Coverage Summary for Class: Platform (com.google.common.collect)

1 /*
2  * Copyright (C) 2008 The Guava Authors
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.common.collect;
18 
19 import com.google.common.annotations.GwtCompatible;
20 import java.lang.reflect.Array;
21 import java.util.Arrays;
22 import java.util.Map;
23 import java.util.Set;
24 import java.util.concurrent.ConcurrentHashMap;
25 
26 /**
27  * Methods factored out so that they can be emulated differently in GWT.
28  *
29  * @author Hayward Chan
30  */
31 @GwtCompatible(emulated = true)
32 final class Platform {
33   private static final java.util.logging.Logger logger =
34       java.util.logging.Logger.getLogger(Platform.class.getName());
35 
36   /** Returns the platform preferred implementation of a map based on a hash table. */
37   static <K, V> Map<K, V> newHashMapWithExpectedSize(int expectedSize) {
38     return Maps.newHashMapWithExpectedSize(expectedSize);
39   }
40 
41   /**
42    * Returns the platform preferred implementation of an insertion ordered map based on a hash
43    * table.
44    */
45   static <K, V> Map<K, V> newLinkedHashMapWithExpectedSize(int expectedSize) {
46     return Maps.newLinkedHashMapWithExpectedSize(expectedSize);
47   }
48 
49   /** Returns the platform preferred implementation of a set based on a hash table. */
50   static <E> Set<E> newHashSetWithExpectedSize(int expectedSize) {
51     return Sets.newHashSetWithExpectedSize(expectedSize);
52   }
53 
54   /** Returns the platform preferred implementation of a thread-safe hash set. */
55   static <E> Set<E> newConcurrentHashSet() {
56     return ConcurrentHashMap.newKeySet();
57   }
58 
59   /**
60    * Returns the platform preferred implementation of an insertion ordered set based on a hash
61    * table.
62    */
63   static <E> Set<E> newLinkedHashSetWithExpectedSize(int expectedSize) {
64     return Sets.newLinkedHashSetWithExpectedSize(expectedSize);
65   }
66 
67   /**
68    * Returns the platform preferred map implementation that preserves insertion order when used only
69    * for insertions.
70    */
71   static <K, V> Map<K, V> preservesInsertionOrderOnPutsMap() {
72     return Maps.newLinkedHashMap();
73   }
74 
75   /**
76    * Returns the platform preferred set implementation that preserves insertion order when used only
77    * for insertions.
78    */
79   static <E> Set<E> preservesInsertionOrderOnAddsSet() {
80     return Sets.newLinkedHashSet();
81   }
82 
83   /**
84    * Returns a new array of the given length with the same type as a reference array.
85    *
86    * @param reference any array of the desired type
87    * @param length the length of the new array
88    */
89   static <T> T[] newArray(T[] reference, int length) {
90     Class<?> type = reference.getClass().getComponentType();
91 
92     // the cast is safe because
93     // result.getClass() == reference.getClass().getComponentType()
94     @SuppressWarnings("unchecked")
95     T[] result = (T[]) Array.newInstance(type, length);
96     return result;
97   }
98 
99   /** Equivalent to Arrays.copyOfRange(source, from, to, arrayOfType.getClass()). */
100   static <T> T[] copy(Object[] source, int from, int to, T[] arrayOfType) {
101     return Arrays.copyOfRange(source, from, to, (Class<? extends T[]>) arrayOfType.getClass());
102   }
103 
104   /**
105    * Configures the given map maker to use weak keys, if possible; does nothing otherwise (i.e., in
106    * GWT). This is sometimes acceptable, when only server-side code could generate enough volume
107    * that reclamation becomes important.
108    */
109   static MapMaker tryWeakKeys(MapMaker mapMaker) {
110     return mapMaker.weakKeys();
111   }
112 
113   static int reduceIterationsIfGwt(int iterations) {
114     return iterations;
115   }
116 
117   static int reduceExponentIfGwt(int exponent) {
118     return exponent;
119   }
120 
121   static void checkGwtRpcEnabled() {
122     String propertyName = "guava.gwt.emergency_reenable_rpc";
123 
124     if (!Boolean.parseBoolean(System.getProperty(propertyName, "false"))) {
125       throw new UnsupportedOperationException(
126           com.google.common.base.Strings.lenientFormat(
127               "We are removing GWT-RPC support for Guava types. You can temporarily reenable"
128                   + " support by setting the system property %s to true. For more about system"
129                   + " properties, see %s. For more about Guava's GWT-RPC support, see %s.",
130               propertyName,
131               "https://stackoverflow.com/q/5189914/28465",
132               "https://groups.google.com/d/msg/guava-announce/zHZTFg7YF3o/rQNnwdHeEwAJ"));
133     }
134     logger.log(
135         java.util.logging.Level.WARNING,
136         "Later in 2020, we will remove GWT-RPC support for Guava types. You are seeing this"
137             + " warning because you are sending a Guava type over GWT-RPC, which will break. You"
138             + " can identify which type by looking at the class name in the attached stack trace.",
139         new Throwable());
140   }
141 
142   private Platform() {}
143 }