parent_rel=str_node::p_invalid;

		while(beg!=fin) {
			if(beg==it.begin() || current_parent_rel!=(*beg).fl.parent_rel) {
				switch((*beg).fl.parent_rel) {
					case str_node::p_super:
						str << "^";
						break;
					case str_node::p_sub:
						str << "_";
						break;
					case str_node::p_property:
						str << "$";
						break;
					case str_node::p_exponent:
						str << "&";
						break;
					default:
						break;
					}
				current_parent_rel=(*beg).fl.parent_rel;
				}
			if(beg==it.begin() || current_bracket!=(*beg).fl.bracket || current_parent_rel!=(*beg).fl.parent_rel) {
				switch((*beg).fl.bracket) {
					case str_node::b_round:
						str << "(";
						break;
					case str_node::b_square:
						str << "[";
						break;
					case str_node::b_curly:
						str << "{";
						break;
					case str_node::b_pointy:
						str << "<";
						break;
					case str_node::b_none: {
						if((*beg).fl.parent_rel==str_node::p_none) str << "(";
						else                                       str << "{";
						}
					break;
					default:
						break;
					}
				current_bracket=(*beg).fl.bracket;
				}

			print_python(str, beg);

			auto nxt=beg;
			++nxt;
			if(nxt!=fin) {
				if((*beg).fl.parent_rel!=str_node::p_none)
					str << " ";
				}
			if(nxt==fin || (*nxt).fl.bracket!=(*beg).fl.bracket || (*beg).fl.parent_rel==str_node::p_none) {
				current_bracket=str_node::b_invalid;
				current_parent_rel=str_node::p_invalid;
				switch((*beg).fl.bracket) {
					case str_node::b_round:
						str << ")";
						break;
					case str_node::b_square:
						str << "]";
						break;
					case str_node::b_curly:
						str << "}";
						break;
					case str_node::b_pointy:
						str << ">";
						break;
					case str_node::b_none: {
						if((*beg).fl.parent_rel==str_node::p_none) str << ")";
						else                                       str << "}";
						}
					break;
					default:
						break;
					}
				}
			++beg;
			}

		return str;
		}

	std::ostream& Ex::print_repr(std::ostream& str, Ex::iterator it) const
		{
		str << *it->name;
		sibling_iterator sib=it.begin();
		while(sib!=it.end()) {
			print_repr(str, sib);
			++sib;
			}
		return str;
		}

	std::ostream& Ex::print_recursive_treeform(std::ostream& str, Ex::iterator it)
		{
		unsigned int num=1;
		switch((*it).fl.parent_rel) {
			case str_node::p_super:
				str << "^";
				break;
			case str_node::p_sub:
				str << "_";
				break;
			case str_node::p_property:
				str << "$";
				break;
			case str_node::p_exponent:
				str << "&";
				break;
			default:
				break;
			}
		return print_recursive_treeform(str, it, num);
		}

	std::ostream& Ex::print_entire_tree(std::ostream& str) const
		{
		sibling_iterator sib=begin();
		unsigned int num=1;
		while(sib!=end()) {
			print_recursive_treeform(str, sib, num);
			++sib;
			++num;
			}
		return str;
		}

	std::ostream& Ex::print_recursive_treeform(std::ostream& str, Ex::iterator it, unsigned int& num)
		{
		bool compact_tree=getenv("CDB_COMPACTTREE");

		Ex::sibling_iterator beg=it.begin();
		Ex::sibling_iterator fin=it.end();

		if((*it).fl.bracket   ==str_node::b_round)       str << "(";
		else if((*it).fl.bracket   ==str_node::b_square) str << "[";
		else if((*it).fl.bracket   ==str_node::b_curly)  str << "\\{";
		else if((*it).fl.bracket   ==str_node::b_pointy) str << "\\<";
		else if((*it).fl.bracket   ==str_node::b_none)   str << "{";
		//	if((*it).fl.mark) str << "\033[1m";
		str << *(*it).name;
		//	if((*it).fl.mark) str << "\033[0m";
		if((*it).fl.bracket   ==str_node::b_round)       str << ")";
		else if((*it).fl.bracket   ==str_node::b_square) str << "]";
		else if((*it).fl.bracket   ==str_node::b_curly)  str << "\\}";
		else if((*it).fl.bracket   ==str_node::b_pointy) str << "\\>";
		else if((*it).fl.bracket   ==str_node::b_none)   str << "}";

