DefineLink.cc

Go to the documentation of this file.

/*
 * DefineLink.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 "DefineLink.h"

using namespace opencog;

void DefineLink::init(const HandleSeq& oset)
{
    // Must have name and body
    if (2 != oset.size())
        throw InvalidParamException(TRACE_INFO,
            "Expecting name and definition, got size %d", oset.size());

    _alias = oset[0];
    _definition = oset[1];

    // The name must not be used in another definition
    IncomingSet defs = _alias->getIncomingSetByType(DEFINE_LINK);
    for (LinkPtr def : defs)
        if (def->isSource(_alias))
            throw InvalidParamException(TRACE_INFO,
                                        "Cannot define %s\n"
                                        "with alias %s\n"
                                        "as it is already defined in %s",
                                        _definition->toString().c_str(),
                                        _alias->toString().c_str(),
                                        def->toString().c_str());
}

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

DefineLink::DefineLink(const Handle& name, const Handle& defn,
                       TruthValuePtr tv, AttentionValuePtr av)
    : Link(DEFINE_LINK, HandleSeq({name, defn}), tv, av)
{
    init(getOutgoingSet());
}

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

    init(l.getOutgoingSet());
}

Handle DefineLink::get_definition(const Handle& alias) {
    // Get all DefineLinks associated with that alias, beware that it
    // will also return DefineLink with that alias as definition body.
    IncomingSet defs = alias->getIncomingSetByType(DEFINE_LINK);

    // Return the first (supposedly unique) definition
    for (LinkPtr defl : defs) {
        DefineLinkPtr def(DefineLinkCast(defl->getHandle()));
        if (def->get_alias() == alias)
            return def->get_definition();
    }

    // There is no definition for that alias
    throw InvalidParamException(TRACE_INFO,
                                "Cannot find defined hypergraph for atom %s",
                                alias->toString().c_str());
    return Handle::UNDEFINED;
}

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