Method doInsertBetween

src/org/apache/pig/impl/plan/OperatorPlan.java:586–614

(
            E after,
            E newNode,
            E before,
            boolean rewire)

     * rewiring operation.
     */
    public void doInsertBetween(
            E after,
            E newNode,
            E before,
            boolean rewire) throws PlanException {
        checkInPlan(newNode);
        List<E> newNodePreds = getPredecessors(newNode);
        //assuming that the newNode has zero or one predecessor
        E newNodePred = (newNodePreds == null? null: newNodePreds.get(0));
        if (!replaceNode(after, newNode, before, mFromEdges) || !replaceNode(before, newNode, after, mToEdges)) {
            int errCode = 1094;
            String msg = "Attempt to insert between two nodes " +
            "that were not connected.";
            PlanException pe = new PlanException(msg, errCode, PigException.INPUT);
            throw pe;
        }
        mFromEdges.put(newNode, before);
        mToEdges.put(newNode, after);

        if(rewire) {
            if((newNodePred != null) && !(newNodePred.equals(after))) {
                newNodePred.regenerateProjectionMap();
                newNode.rewire(newNodePred, 0, after, true);
            }
            newNode.regenerateProjectionMap();
            IndexHelper<E> indexHelper = new IndexHelper<E>(getPredecessors(newNode));
            before.rewire(after, indexHelper.getIndex(after), newNode, false);
        }
    }

    // replaces (src -> dst) entry in multiMap with (src -> replacement)
    private boolean replaceNode(E src, E replacement, E dst, MultiMap<E, E> multiMap) {