proguard.classfile.visitor (ProGuardCORE)

Interface Summary
Interface	Description
ClassPoolVisitor	This interface specifies the methods for a visitor of `ClassPool` instances.
ClassVisitor	This interface specifies the methods for a visitor of `Clazz` instances.
MemberVisitor	This interface specifies the methods for a visitor of `ProgramMember` instances and `LibraryMember` instances.
ParallelAllClassVisitor.ClassVisitorFactory	A factory for `ClassVisitor` objects.
ParameterVisitor	This interface specifies the methods for a visitor of method parameters or field types (which can be considered parameters when storing values).

Class Summary
Class	Description
AllClassVisitor	This `ClassPoolVisitor` lets a given `ClassVisitor` visit all Clazz instances of the class pools it visits.
AllFieldVisitor	This `ClassVisitor` lets a given `MemberVisitor` visit all `Field` instances of the classes it visits.
AllMemberVisitor	This `ClassVisitor` lets a given `MemberVisitor` visit all Member instances of the classes it visits.
AllMethodVisitor	This `ClassVisitor` lets a given `MemberVisitor` visit all `Method` instances of the classes it visits.
BottomClassFilter	This `ClassVisitor` delegates its visits to one of two other given `ClassVisitor` instances, depending on whether they have any subclasses or not.
ClassAccessFilter	This `ClassVisitor` delegates its visits to another given `ClassVisitor`, but only when the visited class has the proper access flags.
ClassCleaner	This `ClassVisitor` removes all processing information of the classes it visits.
ClassCollector	This `ClassVisitor` collects the classes that it visits in the given collection.
ClassConstantClassFilter	This ClassVisitor delegates all visits to another given visitor, but only if the visited class contains the specified class constant.
ClassCounter	This `ClassVisitor` counts the number of classes that has been visited.
ClassFeatureNameCollector	This `ClassVisitor` collects the feature names of the classes that it visits in the given collection.
ClassHierarchyTraveler	This `ClassVisitor` lets a given `ClassVisitor` optionally travel to the visited class, its superclass, its interfaces, and its subclasses.
ClassNameCollector	This `ClassVisitor` collects the names of the classes that it visits in the given collection.
ClassNameFilter	This `ClassVisitor` delegates its visits to another given `ClassVisitor`, but only when the visited class has a name that matches a given regular expression.
ClassPoolClassVisitor	This `ClassPoolVisitor` and `ClassVisitor` remembers the `ClassPool` instances that it visits and applies the given `ClassPoolVisitor` to the most recently remembered one, every time it visits a Clazz instance.
ClassPoolFiller	This `ClassVisitor` collects all the classes it visits in a given class pool.
ClassPoolRemover	This `ClassVisitor` removes all the classes it visits from a given class pool.
ClassPresenceFilter	This `ClassVisitor` delegates its visits to one of two `ClassVisitor` instances, depending on whether the name of the visited class file is present in a given `ClassPool` or not.
ClassPrinter	This `ClassVisitor` prints out the complete internal structure of the classes it visits.
ClassProcessingFlagFilter	This `ClassVisitor` delegates its visits to another given `ClassVisitor`, but only when the visited class has the proper processing flags.
ClassProcessingInfoFilter	Delegates all class visits to another given visitor, depending on if the given predicate passes or not.
ClassVersionFilter	This `ClassVisitor` delegates its visits to program classes to another given `ClassVisitor`, but only when the class version number of the visited program class lies in a given range.
ClassVersionSetter	This `ClassVisitor` sets the version number of the program classes that it visits.
ConcreteClassDownTraveler	This `ClassVisitor` lets a given `ClassVisitor` travel to the first concrete subclasses down in its hierarchy of abstract classes and concrete classes.
ConstantProcessingFlagFilter	This `ConstantVisitor` delegates its visits to another given `ConstantVisitor`, but only when the visited constant has the proper processing flags.
ConstructorMethodFilter	This `MemberVisitor` delegates its visits to one of three delegates, depending on whether the visited method is:
CounterConditionalClassVisitor	This ClassVisitor delegates to a given class visitor, and then, if the given predicate succeeds with the given `Counter` before and after values, also to a second given class visitor.
DotClassClassVisitor	This `InstructionVisitor` lets a given `ClassVisitor` visit all classes involved in any `.class` constructs that it visits.
DynamicReturnedClassVisitor	This `ConstantVisitor` lets a given `ClassVisitor` visit all the referenced classes that are returned by the dynamic constants and invoke dynamic constants that it visits.
ExceptClassesFilter	This `ClassVisitor` delegates its visits to another given `ClassVisitor`, except for classes are in a given list.
ExceptClassFilter	This `ClassVisitor` delegates its visits to another given `ClassVisitor`, except for one given class.
ExceptionCounter	This `ExceptionInfoVisitor` counts the number of exceptions that has been visited.
ExceptionExcludedOffsetFilter	This `ExceptionInfoVisitor` delegates its visits to another given `ExceptionInfoVisitor`, but only when the visited exception does not cover the instruction at the given offset.
ExceptionHandlerConstantVisitor	This `ExceptionInfoVisitor` lets a given `ConstantVisitor` visit all catch class constants of exceptions that it visits.
ExceptionHandlerFilter	This `ExceptionInfoVisitor` delegates its visits to another given `ExceptionInfoVisitor`, but only when the visited exception targets an instruction in the given range of offsets.
ExceptionOffsetFilter	This `ExceptionInfoVisitor` delegates its visits to another given `ExceptionInfoVisitor`, but only when the visited exception covers the instruction at the given offset.
ExceptionRangeFilter	This `ExceptionInfoVisitor` delegates its visits to another given `ExceptionInfoVisitor`, but only when the visited exception overlaps with the given instruction range.
FilteredClassVisitor	This `ClassPoolVisitor` lets a given `ClassVisitor` visit all matching Clazz instances of the class pools it visits.
FunctionalInterfaceFilter	This `ClassVisitor` delegates its visits to another given `ClassVisitor`, but only for functional interfaces, that is, interface classes that have exactly one abstract method.
ImplementedClassConstantFilter	This `ConstantVisitor` delegates its visits to class constants to another given `ConstantVisitor`, except for classes that extend or implement a given class.
