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.codegen;
018    
019    import com.google.common.collect.Lists;
020    import org.jetbrains.annotations.NotNull;
021    
022    import java.util.List;
023    
024    public abstract class ClassBuilderOnDemand {
025    
026        private ClassBuilder classBuilder;
027    
028        private final List<ClassBuilderCallback> optionalDeclarations = Lists.newArrayList();
029    
030        interface ClassBuilderCallback {
031            void doSomething(@NotNull ClassBuilder classBuilder);
032        }
033    
034        @NotNull
035        protected abstract ClassBuilder createClassBuilder();
036    
037        public void addOptionalDeclaration(@NotNull ClassBuilderCallback callback) {
038            optionalDeclarations.add(callback);
039            if (classBuilder != null) {
040                callback.doSomething(classBuilder);
041            }
042        }
043    
044        @NotNull
045        public ClassBuilder getClassBuilder() {
046            if (classBuilder == null) {
047                classBuilder = createClassBuilder();
048                for (ClassBuilderCallback callback : optionalDeclarations) {
049                    callback.doSomething(classBuilder);
050                }
051            }
052            return classBuilder;
053        }
054    
055        public void done() {
056            if (classBuilder != null) {
057                classBuilder.done();
058            }
059        }
060    
061        public boolean isActivated() {
062            return classBuilder != null;
063        }
064    }