/**
* Copyright (c) 2013 ReBAC Java Library
*
* Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated
* documentation files (the "Software"), to deal in the Software without restriction, including without limitation the
* rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit
* persons to whom the Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all copies or substantial portions of the
* Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
* WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
* COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
* OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
package ca.ucalgary.ispia.rebac.util;
import java.util.HashSet;
import java.util.Set;
import ca.ucalgary.ispia.rebac.Direction;
import ca.ucalgary.ispia.rebac.Policy;
import ca.ucalgary.ispia.rebac.impl.AtImpl;
import ca.ucalgary.ispia.rebac.impl.BindImpl;
import ca.ucalgary.ispia.rebac.impl.BoxImpl;
import ca.ucalgary.ispia.rebac.impl.ConjunctionImpl;
import ca.ucalgary.ispia.rebac.impl.DiamondImpl;
import ca.ucalgary.ispia.rebac.impl.DisjunctionImpl;
import ca.ucalgary.ispia.rebac.impl.FalseImpl;
import ca.ucalgary.ispia.rebac.impl.NegationImpl;
import ca.ucalgary.ispia.rebac.impl.RequestorImpl;
import ca.ucalgary.ispia.rebac.impl.ResourceImpl;
import ca.ucalgary.ispia.rebac.impl.TrueImpl;
import ca.ucalgary.ispia.rebac.impl.VariableImpl;
import ca.ucalgary.ispia.rebac.impl.OwnerImpl;
import ca.ucalgary.ispia.rebac.At;
import ca.ucalgary.ispia.rebac.Bind;
import ca.ucalgary.ispia.rebac.Box;
import ca.ucalgary.ispia.rebac.Conjunction;
import ca.ucalgary.ispia.rebac.Diamond;
import ca.ucalgary.ispia.rebac.Disjunction;
import ca.ucalgary.ispia.rebac.False;
import ca.ucalgary.ispia.rebac.Negation;
import ca.ucalgary.ispia.rebac.Requestor;
import ca.ucalgary.ispia.rebac.True;
import ca.ucalgary.ispia.rebac.Variable;
import ca.ucalgary.ispia.rebac.Owner;
import ca.ucalgary.ispia.rebac.util.Constants;
/**
* @author Syed Zain Rizvi
* @author Mona Hosseinkhani
*/
/**
* Offers utility methods for Policies
*/
public class PolicyUtil {
/**
* Consumes a policy and translates it to a policy only composed of primitive
* operators. NOTE: If the given policy is already only composed of primitive
* operators, it is returned as is.
* Primitive Operators: {@link Variable}, {@link Diamond}, {@link Conjunction},
* {@link Negation}, {@link True} , {@link False}, {@link At} and {@link Bind}
* @param tPolicy The policy to be translated.
* @return A policy composed of only primitive operators.
*/
public static Policy translate(Policy tPolicy){
Policy translatedPolicy;
if (tPolicy instanceof VariableImpl){
//Already primitive.
translatedPolicy = tPolicy;
}
else if (tPolicy instanceof OwnerImpl){
//Translate the Owner variant to a variable
translatedPolicy = new VariableImpl(Constants.owner);
}
else if (tPolicy instanceof RequestorImpl){
//Translate the Requestor variant to a variable
translatedPolicy = new VariableImpl(Constants.requestor);
}
else if (tPolicy instanceof ResourceImpl){
//Translate the Resource variant to ta variable
translatedPolicy = new VariableImpl(Constants.resource);
}
else if (tPolicy == FalseImpl.getInstance()){
// Already primitive
translatedPolicy = tPolicy;
}
else if (tPolicy ==TrueImpl.getInstance()){
// Already primitive
translatedPolicy = tPolicy;
}
else if(tPolicy instanceof NegationImpl){
// Already primitive. Recurse on contained policy.
NegationImpl temp = (NegationImpl) tPolicy;
// Get contained fields
Policy tempA = temp.getPolicy();
// Translate contained policy
tempA = translate(tempA);
// Create translated policy
translatedPolicy = new NegationImpl (tempA);
}
else if (tPolicy instanceof ConjunctionImpl){
// Already primitive. Recurse on contained policies.
