opencog-generate / opencog / generate / SimpleCallback.h

/*
 * opencog/generate/SimpleCallback.h
 *
 * Copyright (C) 2020 Linas Vepstas <linasvepstas@gmail.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License v3 as
 * published by the Free Software Foundation and including the exceptions
 * at http://opencog.org/wiki/Licenses
 *
 * 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 Affero General Public License
 * along with this program; if not, write to:
 * Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */

#ifndef _OPENCOG_SIMPLE_CALLBACK_H
#define _OPENCOG_SIMPLE_CALLBACK_H

#include <opencog/util/Counter.h>

#include <opencog/generate/CollectStyle.h>
#include <opencog/generate/Dictionary.h>
#include <opencog/generate/GenerateCallback.h>
#include <opencog/generate/LinkStyle.h>

namespace opencog
{
/** \addtogroup grp_generate
 *  @{
 */

//! a map from handle to unsigned
typedef Counter<Handle, unsigned> HandleUCounter;

/// Callback to provide sections (aka "puzzle pieces") to extend the
/// current assembly. The current implementation here is deterministic,
/// although otherwise arbitrary, when more than one choice is possible.
///
/// The proposed connection always attempts to join together two open
/// connectors, if that is possible, else drawing a new section from a
/// dictionary (lexis).
///
/// This behavior is useful only in certain small, limited cases, where
/// the lexis has been designed to have only a finite number of possible
/// solutions.

class SimpleCallback :
	public GenerateCallback,
	private LinkStyle,
	private CollectStyle
{
private:
	Dictionary _dict;
	size_t _steps_taken;

	// -------------------------------------------
	// Nucleation points.
	HandleSeqSeq _root_sections;
	std::vector<HandleSeq::iterator> _root_iters;

	// -------------------------------------------
	// Lexical selection
	Handle select_from_lexis(const OdoFrame&,
	                         const Handle&, size_t,
	                         const Handle&);

	// Iterator, pointing from a to-connector, to a list of
	// all sections in the dictionary that contain this to-connector.
	// Used by `select()` to return the next attachable section.
	HandleUCounter _lexlit;

	// Stack of iterators into the lists of sections.
	std::stack<HandleUCounter> _lexlit_stack;

	// -------------------------------------------
	Handle select_from_open(const OdoFrame&,
	                        const Handle&, size_t,
	                        const Handle&);
	Handle check_self(const HandleSeq&, const Handle&,
	                  const Handle&, size_t);
	struct OpenSelections
	{
		HandleSeqMap _opensect;

		// Iterator, pointing from a to-connector, to a list of
		// all open sections in the current frame.
		HandleUCounter _openit;
	};

	OpenSelections _opensel;
	std::stack<OpenSelections> _opensel_stack;
	// -------------------------------------------

public:
	SimpleCallback(AtomSpace*, const Dictionary&);
	virtual ~SimpleCallback();

	virtual void clear(AtomSpace*);
	virtual bool step(const OdoFrame&);
	virtual HandleSeq joints(const Handle& con) {
		return _dict.joints(con);
	}

	virtual void root_set(const HandleSet&);
	virtual HandleSet next_root(void);

	virtual Handle select(const OdoFrame&,
	                      const Handle&, size_t,
	                      const Handle&);

	virtual Handle make_link(const Handle&, const Handle&,
	                         const Handle&, const Handle&);
	virtual size_t num_links(const Handle&, const Handle&,
	                         const Handle&);
	virtual void push_frame(const OdoFrame&);
	virtual void pop_frame(const OdoFrame&);
	virtual void push_odometer(const Odometer&);
	virtual void pop_odometer(const Odometer&);
	virtual void solution(const OdoFrame&);
	virtual Handle get_solutions(void);
};


/** @}*/
}  // namespace opencog

#endif // _OPENCOG_SIMPLE_CALLBACK_H