Changes Made in WeTheInter.net's Fork

This fork of the Gwt project has been modified to
support additional features; It tracks Gwt master with periodic rebases; the
first released version is 2.7.0, which is based upon Gwt master a few months
after the pristine 2.7.0 was released. New versions of this fork will be
released as Gwt master is updated, with these and other enhancements.

No warranty is supplied, however, for support, you may reach James -AT- WeTheInter -DOT- net.

Additional features:

• Magic Method Injection
• Java Reflection
• JSNI for Default Methods

Magic Method Injection

This feature is based upon GWT.create, and allows you to declare your own
magic methods. A magic method is a method signature which the compiler swaps
out for some other valid AST nodes. GWT.create uses rebind rules in XML to
determine what instance object is produced, but it does not allow you to pass
in any additional parameters, thus sometimes requiring a lot of boilerplate
code. You can enable its use by inheriting com.google.gwt.core.MagicMethods.

Once enabled, you will be able to declaring a mapping from any method
signature to a class which implements MagicMethodGenerator. The compiler
instantiates your generator (called an injector in most cases), and will
call your injector whenever it transverses a method matching the signature
declared using the "gwt.magic.method" configuration property.

The exact (and yes, ugly) syntax of this configuration property is as follows
foo.ClassName.method(Lfoo/ParamType;)Lfoo/ReturnType; *= bar.dev.MyInjectorClass
This syntax may be updated if community members would rather see something
cleaner, like a classname which has magic method mapping annotations on it.

The reflection support described below uses this mechanism to extract
Class and String literals parameters from core reflection methods to generate
runtime support for methods, fields, constructors and annotations.

Two important features to note are the UnifyAstListener interface,
which is used to allow your injector to be notified when the UnifyAst process
begins and ends, and the @MagicMethod annotation, which can be used to
effectively erase the method body of whatever is inside your magic method.

UnifyAstListener can be used to allow your injector to collect up calls to a
given magic method, and then, once the entire application has been visited,
inject some new code to be included into the application (beware, race
conditions between injectors could exist if generated code calls other magic
methods). It can also be used to inject code at the beginning of the
application that will be run without requiring any particular method to be
called. You may also implement this interface solely for the destroy()
method, so that you can clean up any state that you may have stored in your
injector. Do note that all state should be stored in a ThreadLocal, or else
your code will have trouble when running in multi module super dev mode.

The MagicMethod annotation is simpler; it allows you to document the fact
that the method is magic, and signal to the compiler that the contents of
that method should not be visited. This is vital in cases where you want
a pure java implementation to call into code that is not supported by Gwt.

The classes referenced inside the magic method must be Gwt compatible, but
the methods called by the magic method may themselves call into unsupported
classes, provided @MagicMethod(doNotVisit=true) is added.

By default, the content of the magic method is visited, and will be considered
live. This is useful in cases where you might perform AST stitching
(injecting) when class or string literals are supplied, but fallback to
original method if a class or string reference is passed instead (references
are opaque to the compiler, meaning you cannot know at compile time what the
value of the reference will be). In such cases, your injector can return null
to tell the compiler to leave the JMethodCall untouched.

GwtReflect (Reflection Support)

Reflection support in Gwt is delivered in three formats, ranging from complete
emulation of Java reflection to lightweight reflection invocation that uses
standard reflection in JVMs and JSNI in Gwt.

The different levels of reflection are designed to minimize the amount of
generated code that will be added to your application, while still offering
convenience and flexibility in the code you write.

The first step in using Gwt reflection is to inherit the module which supports
it; com.google.gwt.reflect.Reflect. This will include a class, GwtReflect, plus
enable a number of magic methods that provide reflection support.

Flyweight (Invoke-Only) Reflection Support

In many cases, you do not need access to an actual Field or Method object, you
simply want to perform a reflective operation on a member that you do not have
standard access to.

In such situtations, you can bypass all reflection metadata, and simply invoke
the member you want to access by using helper methods in the GwtReflect class.

These methods are all magic-methods; in a standard JVM they will perform
normal reflection operations (including .setAccessible(true)), and in Gwt,
if all of the parameters required to do a compile-time lookup of the member
are traceable to literal values, then the compiler will emit a method call
that simply performs the given operation (passing along any parameters to
an Executable like Method or Constructor).

In practice, this would look like this:

static final Class[] EQUALS_PARAMS = new Class[]{Object.class};
GwtReflect.invoke(List.class, "equals", EQUALS_PARAMS, list1, list2);

In the contrived example above, the Class, name and parameters were all compile
time constants, so this invocation will be replaced with:

/*-{ return [email protected]::equals(Ljava/lang/Object;)(list2); }-*/
// The actual code will auto-box the boolean to match expect JVM behavior

In a JVM, the invoke method would just perform normal reflection:

return List.class.getMethod("equals", EQUALS_PARAMS).invoke(list1, list2);

This gives you all of the power to access private members interopably in Gwt
and standard JVM runtimes! As an added bonus, you can also (dangerously)
invoke a default method without an instance object; this will obviously
fail spectacularly if you try to invoke other instance methods on the "this"
parameter (which will be null), but in cases where you have default methods
that just return values, this can be a rather powerful tool.

