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.validate;
  
  import org.apache.calcite.sql.SqlNode;
  import org.apache.calcite.sql.SqlNodeList;
  import org.apache.calcite.sql.SqlSelect;
  
  /**
   * Represents the name-resolution context for expressions in an GROUP BY clause.
   *
   * <p>In some dialects of SQL, the GROUP BY clause can reference column aliases
   * in the SELECT clause. For example, the query
   *
   * <blockquote><code>SELECT empno AS x<br>
   * FROM emp<br>
   * GROUP BY x</code></blockquote>
   *
   * <p>is valid.
   */
  public class GroupByScope extends DelegatingScope {
    //~ Instance fields --------------------------------------------------------
  
    private final SqlNodeList groupByList;
    private final SqlSelect select;
  
    //~ Constructors -----------------------------------------------------------
  
    GroupByScope(
        SqlValidatorScope parent,
        SqlNodeList groupByList,
        SqlSelect select) {
      super(parent);
      this.groupByList = groupByList;
      this.select = select;
    }
  
    //~ Methods ----------------------------------------------------------------
  
    @Override public SqlNode getNode() {
      return groupByList;
    }
  
    @Override public void validateExpr(SqlNode expr) {
      SqlNode expanded =
          validator.extendedExpandGroupBy(expr, this, select);
  
      // expression needs to be valid in parent scope too
      parent.validateExpr(expanded);
    }
  }
  