/tags/release-0.1-rc2/hive/external/ql/src/java/org/apache/hadoop/hive/ql/parse/GenMapRedWalker.java
Java | 73 lines | 27 code | 10 blank | 36 comment | 5 complexity | 59085630b9926a4545ce4f1201d9448a MD5 | raw file
Possible License(s): Apache-2.0, BSD-3-Clause, JSON, CPL-1.0
- /**
- * 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.hadoop.hive.ql.parse;
- import java.util.List;
- import org.apache.hadoop.hive.ql.exec.ReduceSinkOperator;
- import org.apache.hadoop.hive.ql.lib.DefaultGraphWalker;
- import org.apache.hadoop.hive.ql.lib.Dispatcher;
- import org.apache.hadoop.hive.ql.lib.Node;
- /**
- * Walks the operator tree in pre order fashion.
- */
- public class GenMapRedWalker extends DefaultGraphWalker {
- /**
- * constructor of the walker - the dispatcher is passed.
- *
- * @param disp
- * the dispatcher to be called for each node visited
- */
- public GenMapRedWalker(Dispatcher disp) {
- super(disp);
- }
- /**
- * Walk the given operator.
- *
- * @param nd
- * operator being walked
- */
- @Override
- public void walk(Node nd) throws SemanticException {
- List<? extends Node> children = nd.getChildren();
- // maintain the stack of operators encountered
- opStack.push(nd);
- dispatch(nd, opStack);
- // kids of reduce sink operator need not be traversed again
- if ((children == null)
- || ((nd instanceof ReduceSinkOperator) && (getDispatchedList()
- .containsAll(children)))) {
- opStack.pop();
- return;
- }
- // move all the children to the front of queue
- for (Node ch : children) {
- walk(ch);
- }
- // done with this operator
- opStack.pop();
- }
- }