/*
 * 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.eigenbase.relopt;

import org.eigenbase.util.Util;

/**
 * RelOptCostImpl provides a default implementation for the {@link RelOptCost}
 * interface. It it defined in terms of a single scalar quantity; somewhat
 * arbitrarily, it returns this scalar for rows processed and zero for both CPU
 * and I/O.
 */
public class RelOptCostImpl implements RelOptCost {
  public static final RelOptCostFactory FACTORY = new Factory();

  //~ Instance fields --------------------------------------------------------

  private final double value;

  //~ Constructors -----------------------------------------------------------

  public RelOptCostImpl(double value) {
    this.value = value;
  }

  //~ Methods ----------------------------------------------------------------

  // implement RelOptCost
  public double getRows() {
    return value;
  }

  // implement RelOptCost
  public double getIo() {
    return 0;
  }

  // implement RelOptCost
  public double getCpu() {
    return 0;
  }

  // implement RelOptCost
  public boolean isInfinite() {
    return Double.isInfinite(value);
  }

  // implement RelOptCost
  public boolean isLe(RelOptCost other) {
    return getRows() <= other.getRows();
  }

  // implement RelOptCost
  public boolean isLt(RelOptCost other) {
    return getRows() < other.getRows();
  }

  @Override
  public int hashCode() {
    return Util.hashCode(getRows());
  }

  // implement RelOptCost
  public boolean equals(RelOptCost other) {
    return getRows() == other.getRows();
  }

  // implement RelOptCost
  public boolean isEqWithEpsilon(RelOptCost other) {
    return Math.abs(getRows() - other.getRows()) < RelOptUtil.EPSILON;
  }

  // implement RelOptCost
  public RelOptCost minus(RelOptCost other) {
    return new RelOptCostImpl(getRows() - other.getRows());
  }

  // implement RelOptCost
  public RelOptCost plus(RelOptCost other) {
    return new RelOptCostImpl(getRows() + other.getRows());
  }

  // implement RelOptCost
  public RelOptCost multiplyBy(double factor) {
    return new RelOptCostImpl(getRows() * factor);
  }

  public double divideBy(RelOptCost cost) {
    RelOptCostImpl that = (RelOptCostImpl) cost;
    return this.getRows() / that.getRows();
  }

  // implement RelOptCost
  public String toString() {
    if (value == Double.MAX_VALUE) {
      return "huge";
    } else {
      return Double.toString(value);
    }
  }

  /** Implementation of {@link RelOptCostFactory} that creates
   * {@link RelOptCostImpl}s. */
  private static class Factory implements RelOptCostFactory {
    // implement RelOptPlanner
    public RelOptCost makeCost(
        double dRows,
        double dCpu,
        double dIo) {
      return new RelOptCostImpl(dRows);
    }

    // implement RelOptPlanner
    public RelOptCost makeHugeCost() {
      return new RelOptCostImpl(Double.MAX_VALUE);
    }

    // implement RelOptPlanner
    public RelOptCost makeInfiniteCost() {
      return new RelOptCostImpl(Double.POSITIVE_INFINITY);
    }

    // implement RelOptPlanner
    public RelOptCost makeTinyCost() {
      return new RelOptCostImpl(1.0);
    }

    // implement RelOptPlanner
    public RelOptCost makeZeroCost() {
      return new RelOptCostImpl(0.0);
    }
  }
}

// End RelOptCostImpl.java