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.apache.calcite.util.ImmutableNullableList;
  
  import org.checkerframework.checker.nullness.qual.Nullable;
  
  import java.util.List;
  
  /**
   * Parse tree node that represents an {@code ORDER BY} on a query other than a
   * {@code SELECT} (e.g. {@code VALUES} or {@code UNION}).
   *
   * <p>It is a purely syntactic operator, and is eliminated by
   * {@link org.apache.calcite.sql.validate.SqlValidatorImpl#performUnconditionalRewrites}
   * and replaced with the ORDER_OPERAND of SqlSelect.
   */
  public class SqlOrderBy extends SqlCall {
    public static final SqlSpecialOperator OPERATOR = new Operator() {
      @SuppressWarnings("argument.type.incompatible")
      @Override public SqlCall createCall(@Nullable SqlLiteral functionQualifier,
          SqlParserPos pos, @Nullable SqlNode... operands) {
        return new SqlOrderBy(pos, operands[0], (SqlNodeList) operands[1],
            operands[2], operands[3]);
      }
    };
  
    public final SqlNode query;
    public final SqlNodeList orderList;
    public final @Nullable SqlNode offset;
    public final @Nullable SqlNode fetch;
  
    //~ Constructors -----------------------------------------------------------
  
    public SqlOrderBy(SqlParserPos pos, SqlNode query, SqlNodeList orderList,
        @Nullable SqlNode offset, @Nullable SqlNode fetch) {
      super(pos);
      this.query = query;
      this.orderList = orderList;
      this.offset = offset;
      this.fetch = fetch;
    }
  
    //~ Methods ----------------------------------------------------------------
  
    @Override public SqlKind getKind() {
      return SqlKind.ORDER_BY;
    }
  
    @Override public SqlOperator getOperator() {
      return OPERATOR;
    }
  
    @SuppressWarnings("nullness")
    @Override public List<SqlNode> getOperandList() {
      return ImmutableNullableList.of(query, orderList, offset, fetch);
    }
  
    /** Definition of {@code ORDER BY} operator. */
    private static class Operator extends SqlSpecialOperator {
      private Operator() {
        // NOTE:  make precedence lower then SELECT to avoid extra parens
        super("ORDER BY", SqlKind.ORDER_BY, 0);
      }
  
      @Override public SqlSyntax getSyntax() {
        return SqlSyntax.POSTFIX;
      }
  
      @Override public void unparse(
          SqlWriter writer,
          SqlCall call,
          int leftPrec,
          int rightPrec) {
        SqlOrderBy orderBy = (SqlOrderBy) call;
        final SqlWriter.Frame frame =
            writer.startList(SqlWriter.FrameTypeEnum.ORDER_BY);
        orderBy.query.unparse(writer, getLeftPrec(), getRightPrec());
        if (orderBy.orderList != SqlNodeList.EMPTY) {
          writer.sep(getName());
          writer.list(SqlWriter.FrameTypeEnum.ORDER_BY_LIST, SqlWriter.COMMA,
              orderBy.orderList);
        }
        if (orderBy.offset != null || orderBy.fetch != null) {
          writer.fetchOffset(orderBy.fetch, orderBy.offset);
        }
        writer.endList(frame);
      }
    }
  }
  