/*
* 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.solr.client.solrj.io.stream;
import java.io.IOException;
import java.util.ArrayList;
import java.util.LinkedList;
import java.util.List;
import java.util.Locale;
import org.apache.solr.client.solrj.io.Tuple;
import org.apache.solr.client.solrj.io.comp.FieldComparator;
import org.apache.solr.client.solrj.io.comp.StreamComparator;
import org.apache.solr.client.solrj.io.stream.expr.Explanation;
import org.apache.solr.client.solrj.io.stream.expr.Expressible;
import org.apache.solr.client.solrj.io.stream.expr.StreamExplanation;
import org.apache.solr.client.solrj.io.stream.expr.StreamExpression;
import org.apache.solr.client.solrj.io.stream.expr.StreamExpressionNamedParameter;
import org.apache.solr.client.solrj.io.stream.expr.StreamExpressionValue;
import org.apache.solr.client.solrj.io.stream.expr.StreamFactory;
import org.apache.solr.client.solrj.io.stream.expr.Explanation.ExpressionType;
/**
* The SortStream emits a stream of Tuples sorted by a Comparator.
**/
public class SortStream extends TupleStream implements Expressible {
private static final long serialVersionUID = 1;
private TupleStream stream;
private StreamComparator comparator;
private Worker worker;
public SortStream(TupleStream stream, StreamComparator comp) throws IOException {
init(stream,comp);
}
public SortStream(StreamExpression expression,StreamFactory factory) throws IOException {
// grab all parameters out
List<StreamExpression> streamExpressions = factory.getExpressionOperandsRepresentingTypes(expression, Expressible.class, TupleStream.class);
StreamExpressionNamedParameter byExpression = factory.getNamedOperand(expression, "by");
// validate expression contains only what we want.
if(expression.getParameters().size() != streamExpressions.size() + 1){
throw new IOException(String.format(Locale.ROOT,"Invalid expression %s - unknown operands found", expression));
}
if(1 != streamExpressions.size()){
throw new IOException(String.format(Locale.ROOT,"Invalid expression %s - expecting a single stream but found %d",expression, streamExpressions.size()));
}
if(null == byExpression || !(byExpression.getParameter() instanceof StreamExpressionValue)){
throw new IOException(String.format(Locale.ROOT,"Invalid expression %s - expecting single 'by' parameter listing fields to sort over but didn't find one",expression));
}
init(
factory.constructStream(streamExpressions.get(0)),
factory.constructComparator(((StreamExpressionValue)byExpression.getParameter()).getValue(), FieldComparator.class)
);
}
private void init(TupleStream stream, StreamComparator comp) throws IOException{
this.stream = stream;
this.comparator = comp;
// standard java modified merge sort
worker = new Worker() {
private LinkedList<Tuple> tuples = new LinkedList<Tuple>();
private Tuple eofTuple;
public void readStream(TupleStream stream) throws IOException {
Tuple tuple = stream.read();
while(!tuple.EOF){
tuples.add(tuple);
tuple = stream.read();
}
eofTuple = tuple;
}
public void sort() {
tuples.sort(comparator);
}
public Tuple read() {
if(tuples.isEmpty()){
return eofTuple;
}
return tuples.removeFirst();
}
};
}
@Override
public StreamExpression toExpression(StreamFactory factory) throws IOException{
return toExpression(factory, true);
}
private StreamExpression toExpression(StreamFactory factory, boolean includeStreams) throws IOException {
// function name
StreamExpression expression = new StreamExpression(factory.getFunctionName(this.getClass()));
if(includeStreams){
// streams
if(stream instanceof Expressible){
expression.addParameter(((Expressible)stream).toExpression(factory));
}
else{
throw new IOException("This SortStream contains a non-expressible TupleStream - it cannot be converted to an expression");
}
}
else{
expression.addParameter("<stream>");
}
// by
if(comparator instanceof Expressible){
expression.addParameter(new StreamExpressionNamedParameter("by",((Expressible)comparator).toExpression(factory)));
}
else{
throw new IOException("This SortStream contains a non-expressible equalitor - it cannot be converted to an expression");
}
return expression;
}
@Override
public Explanation toExplanation(StreamFactory factory) throws IOException {
return new StreamExplanation(getStreamNodeId().toString())
.withChildren(new Explanation[]{
stream.toExplanation(factory)
})
.withFunctionName(factory.getFunctionName(this.getClass()))
.withImplementingClass(this.getClass().getName())
.withExpressionType(ExpressionType.STREAM_DECORATOR)
.withExpression(toExpression(factory, false).toString())
.withHelper(comparator.toExplanation(factory));
}
public void setStreamContext(StreamContext context) {
this.stream.setStreamContext(context);
}
public List<TupleStream> children() {
List<TupleStream> l = new ArrayList<TupleStream>();
l.add(stream);
return l;
}
public void open() throws IOException {
stream.open();
worker.readStream(stream);
worker.sort();
}
public void close() throws IOException {
stream.close();
}
public Tuple read() throws IOException {
// return next from sorted order
return worker.read();
}
/** Return the stream sort - ie, the order in which records are returned */
public StreamComparator getStreamSort(){
return comparator;
}
public int getCost() {
return 0;
}
private interface Worker {
public void readStream(TupleStream stream) throws IOException;
public void sort();
public Tuple read();
}
}