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.sql.SqlCall;
  import org.apache.calcite.sql.SqlKind;
  import org.apache.calcite.sql.SqlSelect;
  import org.apache.calcite.sql.SqlSpecialOperator;
  import org.apache.calcite.sql.SqlWriter;
  import org.apache.calcite.sql.type.OperandTypes;
  import org.apache.calcite.sql.type.ReturnTypes;
  import org.apache.calcite.sql.validate.SqlValidator;
  import org.apache.calcite.sql.validate.SqlValidatorScope;
  
  /**
   * SqlCursorConstructor defines the non-standard CURSOR(&lt;query&gt;)
   * constructor.
   */
  public class SqlCursorConstructor extends SqlSpecialOperator {
    //~ Constructors -----------------------------------------------------------
  
    public SqlCursorConstructor() {
      super(
          "CURSOR",
          SqlKind.CURSOR, MDX_PRECEDENCE,
          false,
          ReturnTypes.CURSOR,
          null,
          OperandTypes.ANY);
    }
  
    //~ Methods ----------------------------------------------------------------
  
    @Override public RelDataType deriveType(
        SqlValidator validator,
        SqlValidatorScope scope,
        SqlCall call) {
      SqlSelect subSelect = call.operand(0);
      validator.declareCursor(subSelect, scope);
      subSelect.validateExpr(validator, scope);
      return super.deriveType(validator, scope, call);
    }
  
    @Override public void unparse(
        SqlWriter writer,
        SqlCall call,
        int leftPrec,
        int rightPrec) {
      writer.keyword("CURSOR");
      final SqlWriter.Frame frame = writer.startList("(", ")");
      assert call.operandCount() == 1;
      call.operand(0).unparse(writer, leftPrec, rightPrec);
      writer.endList(frame);
    }
  
    @Override public boolean argumentMustBeScalar(int ordinal) {
      return false;
    }
  }
  