ConjunctionImpl temp = (ConjunctionImpl) tPolicy;
// Get contained fields
Policy tempA = temp.getPolicyA();
Policy tempB = temp.getPolicyB();
// Translate contained fields
tempA = translate(tempA);
tempB = translate(tempB);
// Create translated policy
translatedPolicy = new ConjunctionImpl(tempA, tempB);
}
else if (tPolicy instanceof DisjunctionImpl){
// Disjunction(policyA, policyB) =
// Negation(Conjunction((Negation(policyA)), (Negation(policyB))))
DisjunctionImpl temp = (DisjunctionImpl) tPolicy;
// Get contained fields
Policy tempA = temp.getPolicyA();
Policy tempB = temp.getPolicyB();
// Translate contained policies
tempA = new NegationImpl (translate(tempA));
tempB = new NegationImpl (translate(tempB));
// Create translated policy
Policy tempC = new ConjunctionImpl(tempA, tempB);
translatedPolicy = new NegationImpl (tempC);
}
else if (tPolicy instanceof BoxImpl){
// Box(policy) = Negation(Diamond(Negation(policy)))
BoxImpl temp = (BoxImpl) tPolicy;
// Get contained fields
Policy tempA = temp.getPolicy();
Object relationID = temp.getRelationIdentifier();
Direction direction = temp.getDirection();
// Translate contained policy
tempA = new NegationImpl (translate(tempA));
// Create translated policy
Policy tempB = new DiamondImpl(tempA, relationID, direction);
translatedPolicy = new NegationImpl (tempB);
}
else if (tPolicy instanceof DiamondImpl){
// Already primitive. Recurse on contained policy.
DiamondImpl temp = (DiamondImpl) tPolicy;
// Get contained fields
Policy tempA = temp.getPolicy();
Object relationID = temp.getRelationIdentifier();
Direction direction = temp.getDirection();
// Translate contained policy
tempA = translate(tempA);
// Create translated policy
translatedPolicy = new DiamondImpl(tempA, relationID, direction);
}
else if (tPolicy instanceof BindImpl){
//Already primitive. Recurse on contained policy
BindImpl temp= (BindImpl) tPolicy;
Policy tempA = temp.getPolicy();
Object var = temp.getVariable();
//translate contained policy
tempA=translate(tempA);
// Create translated policy
translatedPolicy = new BindImpl(var, tempA);
}
else if (tPolicy instanceof AtImpl){
//Already primitive. Recurse on contained policy
AtImpl temp = (AtImpl) tPolicy;
Policy tempA = temp.getPolicy();
Object var = temp.getVariable();
//translate contained policy
tempA=translate(tempA);
// Create translated policy
translatedPolicy = new AtImpl(var, tempA);
}
else {
// Else (not a supported policy variant), throw exception
throw new IllegalArgumentException("The given policy is not supported by the Translate method: " + tPolicy);
}
return translatedPolicy;
}
@SuppressWarnings({ "rawtypes", "unchecked" })
public static Set findFreeVars(Policy policy, Set free_vars){
if (policy instanceof Variable) {
Variable temp = (Variable) policy;
free_vars.add(temp.getVariable());
}
else if (policy instanceof False){
//nothing added
}
else if (policy instanceof True){
//nothing added
}
else if (policy instanceof Requestor){
//noting added
}
else if (policy instanceof Owner){
//nothing added
}
else if(policy instanceof Negation){
Negation temp = (Negation) policy;
findFreeVars(temp.getPolicy(), free_vars);
}
else if (policy instanceof Conjunction){
Conjunction temp = (Conjunction) policy;
Set temp_setA = findFreeVars(temp.getPolicyA(), new HashSet<Object>());
Set temp_setB = findFreeVars(temp.getPolicyB(), new HashSet<Object>());
free_vars.addAll(temp_setA);
free_vars.addAll(temp_setB);
}
else if (policy instanceof Disjunction){
Disjunction temp = (Disjunction) policy;
Set temp_setA = findFreeVars(temp.getPolicyA(), new HashSet<Object>());
Set temp_setB = findFreeVars(temp.getPolicyB(), new HashSet<Object>());
free_vars.addAll(temp_setA);
free_vars.addAll(temp_setB);
}
else if (policy instanceof Box){
Box temp = (Box) policy;
findFreeVars(temp.getPolicy(), free_vars);
}
else if (policy instanceof Diamond){
Diamond temp = (Diamond) policy;
free_vars = findFreeVars(temp.getPolicy(), free_vars);
}
else if (policy instanceof Bind){
Bind temp = (Bind) policy;
findFreeVars(temp.getPolicy(), free_vars);
free_vars.remove(temp.getVariable());
}
else if (policy instanceof At){
At temp = (At) policy;
findFreeVars(temp.getPolicy(), free_vars);
free_vars.add(temp.getVariable());
}
return free_vars;
}
}