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.fun;
  
  import org.apache.calcite.sql.SqlCall;
  import org.apache.calcite.sql.SqlInternalOperator;
  import org.apache.calcite.sql.SqlKind;
  import org.apache.calcite.sql.SqlNode;
  import org.apache.calcite.sql.SqlNodeList;
  import org.apache.calcite.sql.SqlWriter;
  
  /**
   * Operator that appears in a {@code GROUP BY} clause: {@code CUBE},
   * {@code ROLLUP}, {@code GROUPING SETS}.
   */
  class SqlRollupOperator extends SqlInternalOperator {
    SqlRollupOperator(String name, SqlKind kind) {
      super(name, kind, 4);
    }
  
    @Override public void unparse(SqlWriter writer, SqlCall call, int leftPrec,
        int rightPrec) {
      switch (kind) {
      case ROLLUP:
        if (!writer.getDialect().supportsAggregateFunction(kind)
            && writer.getDialect().supportsGroupByWithRollup()) {
          // MySQL version 5: generate "GROUP BY x, y WITH ROLLUP".
          // MySQL version 8 and higher is SQL-compliant,
          // so generate "GROUP BY ROLLUP(x, y)"
          unparseKeyword(writer, call, "WITH ROLLUP");
          return;
        }
        break;
      case CUBE:
        if (!writer.getDialect().supportsAggregateFunction(kind)
            && writer.getDialect().supportsGroupByWithCube()) {
          // Spark SQL: generate "GROUP BY x, y WITH CUBE".
          unparseKeyword(writer, call, "WITH CUBE");
          return;
        }
        break;
      case GROUP_BY_DISTINCT:
        writer.keyword(call.getOperator().getName());
        SqlNodeList groupBy = new SqlNodeList(call.getOperandList(), call.getParserPosition());
        writer.list(SqlWriter.FrameTypeEnum.GROUP_BY_LIST, SqlWriter.COMMA, groupBy);
        return;
      default:
        break;
      }
      unparseCube(writer, call);
    }
  
    private static void unparseKeyword(SqlWriter writer, SqlCall call, String keyword) {
      final SqlWriter.Frame groupFrame =
          writer.startList(SqlWriter.FrameTypeEnum.GROUP_BY_LIST);
      for (SqlNode operand : call.getOperandList()) {
        writer.sep(",");
        operand.unparse(writer, 2, 3);
      }
      writer.endList(groupFrame);
      writer.keyword(keyword);
    }
  
    private static void unparseCube(SqlWriter writer, SqlCall call) {
      writer.keyword(call.getOperator().getName());
      final SqlWriter.Frame frame =
          writer.startList(SqlWriter.FrameTypeEnum.FUN_CALL, "(", ")");
      for (SqlNode operand : call.getOperandList()) {
        writer.sep(",");
        if (operand.getKind() == SqlKind.ROW) {
          final SqlWriter.Frame frame2 =
              writer.startList(SqlWriter.FrameTypeEnum.SIMPLE, "(", ")");
          for (SqlNode operand2 : ((SqlCall) operand).getOperandList()) {
            writer.sep(",");
            operand2.unparse(writer, 0, 0);
          }
          writer.endList(frame2);
        } else if (operand instanceof SqlNodeList
            && ((SqlNodeList) operand).isEmpty()) {
          writer.keyword("()");
        } else {
          operand.unparse(writer, 0, 0);
        }
      }
      writer.endList(frame);
    }
  }
  