		if(*it->multiplier!=multiplier_t(1)) {
			if(compact_tree)
				str << "#" << *it->multiplier;
			else
				str << "  " << *it->multiplier;
			}
		//	str << "  (" << calc_hash(it) << ")";
		//	str << "  (" << depth(it) << ")";
		//	str << "  (" << it->fl.bracket << " " << &(*it) << ")";
		str << "  (" << it->fl.bracket << " " << it.node << ")";
		if(!compact_tree) str << std::endl;

		while(beg!=fin) {
			int offset=1;
			if(num && !compact_tree) {
				str << std::setw(3) << num << ":";
				offset=1;
				}
			if(!compact_tree)
				for(int i=offset; i<depth(beg); ++i)
					str << "  ";
			switch((*beg).fl.parent_rel) {
				case str_node::p_super:
					str << "^";
					break;
				case str_node::p_sub:
					str << "_";
					break;
				case str_node::p_property:
					str << "$";
					break;
				case str_node::p_exponent:
					str << "&";
					break;
				default:
					break;
				}
			if(num) ++num;
			print_recursive_treeform(str, beg, num);
			++beg;
			}
		return str;
		}


	// std::ostream& operator<<(std::ostream& str, const Ex& tr)
	// 	{
	// 	unsigned int number=1;
	// 	Ex::iterator it=tr.begin();
	// 	while(it!=tr.end()) {
	// 		tr.print_recursive_infix(str, it, number, true);
	// 		it.skip_children();
	// 		++it;
	// 		if(it!=tr.end())
	// 			str << std::endl;
	// 		}
	// 	return str;
	// 	}

	Ex::iterator Ex::named_parent(Ex::iterator it, const std::string& nm) const
		{
		//	std::cout << "!!" << *it->name << std::endl << std::flush;
		assert(is_valid(it));
		while(*it->name!=nm /* && it->is_command()==false */) {
			it=parent(it);
			assert(is_valid(it));
			//		std::cout << "  !!" << *it->name << std::endl << std::flush;
			}
		//	std::cout << "  out" << std::endl;
		return it;
		}

	Ex::iterator Ex::erase_expression(Ex::iterator it)
		{
		it=named_parent(it, "\\history");
		return erase(it);
		}


	hashval_t Ex::calc_hash(iterator it) const
		{
		// Hash values do not contain info about the multiplier field,
		// nor do they know about the type of the links (FIXME: is the latter
		// the correct thing to do?)
		//
		// If this algorithm is changed, factorise::calc_restricted_hash in
		// core/algorithms/factor_in.cc should also be modified!

		iterator end=it;
		end.skip_children();
		++end;
		it.skip_children(false);

		hashval_t seed = 0;
		while(it!=end) {
			boost::hash_combine(seed, *it->name);
			++it;
			}

		return seed;
		}

	Ex::sibling_iterator Ex::arg(iterator it, unsigned int num)
		{
		if(*it->name=="\\comma") {
			assert(Ex::number_of_children(it)>num);
			return Ex::child(it,num);
			}
		else return it;
		}

	unsigned int Ex::arg_size(sibling_iterator sib)
		{
		if(*sib->name=="\\comma") return Ex::number_of_children(sib);
		else return 1;
		}

	multiplier_t Ex::arg_to_num(sibling_iterator sib, unsigned int num) const
		{
		sibling_iterator nod;
		if(*sib->name=="\\comma") nod=child(sib,num);
		else                      nod=sib;
		return *nod->multiplier;
		}

