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.validate.SqlNameMatcher;
  
  import org.checkerframework.checker.nullness.qual.Nullable;
  
  import java.util.List;
  
  /**
   * SqlOperatorTable defines a directory interface for enumerating and looking up
   * SQL operators and functions.
   */
  public interface SqlOperatorTable {
    //~ Methods ----------------------------------------------------------------
  
    /**
     * Retrieves a list of operators with a given name and syntax. For example,
     * by passing SqlSyntax.Function, the returned list is narrowed to only
     * matching SqlFunction objects.
     *
     * @param opName   name of operator
     * @param category function category to look up, or null for any matching
     *                 operator
     * @param syntax   syntax type of operator
     * @param operatorList mutable list to which to append matches
     * @param nameMatcher Name matcher
     */
    void lookupOperatorOverloads(SqlIdentifier opName,
        @Nullable SqlFunctionCategory category,
        SqlSyntax syntax,
        List<SqlOperator> operatorList,
        SqlNameMatcher nameMatcher);
  
    /**
     * Retrieves a list of all functions and operators in this table. Used for
     * automated testing. Depending on the table type, may or may not be mutable.
     *
     * @return list of SqlOperator objects
     */
    List<SqlOperator> getOperatorList();
  }
  