/*
 * Licensed to CRATE Technology GmbH ("Crate") under one or more contributor
 * license agreements.  See the NOTICE file distributed with this work for
 * additional information regarding copyright ownership.  Crate licenses
 * this file to you under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.  You may
 * obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
 * License for the specific language governing permissions and limitations
 * under the License.
 *
 * However, if you have executed another commercial license agreement
 * with Crate these terms will supersede the license and you may use the
 * software solely pursuant to the terms of the relevant commercial agreement.
 */

package io.crate.operation.projectors;

import io.crate.core.collections.Row;
import io.crate.operation.RowDownstream;
import io.crate.operation.RowDownstreamHandle;
import io.crate.operation.RowUpstream;

/**
 * a projector that does nothing.
 * Can be used by classes that implement ProjectorUpstream to have a "default" downstream
 * to avoid null checks
 */
public class NoOpProjector implements Projector, RowDownstreamHandle {

    public static NoOpProjector INSTANCE = new NoOpProjector();

    private NoOpProjector() {

    }

    @Override
    public void startProjection() {

    }

    @Override
    public void downstream(RowDownstream downstream) {

    }

    @Override
    public boolean setNextRow(Row row) {
        return false;
    }

    @Override
    public void finish() {

    }

    @Override
    public void fail(Throwable throwable) {

    }

    @Override
    public RowDownstreamHandle registerUpstream(RowUpstream upstream) {
        return this;
    }
}

/*
 * Licensed to CRATE Technology GmbH ("Crate") under one or more contributor
 * license agreements.  See the NOTICE file distributed with this work for
 * additional information regarding copyright ownership.  Crate licenses
 * this file to you under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.  You may
 * obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
 * License for the specific language governing permissions and limitations
 * under the License.
 *
 * However, if you have executed another commercial license agreement
 * with Crate these terms will supersede the license and you may use the
 * software solely pursuant to the terms of the relevant commercial agreement.
 */

package io.crate.operation.projectors;

import io.crate.core.collections.Row;
import io.crate.operation.RowDownstream;
import io.crate.operation.RowDownstreamHandle;
import io.crate.operation.RowUpstream;

/**
 * a projector that does nothing.
 * Can be used by classes that implement ProjectorUpstream to have a "default" downstream
 * to avoid null checks
 */
public class NoOpProjector implements Projector, RowDownstreamHandle {

    public static final NoOpProjector INSTANCE = new NoOpProjector();

    private NoOpProjector() {

    }

    @Override
    public void startProjection() {

    }

    @Override
    public void downstream(RowDownstream downstream) {

    }

    @Override
    public boolean setNextRow(Row row) {
        return false;
    }

    @Override
    public void finish() {

    }

    @Override
    public void fail(Throwable throwable) {

    }

    @Override
    public RowDownstreamHandle registerUpstream(RowUpstream upstream) {
        return this;
    }
}

make NoOpProjector instance final