PutLink.cc

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/*
 * opencog/atoms/core/PutLink.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 Put 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:
 * Put 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 "PutLink.h"

using namespace opencog;

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

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

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

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

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

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

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

void PutLink::init(void)
{
    if (2 != _outgoing.size())
        throw InvalidParamException(TRACE_INFO, "PutLinks should be arity 2!");

    const Handle& body = _outgoing[0];
    if (VARIABLE_NODE == body->getType())
    {
        _varseq.push_back(body);
    }
    else
    {
        LinkPtr lll(LinkCast(body));
        if (lll)
        {
            std::set<Handle> varset;
            find_vars(varset, lll->getOutgoingSet());
        }
    }
    build_index();

    // OK, now for the values.
    if (_varseq.size() == 1) return;

    LinkPtr lval(LinkCast(_outgoing[1]));
    if (lval->getType() == LIST_LINK)
    {
        if (lval->getArity() != _varseq.size())
            throw InvalidParamException(TRACE_INFO,
                "PutLink has mismatched size! Expected %zu, got %zu\n",
                _varseq.size(), lval->getArity());
        return;
    }
    if (lval->getType() != SET_LINK)
        throw InvalidParamException(TRACE_INFO,
            "PutLink was expecting a ListLink or SetLink!");

    for (const Handle& h : lval->getOutgoingSet())
    {
        LinkPtr lse(LinkCast(h));
        if (lse->getType() != LIST_LINK)
            throw InvalidParamException(TRACE_INFO,
                "PutLink was expecting a ListLink here");
        if (lse->getArity() != _varseq.size())
            throw InvalidParamException(TRACE_INFO,
                "PutLink set element has mismatched size! Expected %zu, got %zu\n",
                _varseq.size(), lse->getArity());
    }
}
/* ================================================================= */

Handle PutLink::substitute_nocheck(const Handle& term,
                                   const HandleSeq& args) const
{
    // If it is a singleton, just return that singleton.
    std::map<Handle, unsigned int>::const_iterator idx;
    idx = _index.find(term);
    if (idx != _index.end())
        return args.at(idx->second);

    // If its a node, and its not a variable, then it is a constant,
    // and just return that.
    LinkPtr lterm(LinkCast(term));
    if (NULL == lterm) return term;

    // QuoteLinks halt the reursion
    if (QUOTE_LINK == term->getType()) return term;

    // Recursively fill out the subtrees.
    HandleSeq oset;
    for (const Handle& h : lterm->getOutgoingSet())
    {
        oset.push_back(substitute_nocheck(h, args));
    }
    return Handle(createLink(term->getType(), oset));
}

Handle PutLink::do_reduce(void) const
{
    const Handle& body = _outgoing[0];
    const Handle& vals = _outgoing[1];

    if (1 == _varseq.size())
    {
        HandleSeq oset;
        oset.push_back(vals);
        return substitute_nocheck(body, oset);
    }
    if (vals->getType() == LIST_LINK)
    {
        const HandleSeq& oset = LinkCast(vals)->getOutgoingSet();
        return substitute_nocheck(body, oset);
    }

    OC_ASSERT(vals->getType() == SET_LINK,
        "Should have checked for this earlier, tin the ctor");

    HandleSeq bset;
    for (Handle h : LinkCast(vals)->getOutgoingSet())
    {
        const HandleSeq& oset = LinkCast(h)->getOutgoingSet();
        bset.push_back(substitute_nocheck(body, oset));
    }
    return Handle(createLink(SET_LINK, bset));
}

Handle PutLink::reduce(void)
{
    return do_reduce();
}

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