opencog-sensory / opencog / atoms / sensory-v0 / OpenLink.cc

/*
 * OpenLink.cc
 *
 * Copyright (C) 2022 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/atoms/signature/TypeNode.h>
#include <opencog/atoms/value/ValueFactory.h>
#include "OpenLink.h"
#include "OutputStream.h"

using namespace opencog;

OpenLink::OpenLink(const HandleSeq&& oset, Type t)
	: Link(std::move(oset), t)
{
	if (not nameserver().isA(t, OPEN_LINK))
	{
		const std::string& tname = nameserver().getTypeName(t);
		throw InvalidParamException(TRACE_INFO,
			"Expecting an OpenLink, got %s", tname.c_str());
	}
	init();
}

OpenLink::OpenLink(const Handle& h)
	: Link({h}, OPEN_LINK)
{
	init();
}

void OpenLink::init(void)
{
	if (1 > _outgoing.size())
		throw SyntaxException(TRACE_INFO,
			"Expecting at least one argument!");

	if (TYPE_NODE != _outgoing[0]->get_type())
		throw SyntaxException(TRACE_INFO,
			"Expecting the first argument to be a type!");

	_kind = TypeNodeCast(_outgoing[0])->get_kind();

	// If there is a second argument, then it must be either a
	// SensoryNode, or something executable that returns a
	// SensoryNode.
	if (2 <= _outgoing.size() and
	    not _outgoing[1]->is_type(SENSORY_NODE) and
	    not _outgoing[1]->is_executable())
		throw SyntaxException(TRACE_INFO,
			"Expecting the second argument to be a SensoryNode!");
}

// ---------------------------------------------------------------

/// When executed, create an iterator stream for the given URL.
ValuePtr OpenLink::execute(AtomSpace* as, bool silent)
{
	ValuePtr svp;
	if (2 == _outgoing.size())
		 svp = valueserver().create(_kind, _outgoing[1]);
	else
		 svp = valueserver().create(_kind);

	OutputStreamPtr ost(OutputStreamCast(svp));
	if (nullptr == ost)
		throw RuntimeException(TRACE_INFO,
			"No support for %s", _outgoing[0]->to_string().c_str());
	return ost;
}

DEFINE_LINK_FACTORY(OpenLink, OPEN_LINK)

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