/** Model check a P operator. */ private Result checkExpressionProb(ExpressionProb expr) throws PrismException { boolean min; ExpressionTemporal exprTemp; Expression exprTarget; BitSet targetLocs; int timeBound; boolean timeBoundStrict; double prob; // Check whether Pmin=? or Pmax=? (only two cases allowed) if (expr.getProb() != null) { throw new PrismException( "PTA model checking currently only supports Pmin=? and Pmax=? properties (try the digital clocks engine instead)"); } min = expr.getRelOp().equals("min="); // Check this is a F path property (only case allowed at the moment) if (!(expr.getExpression() instanceof ExpressionTemporal)) throw new PrismException( "PTA model checking currently only supports the F path operator (try the digital clocks engine instead)"); exprTemp = (ExpressionTemporal) expr.getExpression(); if (exprTemp.getOperator() != ExpressionTemporal.P_F || !exprTemp.isSimplePathFormula()) throw new PrismException( "PTA model checking currently only supports the F path operator (try the digital clocks engine instead)"); // Determine locations satisfying target exprTarget = exprTemp.getOperand2(); targetLocs = checkLocationExpression(exprTarget); mainLog.println( "Target (" + exprTarget + ") satisfied by " + targetLocs.cardinality() + " locations."); // mainLog.println(targetLocs); // If there is a time bound, add a clock and encode this into target if (exprTemp.hasBounds()) { mainLog.println("Modifying PTA to encode time bound from property..."); // Get time bound info (is always of form <=T or <T) timeBound = exprTemp.getUpperBound().evaluateInt(constantValues); timeBoundStrict = exprTemp.upperBoundIsStrict(); // Modify PTA to include time bound; get new target targetLocs = buildTimeBoundIntoPta(pta, targetLocs, timeBound, timeBoundStrict); mainLog.println("New PTA: " + pta.infoString()); } // Compute probability of reaching the set of target locations prob = computeProbabilisticReachability(targetLocs, min); // Return result return new Result(new Double(prob)); }
/** Model check a property. */ public Result check(Expression expr) throws PrismException { Modules2PTA m2pta; Result res; String resultString; long timer; // Starting model checking timer = System.currentTimeMillis(); // Check for system...endsystem - not supported yet if (modulesFile.getSystemDefn() != null) { throw new PrismException( "The system...endsystem construct is not supported yet (try the digital clocks engine instead)"); } // Translate ModulesFile object into a PTA object mainLog.println("\nBuilding PTA..."); m2pta = new Modules2PTA(prism, modulesFile); pta = m2pta.translate(); mainLog.println("\nPTA: " + pta.infoString()); // Check for references to clocks - not allowed (yet) // (do this before modifications below for better error reporting) expr.accept( new ASTTraverseModify() { public Object visit(ExpressionVar e) throws PrismLangException { if (e.getType() instanceof TypeClock) { throw new PrismLangException( "Properties cannot contain references to clocks (try the digital clocks engine instead)", e); } else { return e; } } }); // Take a copy of property, since will modify expr = expr.deepCopy(); // Remove property refs ands labels from property expr = (Expression) expr.expandPropRefsAndLabels(propertiesFile, labelList); // Evaluate constants in property (easier to do now) expr = (Expression) expr.replaceConstants(constantValues); // Also simplify expression to optimise model checking expr = (Expression) expr.simplify(); // Do model checking res = checkExpression(expr); // Model checking complete timer = System.currentTimeMillis() - timer; mainLog.println("\nModel checking completed in " + (timer / 1000.0) + " secs."); // Print result to log resultString = "Result"; if (!("Result".equals(expr.getResultName()))) resultString += " (" + expr.getResultName().toLowerCase() + ")"; resultString += ": " + res; mainLog.print("\n" + resultString + "\n"); // Return result return res; }