| 1 | /* |
| 2 | * Copyright (C) 2008 Google Inc. |
| 3 | * |
| 4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | * you may not use this file except in compliance with the License. |
| 6 | * You may obtain a copy of the License at |
| 7 | * |
| 8 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | * |
| 10 | * Unless required by applicable law or agreed to in writing, software |
| 11 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | * See the License for the specific language governing permissions and |
| 14 | * limitations under the License. |
| 15 | */ |
| 16 | |
| 17 | package com.google.gson.internal; |
| 18 | |
| 19 | |
| 20 | import java.lang.reflect.Type; |
| 21 | import java.util.Collections; |
| 22 | import java.util.HashMap; |
| 23 | import java.util.Map; |
| 24 | |
| 25 | /** |
| 26 | * Contains static utility methods pertaining to primitive types and their |
| 27 | * corresponding wrapper types. |
| 28 | * |
| 29 | * @author Kevin Bourrillion |
| 30 | */ |
| 31 | public final class Primitives { |
| 32 | private Primitives() {} |
| 33 | |
| 34 | /** A map from primitive types to their corresponding wrapper types. */ |
| 35 | private static final Map<Class<?>, Class<?>> PRIMITIVE_TO_WRAPPER_TYPE; |
| 36 | |
| 37 | /** A map from wrapper types to their corresponding primitive types. */ |
| 38 | private static final Map<Class<?>, Class<?>> WRAPPER_TO_PRIMITIVE_TYPE; |
| 39 | |
| 40 | // Sad that we can't use a BiMap. :( |
| 41 | |
| 42 | static { |
| 43 | Map<Class<?>, Class<?>> primToWrap = new HashMap<Class<?>, Class<?>>(16); |
| 44 | Map<Class<?>, Class<?>> wrapToPrim = new HashMap<Class<?>, Class<?>>(16); |
| 45 | |
| 46 | add(primToWrap, wrapToPrim, boolean.class, Boolean.class); |
| 47 | add(primToWrap, wrapToPrim, byte.class, Byte.class); |
| 48 | add(primToWrap, wrapToPrim, char.class, Character.class); |
| 49 | add(primToWrap, wrapToPrim, double.class, Double.class); |
| 50 | add(primToWrap, wrapToPrim, float.class, Float.class); |
| 51 | add(primToWrap, wrapToPrim, int.class, Integer.class); |
| 52 | add(primToWrap, wrapToPrim, long.class, Long.class); |
| 53 | add(primToWrap, wrapToPrim, short.class, Short.class); |
| 54 | add(primToWrap, wrapToPrim, void.class, Void.class); |
| 55 | |
| 56 | PRIMITIVE_TO_WRAPPER_TYPE = Collections.unmodifiableMap(primToWrap); |
| 57 | WRAPPER_TO_PRIMITIVE_TYPE = Collections.unmodifiableMap(wrapToPrim); |
| 58 | } |
| 59 | |
| 60 | private static void add(Map<Class<?>, Class<?>> forward, |
| 61 | Map<Class<?>, Class<?>> backward, Class<?> key, Class<?> value) { |
| 62 | forward.put(key, value); |
| 63 | backward.put(value, key); |
| 64 | } |
| 65 | |
| 66 | /** |
| 67 | * Returns true if this type is a primitive. |
| 68 | */ |
| 69 | public static boolean isPrimitive(Type type) { |
| 70 | return PRIMITIVE_TO_WRAPPER_TYPE.containsKey(type); |
| 71 | } |
| 72 | |
| 73 | /** |
| 74 | * Returns {@code true} if {@code type} is one of the nine |
| 75 | * primitive-wrapper types, such as {@link Integer}. |
| 76 | * |
| 77 | * @see Class#isPrimitive |
| 78 | */ |
| 79 | public static boolean isWrapperType(Type type) { |
| 80 | return WRAPPER_TO_PRIMITIVE_TYPE.containsKey( |
| 81 | $Gson$Preconditions.checkNotNull(type)); |
| 82 | } |
| 83 | |
| 84 | /** |
| 85 | * Returns the corresponding wrapper type of {@code type} if it is a primitive |
| 86 | * type; otherwise returns {@code type} itself. Idempotent. |
| 87 | * <pre> |
| 88 | * wrap(int.class) == Integer.class |
| 89 | * wrap(Integer.class) == Integer.class |
| 90 | * wrap(String.class) == String.class |
| 91 | * </pre> |
| 92 | */ |
| 93 | public static <T> Class<T> wrap(Class<T> type) { |
| 94 | // cast is safe: long.class and Long.class are both of type Class<Long> |
| 95 | @SuppressWarnings("unchecked") |
| 96 | Class<T> wrapped = (Class<T>) PRIMITIVE_TO_WRAPPER_TYPE.get( |
| 97 | $Gson$Preconditions.checkNotNull(type)); |
| 98 | return (wrapped == null) ? type : wrapped; |
| 99 | } |
| 100 | |
| 101 | /** |
| 102 | * Returns the corresponding primitive type of {@code type} if it is a |
| 103 | * wrapper type; otherwise returns {@code type} itself. Idempotent. |
| 104 | * <pre> |
| 105 | * unwrap(Integer.class) == int.class |
| 106 | * unwrap(int.class) == int.class |
| 107 | * unwrap(String.class) == String.class |
| 108 | * </pre> |
| 109 | */ |
| 110 | public static <T> Class<T> unwrap(Class<T> type) { |
| 111 | // cast is safe: long.class and Long.class are both of type Class<Long> |
| 112 | @SuppressWarnings("unchecked") |
| 113 | Class<T> unwrapped = (Class<T>) WRAPPER_TO_PRIMITIVE_TYPE.get( |
| 114 | $Gson$Preconditions.checkNotNull(type)); |
| 115 | return (unwrapped == null) ? type : unwrapped; |
| 116 | } |
| 117 | } |