LambdaLink.h

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/*
 * opencog/atoms/LambdaLink.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_LAMBDA_LINK_H
#define _OPENCOG_LAMBDA_LINK_H

#include <map>

#include <opencog/atoms/bind/VariableList.h>

namespace opencog
{
class LambdaLink : public VariableList
{
protected:
    Handle _body;

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

    void init(const HandleSeq&);

    // utility debug print
    static void prt(const Handle& h)
    {
        printf("%s\n", h->toShortString().c_str());
    }
public:
    LambdaLink(const HandleSeq&,
               TruthValuePtr tv = TruthValue::DEFAULT_TV(),
               AttentionValuePtr av = AttentionValue::DEFAULT_AV());

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

    LambdaLink(Link &l);

    // Take the list of values `vals`, and substitute them in for the
    // variables in the body of this lambda. The values must satisfy all
    // type restrictions, else an exception will be thrown.
    Handle substitute (const HandleSeq& vals) const
    {
        return VariableList::substitute(_body, vals);
    }
};

typedef std::shared_ptr<LambdaLink> LambdaLinkPtr;
static inline LambdaLinkPtr LambdaLinkCast(const Handle& h)
    { AtomPtr a(h); return std::dynamic_pointer_cast<LambdaLink>(a); }
static inline LambdaLinkPtr LambdaLinkCast(AtomPtr a)
    { return std::dynamic_pointer_cast<LambdaLink>(a); }

// XXX temporary hack ...
#define createLambdaLink std::make_shared<LambdaLink>

}

#endif // _OPENCOG_LAMBDA_LINK_H