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.utils;
018    
019    import org.jetbrains.annotations.NotNull;
020    import org.jetbrains.annotations.Nullable;
021    
022    public class WrappedValues {
023        private static final Object NULL_VALUE = new Object();
024    
025        private final static class ThrowableWrapper {
026            private final Throwable throwable;
027    
028            private ThrowableWrapper(@NotNull Throwable throwable) {
029                this.throwable = throwable;
030            }
031    
032            @NotNull
033            public Throwable getThrowable() {
034                return throwable;
035            }
036        }
037    
038        private WrappedValues() {
039        }
040    
041        @Nullable
042        @SuppressWarnings("unchecked")
043        public static <V> V unescapeNull(@NotNull Object value) {
044            if (value == NULL_VALUE) return null;
045            return (V) value;
046        }
047    
048        @NotNull
049        public static <V> Object escapeNull(@Nullable V value) {
050            if (value == null) return NULL_VALUE;
051            return value;
052        }
053    
054        @NotNull
055        public static Object escapeThrowable(@NotNull Throwable throwable) {
056            return new ThrowableWrapper(throwable);
057        }
058    
059        @Nullable
060        public static <V> V unescapeExceptionOrNull(@NotNull Object value) {
061            if (value instanceof ThrowableWrapper) {
062                throw ExceptionUtils.rethrow(((ThrowableWrapper) value).getThrowable());
063            }
064    
065            return unescapeNull(value);
066        }
067    }