	unsigned int Ex::equation_number(Ex::iterator it) const
		{
		iterator historynode=named_parent(it, "\\history");
		unsigned int num=0;
		iterator sit=begin();
		//	long totravel=0;
		while(sit!=end()) {
			//		++totravel;
			if(*sit->name=="\\history") {
				++num;
				if(historynode==sit) {
					//				txtout << "had to travel " << totravel << std::endl;
					return num;
					}
				}
			sit.skip_children();
			++sit;
			}
		return 0;
		}

	nset_t::iterator Ex::equation_label(Ex::iterator it) const
		{
		nset_t::iterator ret=name_set.end();

		iterator sit=begin();
		while(sit!=end()) {
			if(*sit->name=="\\history") {
				if(it==sit)
					goto found;
				iterator eit=begin(sit);
				iterator endit=sit;
				endit.skip_children();
				++endit;
				while(eit!=endit) {
					if(it==eit)
						goto found;
					++eit;
					}
				sit.skip_children();
				}
			++sit;
			}
found:
		if(sit!=end()) {
			sibling_iterator lit=begin(sit);
			while(lit!=end(sit)) {
				if(*lit->name=="\\label") {
					ret=begin(lit)->name;
					break;
					}
				++lit;
				}
			}
		return ret;
		}

	// Always returns the \\history node of the equation (i.e. the top node).
	Ex::iterator Ex::equation_by_number(unsigned int i) const
		{
		iterator it=begin();
		unsigned int num=1;
		while(it!=end()) {
			if(*it->name=="\\history") {
				if(num==i) return it;
				else       ++num;
				}
			it.skip_children();
			++it;
			}
		return it;
		//	if(num==number_of_siblings(begin()))
		//		return end();
		//	return it;
		}

	Ex::iterator Ex::equation_by_name(nset_t::iterator nit) const
		{
		unsigned int tmp;
		return equation_by_name(nit, tmp);
		}

	Ex::iterator Ex::equation_by_name(nset_t::iterator nit, unsigned int& tmp) const
		{
		unsigned int num=0;
		iterator it=begin();
		while(it!=end()) {
			if(*it->name=="\\history") {
				++num;
				sibling_iterator lit=begin(it);
				while(lit!=end(it)) {
					if(*lit->name=="\\label") {
						if(begin(lit)->name==nit) {
							tmp=num;
							return it;
							}
						}
					++lit;
					}
				}
			it.skip_children();
			++it;
			}
		return end();
		}

	bool Ex::is_hidden(iterator it) const
		{
		do {
			if(*it->name=="\\ldots") return true;
			if(is_head(it)) break;
			it=parent(it);
			}
		while(true);
		return false;
		}

	Ex::iterator Ex::procedure_by_name(nset_t::iterator nit) const
		{
		iterator it=begin();
		while(it!=end()) {
			if(*it->name=="\\procedure") {
				sibling_iterator lit=begin(it);
				while(lit!=end(it)) {
					if(*lit->name=="\\label") {
						if(begin(lit)->name==nit)
							return it;
						}
					++lit;
					}
				}
			it.skip_children();
			++it;
			}
		return end();
		}

	Ex::iterator Ex::replace_index(iterator pos, const iterator& from, bool keep_parent_rel)
		{
		//	assert(pos->fl.parent_rel==str_node::p_sub || pos->fl.parent_rel==str_node::p_super);
		str_node::bracket_t    bt=pos->fl.bracket;
		str_node::parent_rel_t pr=pos->fl.parent_rel;
		iterator ret=replace(pos, from);
		ret->fl.bracket=bt;
		if(keep_parent_rel)
			ret->fl.parent_rel=pr;
		return ret;
		}