ImplementedClassFilter	This `ClassVisitor` delegates its visits to one of two given `ClassVisitor`s, depending on whether the visited classes extend/implement a given class or not.
ImplementingClassConstantFilter	This `ConstantVisitor` delegates its visits to class constants to another given `ConstantVisitor`, except for classes that are extended or implemented by a given class.
InitializerMethodFilter	This `MemberVisitor` delegates its visits to one of two other given `MemberVisitor` instances, depending on whether the visited method is a static initializer or instance initializer, or not.
LibraryClassFilter	This `ClassVisitor` delegates its visits to another given `ClassVisitor`, but only when visiting library classes.
LibraryMemberFilter	This `MemberVisitor` delegates its visits to another given `MemberVisitor`, but only when visiting members of library classes.
LineNumberFinder	Retrieves the lineNumber for a given offset from a codeattribute.
MemberAccessFilter	This `MemberVisitor` delegates its visits to another given `MemberVisitor`, but only when the visited member has the proper access flags.
MemberAccessFlagCleaner	This `ClassVisitor` and `MemberVisitor` clears the specified access flags of the classes and class members that its visits.
MemberAccessFlagSetter	This `MemberVisitor` sets the specified access flags of the program class members that it visits.
MemberAccessSetter	This `MemberVisitor` sets the access part of the access flags of the program class members that its visits to a given value.
MemberClassAccessFilter	This `MemberVisitor` delegates its visits to another given `MemberVisitor`, but only when the visited member is accessible from the given referencing class.
MemberCollectionFilter	This MemberVisitor delegates its visits to one of two other visitors, depending on whether the member is present in the given member collection or not.
MemberCollector	This `MemberVisitor` collects dot-separated classname.membername.descriptor strings of the class members that it visits.
MemberCounter	This `MemberVisitor` counts the number of class members that have been visited.
MemberDescriptorFilter	This `MemberVisitor` delegates its visits to another given `MemberVisitor`, but only when the visited member has a descriptor that matches a given regular expression.
MemberDescriptorReferencedClassVisitor	This `MemberVisitor` lets a given `ClassVisitor` visit all the classes referenced by the descriptors of the class members that it visits.
MemberNameFilter	This `MemberVisitor` delegates its visits to another given `MemberVisitor`, but only when the visited member has a name that matches a given regular expression.
MemberProcessingFlagFilter	This `MemberVisitor` delegates its visits to another given `MemberVisitor`, but only when the visited member has the proper processing flags.
MemberToClassVisitor	This `MemberVisitor` delegates all visits to a given `ClassVisitor`.
MethodCollector	This `MemberVisitor` collects the methods that it visits in the given collection.
MethodCounter	This `MemberVisitor` counts the number of methods that have been visited.
MethodFilter	This `MemberVisitor` delegates its visits to one of two other given `MemberVisitor` instances, depending on whether the visited method is a method or a field.
MethodImplementationFilter	This `MemberVisitor` delegates its visits to methods to another given `MemberVisitor`, but only when the visited method may have implementations.
MethodImplementationTraveler	This `MemberVisitor` lets a given `MemberVisitor` travel to all concrete and abstract implementations of the visited methods in their class hierarchies.
MultiClassPoolVisitor	This `ClassPoolVisitor` delegates all visits to each `ClassPoolVisitor` in a given list.
MultiClassVisitor	This `ClassVisitor` delegates all visits to each `ClassVisitor` in a given list.
MultiConstantVisitor	This `ConstantVisitor` delegates all visits to each `ConstantVisitor` in a given list.
MultiMemberVisitor	This `MemberVisitor` delegates all visits to each `MemberVisitor` in a given list.
NamedClassVisitor	This `ClassPoolVisitor` lets a given `ClassVisitor` visit `Clazz` instances with a given name, in the class pools that it visits.
NamedFieldVisitor	This class visits `ProgramMember` instances referring to fields, identified by a name and descriptor pair.
NamedMethodVisitor	This class visits `ProgramMember` instances referring to methods, identified by a name and descriptor pair.
ParallelAllClassVisitor	This `ClassPoolVisitor` will visit all Clazz instances of the class pool in a parallel way.
ProcessingInfoSetter	This visitor sets a fixed info object on all the `Processable` instances that it visits.
ProgramClassFilter	This `ClassVisitor` delegates its visits to another given `ClassVisitor`, but only when visiting program classes.
ProgramMemberFilter	This `MemberVisitor` delegates its visits to another given `MemberVisitor`, but only when visiting members of program classes.
ReferencedClassesExtractor	Divides the referenced classes in a program/library method in the classes referenced in return and parameters.
ReferencedClassVisitor	This `ClassVisitor`, `MemberVisitor`, `ConstantVisitor`, `AttributeVisitor`, etc.
ReferencedMemberVisitor	This `ConstantVisitor` and `ElementValueVisitor` lets a given `MemberVisitor` visit all the referenced class members of the elements that it visits.
SignatureAttributeReferencedClassVisitor	This `AttributeVisitor` lets a given `ClassVisitor` visit all the classes referenced by the type descriptors of the signatures that it visits.
SimilarMemberVisitor	This `MemberVisitor` lets a given `MemberVisitor` visit all members that have the same name and type as the visited methods in the class hierarchy of the members' classes or of a given target class.
SimpleClassPrinter	This `ClassVisitor` and `MemberVisitor` prints out the class names of the classes it visits, and the full class member descriptions of the class members it visits.
SingleTimeClassVisitor	This `ClassVisitor` delegates all visits to a given `ClassVisitor`, although only once to the same class in a row.
SubclassFilter	This `ClassVisitor` delegates its visits to another given `ClassVisitor`, except for classes that have a given class as direct subclass.
SubclassTraveler	This `ClassVisitor` lets a given `ClassVisitor` travel to direct subclasses of the visited class.
UniqueClassFilter	This `ClassVisitor` delegates its visits to another given `ClassVisitor`, but at most a single time.
VariableClassVisitor	This `ClassVisitor` delegates all method calls to a `ClassVisitor` that can be changed at any time.
VariableMemberVisitor	This `MemberVisitor` delegates all method calls to a `MemberVisitor` that can be changed at any time.

