/*
* 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.HashMap;
import java.util.List;
import java.util.Locale;
import java.util.Map;
import java.util.Set;
import org.apache.solr.client.solrj.io.Tuple;
import org.apache.solr.client.solrj.io.comp.StreamComparator;
import org.apache.solr.client.solrj.io.eval.EvaluatorException;
import org.apache.solr.client.solrj.io.eval.StreamEvaluator;
import org.apache.solr.client.solrj.io.ops.StreamOperation;
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.StreamExpressionParameter;
import org.apache.solr.client.solrj.io.stream.expr.StreamExpressionParser;
import org.apache.solr.client.solrj.io.stream.expr.StreamExpressionValue;
import org.apache.solr.client.solrj.io.stream.expr.StreamFactory;
/**
* Selects fields from the incoming stream and applies optional field renaming.
* Does not reorder the outgoing stream.
**/
public class SelectStream extends TupleStream implements Expressible {
private static final long serialVersionUID = 1;
private TupleStream stream;
private StreamContext streamContext;
private Map<String,String> selectedFields;
private Map<StreamEvaluator,String> selectedEvaluators;
private List<StreamOperation> operations;
public SelectStream(TupleStream stream, List<String> selectedFields) throws IOException {
this.stream = stream;
this.selectedFields = new HashMap<>();
for(String selectedField : selectedFields){
this.selectedFields.put(selectedField, selectedField);
}
operations = new ArrayList<>();
selectedEvaluators = new HashMap<>();
}
public SelectStream(TupleStream stream, Map<String,String> selectedFields) throws IOException {
this.stream = stream;
this.selectedFields = selectedFields;
operations = new ArrayList<>();
selectedEvaluators = new HashMap<>();
}
public SelectStream(StreamExpression expression,StreamFactory factory) throws IOException {
// grab all parameters out
List<StreamExpression> streamExpressions = factory.getExpressionOperandsRepresentingTypes(expression, Expressible.class, TupleStream.class);
List<StreamExpressionParameter> selectAsFieldsExpressions = factory.getOperandsOfType(expression, StreamExpressionValue.class);
List<StreamExpression> operationExpressions = factory.getExpressionOperandsRepresentingTypes(expression, StreamOperation.class);
List<StreamExpression> evaluatorExpressions = factory.getExpressionOperandsRepresentingTypes(expression, StreamEvaluator.class);
// validate expression contains only what we want.
if(expression.getParameters().size() != streamExpressions.size() + selectAsFieldsExpressions.size() + operationExpressions.size()){
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 single stream but found %d (must be TupleStream types)",expression, streamExpressions.size()));
}
if(0 == selectAsFieldsExpressions.size()){
throw new IOException(String.format(Locale.ROOT,"Invalid expression %s - expecting at least one select field but found %d",expression, streamExpressions.size()));
}
if(0 != evaluatorExpressions.size()){
throw new IOException(String.format(Locale.ROOT,"Invalid expression %s - evaluators must be given a name, like 'add(...) as result' but found %d evaluators without names",expression, evaluatorExpressions.size()));
}
stream = factory.constructStream(streamExpressions.get(0));
selectedFields = new HashMap<String,String>();
selectedEvaluators = new HashMap<StreamEvaluator, String>();
for(StreamExpressionParameter parameter : selectAsFieldsExpressions){
StreamExpressionValue selectField = (StreamExpressionValue)parameter;
String value = selectField.getValue().trim();
// remove possible wrapping quotes
if(value.length() > 2 && value.startsWith("\"") && value.endsWith("\"")){
value = value.substring(1, value.length() - 1);
}
if(value.toLowerCase(Locale.ROOT).contains(" as ")){
String[] parts = value.split("(?i) as "); // ensure we are splitting in a case-insensitive way
if(2 != parts.length){
throw new IOException(String.format(Locale.ROOT,"Invalid expression %s - expecting select field of form 'fieldA' or 'fieldA as alias' but found %s",expression, value));
}
String asValue = parts[0].trim();
String asName = parts[1].trim();
boolean handled = false;
if(asValue.contains("(")){
// possible evaluator
try{