	Ex::iterator Ex::move_index(iterator pos, const iterator& from)
		{
		//	assert(pos->fl.parent_rel==str_node::p_sub || pos->fl.parent_rel==str_node::p_super);
		str_node::bracket_t    bt=pos->fl.bracket;
		str_node::parent_rel_t pr=pos->fl.parent_rel;
		move_ontop(pos, from);
		from->fl.bracket=bt;
		from->fl.parent_rel=pr;
		return from;
		}

	void Ex::list_wrap_single_element(iterator& it)
		{
		if(*it->name!="\\comma") {
			iterator commanode=insert(it, str_node("\\comma"));
			sibling_iterator fr=it, to=it;
			++to;
			reparent(commanode, fr, to);
			it=commanode;
			}
		}

	void Ex::list_unwrap_single_element(iterator& it)
		{
		if(*it->name=="\\comma") {
			if(number_of_children(it)==1) {
				flatten(it);
				it=erase(it);
				}
			}
		}

	Ex::iterator Ex::flatten_and_erase(iterator pos)
		{
		//	assert(number_of_children(pos)==1);

		multiplier_t tmp=*pos->multiplier;
		flatten(pos);
		pos=erase(pos);
		multiply(pos->multiplier, tmp);
		return pos;
		}

	unsigned int Ex::number_of_equations() const
		{
		unsigned int last_eq=0;
		iterator eq=begin();
		while(eq!=end()) {
			if(*eq->name=="\\history")
				++last_eq;
			eq.skip_children();
			++eq;
			}
		return last_eq;
		}

	Ex::iterator Ex::equation_by_number_or_name(iterator it, unsigned int last_used_equation,
	      unsigned int& real_eqno) const
		{
		iterator ret;
		if(it->is_rational()) {
			int eqno=static_cast<int>(it->multiplier->get_d());
			real_eqno=eqno;
			ret=equation_by_number(eqno);
			}
		else {
			if(*it->name=="%") {
				ret=equation_by_number(last_used_equation);
				real_eqno=last_used_equation;
				}
			else {
				ret=equation_by_name(it->name, real_eqno);
				}
			}
		return ret;
		}

	Ex::iterator Ex::equation_by_number_or_name(iterator it, unsigned int last_used_equation) const
		{
		unsigned int tmp;
		return equation_by_number_or_name(it, last_used_equation, tmp);
		}

	std::string Ex::equation_number_or_name(iterator it, unsigned int last_used_equation) const
		{
		std::stringstream ss;
		if(it->is_rational()) {
			int eqno=static_cast<int>(it->multiplier->get_d());
			ss << eqno;
			}
		else {
			if(*it->name=="%") ss << last_used_equation;
			else               ss << *it->name;
			}
		return ss.str();
		}

	bool Ex::operator==(const Ex& other) const
		{
		return equal_subtree(begin(), other.begin());
		}

//	bool Ex::operator<(const Ex& other) const
//		{
//		Ex::iterator_base_less less;
//		return less(begin(), other.begin());
//		}

	void Ex::push_history(const std::vector<Ex::path_t>& paths)
		{
		history.push_back(*this);
		terms.push_back(paths);
		}

	std::vector<Ex::path_t> Ex::pop_history()
		{
		tree<str_node>::operator=(history.back());
		history.pop_back();
		auto ret(terms.back());
		terms.pop_back();
		return ret;
		}

	int Ex::history_size() const
		{
		return history.size();
		}

	str_node::str_node(void)
		{
		multiplier=rat_set.insert(1).first;
		//	fl.modifier=m_none;
		fl.bracket=b_none;
		fl.parent_rel=p_none;
		//	fl.mark=0;
		}

	str_node::str_node(nset_t::iterator nm, bracket_t br, parent_rel_t pr)
		{
		multiplier=rat_set.insert(1).first;
		name=nm;
		//	fl.modifier=m_none;
		fl.bracket=br;
		fl.parent_rel=pr;
		//	fl.mark=0;
		}

	str_node::str_node(const std::u32string& nm, bracket_t br, parent_rel_t pr)
		{
#ifdef _MSC_VER
		std::wstring_convert<std::codecvt_utf8<int32_t>, int32_t> conv;
		auto p = reinterpret_cast<const int32_t*>(nm.data());
		std::string nm8 = conv.to_bytes(p, p + nm.size());
#else
		std::wstring_convert<std::codecvt_utf8<char32_t>, char32_t> conv;
		std::string nm8=conv.to_bytes(nm);
#endif

