protected Node checkReachability(Term n) throws SemanticException {
FlowGraph g = currentFlowGraph();
if (g != null) {
Collection peers = g.peers(n);
if (peers != null && !peers.isEmpty()) {
boolean isInitializer = (n instanceof Initializer);
for (Iterator iter = peers.iterator(); iter.hasNext(); ) {
FlowGraph.Peer p = (FlowGraph.Peer) iter.next();
// the peer is reachable if at least one of its out items
// is reachable. This would cover all cases, except that some
// peers may have no successors (e.g. peers that throw an
// an exception that is not caught by the method). So we need
// to also check the inItem.
if (p.inItem() != null) {
DataFlowItem dfi = (DataFlowItem) p.inItem();
// there will only be one peer for an initializer,
// as it cannot occur in a finally block.
if (isInitializer && !dfi.normalReachable) {
throw new SemanticException(
"Initializers must be able to complete normally.", n.position());
}
if (dfi.reachable) {
return n.reachable(true);
}
}
if (p.outItems != null) {
for (Iterator k = p.outItems.values().iterator(); k.hasNext(); ) {
DataFlowItem item = (DataFlowItem) k.next();
if (item != null && item.reachable) {
// n is reachable.
return n.reachable(true);
}
}
}
}
// if we fall through to here, then no peer for n was reachable.
n = n.reachable(false);
// Compound statements are allowed to be unreachable
// (e.g., "{ // return; }" or "while (true) S"). If a compound
// statement is truly unreachable, one of its sub-statements will
// be also and we will report an error there.
if ((n instanceof Block && ((Block) n).statements().isEmpty())
|| (n instanceof Stmt && !(n instanceof CompoundStmt))) {
throw new SemanticException("Unreachable statement.", n.position());
}
}
}
return n;
}
public Item createInitialItem(FlowGraph graph, Term node, boolean entry) {
if (node == graph.root() && entry) {
return DataFlowItem.REACHABLE;
} else {
return DataFlowItem.NOT_REACHABLE;
}
}
public Item createInitialItem(FlowGraph graph, Term node) {
if (node == graph.entryNode()) {
return DataFlowItem.REACHABLE;
} else {
return DataFlowItem.NOT_REACHABLE;
}
}
protected Node checkReachability(Term n) {
FlowGraph g = currentFlowGraph();
if (g != null) {
Collection<FlowGraph.Peer> peers = g.peers(n, Term.EXIT);
if (peers != null && !peers.isEmpty()) {
boolean isInitializer = (n instanceof Initializer);
for (FlowGraph.Peer p : peers) {
// the peer is reachable if at least one of its out items
// is reachable. This would cover all cases, except that some
// peers may have no successors (e.g. peers that throw an
// an exception that is not caught by the method). So we need
// to also check the inItem.
if (p.inItem() != null) {
DataFlowItem dfi = (DataFlowItem) p.inItem();
// there will only be one peer for an initializer,
// as it cannot occur in a finally block.
if (isInitializer && !dfi.normalReachable) {
reportError(new Errors.InitializersMustCompleteNormally(n.position()));
}
if (dfi.reachable) {
return n.reachable(true);
}
}
if (p.outItems != null) {
for (Item v : p.outItems.values()) {
DataFlowItem item = (DataFlowItem) v;
if (item != null && item.reachable) {
// n is reachable.
return n.reachable(true);
}
}
}
}
// if we fall through to here, then no peer for n was reachable.
n = n.reachable(false);
}
}
return n;
}
/**
* Check that the conditions of initialization are not broken.
*
* <p>To summarize the conditions: - Local variables must be initialized before use, (i.e. min
* count > 0) - Final local variables (including Formals) cannot be assigned to more than once
* (i.e. max count <= 1) - Final non-static fields whose target is this cannot be assigned to more
* than once - Final static fields whose target is the current class cannot be assigned to more
* than once
*
* <p>This method is also responsible for maintaining state between the dataflows over
* Initializers, by copying back the appropriate MinMaxInitCounts to the map
* currClassFinalFieldInitCounts.
*/
public void check(FlowGraph graph, Term n, Item inItem, Map outItems) throws SemanticException {
DataFlowItem dfIn = (DataFlowItem) inItem;
if (dfIn == null) {
// There is no input data flow item. This can happen if we are
// checking an unreachable term, and so no Items have flowed
// through the term. For example, in the code fragment:
// a: do { break a; } while (++i < 10);
// the expression "++i < 10" is unreachable, but the as there is
// no unreachable statement, the Java Language Spec permits it.
// Set inItem to a default Item
dfIn = createInitDFI();
}
DataFlowItem dfOut = null;
if (outItems != null && !outItems.isEmpty()) {
// due to the flow equations, all DataFlowItems in the outItems map
// are the same, so just take the first one.
dfOut = (DataFlowItem) outItems.values().iterator().next();
}
if (n instanceof Local) {
checkLocal(graph, (Local) n, dfIn, dfOut);
} else if (n instanceof LocalAssign) {
checkLocalAssign(graph, (LocalAssign) n, dfIn, dfOut);
} else if (n instanceof FieldAssign) {
checkFieldAssign(graph, (FieldAssign) n, dfIn, dfOut);
} else if (n instanceof ClassBody) {
// we need to check that the locals used inside this class body
// have all been defined at this point.
Set localsUsed = (Set) currCBI.localsUsedInClassBodies.get(n);
if (localsUsed != null) {
checkLocalsUsedByInnerClass(graph, (ClassBody) n, localsUsed, dfIn, dfOut);
}
}
if (n == graph.finishNode()) {
if (currCBI.currCodeDecl instanceof Initializer) {
finishInitializer(graph, (Initializer) currCBI.currCodeDecl, dfIn, dfOut);
}
if (currCBI.currCodeDecl instanceof ConstructorDecl) {
finishConstructorDecl(graph, (ConstructorDecl) currCBI.currCodeDecl, dfIn, dfOut);
}
}
}
/**
* The initial item to be given to the entry point of the dataflow contains the init counts for
* the final fields.
*/
public Item createInitialItem(FlowGraph graph, Term node) {
if (node == graph.startNode()) {
return createInitDFI();
}
return BOTTOM;
}