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/*
* Copyright 2008 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.core.client;
import com.google.gwt.core.client.Scheduler.ScheduledCommand;
import com.google.gwt.core.client.impl.Impl;
/**
* Supports core functionality that in some cases requires direct support from
* the compiler and runtime systems such as runtime type information and
* deferred binding.
*/
public final class GWT {
/**
* This interface is used to catch exceptions at the "top level" just before
* they escape to the browser. This is used in places where the browser calls
* into user code such as event callbacks, timers, and RPC.
*
* In Development Mode, the default handler prints a stack trace to the log
* window. In Production Mode, the default handler is null and thus exceptions
* are allowed to escape, which provides an opportunity to use a JavaScript
* debugger.
*/
public interface UncaughtExceptionHandler {
void onUncaughtException(Throwable e);
}
/**
* An {@link UncaughtExceptionHandler} that logs errors to
* {@link GWT#log(String, Throwable)}. This is the default exception handler
* in Development Mode. In Production Mode, the default exception handler is
* null.
*/
private static final class DefaultUncaughtExceptionHandler implements
UncaughtExceptionHandler {
@Override
public void onUncaughtException(Throwable e) {
log("Uncaught exception escaped", e);
}
}
/**
* This constant is used by {@link #getPermutationStrongName} when running in
* Development Mode.
*/
public static final String HOSTED_MODE_PERMUTATION_STRONG_NAME = "HostedMode";
/**
* Defaults to null in Production Mode and an instance of
* {@link DefaultUncaughtExceptionHandler} in Development Mode.
*/
private static UncaughtExceptionHandler uncaughtExceptionHandler = null;
/**
* Instantiates a class via deferred binding.
*
*
* The argument to {@link #create(Class)} must be a class literal
* because the Production Mode compiler must be able to statically determine
* the requested type at compile-time. This can be tricky because using a
* {@link Class} variable may appear to work correctly in Development Mode.
*
*
* @param classLiteral a class literal specifying the base class to be
* instantiated
* @return the new instance, which must be cast to the requested class
*/
public static T create(Class classLiteral) {
/*
* In Production Mode, the compiler directly replaces calls to this method
* with a new Object() type expression of the correct rebound type.
*/
return com.google.gwt.core.shared.GWT.createImpl(classLiteral);
}
/**
* Gets the URL prefix of the hosting page, useful for prepending to relative
* paths of resources which may be relative to the host page. Typically, you
* should use {@link #getModuleBaseURL()} unless you have a specific reason to
* load a resource relative to the host page.
*
* @return if non-empty, the base URL is guaranteed to end with a slash
*/
public static String getHostPageBaseURL() {
return Impl.getHostPageBaseURL();
}
/**
* Gets the URL prefix that should be prepended to URLs that point to
* static files generated by the GWT compiler, such as files in the
* module's public path.
*
*
* Normally this will be the same value as {@link #getModuleBaseURL}, but
* may be different when a GWT app is configured to get its static resources
* from a different server.
*
*
* @return if non-empty, the base URL is guaranteed to end with a slash
*/
public static String getModuleBaseForStaticFiles() {
return Impl.getModuleBaseURLForStaticFiles();
}
/**
* Gets the URL prefix that should be prepended to URLs that
* are intended to be module-relative, such as RPC entry points.
*
* If the URL points to an output file of the GWT compiler (such as
* a file in the public path), use {@link #getModuleBaseForStaticFiles()}
* instead.
*
* @return if non-empty, the base URL is guaranteed to end with a slash
*/
public static String getModuleBaseURL() {
return Impl.getModuleBaseURL();
}
/**
* Gets the name of the running module.
*/
public static String getModuleName() {
return Impl.getModuleName();
}
/**
* Returns the permutation's strong name. This can be used to distinguish
* between different permutations of the same module. In Development Mode,
* this method will return {@value #HOSTED_MODE_PERMUTATION_STRONG_NAME}.
*/
public static String getPermutationStrongName() {
if (GWT.isScript()) {
return Impl.getPermutationStrongName();
} else {
return HOSTED_MODE_PERMUTATION_STRONG_NAME;
}
}
/**
* @deprecated Use {@link Object#getClass()}, {@link Class#getName()}
*/
@Deprecated
public static String getTypeName(Object o) {
return (o == null) ? null : o.getClass().getName();
}
/**
* Returns the currently active uncaughtExceptionHandler.
