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.util;
  
  import org.apache.calcite.runtime.ConsList;
  import org.apache.calcite.sql.SqlFunction;
  import org.apache.calcite.sql.SqlFunctionCategory;
  import org.apache.calcite.sql.SqlIdentifier;
  import org.apache.calcite.sql.SqlOperator;
  import org.apache.calcite.sql.SqlOperatorTable;
  import org.apache.calcite.sql.SqlSyntax;
  import org.apache.calcite.sql.validate.SqlNameMatcher;
  
  import com.google.common.collect.ImmutableSet;
  
  import org.checkerframework.checker.nullness.qual.Nullable;
  
  import java.util.List;
  
  /**
   * Implementation of the {@link SqlOperatorTable} interface by using a list of
   * {@link SqlOperator operators}.
   */
  public class ListSqlOperatorTable
      extends SqlOperatorTables.IndexedSqlOperatorTable
      implements SqlOperatorTable {
  
    //~ Constructors -----------------------------------------------------------
  
    /** Creates an empty, mutable ListSqlOperatorTable.
     *
     * @deprecated Use {@link SqlOperatorTables#of}, which creates an immutable
     * table. */
    @Deprecated // to be removed before 2.0
    public ListSqlOperatorTable() {
      this(ImmutableSet.of());
    }
  
    /** Creates a mutable ListSqlOperatorTable backed by a given list.
     *
     * @deprecated Use {@link SqlOperatorTables#of}, which creates an immutable
     * table. */
    @Deprecated // to be removed before 2.0
    public ListSqlOperatorTable(List<SqlOperator> operatorList) {
      this((Iterable<SqlOperator>) operatorList);
    }
  
    // internal constructor
    ListSqlOperatorTable(Iterable<? extends SqlOperator> operatorList) {
      super(operatorList);
    }
  
    //~ Methods ----------------------------------------------------------------
  
    /** Adds an operator to this table.
     *
     * @deprecated Use {@link SqlOperatorTables#of}, which creates an immutable
     * table. */
    @Deprecated // to be removed before 2.0
    public void add(SqlOperator op) {
      // Rebuild the immutable collections with their current contents plus one.
      setOperators(buildIndex(ConsList.of(op, getOperatorList())));
    }
  
    @Override public void lookupOperatorOverloads(SqlIdentifier opName,
        @Nullable SqlFunctionCategory category,
        SqlSyntax syntax,
        List<SqlOperator> operatorList,
        SqlNameMatcher nameMatcher) {
      if (!opName.isSimple()) {
        return;
      }
      final String simpleName = opName.getSimple();
      lookUpOperators(simpleName, nameMatcher.isCaseSensitive(), op -> {
        if (op.getSyntax() != syntax
            && op.getSyntax().family != syntax.family) {
          // Allow retrieval on exact syntax or family; for example,
          // CURRENT_DATETIME has FUNCTION_ID syntax but can also be called with
          // both FUNCTION_ID and FUNCTION syntax (e.g. SELECT CURRENT_DATETIME,
          // CURRENT_DATETIME('UTC')).
          return;
        }
        if (category != null
            && category != category(op)
            && !category.isUserDefinedNotSpecificFunction()) {
          return;
        }
        operatorList.add(op);
      });
    }
  
    protected static SqlFunctionCategory category(SqlOperator operator) {
      if (operator instanceof SqlFunction) {
        return ((SqlFunction) operator).getFunctionType();
      } else {
        return SqlFunctionCategory.SYSTEM;
      }
    }
  }
  