1   /*
2    * Copyright (C) 2009 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.base;
18  
19  import com.google.common.annotations.GwtCompatible;
20  
21  import java.lang.ref.WeakReference;
22  
23  /**
24   * Methods factored out so that they can be emulated differently in GWT.
25   *
26   * @author Jesse Wilson
27   */
28  @GwtCompatible(emulated = true)
29  final class Platform {
30    private Platform() {}
31  
32    /** Calls {@link System#nanoTime()}. */
33    static long systemNanoTime() {
34      return System.nanoTime();
35    }
36  
37    static CharMatcher precomputeCharMatcher(CharMatcher matcher) {
38      return matcher.precomputedInternal();
39    }
40  
41    static <T extends Enum<T>> Optional<T> getEnumIfPresent(Class<T> enumClass, String value) {
42      WeakReference<? extends Enum<?>> ref = Enums.getEnumConstants(enumClass).get(value);
43      return ref == null
44          ? Optional.<T>absent()
45          : Optional.of(enumClass.cast(ref.get()));
46    }
47  }