org.apache.druid.sql.guice.SqlBindings Maven / Gradle / Ivy

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/*
 * 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.druid.sql.guice;

import com.google.inject.Binder;
import com.google.inject.Key;
import com.google.inject.Scopes;
import com.google.inject.multibindings.Multibinder;
import org.apache.druid.guice.PolyBind;
import org.apache.druid.sql.calcite.aggregation.SqlAggregator;
import org.apache.druid.sql.calcite.expression.SqlOperatorConversion;
import org.apache.druid.sql.calcite.schema.NamedSchema;

/**
 * Utility class that provides bindings to extendable components in the SqlModule
 */
public class SqlBindings
{
  public static void addAggregator(
      final Binder binder,
      final Class aggregatorClass
  )
  {
    Multibinder.newSetBinder(binder, SqlAggregator.class).addBinding().to(aggregatorClass);
  }

  /**
   * Add a choice for {@code APPROX_COUNT_DISTINCT} implementation.
   *
   * The SqlAggregator's {@link SqlAggregator#calciteFunction()} method will be ignored and replaced by the
   * version from {@link org.apache.druid.sql.calcite.aggregation.ApproxCountDistinctSqlAggregator}. For sane results,
   * the provided aggregator class must be compatible with that function signature.
   */
  public static void addApproxCountDistinctChoice(
      final Binder binder,
      final String name,
      final Class clazz
  )
  {
    PolyBind.optionBinder(binder, Key.get(SqlAggregator.class, ApproxCountDistinct.class))
            .addBinding(name)
            .to(clazz);
  }

  public static void addOperatorConversion(
      final Binder binder,
      final Class clazz
  )
  {
    Multibinder.newSetBinder(binder, SqlOperatorConversion.class).addBinding().to(clazz);
  }

  /**
   * Returns a multiBinder that can modules can use to bind {@link NamedSchema} to be used by the SqlModule
   */
  public static void addSchema(
      final Binder binder,
      final Class clazz
  )
  {
    binder.bind(clazz).in(Scopes.SINGLETON);
    Multibinder.newSetBinder(binder, NamedSchema.class).addBinding().to(clazz);
  }
}