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Core Calcite APIs and engine.
There is a newer version: 1.21.0.265
/*
 * 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.calcite.profile;

import org.apache.calcite.materialize.Lattice;
import org.apache.calcite.util.ImmutableBitSet;
import org.apache.calcite.util.JsonBuilder;
import org.apache.calcite.util.Util;

import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableMap;
import com.google.common.collect.ImmutableSortedSet;

import java.math.BigDecimal;
import java.math.MathContext;
import java.math.RoundingMode;
import java.util.ArrayList;
import java.util.Collection;
import java.util.List;
import java.util.Map;
import java.util.NavigableSet;
import java.util.SortedSet;
import javax.annotation.Nonnull;

/**
 * Analyzes data sets.
 */
public interface Profiler {
  /** Creates a profile of a data set.
   *
   * @param rows List of rows. Can be iterated over more than once (maybe not
   *             cheaply)
   * @param columns Column definitions
   *
   * @param initialGroups List of combinations of columns that should be
   *                     profiled early, because they may be interesting
   *
   * @return A profile describing relationships within the data set
   */
  Profile profile(Iterable> rows, List columns,
      Collection initialGroups);

  /** Column. */
  class Column implements Comparable {
    public final int ordinal;
    public final String name;

    /** Creates a Column.
     *
     * @param ordinal Unique and contiguous within a particular data set
     * @param name Name of the column
     */
    public Column(int ordinal, String name) {
      this.ordinal = ordinal;
      this.name = name;
    }

    static ImmutableBitSet toOrdinals(Iterable columns) {
      final ImmutableBitSet.Builder builder = ImmutableBitSet.builder();
      for (Column column : columns) {
        builder.set(column.ordinal);
      }
      return builder.build();
    }

    @Override public int hashCode() {
      return ordinal;
    }

    @Override public boolean equals(Object o) {
      return this == o
          || o instanceof Column
          && ordinal == ((Column) o).ordinal;
    }

    @Override public int compareTo(@Nonnull Column column) {
      return Integer.compare(ordinal, column.ordinal);
    }

    @Override public String toString() {
      return name;
    }
  }

  /** Statistic produced by the profiler. */
  interface Statistic {
    Object toMap(JsonBuilder jsonBuilder);
  }

  /** Whole data set. */
  class RowCount implements Statistic {
    final int rowCount;

    public RowCount(int rowCount) {
      this.rowCount = rowCount;
    }

    public Object toMap(JsonBuilder jsonBuilder) {
      final Map map = jsonBuilder.map();
      map.put("type", "rowCount");
      map.put("rowCount", rowCount);
      return map;
    }
  }

  /** Unique key. */
  class Unique implements Statistic {
    final NavigableSet columns;

    public Unique(SortedSet columns) {
      this.columns = ImmutableSortedSet.copyOf(columns);
    }

    public Object toMap(JsonBuilder jsonBuilder) {
      final Map map = jsonBuilder.map();
      map.put("type", "unique");
      map.put("columns", FunctionalDependency.getObjects(jsonBuilder, columns));
      return map;
    }
  }

  /** Functional dependency. */
  class FunctionalDependency implements Statistic {
    final NavigableSet columns;
    final Column dependentColumn;

    FunctionalDependency(SortedSet columns, Column dependentColumn) {
      this.columns = ImmutableSortedSet.copyOf(columns);
      this.dependentColumn = dependentColumn;
    }

    public Object toMap(JsonBuilder jsonBuilder) {
      final Map map = jsonBuilder.map();
      map.put("type", "fd");
      map.put("columns", getObjects(jsonBuilder, columns));
      map.put("dependentColumn", dependentColumn.name);
      return map;
    }

    private static List