Link.h

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/*
 * opencog/atomspace/Link.h
 *
 * Copyright (C) 2002-2007 Novamente LLC
 * Copyright (C) 2008-2010 OpenCog Foundation
 * 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_LINK_H
#define _OPENCOG_LINK_H

#include <string>

#include <opencog/util/oc_assert.h>
#include <opencog/atomspace/Atom.h>

namespace opencog
{
class AtomTable;
typedef unsigned short Arity;

class Link : public Atom
{
    friend class AtomTable;

private:
    void init(const HandleSeq&) throw (InvalidParamException);
    void resort(void);

    Link(const Link &l) : Atom(0)
    { OC_ASSERT(false, "Link: bad use of copy ctor"); }

protected:

    HandleSeq _outgoing;

public:
    Link(Type t, const HandleSeq& oset,
         TruthValuePtr tv = TruthValue::DEFAULT_TV(),
         AttentionValuePtr av = AttentionValue::DEFAULT_AV())
        : Atom(t, tv, av)
    {
        init(oset);
    }

    Link(Type t, const Handle& h,
         TruthValuePtr tv = TruthValue::DEFAULT_TV(),
         AttentionValuePtr av = AttentionValue::DEFAULT_AV())
        : Atom(t, tv, av)
    {
        HandleSeq oset;
        oset.push_back(h);
        init(oset);
    }

    Link(Type t, const Handle& ha, const Handle &hb,
         TruthValuePtr tv = TruthValue::DEFAULT_TV(),
         AttentionValuePtr av = AttentionValue::DEFAULT_AV())
        : Atom(t, tv, av)
    {
        HandleSeq oset;
        oset.push_back(ha);
        oset.push_back(hb);
        init(oset);
    }

    Link(Type t, const Handle& ha, const Handle &hb, const Handle &hc,
         TruthValuePtr tv = TruthValue::DEFAULT_TV(),
         AttentionValuePtr av = AttentionValue::DEFAULT_AV())
        : Atom(t, tv, av)
    {
        HandleSeq oset;
        oset.push_back(ha);
        oset.push_back(hb);
        oset.push_back(hc);
        init(oset);
    }
    Link(Type t, const Handle& ha, const Handle &hb,
          const Handle &hc, const Handle &hd,
         TruthValuePtr tv = TruthValue::DEFAULT_TV(),
         AttentionValuePtr av = AttentionValue::DEFAULT_AV())
        : Atom(t, tv, av)
    {
        HandleSeq oset;
        oset.push_back(ha);
        oset.push_back(hb);
        oset.push_back(hc);
        oset.push_back(hd);
        init(oset);
    }

    Link(Link &l)
        : Atom(l.getType(),
               l.getTruthValue()->clone(),
               l.getAttentionValue()->clone())
    {
        init(l.getOutgoingSet());
    }

    ~Link();

    inline Arity getArity() const {
        return _outgoing.size();
    }

    inline const HandleSeq& getOutgoingSet() const
    {
        return _outgoing;
    }
    inline Handle getOutgoingAtom(Arity pos) const throw (RuntimeException)
    {
        // Checks for a valid position
        if (pos < getArity()) {
            return _outgoing[pos];
        } else {
            throw RuntimeException(TRACE_INFO, "invalid outgoing set index %d", pos);
        }
    }

    template<class T>
    inline bool foreach_outgoing(bool (T::*cb)(const Handle&), T *data)
    {
        for (const Handle& out_h : getOutgoingSet()) {
            if ((data->*cb)(out_h)) return true;
        }
        return false;
    }

    std::string toString(std::string indent = "");

    std::string toShortString(std::string indent = "");

    bool isSource(Handle) const throw (InvalidParamException);

    bool isSource(size_t) const throw (IndexErrorException, InvalidParamException);

    bool isTarget(Handle) const throw (InvalidParamException);

    bool isTarget(size_t) const throw (IndexErrorException, InvalidParamException);

    virtual bool operator==(const Atom&) const;

    virtual bool operator!=(const Atom&) const;
};

static inline LinkPtr LinkCast(const Handle& h)
    { AtomPtr a(h); return std::dynamic_pointer_cast<Link>(a); }
static inline LinkPtr LinkCast(const AtomPtr& a)
    { return std::dynamic_pointer_cast<Link>(a); }

// XXX temporary hack ...
#define createLink std::make_shared<Link>

} // namespace opencog

#endif // _OPENCOG_LINK_H