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.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.ImmutableNullableList;
  import org.apache.calcite.util.Pair;
  
  import com.google.common.collect.ImmutableList;
  
  import org.checkerframework.checker.nullness.qual.Nullable;
  
  import java.util.AbstractList;
  import java.util.List;
  
  import static com.google.common.base.Preconditions.checkArgument;
  
  import static org.apache.calcite.linq4j.Nullness.castNonNull;
  
  import static java.util.Objects.requireNonNull;
  
  /**
   * Parse tree for {@code CREATE FOREIGN SCHEMA} statement.
   */
  public class SqlCreateForeignSchema extends SqlCreate {
    public final SqlIdentifier name;
    public final @Nullable SqlNode type;
    public final @Nullable SqlNode library;
    private final @Nullable SqlNodeList optionList;
  
    private static final SqlOperator OPERATOR =
        new SqlSpecialOperator("CREATE FOREIGN SCHEMA",
            SqlKind.CREATE_FOREIGN_SCHEMA);
  
    /** Creates a SqlCreateForeignSchema. */
    SqlCreateForeignSchema(SqlParserPos pos, boolean replace, boolean ifNotExists,
        SqlIdentifier name, @Nullable SqlNode type, @Nullable SqlNode library,
        @Nullable SqlNodeList optionList) {
      super(OPERATOR, pos, replace, ifNotExists);
      this.name = requireNonNull(name, "name");
      this.type = type;
      this.library = library;
      checkArgument((type == null) != (library == null),
          "of type and library, exactly one must be specified");
      this.optionList = optionList; // may be null
    }
  
    @SuppressWarnings("nullness")
    @Override public List<SqlNode> getOperandList() {
      return ImmutableNullableList.of(name, type, library, optionList);
    }
  
    @Override public void unparse(SqlWriter writer, int leftPrec, int rightPrec) {
      if (getReplace()) {
        writer.keyword("CREATE OR REPLACE");
      } else {
        writer.keyword("CREATE");
      }
      writer.keyword("FOREIGN SCHEMA");
      if (ifNotExists) {
        writer.keyword("IF NOT EXISTS");
      }
      name.unparse(writer, leftPrec, rightPrec);
      if (library != null) {
        writer.keyword("LIBRARY");
        library.unparse(writer, 0, 0);
      }
      if (type != null) {
        writer.keyword("TYPE");
        type.unparse(writer, 0, 0);
      }
      if (optionList != null) {
        writer.keyword("OPTIONS");
        SqlWriter.Frame frame = writer.startList("(", ")");
        int i = 0;
        for (Pair<SqlIdentifier, SqlNode> c : options()) {
          if (i++ > 0) {
            writer.sep(",");
          }
          c.left.unparse(writer, 0, 0);
          c.right.unparse(writer, 0, 0);
        }
        writer.endList(frame);
      }
    }
  
    /** Returns options as a list of (name, value) pairs. */
    public List<Pair<SqlIdentifier, SqlNode>> options() {
      return options(optionList);
    }
  
    private static List<Pair<SqlIdentifier, SqlNode>> options(
        final @Nullable SqlNodeList optionList) {
      if (optionList == null) {
        return ImmutableList.of();
      }
      return new AbstractList<Pair<SqlIdentifier, SqlNode>>() {
        @Override public Pair<SqlIdentifier, SqlNode> get(int index) {
          return Pair.of((SqlIdentifier) castNonNull(optionList.get(index * 2)),
              castNonNull(optionList.get(index * 2 + 1)));
        }
  
        @Override public int size() {
          return optionList.size() / 2;
        }
      };
    }
  }
  