jif.types
Interface Label

All Superinterfaces:

java.lang.Cloneable, polyglot.util.Copy, Param, java.io.Serializable, polyglot.types.TypeObject

All Known Subinterfaces:

ArgLabel, CovariantLabel, DynamicArgLabel, DynamicLabel, DynrecLabel, JoinLabel, LabelOfVar, MeetLabel, NotTaken, ParamLabel, PolicyLabel, RuntimeLabel, TopLabel, UnknownLabel, VarLabel

All Known Implementing Classes:

ArgLabel_c, CovariantLabel_c, DynamicArgLabel_c, DynamicLabel_c, DynrecLabel_c, JoinLabel_c, Label_c, LabelOfVar_c, MeetLabel_c, NotTaken_c, ParamLabel_c, PolicyLabel_c, RuntimeLabel_c, TopLabel_c, UnknownLabel_c, VarLabel_c

public interface Label

extends Param

This class represents the Jif security label.

Method Summary

Label	bound(VarMap ub, java.util.Set visited) Gets the upper bound of this label.
java.util.Collection	components() Retrieve the collection of components.
java.lang.String	componentString()
java.lang.String	description()
Label	description(java.lang.String d)
Label	fold(UID uid) Substitutes any occurences of for .
boolean	hasVariables() Does this label (or any of its components) contain any label variables?
boolean	isBottom() Is this label equivalent to bottom?
boolean	isComparable() Is this label comparable to other labels?
boolean	isCovariant() Is this label covariant?
boolean	isEnumerable() Are the components of this label enumerable?
boolean	isInvariant() Is this label invariant?
boolean	isMeetable() Can this label be used in a meet operation with another label?
boolean	isSingleton() Does this label represent only a single label?
boolean	isTop() Is this label equivalent to top?
Label	join(Label L) Returns the join of this label and L.
Label	join(Label L, PrincipalHierarchy ph) Returns the join of this label and L, and simplifies it, based on the given PrincipalHierarchy
Label	labelOf() Gets labelOf this label.
boolean	leq_(Label L)
boolean	leq_(Label L, LabelEnv env) Implementation of leq, should only be called by JifTypeSystem
Label	meet_(Label L, PrincipalHierarchy ph) Implementation of the meet operation, should only be called by JifTypeSystem
Label	meet(Label L) Returns the meet of this label and L.
Label	meet(Label L, PrincipalHierarchy ph) Returns the meet of this label and L, and simplifies it, based on the given PrincipalHierarchy
Label	minus(Label L) Returns a copy of this Label, with the Label L removed from the components.
Label	simplify() Returns a simplified copy of this Label.
Label	singletonComponent() Retrieve the singleton component that this label represents.
Label	subst(LabelSubstitution substitution) Accepts a LabelSubstitution and returns the result of substituting according to the given LabelSubstitution.
Label	subst(UID uid, Label L) Substitutes any occurences of for L.
polyglot.ast.Expr	toJava(JifToJavaRewriter rw)
void	translate(polyglot.types.Resolver c, polyglot.util.CodeWriter w)
java.util.Collection	variables() The collection of variables contained by this label (or any of its components).

Methods inherited from interface jif.types.Param

isCanonical, isRuntimeRepresentable

Methods inherited from interface polyglot.types.TypeObject

equalsImpl, position, typeSystem

Methods inherited from interface polyglot.util.Copy

copy

Method Detail

bound

public Label bound(VarMap ub,
                   java.util.Set visited)

Gets the upper bound of this label.

Parameters:

ub - the upper bound map for variable labels

visited - the set of UIDs visited. if the upper bound is <dynamic uid...>,

• if uid is contained in visited, will be returned;
• otherwise, uid is added into visited.

isBottom

public boolean isBottom()

Is this label equivalent to bottom?

For example, a JoinLabel with no components would return true for this method.

isTop

public boolean isTop()

Is this label equivalent to top?

For example, a JoinLabel with two components, one of which is Top, would return true for this method.

isEnumerable

public boolean isEnumerable()

Are the components of this label enumerable?

For example, Singletons are enumerable, JoinLabels are enumerable, RuntimeLabel (the label of all runtime representable components) is not enumerable. NOTE: The components of a label are not neccessarily stuck together with a join operation. For example, the MeetLabel uses the meet operation between its components.

components

public java.util.Collection components()

Retrieve the collection of components. This method should only be called if isEnumerable returns true. This collection should not be modified.

isSingleton

public boolean isSingleton()

Does this label represent only a single label?

For example, a JoinLabel with more than one component returns false, a MeetLabel with more than one component returns false, most other Labels return true.

singletonComponent

public Label singletonComponent()

Retrieve the singleton component that this label represents. Should only be called is isSingleton returns true.

isInvariant

public boolean isInvariant()

Is this label invariant?

isCovariant

public boolean isCovariant()

Is this label covariant?

hasVariables

public boolean hasVariables()

Does this label (or any of its components) contain any label variables?

variables

public java.util.Collection variables()

The collection of variables contained by this label (or any of its components).

subst

public Label subst(LabelSubstitution substitution)

Accepts a LabelSubstitution and returns the result of substituting according to the given LabelSubstitution.

Parameters:

substitution - the LabelSubstitution to use

Returns:

the result of the substitution

labelOf

public Label labelOf()

Gets labelOf this label. Refer to Andrew's thesis, Figure 5.4

subst

public Label subst(UID uid,
                   Label L)

Substitutes any occurences of for L. Refer to Andrew's thesis, Figure 5.5

fold

public Label fold(UID uid)

Substitutes any occurences of for .

join

public Label join(Label L)

Returns the join of this label and L.

join

public Label join(Label L,
                  PrincipalHierarchy ph)

Returns the join of this label and L, and simplifies it, based on the given PrincipalHierarchy

isMeetable

public boolean isMeetable()

Can this label be used in a meet operation with another label?

For example, UnknownLabel returns false. Most other Labels return true.

meet

public Label meet(Label L)

Returns the meet of this label and L.

meet

public Label meet(Label L,
                  PrincipalHierarchy ph)

Returns the meet of this label and L, and simplifies it, based on the given PrincipalHierarchy

minus

public Label minus(Label L)

Returns a copy of this Label, with the Label L removed from the components.

Throws:

InternalCompilerError - if Label L is not a component of this label

simplify

public Label simplify()

Returns a simplified copy of this Label.

isComparable

public boolean isComparable()

Is this label comparable to other labels?

For example, an UnknownLabel is not comparable to others, neither is a VarLabel. Most other labels are.

translate

public void translate(polyglot.types.Resolver c,
                      polyglot.util.CodeWriter w)

meet_

public Label meet_(Label L,
                   PrincipalHierarchy ph)

Implementation of the meet operation, should only be called by JifTypeSystem

Parameters:

L - label to meet with.

ph - the principal hierarchy in which to perform the meet. This param may be null, in which case perform all meets possible that are indpependent of the principal hierarchy.

leq_

public boolean leq_(Label L,
                    LabelEnv env)

Implementation of leq, should only be called by JifTypeSystem

Parameters:

L - the label to determine if this label is leq to.

leq_

public boolean leq_(Label L)

componentString

public java.lang.String componentString()

description

public java.lang.String description()

description

public Label description(java.lang.String d)

toJava

public polyglot.ast.Expr toJava(JifToJavaRewriter rw)
                         throws polyglot.types.SemanticException

polyglot.types.SemanticException