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/*
* 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.List;
import java.util.Locale;
import org.apache.solr.client.solrj.io.Tuple;
import org.apache.solr.client.solrj.io.comp.StreamComparator;
import org.apache.solr.client.solrj.io.eq.FieldEqualitor;
import org.apache.solr.client.solrj.io.eq.StreamEqualitor;
import org.apache.solr.client.solrj.io.stream.expr.Explanation;
import org.apache.solr.client.solrj.io.stream.expr.Explanation.ExpressionType;
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;
/**
* Emits tuples from streamA which do not exist in streamB. Resulting tuples are ordered
* the same as they were in streamA. Both streams must be sorted by the fields being compared.
**/
public class ComplementStream extends TupleStream implements Expressible {
private static final long serialVersionUID = 1;
private PushBackStream streamA;
private PushBackStream streamB;
private TupleStream originalStreamB;
private StreamEqualitor eq;
public ComplementStream(TupleStream streamA, TupleStream streamB, StreamEqualitor eq) throws IOException {
init(streamA, streamB, eq);
}
public ComplementStream(StreamExpression expression,StreamFactory factory) throws IOException {
// grab all parameters out
List streamExpressions = factory.getExpressionOperandsRepresentingTypes(expression, Expressible.class, TupleStream.class);
StreamExpressionNamedParameter onExpression = factory.getNamedOperand(expression, "on");
// 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(2 != streamExpressions.size()){
throw new IOException(String.format(Locale.ROOT,"Invalid expression %s - expecting two streams but found %d (must be TupleStream types)",expression, streamExpressions.size()));
}
if(null == onExpression || !(onExpression.getParameter() instanceof StreamExpressionValue)){
throw new IOException(String.format(Locale.ROOT,"Invalid expression %s - expecting single 'on' parameter listing fields to merge on but didn't find one",expression));
}
init( factory.constructStream(streamExpressions.get(0)),
factory.constructStream(streamExpressions.get(1)),
factory.constructEqualitor(((StreamExpressionValue)onExpression.getParameter()).getValue(), FieldEqualitor.class)
);
}
private void init(TupleStream streamA, TupleStream streamB, StreamEqualitor eq) throws IOException {
this.streamA = new PushBackStream(streamA);
this.streamB = new PushBackStream(new UniqueStream(streamB, eq));
this.originalStreamB = streamB; // hold onto this for toExpression
this.eq = eq;
// streamA and streamB must both be sorted so that comp can be derived from
if(!eq.isDerivedFrom(streamA.getStreamSort()) || !eq.isDerivedFrom(streamB.getStreamSort())){
throw new IOException("Invalid ComplementStream - both substream comparators (sort) must be a superset of this stream's equalitor.");
}
}
@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(streamA instanceof Expressible){
expression.addParameter(((Expressible)streamA).toExpression(factory));
}
else{
throw new IOException("This IntersectionStream contains a non-expressible TupleStream - it cannot be converted to an expression");
}
if(originalStreamB instanceof Expressible){
expression.addParameter(((Expressible)originalStreamB).toExpression(factory));
}
else{
throw new IOException("This IntersectStream contains a non-expressible TupleStream - it cannot be converted to an expression");
}
}
else{
expression.addParameter("");
expression.addParameter("");
}
// on
expression.addParameter(new StreamExpressionNamedParameter("on",eq.toExpression(factory)));
return expression;
}
@Override
public Explanation toExplanation(StreamFactory factory) throws IOException {
return new StreamExplanation(getStreamNodeId().toString())
.withChildren(new Explanation[]{
streamA.toExplanation(factory),
originalStreamB.toExplanation(factory)
})
.withFunctionName(factory.getFunctionName(this.getClass()))
.withImplementingClass(this.getClass().getName())
.withExpressionType(ExpressionType.STREAM_DECORATOR)
.withExpression(toExpression(factory, false).toString())
.withHelper(eq.toExplanation(factory))
;
}
public void setStreamContext(StreamContext context) {
this.streamA.setStreamContext(context);
this.streamB.setStreamContext(context);
}
public List children() {
List l = new ArrayList();
l.add(streamA);
l.add(streamB);
return l;
}
public void open() throws IOException {
streamA.open();
streamB.open();
}
public void close() throws IOException {
streamA.close();
streamB.close();
}
public Tuple read() throws IOException {
while(true){
Tuple a = streamA.read();
Tuple b = streamB.read();
// if a is EOF then we're done
if(a.EOF){ return a; }
// if b is EOF then return a
if(b.EOF){
streamB.pushBack(b);
return a;
}
// if a != b && a < b then we know there is no b which a might equal so return a
if(!eq.test(a, b) && streamA.getStreamSort().compare(a, b) < 0){
streamB.pushBack(b);
return a;
}
// if a == b then ignore a cause it exists in b
// else we know that b < a so we can ignore b
if(eq.test(a, b)){
streamB.pushBack(b);
}
else{
streamA.pushBack(a);
}
}
}
/** Return the stream sort - ie, the order in which records are returned */
public StreamComparator getStreamSort(){
return streamA.getStreamSort();
}
public int getCost() {
return 0;
}
}
