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.ddl;
  
  import org.apache.calcite.sql.SqlCreate;
  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.SqlNodeList;
  import org.apache.calcite.sql.SqlOperator;
  import org.apache.calcite.sql.SqlSpecialOperator;
  import org.apache.calcite.sql.SqlWriter;
  import org.apache.calcite.sql.parser.SqlParserPos;
  import org.apache.calcite.util.Pair;
  import org.apache.calcite.util.Util;
  
  import java.util.Arrays;
  import java.util.List;
  
  import static com.google.common.base.Preconditions.checkArgument;
  
  import static java.util.Objects.requireNonNull;
  
  /**
   * Parse tree for {@code CREATE FUNCTION} statement.
   */
  public class SqlCreateFunction extends SqlCreate {
    private final SqlIdentifier name;
    private final SqlNode className;
    private final SqlNodeList usingList;
  
    private static final SqlSpecialOperator OPERATOR =
        new SqlSpecialOperator("CREATE FUNCTION", SqlKind.CREATE_FUNCTION);
  
    /** Creates a SqlCreateFunction. */
    public SqlCreateFunction(SqlParserPos pos, boolean replace,
        boolean ifNotExists, SqlIdentifier name,
        SqlNode className, SqlNodeList usingList) {
      super(OPERATOR, pos, replace, ifNotExists);
      this.name = requireNonNull(name, "name");
      this.className = requireNonNull(className, "className");
      this.usingList = requireNonNull(usingList, "usingList");
      checkArgument(usingList.size() % 2 == 0);
    }
  
    @Override public void unparse(SqlWriter writer, int leftPrec,
        int rightPrec) {
      writer.keyword(getReplace() ? "CREATE OR REPLACE" : "CREATE");
      writer.keyword("FUNCTION");
      if (ifNotExists) {
        writer.keyword("IF NOT EXISTS");
      }
      name.unparse(writer, 0, 0);
      writer.keyword("AS");
      className.unparse(writer, 0, 0);
      if (!usingList.isEmpty()) {
        writer.keyword("USING");
        final SqlWriter.Frame frame =
            writer.startList(SqlWriter.FrameTypeEnum.SIMPLE);
        for (Pair<SqlLiteral, SqlLiteral> using : pairs()) {
          writer.sep(",");
          using.left.unparse(writer, 0, 0); // FILE, URL or ARCHIVE
          using.right.unparse(writer, 0, 0); // e.g. 'file:foo/bar.jar'
        }
        writer.endList(frame);
      }
    }
  
    @SuppressWarnings("unchecked")
    private List<Pair<SqlLiteral, SqlLiteral>> pairs() {
      return Util.pairs((List) usingList);
    }
  
    @Override public SqlOperator getOperator() {
      return OPERATOR;
    }
  
    @Override public List<SqlNode> getOperandList() {
      return Arrays.asList(name, className, usingList);
    }
  }
  