/*
 * Copyright (C) 2009 The Guava Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
 * in compliance with the License. You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software distributed under the License
 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
 * or implied. See the License for the specific language governing permissions and limitations under
 * the License.
 */

package com.google.common.base;

import com.google.common.annotations.GwtCompatible;

import java.lang.ref.WeakReference;
import java.util.Locale;

/**
 * Methods factored out so that they can be emulated differently in GWT.
 *
 * @author Jesse Wilson
 */
@GwtCompatible(emulated = true)
final class Platform {
  private Platform() {}

  /** Calls {@link System#nanoTime()}. */
  static long systemNanoTime() {
    return System.nanoTime();
  }

  static CharMatcher precomputeCharMatcher(CharMatcher matcher) {
    return matcher.precomputedInternal();
  }

  static <T extends Enum<T>> Optional<T> getEnumIfPresent(Class<T> enumClass, String value) {
    WeakReference<? extends Enum<?>> ref = Enums.getEnumConstants(enumClass).get(value);
    return ref == null
        ? Optional.<T>absent()
        : Optional.of(enumClass.cast(ref.get()));
  }
  
  static String formatCompact4Digits(double value) {
    return String.format(Locale.ROOT, "%.4g", value);
  }
}