Although the method signatures for these helpers are fairly bulky, their use
affords you powerful, interoperable reflection functionality, without a bunch
of extra code / data needed to implement Method, Field or Constructor objects!

Mediumweight (On Demand) Reflection Support

The medium-weight option is to only generate a Field, Method or Constructor as
needed. This is done by making the reflection methods on the Class object
magic methods. For example, if you call MyClass.class.getField("myField");,
and both MyClass.class and "myField" are compile-time literals (meaning the
compiler can figure out what Class and String they are), then we will inject
just the one field you have asked for, instead of enhancing the entire class.

Now, the constraint here is that all of the parameters needed to determine
which Field, Method or Constructor you want must evaluate to compile time
literals; if any of them resolve to opaque references, the compiler will either
fail fast, or will create code that checks at runtime to see if the class
referenced has already been enhanced (more on this below).

The default behavior is to allow runtime lookups, but if you want the fail-fast
behavior because you never want to pay for full class enhancement, just set the
configuration property gwt.reflect.never.fail=false.

Note that, in this fork, the process for looking up compile-time literals is
a little more relaxed than the standard GWT.create lookup rules. In addition
to class / String literals, you may also use constant field references, or
final methods with a single return statement (thus allowing super-source
to override a given literal at compile time).

Good examples:

• List.class.getMethod("equals", new Class<?>[]{Object.class}});
• final static Class<List> LIST = List.class;
final static Class<?>[] params() { return new Class<?>[]{Object.class};}
LIST.getMethod("equals", params());

Bad examples:

• myList.getClass().getMethod("size");
• List.class.getMethod("equals", new Class<?>[]{myObject.getClass()});

Heavyweight (Complete) Reflection Support

The most flexible option is complete emulation, where you simply send a class
literal to a single magic method (GwtReflect.magicClass), and then you can use
any kind of reflective construct on the class. Once a class has been enhanced,
you will be able to use reflection on non-literal references to that class (for
example: someObject.getClass().getField("someField").get(someObject) will work.

The price you pay for this simplicity is a fair amount of extra code added to
your project. The generated Class enhancer will create Field, Method,
Constructor and Annotation objects for every member in that class (as well as
inner classes). There are levers and knobs provided to reduce this overhead,
which will be covered in greater detail below.

It is only recommended to use this heavyweight option when you are using code
you do not control which relies on runtime reflection (ex: Spring or JUnit).

Mitigating Code Bloat from Reflection Metadata

## GWT (Original Documentation)

GWT is the official open source project for GWT releases 2.5 and onwards.

In this document you have some quick instructions to build the SDK from source code and to run its tests.

For a more detailed documentation visit our web site. If you are interested in contributing with the project, please read the Making GWT better section.

Building the GWT SDK:

• In order to build GWT, java and ant are required in your system.

• Optional: if you want to compile elemental you need python and g++ installed.

• You need the gwt-tools checked out and up-to-date, and it will be placed by default at ../tools. You can override the default location using the GWT_TOOLS environment variable or passing -Dgwt.tools= argument to ant.

  Note: that you need svn to checkout gwt-tools

• To create the SDK distribution files run:

  $ ant clean elemental dist-dev

  or if you don't have python and g++ just run

  $ ant clean dist-dev

  Then you will get all .jar files in the folder build/lib and the redistributable file will be: build/dist/gwt-0.0.0.zip

  if you want to specify a different version number run:

  $ ant elemental clean dist-dev -Dgwt.version=x.x.x

• To compile everything including examples you have to run

  $ ant clean elemental dist

How to verify GWT code conventions:

• In GWT we have some conventions so as all code written by contributors look similar being easier to review.

• After you make any modification, run this command to compile everything including tests, to check APIs, and to verify code style. It shouldn't take longer than 3-4 minutes.

  $ ant compile.tests apicheck checkstyle -Dprecompile.disable=true

How to run GWT tests

• Previously to run any test you have to set some environment variables to guarantee that they are run in the same conditions for all developers.

  In a Unix like platform you can use the export command:

  $ export TZ=America/Los_Angeles ANT_OPTS=-Dfile.encoding=UTF-8

  But in Windows™ you have to set the time-zone in your control panel, and the environment variables using the command set.

• Finally you can run all test suites with the following command, but be prepared because it could take hours, and probably it would fail because of timeouts, etc.

  $ ant test

• Thus, you might want to run only certain tests so as you can focus on checking the modifications you are working on.

  GWT build scripts use specific ant tasks and a bunch of system properties listed in the following table to specify which tests to run and how.

