FreeLink.cc

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/*
 * opencog/atoms/core/FreeLink.cc
 *
 * 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.
 */

#include <opencog/atomspace/atom_types.h>
#include <opencog/atomspace/ClassServer.h>
#include "FreeLink.h"

using namespace opencog;

FreeLink::FreeLink(const HandleSeq& oset,
                   TruthValuePtr tv,
                   AttentionValuePtr av)
    : Link(FREE_LINK, oset, tv, av)
{
    init();
}

FreeLink::FreeLink(const Handle& a,
                   TruthValuePtr tv,
                   AttentionValuePtr av)
    : Link(FREE_LINK, a, tv, av)
{
    init();
}

FreeLink::FreeLink(Type t, const HandleSeq& oset,
                   TruthValuePtr tv,
                   AttentionValuePtr av)
    : Link(t, oset, tv, av)
{
    if (not classserver().isA(t, FREE_LINK))
        throw InvalidParamException(TRACE_INFO, "Expecting a FreeLink");

    // Derived classes have thier own init routines.
    if (FREE_LINK != t) return;
    init();
}

FreeLink::FreeLink(Type t, const Handle& a,
                   TruthValuePtr tv,
                   AttentionValuePtr av)
    : Link(t, a, tv, av)
{
    if (not classserver().isA(t, FREE_LINK))
        throw InvalidParamException(TRACE_INFO, "Expecting a FreeLink");

    // Derived classes have thier own init routines.
    if (FREE_LINK != t) return;
    init();
}

FreeLink::FreeLink(Type t, const Handle& a, const Handle& b,
                   TruthValuePtr tv,
                   AttentionValuePtr av)
    : Link(t, a, b, tv, av)
{
    if (not classserver().isA(t, FREE_LINK))
        throw InvalidParamException(TRACE_INFO, "Expecting a FreeLink");

    // Derived classes have thier own init routines.
    if (FREE_LINK != t) return;
    init();
}

FreeLink::FreeLink(Link& l)
    : Link(l)
{
    Type tscope = l.getType();
    if (not classserver().isA(tscope, FREE_LINK))
        throw InvalidParamException(TRACE_INFO, "Expecting a FreeLink");

    // Derived classes have thier own init routines.
    if (FREE_LINK != tscope) return;
    init();
}

/* ================================================================= */
void FreeLink::find_vars(std::set<Handle>& varset, const HandleSeq& oset)
{
    for (const Handle& h : oset)
    {
        Type t = h->getType();
        if (QUOTE_LINK == t) continue;
        if (VARIABLE_NODE == t and
            0 == varset.count(h))
        {
            _varseq.push_back(h);
            varset.insert(h);
        }
        LinkPtr lll(LinkCast(h));
        if (NULL == lll) continue;

        find_vars(varset, lll->getOutgoingSet());
    }
}

/* ================================================================= */
void FreeLink::build_index(void)
{
    if (0 < _index.size()) return;
    size_t sz = _varseq.size();
    for (size_t i=0; i<sz; i++)
        _index.insert(std::pair<Handle, unsigned int>(_varseq[i], i));
}

/* ================================================================= */

void FreeLink::init(void)
{
    std::set<Handle> varset;
    find_vars(varset, _outgoing);
    build_index();
}

Handle FreeLink::reduce(void)
{
   throw RuntimeException(TRACE_INFO, "Not reducible!");
}