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; }
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; }