com.google.gwt.useragent.client.UserAgentAsserter Maven / Gradle / Ivy
/*
* Copyright 2011 Google Inc.
*
* 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.gwt.useragent.client;
import com.google.gwt.core.client.EntryPoint;
import com.google.gwt.core.client.GWT;
/**
* Helper class, which, during startup, asserts that the specified user.agent
* selection property value indeed matches the expected value for this browser /
* user agent, thus avoid long hours debugging strange error messages when a
* single user agent compile, typically created for testing purposes, ends up
* being executed in the wrong browser.
*/
public class UserAgentAsserter implements EntryPoint {
/**
* Replacement for UserAgentAsserter to disable it.
*/
public static class UserAgentAsserterDisabled implements EntryPoint {
@Override
public void onModuleLoad() { /* Empty - no assertions */}
}
@Override
public void onModuleLoad() {
scheduleUserAgentCheck();
}
private static native void scheduleUserAgentCheck() /*-{
// Keeping minimal dependency to reduce risk of problems due to use of wrong permutation:
$wnd.setTimeout($entry(@com.google.gwt.useragent.client.UserAgentAsserter::assertCompileTimeUserAgent()));
}-*/;
private static void assertCompileTimeUserAgent() {
UserAgent impl = GWT.create(UserAgent.class);
String compileTimeValue = impl.getCompileTimeValue();
String runtimeValue = impl.getRuntimeValue();
if (!compileTimeValue.equals(runtimeValue)) {
// Let it escape and get handled by UCEH:
throw new UserAgentAssertionError(compileTimeValue, runtimeValue);
}
}
/**
* An error object that indicates that the user agent detected at runtime did
* not match the user agent that the module expected to find.
*/
public static class UserAgentAssertionError extends AssertionError {
/**
* Default constructor for serialization.
*/
public UserAgentAssertionError() {
}
/**
* Creates an error with the given expected and actual user.agent value.
*
* @param compileTimeValue the compile time user.agent value, either in this
* permutation or soft permutation
* @param runtimeValue the detected user.agent value after the module started
*/
public UserAgentAssertionError(String compileTimeValue, String runtimeValue) {
super("Possible problem with your *.gwt.xml module file.\n"
+ "The compile time user.agent value (" + compileTimeValue + ") "
+ "does not match the runtime user.agent value (" + runtimeValue + ").\n"
+ "Expect more errors.");
}
}
}