#ifdef DEBUG
		std::cerr << "str_node: " << nm8 << std::endl;
#endif
		multiplier=rat_set.insert(1).first;
		name=name_set.insert(nm8).first;
		//	fl.modifier=m_none;
		fl.bracket=br;
		fl.parent_rel=pr;
		}

	str_node::str_node(const std::string& nm, bracket_t br, parent_rel_t pr)
		{
		multiplier=rat_set.insert(1).first;
		name=name_set.insert(nm).first;
		//	fl.modifier=m_none;
		fl.bracket=br;
		fl.parent_rel=pr;
		//	fl.mark=0;
		}

	void str_node::flip_parent_rel()
		{
		if(fl.parent_rel==p_super)       fl.parent_rel=p_sub;
		else if(fl.parent_rel==p_sub)    fl.parent_rel=p_super;
		else throw std::logic_error("flip_parent_rel called on non-index");
		}

	bool str_node::is_zero() const
		{
		if(*multiplier==0) return true;
		return false;
		}

	bool str_node::is_identity() const
		{
		if(*name=="1" && *multiplier==1) return true;
		return false;
		}

	bool str_node::is_rational() const
		{
		return (*name=="1");
		}

	bool str_node::is_integer() const
		{
		if(*name=="1") {
			if(multiplier->get_den()==1)
				return true;
			}
		return false;
		}

	bool str_node::is_unsimplified_rational() const
		{
		if((*name).size()==0) return false;
		for(unsigned int i=0; i<(*name).size(); ++i) {
			if(!isdigit((*name)[i]) && (*name)[i]!='/' && (*name)[i]!='-')
				return false;
			}
		return true;
		}

	bool str_node::is_unsimplified_integer() const
		{
		if((*name).size()==0) return false;
		for(unsigned int i=0; i<(*name).size(); ++i) {
			if(!isdigit((*name)[i]) && (*name)[i]!='-')
				return false;
			}
		return true;
		}

	bool str_node::is_index() const
		{
		if(fl.parent_rel==p_sub || fl.parent_rel==p_super) return true;
		return false;
		}



	bool str_node::is_quoted_string() const
		{
		if((*name).size()<2) return false;
		if((*name)[0]!='\"') return false;
		if((*name)[(*name).size()-1]!='\"') return false;
		return true;
		}

	bool str_node::is_command() const
		{
		if((*name).size()>0)
			if((*name)[0]=='@') {
				if((*name).size()>1) {
					if((*name)[1]!='@')
						return true;
					}
				else return true;
				}
		return false;
		}

	bool str_node::is_inert_command() const
		{
		if((*name).size()>1)
			if((*name)[0]=='@')
				if((*name)[1]=='@')
					return true;
		return false;
		}

	bool str_node::is_name_wildcard() const
		{
		if((*name).size()>0)
			if((*name)[name->size()-1]=='?') {
				if(name->size()>1) {
					if((*name)[name->size()-2]!='?')
						return true;
					}
				else return true;
				}
		return false;
		}

	bool str_node::is_object_wildcard() const
		{
		if((*name).size()>1)
			if((*name)[name->size()-1]=='?')
				if((*name)[name->size()-2]=='?')
					return true;
		return false;
		}

	bool str_node::is_range_wildcard() const
		{
		if(name->size()>0) {
			if((*name)[0]=='#')
				return true;
			}
		return false;
		}

	bool str_node::is_siblings_wildcard() const
		{
		if(name->size()>0) {
			if((*name)[name->size()-1]=='@')
				return true;
			}
		return false;
		}

	bool str_node::is_autodeclare_wildcard() const
		{
		if(name->size()>0)
			if((*name)[name->size()-1]=='#')
				return true;
		return false;
		}

	bool str_node::is_indexstar_wildcard() const
		{
		if((*name).size()>1)
			if((*name)[name->size()-1]=='?')
				if((*name)[name->size()-2]=='*')
					return true;
		return false;
		}

