Method swap

src/org/apache/pig/impl/plan/OperatorPlan.java:1076–1220

Swap two operators in a plan. Both of the operators must have single inputs and single outputs. @param first operator @param second operator @throws PlanException if either operator is not single input and output.

(E first, E second)

     * @throws PlanException if either operator is not single input and output.
     */
    public void swap(E first, E second) throws PlanException {
        E firstNode = first;
        E secondNode = second;
        
        if(firstNode == null) {
            int errCode = 1092;
            String msg = "First operator in swap is null. Cannot swap null operators.";
            throw new PlanException(msg, errCode, PigException.INPUT);
        }
        
        if(secondNode == null) {
            int errCode = 1092;
            String msg = "Second operator in swap is null. Cannot swap null operators.";
            throw new PlanException(msg, errCode, PigException.INPUT);
        }
        
        checkInPlan(firstNode);
        checkInPlan(secondNode);
        
        List<E> firstNodePredecessors = (ArrayList<E>)mToEdges.get(firstNode);
        
        if(firstNodePredecessors != null && firstNodePredecessors.size() > 1) {
            int errCode = 1093;
            String msg = "Swap supports swap of operators with at most one input."
                            + " Found first operator with " + firstNodePredecessors.size() + " inputs.";
            throw new PlanException(msg, errCode, PigException.INPUT);
        }
        
        List<E> firstNodeSuccessors = (ArrayList<E>)mFromEdges.get(firstNode);
        
        if(firstNodeSuccessors != null && firstNodeSuccessors.size() > 1) {
            int errCode = 1093;
            String msg = "Swap supports swap of operators with at most one output."
                + " Found first operator with " + firstNodeSuccessors.size() + " outputs.";
            throw new PlanException(msg, errCode, PigException.INPUT);
        }
        
        List<E> secondNodePredecessors = (ArrayList<E>)mToEdges.get(secondNode);
        
        if(secondNodePredecessors != null && secondNodePredecessors.size() > 1) {
            int errCode = 1093;
            String msg = "Swap supports swap of operators with at most one input."
                + " Found second operator with " + secondNodePredecessors.size() + " inputs.";
            throw new PlanException(msg, errCode, PigException.INPUT);
        }
        
        List<E> secondNodeSuccessors = (ArrayList<E>)mFromEdges.get(secondNode);
        
        if(secondNodeSuccessors != null && secondNodeSuccessors.size() > 1) {
            int errCode = 1093;
            String msg = "Swap supports swap of operators with at most one output."
                + " Found second operator with " + secondNodeSuccessors.size() + " outputs.";
            throw new PlanException(msg, errCode, PigException.INPUT);
        }
        
        E firstNodePredecessor = null;
        E firstNodeSuccessor = null;
        E secondNodePredecessor = null;