javassist.bytecode.analysis

Class MultiType

java.lang.Object

javassist.bytecode.analysis.Type

javassist.bytecode.analysis.MultiType

public class MultiType
extends Type

MultiType represents an unresolved type. Whenever two Type instances are merged, if they share more than one super type (either an interface or a superclass), then a MultiType is used to represent the possible super types. The goal of a MultiType is to reduce the set of possible types down to a single resolved type. This is done by eliminating non-assignable types from the typeset when the MultiType is passed as an argument to Type.isAssignableFrom(Type), as well as removing non-intersecting types during a merge. Note: Currently the MultiType instance is reused as much as possible so that updates are visible from all frames. In addition, all MultiType merge paths are also updated. This is somewhat hackish, but it appears to handle most scenarios.

Field Summary

Fields

Modifier and Type	Field and Description
private boolean	changed
private java.util.Map	interfaces
private MultiType	mergeSource
private Type	potentialClass
private Type	resolved

Fields inherited from class javassist.bytecode.analysis.Type

BOGUS, BOOLEAN, BYTE, CHAR, CLONEABLE, DOUBLE, FLOAT, INTEGER, LONG, OBJECT, RETURN_ADDRESS, SERIALIZABLE, SHORT, THROWABLE, TOP, UNINIT, VOID

Constructor Summary

Constructors

Constructor and Description
MultiType(java.util.Map interfaces)
MultiType(java.util.Map interfaces, Type potentialClass)

Method Summary

Modifier and Type	Method and Description
boolean	equals(java.lang.Object o)
private java.util.Map	getAllMultiInterfaces(MultiType type)
Type	getComponent() Always returns null since this type is never used for an array.
CtClass	getCtClass() Gets the class that corresponds with this type.
int	getSize() Always returns 1, since this type is a reference.
private boolean	inMergeSource(MultiType source)
boolean	isArray() Always reutnrs false since this type is never used for an array
boolean	isAssignableFrom(Type type) Determines whether this type is assignable, to the passed type.
boolean	isAssignableTo(Type type)
boolean	isReference() Always returns true, since this type is always a reference.
Type	merge(Type type) Finds the common base type, or interface which both this and the specified type can be assigned.
private java.util.Map	mergeMultiAndSingle(MultiType multi, Type single)
private java.util.Map	mergeMultiInterfaces(MultiType type1, MultiType type2)
(package private) boolean	popChanged() Returns true if the internal state has changed.
private void	propogateResolved()
private void	propogateState()
java.lang.String	toString()

Methods inherited from class javassist.bytecode.analysis.Type

arrayName, eq, findCommonInterfaces, get, getAllInterfaces, getDeclaredInterfaces, getDimensions, getRootComponent, isSpecial

Methods inherited from class java.lang.Object

clone, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

interfaces

private java.util.Map interfaces

resolved

private Type resolved

potentialClass

private Type potentialClass

mergeSource

private MultiType mergeSource

changed

private boolean changed

Constructor Detail

MultiType

public MultiType(java.util.Map interfaces)

MultiType

public MultiType(java.util.Map interfaces,
                 Type potentialClass)

Method Detail

getCtClass

public CtClass getCtClass()

Gets the class that corresponds with this type. If this information is not yet known, java.lang.Object will be returned.

Overrides:

getCtClass in class Type

Returns:

the class for this type, or null if special

getComponent

public Type getComponent()

Always returns null since this type is never used for an array.

Overrides:

getComponent in class Type

Returns:

the array component if an array, otherwise null

getSize

public int getSize()

Always returns 1, since this type is a reference.

Overrides:

getSize in class Type

Returns:

the number of words needed to hold this type

isArray

public boolean isArray()

Always reutnrs false since this type is never used for an array

Overrides:

isArray in class Type

Returns:

true if an array, false if not

popChanged

boolean popChanged()

Returns true if the internal state has changed.

Overrides:

popChanged in class Type

isAssignableFrom

public boolean isAssignableFrom(Type type)

Description copied from class: Type

Determines whether this type is assignable, to the passed type. A type is assignable to another if it is either the same type, or a sub-type.

Overrides:

isAssignableFrom in class Type

Parameters:

type - the type to test assignability to

Returns:

true if this is assignable to type, otherwise false

isAssignableTo

public boolean isAssignableTo(Type type)

propogateState

private void propogateState()

propogateResolved

private void propogateResolved()

isReference

public boolean isReference()

Always returns true, since this type is always a reference.

Overrides:

isReference in class Type

Returns:

true

getAllMultiInterfaces

private java.util.Map getAllMultiInterfaces(MultiType type)

mergeMultiInterfaces

private java.util.Map mergeMultiInterfaces(MultiType type1,
                                           MultiType type2)

mergeMultiAndSingle

private java.util.Map mergeMultiAndSingle(MultiType multi,
                                          Type single)

inMergeSource

private boolean inMergeSource(MultiType source)

merge

public Type merge(Type type)

Description copied from class: Type

Finds the common base type, or interface which both this and the specified type can be assigned. If there is more than one possible answer, then a MultiType, or a MultiArrayType is returned. Multi-types have special rules, and successive merges and assignment tests on them will alter their internal state, as well as other multi-types they have been merged with. This method is used by the data-flow analyzer to merge the type state from multiple branches.

Overrides:

merge in class Type

Parameters:

type - the type to merge with

Returns:

the merged type

equals

public boolean equals(java.lang.Object o)

Overrides:

equals in class Type

toString

public java.lang.String toString()

Overrides:

toString in class Type