| /* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you under the Apache License, Version 2.0 (the |
| * "License"); you may not use this file except in compliance |
| * with the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| package org.apache.pig.impl.plan; |
| |
| import java.io.Serializable; |
| import java.lang.StringBuilder; |
| import java.util.ArrayList; |
| import java.util.List; |
| |
| import org.apache.pig.impl.plan.OperatorKey; |
| |
| /** |
| * Base class for all types of operators. |
| */ |
| // Suppress "unchecked" warnings for all logical plan related classes. Will revisit in logical plan rework |
| @SuppressWarnings("unchecked") |
| abstract public class Operator<V extends PlanVisitor> implements Serializable, Comparable<Operator>, Cloneable { |
| private static final long serialVersionUID = 1L; |
| |
| /** |
| * OperatorKey associated with this operator. This key is used to find the |
| * operator in an OperatorPlan. |
| */ |
| protected OperatorKey mKey; |
| |
| /** |
| * @param k Operator key to assign to this node. |
| */ |
| public Operator(OperatorKey k) { |
| mKey = k; |
| } |
| |
| /** |
| * Get the operator key for this operator. |
| */ |
| public OperatorKey getOperatorKey() { |
| return mKey; |
| } |
| |
| /** |
| * Visit this node with the provided visitor. This should only be called by |
| * the visitor class itself, never directly. |
| * |
| * @param v |
| * Visitor to visit with. |
| * @throws VisitorException |
| * if the visitor has a problem. |
| */ |
| public abstract void visit(V v) throws VisitorException; |
| |
| /** |
| * Indicates whether this operator supports multiple inputs. |
| * |
| * @return true if it does, otherwise false. |
| */ |
| public abstract boolean supportsMultipleInputs(); |
| |
| /** |
| * Indicates whether this operator supports multiple outputs. |
| * |
| * @return true if it does, otherwise false. |
| */ |
| public abstract boolean supportsMultipleOutputs(); |
| |
| public abstract String name(); |
| |
| @Override |
| public String toString() { |
| return "(Name: " + name() + " Operator Key: " + mKey + ")"; |
| } |
| |
| /** |
| * Compares to Operators based on their opKey |
| */ |
| @Override |
| public boolean equals(Object obj) { |
| if(obj==this) |
| return true; |
| else |
| return false; |
| } |
| |
| /** |
| * Needed to ensure that the list iterators' |
| * outputs are deterministic. Without this |
| * we are totally at object id's mercy. |
| */ |
| @Override |
| public int hashCode() { |
| return mKey.hashCode(); |
| } |
| |
| public int compareTo(Operator o) { |
| return mKey.compareTo(o.mKey); |
| } |
| |
| /** |
| * @see java.lang.Object#clone() |
| * Do not use the clone method directly. Operators are cloned when logical plans |
| * are cloned using {@link LogicalPlanCloner} |
| */ |
| @Override |
| protected Object clone() throws CloneNotSupportedException { |
| Object o = super.clone(); |
| Operator opClone = (Operator)o; |
| opClone.mKey = new OperatorKey(mKey.scope, NodeIdGenerator.getGenerator().getNextNodeId(mKey.scope)); |
| return opClone; |
| } |
| |
| /** |
| * Produce a map describing how this operator modifies its projection. |
| * @return ProjectionMap null indicates it does not know how the projection |
| * changes, for example a join of two inputs where one input does not have |
| * a schema. |
| */ |
| public ProjectionMap getProjectionMap() { |
| //TODO |
| //this method should be made abstract in the future |
| return null; |
| }; |
| |
| /** |
| * Unset the projection map as if it had not been calculated. This is used by |
| * anyone who reorganizes the tree and needs to have projection maps recalculated. |
| */ |
| public void unsetProjectionMap() { |
| //TODO |
| //this method should be made abstract in the future |
| } |
| |
| /** |
| * Regenerate the projection map by unsetting and getting the projection map |
| */ |
| public ProjectionMap regenerateProjectionMap() { |
| unsetProjectionMap(); |
| return getProjectionMap(); |
| } |
| |
| |
| /** |
| * Make any necessary changes to a node based on a change of position in the |
| * plan. This allows operators to rewire their projections, etc. when they |
| * are relocated in a plan. |
| * |
| * @param oldPred |
| * Operator that was previously the predecessor. |
| * @param oldPredIndex |
| * position of the old predecessor in the list of predecessors |
| * @param newPred |
| * Operator that will now be the predecessor. |
| * @param useOldPred |
| * If true use oldPred's projection map for the rewire; otherwise |
| * use newPred's projection map |
| * @throws PlanException |
| */ |
| public void rewire(Operator<V> oldPred, int oldPredIndex, |
| Operator<V> newPred, boolean useOldPred) throws PlanException { |
| //TODO |
| //this method should be made abstract in the future |
| if (oldPred == null) { |
| return; |
| } |
| } |
| |
| } |