content: /*
   * 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.arrow.vector.compare;
  
  import java.util.function.BiFunction;
  import org.apache.arrow.vector.BaseFixedWidthVector;
  import org.apache.arrow.vector.Float4Vector;
  import org.apache.arrow.vector.Float8Vector;
  import org.apache.arrow.vector.ValueVector;
  import org.apache.arrow.vector.compare.util.ValueEpsilonEqualizers;
  
  /** Visitor to compare floating point vectors approximately. */
  public class ApproxEqualsVisitor extends RangeEqualsVisitor {
  
    /** Functions to calculate difference between float/double values. */
    private final VectorValueEqualizer<Float4Vector> floatDiffFunction;
  
    private final VectorValueEqualizer<Float8Vector> doubleDiffFunction;
  
    /** Default epsilons for diff functions. */
    public static final float DEFAULT_FLOAT_EPSILON = 1.0E-6f;
  
    public static final double DEFAULT_DOUBLE_EPSILON = 1.0E-6;
  
    /**
     * Constructs a new instance with default tolerances.
     *
     * @param left left vector
     * @param right right vector
     */
    public ApproxEqualsVisitor(ValueVector left, ValueVector right) {
      this(left, right, DEFAULT_FLOAT_EPSILON, DEFAULT_DOUBLE_EPSILON);
    }
  
    /**
     * Constructs a new instance.
     *
     * @param left left vector
     * @param right right vector
     * @param floatEpsilon difference for float values
     * @param doubleEpsilon difference for double values
     */
    public ApproxEqualsVisitor(
        ValueVector left, ValueVector right, float floatEpsilon, double doubleEpsilon) {
      this(
          left,
          right,
          new ValueEpsilonEqualizers.Float4EpsilonEqualizer(floatEpsilon),
          new ValueEpsilonEqualizers.Float8EpsilonEqualizer(doubleEpsilon));
    }
  
    /** Constructs a new instance. */
    public ApproxEqualsVisitor(
        ValueVector left,
        ValueVector right,
        VectorValueEqualizer<Float4Vector> floatDiffFunction,
        VectorValueEqualizer<Float8Vector> doubleDiffFunction) {
      this(left, right, floatDiffFunction, doubleDiffFunction, DEFAULT_TYPE_COMPARATOR);
    }
  
    /**
     * Constructs a new instance.
     *
     * @param left the left vector.
     * @param right the right vector.
     * @param floatDiffFunction the equalizer for float values.
     * @param doubleDiffFunction the equalizer for double values.
     * @param typeComparator type comparator to compare vector type.
     */
    public ApproxEqualsVisitor(
        ValueVector left,
        ValueVector right,
        VectorValueEqualizer<Float4Vector> floatDiffFunction,
        VectorValueEqualizer<Float8Vector> doubleDiffFunction,
        BiFunction<ValueVector, ValueVector, Boolean> typeComparator) {
      super(left, right, typeComparator);
      this.floatDiffFunction = floatDiffFunction;
      this.doubleDiffFunction = doubleDiffFunction;
    }
  
    @Override
    public Boolean visit(BaseFixedWidthVector left, Range range) {
      if (left instanceof Float4Vector) {
        if (!validate(left)) {
          return false;
        }
        return float4ApproxEquals(range);
      } else if (left instanceof Float8Vector) {
        if (!validate(left)) {
          return false;
        }
        return float8ApproxEquals(range);
      } else {
        return super.visit(left, range);
      }
    }
  
    @Override
    protected ApproxEqualsVisitor createInnerVisitor(
        ValueVector left,
        ValueVector right,
        BiFunction<ValueVector, ValueVector, Boolean> typeComparator) {
      return new ApproxEqualsVisitor(
          left, right, floatDiffFunction.clone(), doubleDiffFunction.clone(), typeComparator);
    }
  
    private boolean float4ApproxEquals(Range range) {
      Float4Vector leftVector = (Float4Vector) getLeft();
      Float4Vector rightVector = (Float4Vector) getRight();
  
      for (int i = 0; i < range.getLength(); i++) {
        int leftIndex = range.getLeftStart() + i;
        int rightIndex = range.getRightStart() + i;
  
        if (!floatDiffFunction.valuesEqual(leftVector, leftIndex, rightVector, rightIndex)) {
          return false;
        }
      }
      return true;
    }
  
    private boolean float8ApproxEquals(Range range) {
      Float8Vector leftVector = (Float8Vector) getLeft();
      Float8Vector rightVector = (Float8Vector) getRight();
  
      for (int i = 0; i < range.getLength(); i++) {
        int leftIndex = range.getLeftStart() + i;
        int rightIndex = range.getRightStart() + i;
  
        if (!doubleDiffFunction.valuesEqual(leftVector, leftIndex, rightVector, rightIndex)) {
          return false;
        }
      }
      return true;
    }
  }
  