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.rel.type.RelDataType;
  import org.apache.calcite.sql.parser.SqlParserPos;
  import org.apache.calcite.sql.validate.SqlValidator;
  import org.apache.calcite.sql.validate.SqlValidatorScope;
  
  import org.checkerframework.checker.nullness.qual.Nullable;
  
  import java.util.List;
  
  import static java.util.Objects.requireNonNull;
  
  /**
   * SetSemanticsTable appears as an parameter in a table function.
   * It represents as an input table with set semantics.
   * Set semantics means that the outcome of the function depends on how
   * the data is partitioned.
   * When the table function is called from a query, the table parameter can
   * optionally be extended with either a PARTITION BY clause or
   * an ORDER BY clause or both.
   *
   */
  public class SqlSetSemanticsTableOperator extends SqlInternalOperator {
  
    //~ Constructors -----------------------------------------------------------
  
    public SqlSetSemanticsTableOperator() {
      super("SET_SEMANTICS_TABLE", SqlKind.SET_SEMANTICS_TABLE);
    }
  
    @Override public SqlCall createCall(
        @Nullable SqlLiteral functionQualifier,
        SqlParserPos pos,
        @Nullable SqlNode... operands) {
      assert operands.length == 3;
      SqlNode partitionList = operands[1];
      SqlNode orderList = operands[2];
      assert (partitionList != null && !SqlNodeList.isEmptyList(partitionList))
          || (orderList != null && !SqlNodeList.isEmptyList(orderList));
      return super.createCall(functionQualifier, pos, operands);
    }
  
    @Override public void unparse(
        SqlWriter writer,
        SqlCall call,
        int leftPrec,
        int rightPrec) {
      call.operand(0).unparse(writer, 0, 0);
  
      SqlNodeList partitionList = call.operand(1);
      if (!partitionList.isEmpty()) {
        writer.sep("PARTITION BY");
        final SqlWriter.Frame partitionFrame = writer.startList("", "");
        partitionList.unparse(writer, 0, 0);
        writer.endList(partitionFrame);
      }
      SqlNodeList orderList = call.operand(2);
      if (!orderList.isEmpty()) {
        writer.sep("ORDER BY");
        writer.list(
            SqlWriter.FrameTypeEnum.ORDER_BY_LIST,
            SqlWriter.COMMA,
            orderList);
      }
    }
  
    @Override public RelDataType deriveType(
        SqlValidator validator,
        SqlValidatorScope scope, SqlCall call) {
      final List<SqlNode> operands = call.getOperandList();
      return requireNonNull(validator.deriveType(scope, operands.get(0)));
    }
  
    @Override public boolean argumentMustBeScalar(int ordinal) {
      return false;
    }
  }
  