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.beam.sdk.extensions.sql.meta;
  
  import java.util.List;
  import org.apache.beam.vendor.calcite.v1_40_0.org.apache.calcite.rex.RexCall;
  import org.apache.beam.vendor.calcite.v1_40_0.org.apache.calcite.rex.RexNode;
  
  /** This interface defines Beam SQL Table Filter. */
  public interface BeamSqlTableFilter {
    /**
     * Identify parts of a predicate that are not supported by the IO push-down capabilities to be
     * preserved in a {@code Calc} following {@code BeamIOSourceRel}.
     *
     * @return {@code List<RexNode>} unsupported by the IO API. Should be empty when an entire
     *     condition is supported, or an unchanged {@code List<RexNode>} when predicate push-down is
     *     not supported at all.
     */
    List<RexNode> getNotSupported();
  
    /**
     * This is primarily used by the cost based optimization to determine the benefit of performing
     * predicate push-down for an IOSourceRel.
     *
     * @return number of supported filters.
     */
    int numSupported();
  
    /**
     * Count a number of {@code RexNode}s involved in all supported filters.
     *
     * @param filterNodes {@code List<RexNode>} supported filters.
     * @return number of expressions involved in all supported filters.
     */
    static int expressionsInFilter(List<RexNode> filterNodes) {
      int childSum =
          filterNodes.stream()
              .filter(n -> n instanceof RexCall)
              .mapToInt(n -> expressionsInFilter(((RexCall) n).getOperands()))
              .sum();
      return filterNodes.size() + childSum;
    }
  }
  