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.parser.SqlParserPos;
  
  import org.checkerframework.checker.nullness.qual.Nullable;
  
  /**
   * Base class for an ALTER statements parse tree nodes. The portion of the
   * statement covered by this class is "ALTER &lt;SCOPE&gt;. Subclasses handle
   * whatever comes after the scope.
   */
  public abstract class SqlAlter extends SqlCall {
  
    /** Scope of the operation. Values "SYSTEM" and "SESSION" are typical. */
    @Nullable String scope;
  
    protected SqlAlter(SqlParserPos pos) {
      this(pos, null);
    }
  
    protected SqlAlter(SqlParserPos pos, @Nullable String scope) {
      super(pos);
      this.scope = scope;
    }
  
    @Override public void unparse(SqlWriter writer, int leftPrec, int rightPrec) {
      String scope = this.scope;
      if (scope != null) {
        writer.keyword("ALTER");
        writer.keyword(scope);
      }
      unparseAlterOperation(writer, leftPrec, rightPrec);
    }
  
    protected abstract void unparseAlterOperation(SqlWriter writer, int leftPrec, int rightPrec);
  
    public @Nullable String getScope() {
      return scope;
    }
  
    public void setScope(@Nullable String scope) {
      this.scope = scope;
    }
  
  }
  