Package proguard.classfile.visitor Description

This package contains interfaces and classes for processing class files from the proguard.classfile package using the visitor pattern. Cfr., for instance, "Design Patterns, Elements of Reusable OO Software", by Gamma, Helm, Johnson, and Vlissider.

Why the visitor pattern? Class files frequently contain lists of elements of various mixed types: class items, constant pool entries, attributes,... These lists and types are largely fixed; they won't change much in future releases of the Java class file specifications. On the other hand, the kinds of operations that we may wish to perform on the class files may change and expand. We want to separate the objects and the operations performed upon them. This is a good place to use the visitor pattern.

Visitor interfaces avoid having to do series of instanceof tests on the elements of a list, followed by type casts and the proper operations. Every list element is a processable. When its accept method is called by a visitor, it calls its corresponding visitX method in the visitor, passing itself as an argument. This technique is called double-dispatch.

As already mentioned, the main advantage is avoiding lots of instanceof tests and type casts. Also, implementing a visitor interface ensures you're handling all possible processable types. Each type has its own method, which you simply have to implement.

A disadvantage is that the visitor methods always get the same names, specified by the visitor interface. These names aren't descriptive at all, making code harder to read. It's the visitor classes that describe the operations now.

Also, the visitor methods always have the same parameters and return values, as specified by the visitor interfaces. Passing additional parameters is done by means of extra fields in the visitor, which is somewhat of a kludge.

Because objects (the processables) and the operations performed upon them (the visitors) are now separated, it becomes harder to associate some state with the objects. For convenience, we always provide an extra visitor info field in processables, in which visitors can put any temporary information they want.