PatternLink.h

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/*
 * opencog/atoms/PatternLink.h
 *
 * Copyright (C) 2015 Linas Vepstas
 * All Rights Reserved
 *
 * 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_PATTERN_LINK_H
#define _OPENCOG_PATTERN_LINK_H

#include <unordered_map>

#include <opencog/query/Pattern.h>
#include <opencog/atoms/bind/VariableList.h>
#include <opencog/query/PatternMatchCallback.h>

namespace opencog
{

class PatternLink : public Link
{
protected:
    // The link to be grounded.
    Handle _body;

    // The variables to be grounded
    Variables _varlist;

    // The pattern that is specified by this link.
    Pattern _pat;

    HandleSeq _fixed;
    size_t _num_virts;
    HandleSeq _virtual;

    size_t _num_comps;
    std::vector<HandleSeq> _components;
    std::vector<std::set<Handle>> _component_vars;
    HandleSeq _component_patterns;

    void extract_variables(const HandleSeq& oset);
    void init_scoped_variables(const Handle& hvar);
    void unbundle_clauses(const Handle& body);
    void validate_clauses(std::set<Handle>& vars,
                          HandleSeq& clauses);

    void extract_optionals(const std::set<Handle> &vars,
                           const std::vector<Handle> &component);

    void unbundle_virtual(const std::set<Handle>& vars,
                          const HandleSeq& clauses,
                          HandleSeq& concrete_clauses,
                          HandleSeq& virtual_clauses,
                          std::set<Handle>& black_clauses);

    void trace_connectives(const std::set<Type>&,
                           const HandleSeq& clauses);

    void make_connectivity_map(const HandleSeq&);
    void check_connectivity(const std::vector<HandleSeq>&);
    void make_map_recursive(const Handle&, const Handle&);

    void make_term_trees();
    void make_term_tree_recursive(const Handle&, const Handle&,
                                  PatternTermPtr&);

    void init(void);
    void common_init(void);
    void setup_components(void);

    // Only derived classes can call this
    PatternLink(Type, const HandleSeq&,
                TruthValuePtr tv = TruthValue::DEFAULT_TV(),
                AttentionValuePtr av = AttentionValue::DEFAULT_AV());

    // utility debug print
    static void prt(const Handle& h)
    {
        printf("%s\n", h->toShortString().c_str());
    }

public:
    PatternLink(const HandleSeq&,
                TruthValuePtr tv = TruthValue::DEFAULT_TV(),
                AttentionValuePtr av = AttentionValue::DEFAULT_AV());

    PatternLink(const Handle& body,
                TruthValuePtr tv = TruthValue::DEFAULT_TV(),
                AttentionValuePtr av = AttentionValue::DEFAULT_AV());

    PatternLink(const Handle& varcdecls, const Handle& body,
                TruthValuePtr tv = TruthValue::DEFAULT_TV(),
                AttentionValuePtr av = AttentionValue::DEFAULT_AV());

    PatternLink(Link &l);

    // Used only to set up multi-component links.
    // DO NOT call this!
    PatternLink(const std::set<Handle>& vars,
                const VariableTypeMap& typemap,
                const HandleSeq& component,
                const std::set<Handle>& optionals);

    // A backwards-compatibility constructor. Do not use.
    PatternLink(const std::set<Handle>&,
                const HandleSeq&);

    // Return the list of variables we are holding.
    const Variables& get_variables(void) const { return _varlist; }

    const Handle& get_body(void) const { return _body; }

    // XXX temp hack till things get sorted out; remove this method
    // later.
    const Pattern& get_pattern(void) { return _pat; }

    bool satisfy(PatternMatchCallback&) const;

    void debug_print(void) const;
};

typedef std::shared_ptr<PatternLink> PatternLinkPtr;
static inline PatternLinkPtr PatternLinkCast(const Handle& h)
    { AtomPtr a(h); return std::dynamic_pointer_cast<PatternLink>(a); }
static inline PatternLinkPtr PatternLinkCast(AtomPtr a)
    { return std::dynamic_pointer_cast<PatternLink>(a); }

// XXX temporary hack ...
#define createPatternLink std::make_shared<PatternLink>

}

#endif // _OPENCOG_PATTERN_LINK_H