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.calcite.sql.fun;
  
  import org.apache.calcite.rel.type.RelDataType;
  import org.apache.calcite.rex.RexUnknownAs;
  import org.apache.calcite.sql.SqlInternalOperator;
  import org.apache.calcite.sql.SqlKind;
  import org.apache.calcite.sql.SqlOperatorBinding;
  import org.apache.calcite.sql.type.InferTypes;
  import org.apache.calcite.sql.type.OperandTypes;
  import org.apache.calcite.sql.type.ReturnTypes;
  import org.apache.calcite.util.Sarg;
  
  import static org.apache.calcite.sql.validate.SqlNonNullableAccessors.getOperandLiteralValueOrThrow;
  
  /** Operator that tests whether its left operand is included in the range of
   * values covered by search arguments. */
  class SqlSearchOperator extends SqlInternalOperator {
    SqlSearchOperator() {
      super("SEARCH", SqlKind.SEARCH, 30, true,
          ReturnTypes.BOOLEAN.andThen(SqlSearchOperator::makeNullable),
          InferTypes.FIRST_KNOWN,
          OperandTypes.COMPARABLE_UNORDERED_COMPARABLE_UNORDERED);
    }
  
    /** Sets whether a call to SEARCH should allow nulls.
     *
     * <p>For example, if the type of {@code x} is NOT NULL, then
     * {@code SEARCH(x, Sarg[10])} will never return UNKNOWN.
     * It is evident from the expansion, "x = 10", but holds for all Sarg
     * values.
     *
     * <p>If {@link Sarg#nullAs} is TRUE or FALSE, SEARCH will never return
     * UNKNOWN. For example, {@code SEARCH(x, Sarg[10; NULL AS UNKNOWN])} expands
     * to {@code x = 10 OR x IS NOT NULL}, which returns {@code TRUE} if
     * {@code x} is NULL, {@code TRUE} if {@code x} is 10, and {@code FALSE}
     * for all other values.
     */
    private static RelDataType makeNullable(SqlOperatorBinding binding,
        RelDataType type) {
      final boolean nullable = binding.getOperandType(0).isNullable()
          && getOperandLiteralValueOrThrow(binding, 1, Sarg.class).nullAs
          == RexUnknownAs.UNKNOWN;
      return binding.getTypeFactory().createTypeWithNullability(type, nullable);
    }
  }
  