com.google.gwt.dev.jjs.impl

Class EnumOrdinalizer

java.lang.Object

com.google.gwt.dev.jjs.impl.EnumOrdinalizer

public class EnumOrdinalizer
extends Object

This optimizer replaces enum constants with their ordinal value (a simple int) when possible. We call this process "ordinalization". Generally, this can be done for enums that are only ever referred to by reference, or by their ordinal value. For the specific set of conditions under which ordinalization can proceed, see the notes for the nested class EnumOrdinalizer.CannotBeOrdinalAnalyzer below. This optimizer modifies enum classes to change their field constants to ints, and to remove initialization of those constants in the clinit method. An ordinalized enum class will not be removed from the AST by this optimizer, but as long as all references to it are replaced, then the enum class itself will be pruned by subsequent optimizer passes. Some enum classes may not be completely removed however. Ordinalization can proceed in cases where there are added static fields or methods in the enum class. In such cases a reduced version of the original enum class can remain in the AST, containing only static fields and methods which aren't part of the enum infrastructure (in which case it will no longer behave as an enum class at all). Regardless of whether an ordinalized enum class ends up being completely pruned away, the AST is expected to be in a coherent and usable state after any pass of this optimizer. Thus, this optimizer should be considered to be stateless. The process is broken up into 3 separate passes over the AST, each implemented as a separate visitor class. The first visitor, EnumOrdinalizer.CannotBeOrdinalAnalyzer compiles information about each enum class in the AST, and looks for reasons not to ordinalize each enum. Thus, it prepares a "black-list" of enum classes that cannot be ordinalized (and it follows that all enums that don't get entered in the black-list, will be allowed to be ordinalized. The set of conditions which cause an enum to be black-listed are outlined below. If there are enum classes that didn't get black-listed remaining, the subsequent passes of the optimizer will be invoked. The first, EnumOrdinalizer.ReplaceEnumTypesWithInteger, replaces the type info for each field or expression involved with a target enum constant with an integer. The final visitor, descriptively named EnumOrdinalizer.ReplaceOrdinalFieldAndMethodRefsWithOrdinal, will do the job of replacing the value for references to the Enum ordinal field or method of an enum constant that has been ordinalized.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	EnumOrdinalizer.Tracker A simple Tracker class for compiling lists of enum classes processed by this optimizer.

Constructor Summary

Constructors

Constructor and Description
EnumOrdinalizer(JProgram program)

Method Summary

Modifier and Type	Method and Description
static void	enableTracker()
static OptimizerStats	exec(JProgram program)
static EnumOrdinalizer.Tracker	getTracker()
static void	resetTracker()

Methods inherited from class java.lang.Object

equals, finalize, getClass, hashCode, toString

Constructor Detail

EnumOrdinalizer

public EnumOrdinalizer(JProgram program)

Method Detail

enableTracker

public static void enableTracker()

exec

public static OptimizerStats exec(JProgram program)

getTracker

public static EnumOrdinalizer.Tracker getTracker()

resetTracker

public static void resetTracker()