guava-gwt/src-super/com/google/common/base/super/com/google/common/base/Platform.java

/*
 * 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 static jsinterop.annotations.JsPackage.GLOBAL;

import java.util.concurrent.TimeUnit;
import jsinterop.annotations.JsMethod;
import jsinterop.annotations.JsType;
import org.checkerframework.checker.nullness.qual.Nullable;

/** @author Jesse Wilson */
final class Platform {
  static CharMatcher precomputeCharMatcher(CharMatcher matcher) {
    // CharMatcher.precomputed() produces CharMatchers that are maybe a little
    // faster (and that's debatable), but definitely more memory-hungry. We're
    // choosing to turn .precomputed() into a no-op in GWT, because it doesn't
    // seem to be a worthwhile tradeoff in a browser.
    return matcher;
  }

  @SuppressWarnings("GoodTime") // reading system time without TimeSource
  static long systemNanoTime() {
    // System.nanoTime() is not available in GWT, so we get milliseconds
    // and convert to nanos.
    return TimeUnit.MILLISECONDS.toNanos(System.currentTimeMillis());
  }

  static <T extends Enum<T>> Optional<T> getEnumIfPresent(Class<T> enumClass, String value) {
    try {
      return Optional.of(Enum.valueOf(enumClass, value));
    } catch (IllegalArgumentException iae) {
      return Optional.absent();
    }
  }

  static String formatCompact4Digits(double value) {
    return "" + ((Number) (Object) value).toPrecision(4);
  }

  @JsMethod
  static native boolean stringIsNullOrEmpty(@Nullable String string) /*-{
    return !string;
  }-*/;

  @JsMethod
  static native String nullToEmpty(@Nullable String string) /*-{
    return string || "";
  }-*/;

  @JsMethod
  static native String emptyToNull(@Nullable String string) /*-{
    return string || null;
  }-*/;

  @JsType(isNative = true, name = "number", namespace = GLOBAL)
  private interface Number {
    double toPrecision(int precision);
  }

  static CommonPattern compilePattern(String pattern) {
    throw new UnsupportedOperationException();
  }

  static boolean patternCompilerIsPcreLike() {
    throw new UnsupportedOperationException();
  }

  /*
   * We will eventually disable GWT-RPC on the server side, but we'll leave it nominally enabled on
   * the client side. There's little practical difference: If it's disabled on the server, it won't
   * work. It's just a matter of how quickly it fails. I'm not sure if failing on the client would
   * be better or not, but it's harder: GWT's System.getProperty reads from a different property
   * list than Java's, so anyone who needs to reenable GWT-RPC in an emergency would have to figure
   * out how to set both properties. It's easier to have to set only one, and it might as well be
   * the Java property, since Guava already reads another Java property.
   */
  static void checkGwtRpcEnabled() {}

  private Platform() {}
}