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;
  
  import org.apache.calcite.sql.type.SqlReturnTypeInference;
  
  import org.checkerframework.checker.nullness.qual.Nullable;
  
  /**
   * A function that returns a table.
   */
  public interface SqlTableFunction {
    /**
     * Returns the record type of the table yielded by this function when
     * applied to given arguments. Only literal arguments are passed,
     * non-literal are replaced with default values (null, 0, false, etc).
     *
     * @return strategy to infer the row type of a call to this function
     */
    SqlReturnTypeInference getRowTypeInference();
  
    /**
     * Returns the table parameter characteristics for <code>ordinal</code>th
     * parameter to this table function.
     *
     * <p>Returns <code>null</code> if the <code>ordinal</code>th argument is
     * not table parameter or the <code>ordinal</code> is smaller than 0 or
     * the <code>ordinal</code> is greater than or equals to the number of
     * parameters.
     */
    default @Nullable TableCharacteristic tableCharacteristic(int ordinal) {
      return null;
    }
  }
  