exec/java-exec/src/main/java/org/apache/drill/exec/planner/sql/parser/DrillSqlSetOption.java

/*
 * 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.drill.exec.planner.sql.parser;

import org.apache.calcite.sql.SqlCall;
import org.apache.calcite.sql.SqlIdentifier;
import org.apache.calcite.sql.SqlKind;
import org.apache.calcite.sql.SqlLiteral;
import org.apache.calcite.sql.SqlNode;
import org.apache.calcite.sql.SqlOperator;
import org.apache.calcite.sql.SqlSetOption;
import org.apache.calcite.sql.SqlSpecialOperator;
import org.apache.calcite.sql.SqlWriter;
import org.apache.calcite.sql.parser.SqlParserPos;
import org.apache.drill.exec.planner.sql.handlers.SetOptionHandler;

/**
 * Sql parse tree node to represent statement: {@code SET <NAME> [ = VALUE ]}.
 * Statement handled in: {@link SetOptionHandler}
 */
public final class DrillSqlSetOption extends SqlSetOption {

  public static final SqlSpecialOperator OPERATOR = new SqlSpecialOperator("SET_OPTION", SqlKind.SET_OPTION) {
    @Override
    public SqlCall createCall(SqlLiteral functionQualifier, SqlParserPos pos, SqlNode... operands) {
      SqlNode scopeNode = operands[0];
      String scope = scopeNode == null ? null : scopeNode.toString();
      return new DrillSqlSetOption(pos, scope, (SqlIdentifier) operands[1], operands[2]);
    }
  };

    public DrillSqlSetOption(SqlParserPos pos, String scope, SqlIdentifier name, SqlNode value) {
    super(pos, scope, name, value);
  }

  @Override
  public SqlKind getKind() {
    return SqlKind.SET_OPTION;
  }

  @Override
  public SqlOperator getOperator() {
    return OPERATOR;
  }

  @Override
  protected void unparseAlterOperation(SqlWriter writer, int leftPrec, int rightPrec) {
    writer.keyword("SET");

    SqlWriter.Frame frame = writer.startList(SqlWriter.FrameTypeEnum.SIMPLE);
    this.getName().unparse(writer, leftPrec, rightPrec);

    if (this.getValue() != null) {
      writer.sep("=");
      this.getValue().unparse(writer, leftPrec, rightPrec);
    }

    writer.endList(frame);
  }
}