001    /*
002     * Copyright 2010-2013 JetBrains s.r.o.
003     *
004     * Licensed under the Apache License, Version 2.0 (the "License");
005     * you may not use this file except in compliance with the License.
006     * You may obtain a copy of the License at
007     *
008     * http://www.apache.org/licenses/LICENSE-2.0
009     *
010     * Unless required by applicable law or agreed to in writing, software
011     * distributed under the License is distributed on an "AS IS" BASIS,
012     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013     * See the License for the specific language governing permissions and
014     * limitations under the License.
015     */
016    
017    package org.jetbrains.jet.lang.resolve.java.resolver;
018    
019    import org.jetbrains.annotations.NotNull;
020    
021    import java.util.Iterator;
022    import java.util.ServiceLoader;
023    
024    public abstract class ProgressChecker {
025        private static ProgressChecker instance;
026    
027        @NotNull
028        public static ProgressChecker getInstance() {
029            if (instance == null) {
030                Iterator<ProgressChecker> iterator =
031                        ServiceLoader.load(ProgressChecker.class, ProgressChecker.class.getClassLoader()).iterator();
032                assert iterator.hasNext() : "No service found: " + ProgressChecker.class.getName();
033                instance = iterator.next();
034            }
035            return instance;
036        }
037    
038        public abstract void checkCanceled();
039    }