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.rel.type.RelDataType;
  import org.apache.calcite.rel.type.RelDataTypeFactory;
  import org.apache.calcite.sql.SqlCall;
  import org.apache.calcite.sql.SqlKind;
  import org.apache.calcite.sql.SqlOperatorBinding;
  import org.apache.calcite.sql.SqlSpecialOperator;
  import org.apache.calcite.sql.SqlUtil;
  import org.apache.calcite.sql.SqlWriter;
  import org.apache.calcite.sql.type.InferTypes;
  import org.apache.calcite.sql.type.OperandTypes;
  
  /**
   * SqlRowOperator represents the special ROW constructor.
   *
   * <p>TODO: describe usage for row-value construction and row-type construction
   * (SQL supports both).
   */
  public class SqlRowOperator extends SqlSpecialOperator {
    //~ Constructors -----------------------------------------------------------
  
    public SqlRowOperator(String name) {
      super(name,
          SqlKind.ROW, MDX_PRECEDENCE,
          false,
          null,
          InferTypes.RETURN_TYPE,
          OperandTypes.VARIADIC);
    }
  
    //~ Methods ----------------------------------------------------------------
  
    @Override public RelDataType inferReturnType(
        final SqlOperatorBinding opBinding) {
      // The type of a ROW(e1,e2) expression is a record with the types
      // {e1type,e2type}.  According to the standard, field names are
      // implementation-defined.
      final RelDataTypeFactory typeFactory = opBinding.getTypeFactory();
      final RelDataTypeFactory.Builder builder = typeFactory.builder();
      for (int index = 0; index < opBinding.getOperandCount(); index++) {
        builder.add(SqlUtil.deriveAliasFromOrdinal(index),
            opBinding.getOperandType(index));
      }
      final RelDataType recordType = builder.build();
  
      // The value of ROW(e1,e2) is considered null if and only all of its
      // fields (i.e., e1, e2) are null. Otherwise, ROW can not be null.
      final boolean nullable =
          recordType.getFieldList().stream()
              .allMatch(f -> f.getType().isNullable());
      return typeFactory.createTypeWithNullability(recordType, nullable);
    }
  
    @Override public void unparse(
        SqlWriter writer,
        SqlCall call,
        int leftPrec,
        int rightPrec) {
      SqlUtil.unparseFunctionSyntax(this, writer, call, false);
    }
  
    // override SqlOperator
    @Override public boolean requiresDecimalExpansion() {
      return false;
    }
  }
  