jif.types.principal
Interface Principal

All Superinterfaces:

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

All Known Subinterfaces:

BottomPrincipal, ConjunctivePrincipal, DisjunctivePrincipal, DynamicPrincipal, ExternalPrincipal, ParamPrincipal, TopPrincipal, UnknownPrincipal, VarPrincipal

All Known Implementing Classes:

BottomPrincipal_c, ConjunctivePrincipal_c, DisjunctivePrincipal_c, DynamicPrincipal_c, ExternalPrincipal_c, ParamPrincipal_c, Principal_c, TopPrincipal_c, UnknownPrincipal_c, VarPrincipal_c

public interface Principal
extends Param

The root interface of all kinds of Jif principals.

Method Summary

boolean	hasVariables() Does the label contain any variables at all? This includes variables that are in bounds of arg labels.
boolean	isBottomPrincipal()
boolean	isTopPrincipal()
PathMap	labelCheck(JifContext A, LabelChecker lc) Label check the principal, which will determine how much information may be gained if the principal is evaluated at runtime.
Principal	simplify() Simplify the label, using the actsfor relation if needed
Principal	subst(LabelSubstitution labelSubst)
java.util.List	throwTypes(polyglot.types.TypeSystem ts) If the principal is runtime representable, when it is evaluated at runtime it may throw exceptions.
polyglot.ast.Expr	toJava(JifToJavaRewriter rw)
java.util.Set	variables() The set of variables that this label contains including variables contained in upper bounds of arg labels.

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

subst

Principal subst(LabelSubstitution labelSubst)
                throws polyglot.types.SemanticException

Parameters:

labelSubst - The LabelSubstitution to apply to this principal

Returns:

the result of applying labelSubst to this principal.

Throws:

polyglot.types.SemanticException

labelCheck

PathMap labelCheck(JifContext A,
                   LabelChecker lc)

Label check the principal, which will determine how much information may be gained if the principal is evaluated at runtime. For example, given the dynamic principal p, where p is a local variable, evaluation of this label at runtime will reveal as much information as the label of p. For example, the following code is illegal, as the runtime evaluation of the principal reveals too much information

 boolean{Alice:} secret = ...;
 final principal{Alice:} p = secret?Bob:Chuck;
 boolean{} leak = false;
 if (p actsfor Bob) { // evaluation of p reveals
                      // information at level {Alice:}
     leak = true;
        } 
 

See Also:

Jif.labelCheck(LabelChecker), Label.labelCheck(JifContext, LabelChecker)

toJava

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

Throws:

polyglot.types.SemanticException

throwTypes

java.util.List throwTypes(polyglot.types.TypeSystem ts)

If the principal is runtime representable, when it is evaluated at runtime it may throw exceptions. This method returns a list of the exceptions that the runtime evaluation of the principal may produce. If the principal cannot be evaluated at runtime, an empty list should be returned.

hasVariables

boolean hasVariables()

Does the label contain any variables at all? This includes variables that are in bounds of arg labels.

variables

java.util.Set variables()

The set of variables that this label contains including variables contained in upper bounds of arg labels.

isTopPrincipal

boolean isTopPrincipal()

isBottomPrincipal

boolean isBottomPrincipal()

simplify

Principal simplify()

Simplify the label, using the actsfor relation if needed