tajo-core/src/main/java/org/apache/tajo/engine/planner/physical/SelectionExec.java

/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF 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.
 */

package org.apache.tajo.engine.planner.physical;

import org.apache.tajo.engine.codegen.CompilationError;
import org.apache.tajo.plan.expr.EvalNode;
import org.apache.tajo.plan.logical.SelectionNode;
import org.apache.tajo.storage.Tuple;
import org.apache.tajo.worker.TaskAttemptContext;

import java.io.IOException;

public class SelectionExec extends UnaryPhysicalExec  {
  private EvalNode qual;

  public SelectionExec(TaskAttemptContext context,
                       SelectionNode plan,
                       PhysicalExec child) {
    super(context, plan.getInSchema(), plan.getOutSchema(), child);
    this.qual = plan.getQual();
  }

  @Override
  public void init() throws IOException {
    super.init();
    qual.bind(context.getEvalContext(), inSchema);
  }

  @Override
  public void compile() throws CompilationError {
    qual = context.getPrecompiledEval(inSchema, qual);
  }

  @Override
  public Tuple next() throws IOException {
    Tuple tuple;
    while (!context.isStopped() && (tuple = child.next()) != null) {
      if (qual.eval(tuple).isTrue()) {
        return tuple;
      }
    }

    return null;
  }
}