Examples with ArithExpr com.microsoft.z3.ArithExpr used on opensource projects

Example 11 with ArithExpr

use of com.microsoft.z3.ArithExpr in project batfish by batfish.

the class CounterExample method buildFailedLinks.

SortedSet<Edge> buildFailedLinks(Encoder enc) {
    Set<GraphEdge> failed = new HashSet<>();
    Graph g = enc.getMainSlice().getGraph();
    for (List<GraphEdge> edges : g.getEdgeMap().values()) {
        for (GraphEdge ge : edges) {
            ArithExpr e = enc.getSymbolicFailures().getFailedVariable(ge);
            assert e != null;
            if (intVal(e) != 0) {
                // Don't add both directions?
                GraphEdge other = g.getOtherEnd().get(ge);
                if (other == null || !failed.contains(other)) {
                    failed.add(ge);
                }
            }
        }
    }
    // Convert to Batfish Edge type
    SortedSet<Edge> failedEdges = new TreeSet<>();
    for (GraphEdge ge : failed) {
        failedEdges.add(fromGraphEdge(ge));
    }
    return failedEdges;
}

Example 12 with ArithExpr

use of com.microsoft.z3.ArithExpr in project batfish by batfish.

the class PropertyChecker method checkBoundedLength.

/*
   * Compute whether the path length will always be bounded by a constant k
   * for a collection of source routers to any of a number of destination ports.
   */
public AnswerElement checkBoundedLength(HeaderLocationQuestion q, int k) {
    return checkProperty(q, (enc, srcRouters, destPorts) -> {
        ArithExpr bound = enc.mkInt(k);
        PropertyAdder pa = new PropertyAdder(enc.getMainSlice());
        Map<String, ArithExpr> lenVars = pa.instrumentPathLength(destPorts);
        Map<String, BoolExpr> boundVars = new HashMap<>();
        lenVars.forEach((n, ae) -> boundVars.put(n, enc.mkLe(ae, bound)));
        return boundVars;
    }, (vp) -> new SmtOneAnswerElement(vp.getResult()));
}

Example 13 with ArithExpr

use of com.microsoft.z3.ArithExpr in project batfish by batfish.

the class TransferSSA method computeIntermediatePrefixLen.

/*
   * Create a new variable representing the new prefix length after
   * applying the effect of aggregation.
   */
private void computeIntermediatePrefixLen(TransferParam<SymbolicRoute> param) {
    ArithExpr prefixLen = param.getData().getPrefixLength();
    if (_isExport && _proto.isBgp()) {
        _aggregates = aggregateRoutes();
        if (_aggregates.size() > 0) {
            for (Map.Entry<Prefix, Boolean> entry : _aggregates.entrySet()) {
                Prefix p = entry.getKey();
                Boolean isSuppressed = entry.getValue();
                ArithExpr len = _enc.mkInt(p.getPrefixLength());
                BoolExpr relevantPfx = _enc.isRelevantFor(p, _enc.getSymbolicPacket().getDstIp());
                BoolExpr relevantLen = _enc.mkGt(param.getData().getPrefixLength(), len);
                BoolExpr relevant = _enc.mkAnd(relevantPfx, relevantLen, _enc.mkBool(isSuppressed));
                prefixLen = _enc.mkIf(relevant, len, prefixLen);
            }
            ArithExpr i = createArithVariableWith(param, "PREFIX-LEN", prefixLen);
            param.getData().setPrefixLength(i);
        }
    }
}

Example 14 with ArithExpr

use of com.microsoft.z3.ArithExpr in project batfish by batfish.

the class TransferSSA method applyMetricUpdate.

private void applyMetricUpdate(TransferParam<SymbolicRoute> p) {
    boolean updateOspf = (!_isExport && _proto.isOspf());
    boolean updateBgp = (_isExport && _proto.isBgp());
    boolean updateMetric = updateOspf || updateBgp;
    if (updateMetric) {
        // If it is a BGP route learned from IGP, then we use metric 0
        ArithExpr newValue;
        ArithExpr cost = _enc.mkInt(_addedCost);
        ArithExpr sum = _enc.mkSum(p.getData().getMetric(), cost);
        if (_proto.isBgp()) {
            BoolExpr isBGP;
            String router = _conf.getName();
            boolean hasProtocolVar = _other.getProtocolHistory() != null;
            boolean onlyBGP = _enc.getOptimizations().getSliceHasSingleProtocol().contains(router);
            if (hasProtocolVar) {
                isBGP = _other.getProtocolHistory().checkIfValue(Protocol.BGP);
            } else if (onlyBGP) {
                isBGP = _enc.mkTrue();
            } else {
                isBGP = _enc.mkFalse();
            }
            newValue = _enc.mkIf(isBGP, sum, cost);
        } else {
            newValue = sum;
        }
        p.getData().setMetric(newValue);
    }
}

Example 15 with ArithExpr

use of com.microsoft.z3.ArithExpr in project batfish by batfish.

the class TransferSSA method createArithVariableWith.

/*
   * A collection of functions to create new SSA variables on-the-fly,
   * while also simultaneously setting their value based on an old value.
   */
private ArithExpr createArithVariableWith(TransferParam<SymbolicRoute> p, String name, ArithExpr e) {
    e = (ArithExpr) e.simplify();
    if (canInline(e)) {
        p.debug(name + "=" + e);
        return e;
    }
    String s = "SSA_" + name + generateId();
    ArithExpr x = _enc.getCtx().mkIntConst(s);
    // _enc.getAllVariables().add(x);
    BoolExpr eq = _enc.mkEq(x, e);
    _enc.add(eq);
    p.debug(eq.toString());
    return x;
}