	bool str_node::is_indexplus_wildcard() const
		{
		if((*name).size()>1)
			if((*name)[name->size()-1]=='?')
				if((*name)[name->size()-2]=='+')
					return true;
		return false;
		}

	bool str_node::is_numbered_symbol() const
		{
		int len=(*name).size();
		if(len>1)
			if(isdigit((*name)[len-1]))
				return true;
		return false;
		}

	nset_t::iterator str_node::name_only()
		{
		if(is_name_wildcard()) {
			std::string tmp=(*name).substr(0, name->size()-1);
			return name_set.insert(tmp).first;
			}
		else if(is_object_wildcard()) {
			std::string tmp=(*name).substr(0, name->size()-2);
			return name_set.insert(tmp).first;
			}
		else if(is_autodeclare_wildcard()) {
			size_t pos=name->find('#');
			std::string tmp=(*name).substr(0, pos);
			return name_set.insert(tmp).first;
			}
		else if(is_numbered_symbol()) {
			size_t pos=name->find_first_of("0123456789");
			std::string tmp=(*name).substr(0, pos);
			return name_set.insert(tmp).first;
			}
		return name;
		}

	bool str_node::operator==(const str_node& other) const
		{
		if(*name==*other.name &&
		      fl.bracket==other.fl.bracket &&
		      fl.parent_rel==other.fl.parent_rel &&
		      multiplier==other.multiplier)
			return true;
		else return false;
		}

	bool str_node::compare_names_only(const str_node& one, const str_node& two)
		{
		if(one.name==two.name) return true;
		else                   return false;
		}

	bool str_node::compare_name_brack_par(const str_node& one, const str_node& two)
		{
		if(one.name==two.name &&
		      one.fl.bracket==two.fl.bracket &&
		      one.fl.parent_rel==two.fl.parent_rel) return true;
		else                                     return false;
		}

	bool str_node::compare_name_inverse_par(const str_node& one, const str_node& two)
		{
		if(one.name==two.name &&
		      ( (one.fl.parent_rel==str_node::p_super && two.fl.parent_rel==str_node::p_sub) ||
		        (one.fl.parent_rel==str_node::p_sub && two.fl.parent_rel==str_node::p_super)))
			return true;
		return false;
		}

	bool nset_it_less::operator()(nset_t::iterator first, nset_t::iterator second) const
		{
		if(*first < *second)
			return true;
		return false;
		}


	void multiply(rset_t::iterator& num, multiplier_t fac)
		{
		fac*=*num;
		fac.canonicalize();
		num=rat_set.insert(fac).first;
		}

	void add(rset_t::iterator& num, multiplier_t fac)
		{
		fac+=*num;
		fac.canonicalize();
		num=rat_set.insert(fac).first;
		}

	void zero(rset_t::iterator& num)
		{
		num=rat_set.insert(0).first;
		}

	void one(rset_t::iterator& num)
		{
		num=rat_set.insert(1).first;
		}

	void flip_sign(rset_t::iterator& num)
		{
		multiplier_t fac=-(*num);
		fac.canonicalize();
		num=rat_set.insert(fac).first;
		}

	void half(rset_t::iterator& num)
		{
		multiplier_t fac=(*num)/2;
		fac.canonicalize();
		num=rat_set.insert(fac).first;
		}

	bool str_node::operator<(const cadabra::str_node& other) const
		{
		if(*name<*other.name) return true;
		else return false;
		}

	}

// Keep operator overloading outside of the cadabra namespace.

std::ostream& operator<<(std::ostream& str, const cadabra::Ex& ex)
	{
	if(ex.begin()==ex.end()) return str;
	ex.print_recursive_treeform(str, ex.begin());
	//	ex.print_python(str, ex.begin());
	return str;
	}

std::ostream& operator<<(std::ostream& str, cadabra::Ex::iterator it)
	{
	cadabra::Ex::print_recursive_treeform(str, it);
	//	ex.print_python(str, ex.begin());
	return str;
	}