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   1 /**
   2  * Copyright (c) 2010-2023 Contributors to the openHAB project
   3  *
   4  * See the NOTICE file(s) distributed with this work for additional
   5  * information.
   6  *
   7  * This program and the accompanying materials are made available under the
   8  * terms of the Eclipse Public License 2.0 which is available at
   9  * http://www.eclipse.org/legal/epl-2.0
  10  *
  11  * SPDX-License-Identifier: EPL-2.0
  12  */
  13 package org.openhab.binding.dbquery.internal.domain;
  14
  15 import java.util.concurrent.CompletableFuture;
  16
  17 import org.eclipse.jdt.annotation.NonNullByDefault;
  18 import org.openhab.binding.dbquery.internal.error.DatabaseException;
  19
  20 /**
  21  * Abstracts database operations needed for query execution
  22  *
  23  * @author Joan Pujol - Initial contribution
  24  */
  25 @NonNullByDefault
  26 public interface Database {
  27     boolean isConnected();
  28
  29     CompletableFuture<Boolean> connect();
  30
  31     CompletableFuture<Boolean> disconnect();
  32
  33     QueryFactory queryFactory() throws DatabaseException;
  34
  35     CompletableFuture<QueryResult> executeQuery(Query query);
  36
  37     Database EMPTY = new Database() {
  38         @Override
  39         public boolean isConnected() {
  40             return false;
  41         }
  42
  43         @Override
  44         public CompletableFuture<Boolean> connect() {
  45             return CompletableFuture.completedFuture(false);
  46         }
  47
  48         @Override
  49         public CompletableFuture<Boolean> disconnect() {
  50             return CompletableFuture.completedFuture(false);
  51         }
  52
  53         @Override
  54         public QueryFactory queryFactory() {
  55             return QueryFactory.EMPTY;
  56         }
  57
  58         @Override
  59         public CompletableFuture<QueryResult> executeQuery(Query query) {
  60             return CompletableFuture.completedFuture(QueryResult.ofIncorrectResult("Empty database"));
  61         }
  62     };
  63 }