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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 | } |