jif.types
Class PrincipalConstraint

java.lang.Object
  jif.types.Constraint
      jif.types.PrincipalConstraint

public class PrincipalConstraint
extends Constraint

A PrincipalConstraint represents a constraint on principals, which may either be an actsfor or an equivalence constraint. PrincipalConstraints are generated during type checking and label checking. PrincipalConstraints in turn produce Equations which are what the Solver will use to find a satisfying assignment for Variables.

Nested Class Summary

Nested classes/interfaces inherited from class jif.types.Constraint

Constraint.Kind

Field Summary

static Constraint.Kind	ACTSFOR An actsfor kind of constraint.
static Constraint.Kind	EQUIV An equivalence kind of constraint.

Fields inherited from class jif.types.Constraint

env, kind, lhs, messages, pos, report, rhs

Constructor Summary

PrincipalConstraint(Principal lhs, Constraint.Kind kind, Principal rhs, LabelEnv env, polyglot.util.Position pos, ConstraintMessage msg, boolean report)

Method Summary

protected void	addActsforEqns(java.util.Collection eqns, Principal left, Principal right) Produce equations that require left to act for right, and add them to eqns.
java.util.Collection	getEquations() Produce a Collection of Equations for this constraint.
boolean	hasVariables()
Principal	lhsPrincipal()
Principal	rhsPrincipal()

Methods inherited from class jif.types.Constraint

detailMsg, env, isCanonical, kind, messages, msg, position, report, technicalMsg, toString

Methods inherited from class java.lang.Object

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

Field Detail

EQUIV

public static final Constraint.Kind EQUIV

An equivalence kind of constraint. That is, the constraint requires that lhs actsfor rhs and rhs actsfor lhs.

ACTSFOR

public static final Constraint.Kind ACTSFOR

An actsfor kind of constraint. That is, the constraint requires that lhs actsfor rhs.

Constructor Detail

PrincipalConstraint

public PrincipalConstraint(Principal lhs,
                           Constraint.Kind kind,
                           Principal rhs,
                           LabelEnv env,
                           polyglot.util.Position pos,
                           ConstraintMessage msg,
                           boolean report)

Method Detail

lhsPrincipal

public Principal lhsPrincipal()

rhsPrincipal

public Principal rhsPrincipal()

getEquations

public java.util.Collection getEquations()

Produce a Collection of Equations for this constraint.

Specified by:

getEquations in class Constraint

addActsforEqns

protected void addActsforEqns(java.util.Collection eqns,
                              Principal left,
                              Principal right)

Produce equations that require left to act for right, and add them to eqns.

hasVariables

public boolean hasVariables()

Specified by:

hasVariables in class Constraint