  For instance to run the task test in the module user you have to change to the user folder and run ant with the task as argument, adding any other property with the -D flag:

  $ ( cd user && ant test -Dtest.emma.htmlunit.disable=true ; cd .. )

  Module	Task	Property to skip
  dev	test	test.dev.disable
  codeserver	test	test.codeserver.disable
  user	test	test.user.disable
  user	test.nongwt	test.nongwt.disable
  user	test.dev.htmlunit	test.dev.htmlunit.disable
  user	test.web.htmlunit	test.web.htmlunit.disable
  user	test.draft.htmlunit	test.draft.htmlunit.disable
  user	test.nometa.htmlunit	test.nometa.htmlunit.disable
  user	test.emma.htmlunit	test.emma.htmlunit.disable
  user	test.coverage.htmlunit	test.coverage.htmlunit.disable
  user	test.dev.selenium	test.dev.selenium.disable
  user	test.web.selenium	test.web.selenium.disable
  user	test.draft.selenium	test.draft.selenium.disable
  user	test.nometa.selenium	test.nometa.selenium.disable
  user	test.emma.selenium	test.emma.selenium.disable
  requestfactory	test
  elemental	test
  elemental	test.nongwt
  elemental	test.dev.htmlunit
  elemental	test.web.htmlunit
  tools	test

  Additionally you can utilize some variables to filter which test to run in each task:

  Module	Task	Properties	Default
  dev/core	test	gwt.junit.testcase.dev.core.includes	**/com/google/**/*Test.class

              |                                       | gwt.junit.testcase.dev.core.excludes |
  

  user | test | gwt.junit.testcase.includes | **/*Suite.class user | test.nongwt | gwt.nongwt.testcase.includes | **/*JreSuite.class | | gwt.nongwt.testcase.excludes | user | test.web.* test.draft.* test.nometa.* | gwt.junit.testcase.web.includes | **/*Suite.class | | gwt.junit.testcase.web.excludes | **/*JsInteropSuite.class,**/*JreSuite.class,***/OptimizedOnly* user | test.dev.* test.emma.* | gwt.junit.testcase.dev.includes | **/*Suite.class | | gwt.junit.testcase.dev.excludes | **/*JsInteropSuite.class,**/*JreSuite.class,***/OptimizedOnly*

Examples

• Run all tests in dev

  $ ( cd dev && ant test ; cd .. )

  Note: that the last `cd ..' is only needed in Windows.

• There is another option to do the same but without changing to the module folder. We have to specify the module as the ant task, and the task as a target argument.

  $ ant dev -Dtarget=test

• Run all tests in codeserver

  $ ( cd dev/codeserver && ant test )

  or

  $ ant codeserver -Dtarget=test -Dtest.dev.disable=true

  Note: that we disable dev tests because code server depends on dev and we don`t want to run its tests.

• Run all tests in elemental:

  $ ( cd elemental && ant test.nongwt )

  or

  $ ant elemental -Dtarget=test -Dtest.dev.disable=true -Dtest.user.disable=true

  Note: that we have to disable dev and user tests because elemental depends on both.

• Run all tests in tools

  $ ant tools -Dtarget=test -Dtest.dev.disable=true -Dtest.user.disable=true

• Run only the JsniRefTest in dev

  $ ant dev -Dtarget=test \
      -Dgwt.junit.testcase.dev.core.includes="**/JsniRefTest.class"
  

• Run a couple of tests in dev

  $ ant dev -Dtarget=test \
      -Dgwt.junit.testcase.dev.core.includes="**/JsniRefTest.class,**/JsParserTest.class"
  

  Note: that you have to use regular expressions separated by comma to select the test classes to execute.

• Run all Jre tests in user, they should take not longer than 3min. We have two ways to run them. Although the second case is more complex it is here to know how disable properties work.

  $ ( cd user && ant test.nongwt )

  or

  $ ant user -Dtarget=test -Dtest.dev.disable=true \
         -Dtest.dev.htmlunit.disable=true \
         -Dtest.web.htmlunit.disable=true \
         -Dtest.coverage.htmlunit.disable=true \
         -Dtest.dev.selenium.disable=true \
         -Dtest.draft.htmlunit.disable=true \
         -Dtest.draft.selenium.disable=true \
         -Dtest.emma.htmlunit.disable=true \
         -Dtest.emma.selenium.disable=true \
         -Dtest.nometa.htmlunit.disable=true \
         -Dtest.nometa.selenium.disable=true \
         -Dtest.web.selenium.disable=true
  

  Note: that we have to set all disable variables but test.nongwt.disable

• Run certain Jre tests in the user module.

  $ ( cd user && ant test.nongwt -Dgwt.nongwt.testcase.includes="**/I18NJreSuite.class" )

• Run all GWT tests in user using htmlunit in dev mode.

  $ ( cd user && ant test.dev.htmlunit )