package org.mit.jstreamit;

import java.util.ArrayList;
import java.util.List;

/**
 * A PrimitiveWorker encapsulates a primitive worker in the stream graph (a
 * Filter, Splitter or Joiner) and manages its connections to other workers in
 * support of the interpreter.
 * @author Jeffrey Bosboom <jeffreybosboom@gmail.com>
 * @since 11/19/2012
 */
/* package private */ abstract class PrimitiveWorker<I, O> {
	private List<PrimitiveWorker<?, ? extends I>> predecessors = new ArrayList<>(1);
	private List<PrimitiveWorker<? super O, ?>> successors = new ArrayList<>(1);
	private List<Channel<? extends I>> inputChannels = new ArrayList<>(1);
	private List<Channel<? super O>> outputChannels = new ArrayList<>(1);

	void addPredecessor(PrimitiveWorker<?, ? extends I> predecessor, Channel<? extends I> channel) {
		predecessors.add(predecessor);
		inputChannels.add(channel);
	}
	void addSuccessor(PrimitiveWorker<? super O, ?> successor, Channel<? super O> channel) {
		successors.add(successor);
		outputChannels.add(channel);
	}

	List<PrimitiveWorker<?, ? extends I>> getPredecessors() {
		return predecessors;
	}

	List<PrimitiveWorker<? super O, ?>> getSuccessors() {
		return successors;
	}

	List<Channel<? extends I>> getInputChannels() {
		return inputChannels;
	}

	List<Channel<? super O>> getOutputChannels() {
		return outputChannels;
	}

	public abstract void work();

	/*
	 * Ideally, subclasses would provide their rates to our constructor.  But
	 * that would require splitters and joiners to commit to their rates before
	 * knowing how many outputs/inputs they have.  If the user wants to build
	 * a splitjoin with a variable number of elements, he or she would have to
	 * figure out how many before constructing the splitjoin, rather than being
	 * able to call Splitjoin.add() in a loop.  Even if the user wants a fixed
	 * number of elements in the splitjoin, he or she shouldn't have to repeat
	 * him or herself by specifying a splitter size, joiner size and then adding
	 * that many elements (the StreamIt language doesn't require this, for
	 * example).
	 */

	/**
	 * Returns a list of peek rates, such that the rate for the i-th channel is
	 * returned at index i.  Workers with only one input will return a singleton
	 * list.
	 * @return a list of peek rates
	 */
	abstract List<Rate> getPeekRates();

	/**
	 * Returns a list of pop rates, such that the rate for the i-th channel is
	 * returned at index i.  Workers with only one input will return a singleton
	 * list.
	 * @return a list of pop rates
	 */
	abstract List<Rate> getPopRates();

	/**
	 * Returns a list of push rates, such that the rate for the i-th channel is
	 * returned at index i. Workers with only one output will return a singleton
	 * list.
	 * @return a list of push rates
	 */
	abstract List<Rate> getPushRates();
}

@@ -805,16 +805,167 @@
 nnel) %7B%0A
+%09%09if (predecessor == null %7C%7C channel == null)%0A%09%09%09throw new NullPointerException();%0A%09%09if (predecessor == this)%0A%09%09%09throw new IllegalArgumentException();%0A
 %09%09predec
@@ -1112,16 +1112,163 @@
 nnel) %7B%0A
+%09%09if (successor == null %7C%7C channel == null)%0A%09%09%09throw new NullPointerException();%0A%09%09if (successor == this)%0A%09%09%09throw new IllegalArgumentException();%0A
 %09%09succes

check some preconditions