/** @file expairseq.h
 *
 *  Interface to sequences of expression pairs. */

/*
 *  GiNaC Copyright (C) 1999-2020 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
 *  the Free Software Foundation; either version 2 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, write to the Free Software
 *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 */

#ifndef GINAC_EXPAIRSEQ_H
#define GINAC_EXPAIRSEQ_H

#include "expair.h"
#include "indexed.h"

#include <vector>

namespace GiNaC {

typedef std::vector<expair> epvector;       ///< expair-vector
typedef epvector::iterator epp;             ///< expair-vector pointer

/** Complex conjugate every element of an epvector. Returns zero if this
 *  does not change anything. */
epvector* conjugateepvector(const epvector&);

/** A sequence of class expair.
 *  This is used for time-critical classes like sums and products of terms
 *  since handling a list of coeff and rest is much faster than handling a
 *  list of products or powers, respectively. (Not incidentally, Maple does it
 *  the same way, maybe others too.)  The semantics is (at least) twofold:
 *  one for addition and one for multiplication and several methods have to
 *  be overridden by derived classes to reflect the change in semantics.
 *  However, most functionality turns out to be shared between addition and
 *  multiplication, which is the reason why there is this base class. */
class expairseq : public basic
{
	GINAC_DECLARE_REGISTERED_CLASS(expairseq, basic)

	// other constructors
public:
	expairseq(const ex & lh, const ex & rh);
	expairseq(const exvector & v);
	expairseq(const epvector & v, const ex & oc, bool do_index_renaming = false);
	expairseq(epvector && vp, const ex & oc, bool do_index_renaming = false);
	
	// functions overriding virtual functions from base classes
public:
	unsigned precedence() const override {return 10;}
	bool info(unsigned inf) const override;
	size_t nops() const override;
	ex op(size_t i) const override;
	ex map(map_function & f) const override;
	ex eval() const override;
	ex to_rational(exmap & repl) const override;
	ex to_polynomial(exmap & repl) const override;
	bool match(const ex & pattern, exmap& repl_lst) const override;
	ex subs(const exmap & m, unsigned options = 0) const override;
	ex conjugate() const override;

	void archive(archive_node& n) const override;
	void read_archive(const archive_node& n, lst& syms) override;
protected:
	bool is_equal_same_type(const basic & other) const override;
	unsigned return_type() const override;
	unsigned calchash() const override;
	ex expand(unsigned options=0) const override;
	
	// new virtual functions which can be overridden by derived classes
protected:
	virtual ex thisexpairseq(const epvector & v, const ex & oc, bool do_index_renaming = false) const;
	virtual ex thisexpairseq(epvector && vp, const ex & oc, bool do_index_renaming = false) const;
	virtual void printseq(const print_context & c, char delim,
	                      unsigned this_precedence,
	                      unsigned upper_precedence) const;
	virtual void printpair(const print_context & c, const expair & p,
	                       unsigned upper_precedence) const;
	virtual expair split_ex_to_pair(const ex & e) const;
	virtual expair combine_ex_with_coeff_to_pair(const ex & e,
	                                             const ex & c) const;
	virtual expair combine_pair_with_coeff_to_pair(const expair & p,
	                                               const ex & c) const;
	virtual ex recombine_pair_to_ex(const expair & p) const;
	virtual bool expair_needs_further_processing(epp it);
	virtual ex default_overall_coeff() const;
	virtual void combine_overall_coeff(const ex & c);
	virtual void combine_overall_coeff(const ex & c1, const ex & c2);
	virtual bool can_make_flat(const expair & p) const;
	
	// non-virtual functions in this class
protected:
	void do_print(const print_context & c, unsigned level) const;
	void do_print_tree(const print_tree & c, unsigned level) const;
	void construct_from_2_ex(const ex & lh, const ex & rh);
	void construct_from_2_expairseq(const expairseq & s1,
	                                const expairseq & s2);
	void construct_from_expairseq_ex(const expairseq & s,
	                                 const ex & e);
	void construct_from_exvector(const exvector & v);
	void construct_from_epvector(const epvector & v, bool do_index_renaming = false);
	void construct_from_epvector(epvector && v, bool do_index_renaming = false);
	void make_flat(const exvector & v);
	void make_flat(const epvector & v, bool do_index_renaming = false);
	void canonicalize();
	void combine_same_terms_sorted_seq();
	bool is_canonical() const;
	epvector expandchildren(unsigned options) const;
	epvector evalchildren() const;
	epvector subschildren(const exmap & m, unsigned options = 0) const;
	
// member variables
	
protected:
	epvector seq;
	ex overall_coeff;
};

/** Class to handle the renaming of dummy indices. It holds a vector of
 *  indices that are being used in the expression so far. If the same
 *  index occurs again as a dummy index in a factor, it is to be renamed.
 *  Unless dummy index renaming was switched off, of course ;-) . */
class make_flat_inserter
{
	public:
		make_flat_inserter(const epvector &epv, bool b): do_renaming(b)
		{
			if (!do_renaming)
				return;
			for (epvector::const_iterator i=epv.begin(); i!=epv.end(); ++i)
				if(are_ex_trivially_equal(i->coeff, 1))
					combine_indices(i->rest.get_free_indices());
		}
		make_flat_inserter(const exvector &v, bool b): do_renaming(b)
		{
			if (!do_renaming)
				return;
			for (exvector::const_iterator i=v.begin(); i!=v.end(); ++i)
				combine_indices(i->get_free_indices());
		}
		ex handle_factor(const ex &x, const ex &coeff)
		{
			if (!do_renaming)
				return x;
			exvector dummies_of_factor;
			if (is_a<numeric>(coeff) && coeff.is_equal(GiNaC::numeric(1)))
				dummies_of_factor = get_all_dummy_indices_safely(x);
			else if (is_a<numeric>(coeff) && coeff.is_equal(GiNaC::numeric(2)))
				dummies_of_factor = x.get_free_indices();
			else
				return x;
			if (dummies_of_factor.size() == 0)
				return x;
			sort(dummies_of_factor.begin(), dummies_of_factor.end(), ex_is_less());
			ex new_factor = rename_dummy_indices_uniquely(used_indices,
			                                              dummies_of_factor, x);
			combine_indices(dummies_of_factor);
			return new_factor;
		}
	private:
		void combine_indices(const exvector &dummies_of_factor)
		{
			exvector new_dummy_indices;
			set_union(used_indices.begin(), used_indices.end(),
			          dummies_of_factor.begin(), dummies_of_factor.end(),
			          std::back_insert_iterator<exvector>(new_dummy_indices), ex_is_less());
			used_indices.swap(new_dummy_indices);
		}
		bool do_renaming;
		exvector used_indices;
};

} // namespace GiNaC

#endif // ndef GINAC_EXPAIRSEQ_H