*
* @return the currently active handler, or null if no handler is active.
*
* @see #reportUncaughtException(Throwable)
*/
public static UncaughtExceptionHandler getUncaughtExceptionHandler() {
return uncaughtExceptionHandler;
}
/**
* Reports an exception caught at the "top level" to a handler set via
* {@link #setUncaughtExceptionHandler(UncaughtExceptionHandler)}. This is
* used in places where the browser calls into user code such as event
* callbacks, timers, and RPC.
*
* If no {@code UncaughtExceptionHandler} is set, the exception is reported
* to browser. Browsers usually log these exceptions to the JavaScript
* console.
*/
public static void reportUncaughtException(Throwable e) {
Impl.reportUncaughtException(e);
}
/**
* Returns the empty string when running in Production Mode, but returns a
* unique string for each thread in Development Mode (for example, different
* windows accessing the dev mode server will each have a unique id, and
* hitting refresh without restarting dev mode will result in a new unique id
* for a particular window.
*
* TODO(unnurg): Remove this function once Dev Mode rewriting classes are in
* gwt-dev.
*/
public static String getUniqueThreadId() {
return com.google.gwt.core.shared.GWT.getUniqueThreadId();
}
public static String getVersion() {
String version = com.google.gwt.core.shared.GWT.getVersion();
if (version == null) {
version = getVersion0();
}
return version;
}
/**
* Returns true when running inside the normal GWT environment,
* either in Development Mode or Production Mode. Returns false
* if this code is running in a plain JVM. This might happen when running
* shared code on the server, or during the bootstrap sequence of a
* GWTTestCase test.
*/
public static boolean isClient() {
return com.google.gwt.core.shared.GWT.isClient();
}
/**
* Returns true when running in production mode. Returns
* false when running either in development mode, or when running
* in a plain JVM.
*/
public static boolean isProdMode() {
return com.google.gwt.core.shared.GWT.isProdMode();
}
/**
* Determines whether or not the running program is script or bytecode.
*/
public static boolean isScript() {
return com.google.gwt.core.shared.GWT.isScript();
}
/**
* Logs a message to the development shell logger in Development Mode, or to
* the console in Super Dev Mode. Calls are optimized out in Production Mode.
*/
public static void log(String message) {
com.google.gwt.core.shared.GWT.log(message);
}
/**
* Logs a message to the development shell logger in Development Mode, or to
* the console in Super Dev Mode. Calls are optimized out in Production Mode.
*/
public static void log(String message, Throwable e) {
com.google.gwt.core.shared.GWT.log(message, e);
}
/**
* Emits a JavaScript "debugger" statement on the line that called this method.
* If the user has the browser's debugger open, the debugger will stop when the
* GWT application executes that line. There is no effect in Dev Mode or in
* server-side code.
*/
public static void debugger() {
}
/**
* The same as {@link #runAsync(RunAsyncCallback)}, except with an extra
* parameter to provide a name for the call. The name parameter should be
* supplied with a class literal. If two GWT.runAsync calls use the same
* class literal, the codesplitter will put the corresponding code in
* the same code fragment.
*/
@SuppressWarnings("unused") // parameter will be used following replacement
public static void runAsync(Class name, final RunAsyncCallback callback) {
runAsyncImpl(callback);
}
/**
* Run the specified callback once the necessary code for it has been loaded.
*/
public static void runAsync(final RunAsyncCallback callback) {
runAsyncImpl(callback);
}
private static void runAsyncImpl(final RunAsyncCallback callback) {
Scheduler.get().scheduleDeferred(new ScheduledCommand() {
@Override public void execute() {
callback.onSuccess();
}
});
}
/**
* Sets a custom uncaught exception handler. See
* {@link #getUncaughtExceptionHandler()} for details.
*
* @param handler the handler that should be called when an exception is
* about to escape to the browser, or null to clear the
* handler and allow exceptions to escape.
*/
public static void setUncaughtExceptionHandler(
UncaughtExceptionHandler handler) {
uncaughtExceptionHandler = handler;
}
/**
* Called via reflection in Development Mode; do not ever call this method in
* Production Mode.
*/
static void setBridge(GWTBridge bridge) {
com.google.gwt.core.shared.GWT.setBridge(bridge);
if (bridge != null) {
setUncaughtExceptionHandler(new DefaultUncaughtExceptionHandler());
}
}
private static native String getVersion0() /*-{
return $gwt_version;
}-*/;
}