StreamExpression asValueExpression = StreamExpressionParser.parse(asValue);
if(factory.doesRepresentTypes(asValueExpression, StreamEvaluator.class)){
selectedEvaluators.put(factory.constructEvaluator(asValueExpression), asName);
handled = true;
}
} catch(Throwable e) {
Throwable t = e;
while(true) {
if(t instanceof EvaluatorException) {
throw new IOException(t);
}
t = t.getCause();
if(t == null) {
break;
}
}
// it was not handled, so treat as a non-evaluator
}
}
if(!handled){
selectedFields.put(asValue, asName);
}
}
else{
selectedFields.put(value,value);
}
}
operations = new ArrayList<>();
for(StreamExpression expr : operationExpressions){
operations.add(factory.constructOperation(expr));
}
}
@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){
// stream
if(stream instanceof Expressible){
expression.addParameter(((Expressible)stream).toExpression(factory));
}
else{
throw new IOException("This SelectStream contains a non-expressible TupleStream - it cannot be converted to an expression");
}
}
else{
expression.addParameter("<stream>");
}
// selected fields
for(Map.Entry<String, String> selectField : selectedFields.entrySet()) {
if(selectField.getKey().equals(selectField.getValue())){
expression.addParameter(selectField.getKey());
}
else{
expression.addParameter(String.format(Locale.ROOT, "%s as %s", selectField.getKey(), selectField.getValue()));
}
}
// selected evaluators
for(Map.Entry<StreamEvaluator, String> selectedEvaluator : selectedEvaluators.entrySet()) {
expression.addParameter(String.format(Locale.ROOT, "%s as %s", selectedEvaluator.getKey().toExpression(factory), selectedEvaluator.getValue()));
}
for(StreamOperation operation : operations){
expression.addParameter(operation.toExpression(factory));
}
return expression;
}
@Override
public Explanation toExplanation(StreamFactory factory) throws IOException {
Explanation explanation = 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());
for(StreamEvaluator evaluator : selectedEvaluators.keySet()){
explanation.addHelper(evaluator.toExplanation(factory));
}
for(StreamOperation operation : operations){
explanation.addHelper(operation.toExplanation(factory));
}
return explanation;
}
public void setStreamContext(StreamContext context) {
this.streamContext = context;
this.stream.setStreamContext(context);
Set<StreamEvaluator> evaluators = selectedEvaluators.keySet();
for(StreamEvaluator evaluator : evaluators) {
evaluator.setStreamContext(context);
}
}
public List<TupleStream> children() {
List<TupleStream> l = new ArrayList();
l.add(stream);
return l;
}
public void open() throws IOException {
stream.open();
}
public void close() throws IOException {
stream.close();
}
public Tuple read() throws IOException {
Tuple original = stream.read();
if(original.EOF){
return original;
}
// create a copy with the limited set of fields
Tuple workingToReturn = new Tuple(new HashMap<>());
Tuple workingForEvaluators = new Tuple(new HashMap<>());
//Clear the TupleContext before running the evaluators.
//The TupleContext allows evaluators to cache values within the scope of a single tuple.
//For example a LocalDateTime could be parsed by one evaluator and used by other evaluators within the scope of the tuple.
//This avoids the need to create multiple LocalDateTime instances for the same tuple to satisfy a select expression.
streamContext.getTupleContext().clear();
for(Object fieldName : original.fields.keySet()){
workingForEvaluators.put(fieldName, original.get(fieldName));
if(selectedFields.containsKey(fieldName)){
workingToReturn.put(selectedFields.get(fieldName), original.get(fieldName));
}
}
// apply all operations
for(StreamOperation operation : operations){
operation.operate(workingToReturn);
operation.operate(workingForEvaluators);
}
// Apply all evaluators
for(Map.Entry<StreamEvaluator, String> selectedEvaluator : selectedEvaluators.entrySet()) {
workingToReturn.put(selectedEvaluator.getValue(), selectedEvaluator.getKey().evaluate(workingForEvaluators));
}
return workingToReturn;
}
/** Return the stream sort - ie, the order in which records are returned */
public StreamComparator getStreamSort(){
// apply aliasing to comparator
return stream.getStreamSort().copyAliased(selectedFields);
}
public int getCost() {
return 0;
}
}