DeleteLink.cc

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/*
 * DeleteLink.cc
 *
 * Copyright (C) 2015 Linas Vepstas
 *
 * Author: Linas Vepstas <linasvepstas@gmail.com>  January 2009
 *
 * 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/ClassServer.h>
#include <opencog/atomspace/AtomSpace.h>
#include <opencog/atomspace/AtomTable.h>
#include <opencog/atomutils/FindUtils.h>

#include "DeleteLink.h"

using namespace opencog;

void DeleteLink::init(void)
{
    // The handleset must contain a free variable in it, somewhere.
    // If it doesn't, then the entire Handleset should be deleted
    // (removed from the atomspace). We can't do this at constructor
    // time, because we don't know the atomspace yet.  So we hack
    // around this by thowing at construtor time.
    //
    if (0 == _varseq.size())
        // throw DeleteException();
        throw InvalidParamException(TRACE_INFO,
            "Cannot create a fully grounded DeleteLink!");
} 

#if 0
/*****
Well, we cannot really implement this here; but this is what
it should actually do.  We can't implement it here, because
fully-grounded DeleteLink's cannot exist.
****/
Handle DeleteLink::execute(AtomSpace * as) const
{
    const HandleSeq& oset = _outgoing;
    for (const Handle& h : oset)
    {
        Type t = h->getType();
        if (VARIABLE_NODE != t)
            as->removeAtom(h, true);
    }
    return Handle::UNDEFINED;
}
#endif

DeleteLink::DeleteLink(const HandleSeq& oset,
                       TruthValuePtr tv, AttentionValuePtr av)
    : FunctionLink(DELETE_LINK, oset, tv, av)
{
    init();
}

DeleteLink::DeleteLink(Link &l)
    : FunctionLink(l)
{
    // Type must be as expected
    Type tscope = l.getType();
    if (not classserver().isA(tscope, DELETE_LINK))
    {
        const std::string& tname = classserver().getTypeName(tscope);
        throw InvalidParamException(TRACE_INFO,
            "Expecting a DeleteLink, got %s", tname.c_str());
    }

    init();
}

/* ===================== END OF FILE ===================== */