/*
* 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.tinkerpop.gremlin.process.traversal.util;
import org.apache.tinkerpop.gremlin.process.traversal.Traversal;
import org.apache.tinkerpop.gremlin.process.traversal.TraversalStrategies;
import org.apache.tinkerpop.gremlin.process.traversal.TraversalStrategy;
import org.javatuples.Pair;
import java.io.Serializable;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
import java.util.stream.Stream;
/**
* A TraversalExplanation takes a {@link Traversal} and, for each registered {@link TraversalStrategy}, it creates a
* mapping reflecting how each strategy alters the traversal. This is useful for understanding how each traversal
* strategy mutates the traversal. This is useful in debugging and analysis of traversal compilation. The
* {@link TraversalExplanation#toString()} has a pretty-print representation that is useful in the Gremlin Console.
*
* @author Marko A. Rodriguez (http://markorodriguez.com)
*/
public class TraversalExplanation implements Serializable {
private Traversal.Admin<?, ?> traversal;
private List<Pair<TraversalStrategy, Traversal.Admin<?, ?>>> strategyTraversals = new ArrayList<>();
private TraversalExplanation() {
// no arg constructor for serialization
}
public TraversalExplanation(final Traversal.Admin<?, ?> traversal) {
this.traversal = traversal.clone();
TraversalStrategies mutatingStrategies = new DefaultTraversalStrategies();
for (final TraversalStrategy strategy : this.traversal.getStrategies().toList()) {
final Traversal.Admin<?, ?> mutatingTraversal = this.traversal.clone();
mutatingStrategies.addStrategies(strategy);
mutatingTraversal.setStrategies(mutatingStrategies);
mutatingTraversal.applyStrategies();
this.strategyTraversals.add(Pair.with(strategy, mutatingTraversal));
}
}
/**
* Get the list of {@link TraversalStrategy} applications. For strategy, the resultant mutated {@link Traversal} is provided.
*
* @return the list of strategy/traversal pairs
*/
public List<Pair<TraversalStrategy, Traversal.Admin<?, ?>>> getStrategyTraversals() {
return Collections.unmodifiableList(this.strategyTraversals);
}
/**
* Get the original {@link Traversal} used to create this explanation.
*
* @return the original traversal
*/
public Traversal.Admin<?, ?> getOriginalTraversal() {
return this.traversal;
}
@Override
public String toString() {
return this.prettyPrint(Integer.MAX_VALUE);
}
public String prettyPrint() {
return this.prettyPrint(100);
}
/**
* A pretty-print representation of the traversal explanation.
*
* @return a {@link String} representation of the traversal explanation
*/
public String prettyPrint(final int maxLineLength) {
final String originalTraversal = "Original Traversal";
final String finalTraversal = "Final Traversal";
final int maxStrategyColumnLength = this.strategyTraversals.stream()
.map(Pair::getValue0)
.map(Object::toString)
.map(String::length)
.max(Comparator.naturalOrder())
.orElse(15);
final int newLineIndent = maxStrategyColumnLength + 10;
final int maxTraversalColumn = maxLineLength - newLineIndent;
if (maxTraversalColumn < 1)
throw new IllegalArgumentException("The maximum line length is too small to present the " + TraversalExplanation.class.getSimpleName() + ": " + maxLineLength);
int largestTraversalColumn = Stream.concat(Stream.of(Pair.with(null, this.traversal)), this.strategyTraversals.stream())
.map(Pair::getValue1)
.map(Object::toString)
.map(s -> wordWrap(s, maxTraversalColumn, newLineIndent))
.flatMap(s -> Stream.of(s.split("\n")))
.map(String::trim)
.map(s -> s.trim().startsWith("[") ? s : " " + s) // 3 indent on new lines
.map(String::length)
.max(Comparator.naturalOrder())
.get();
final StringBuilder builder = new StringBuilder("Traversal Explanation\n");
for (int i = 0; i < (maxStrategyColumnLength + 7 + largestTraversalColumn); i++) {
builder.append("=");
}
builder.append("\n");
builder.append(originalTraversal);
for (int i = 0; i < maxStrategyColumnLength - originalTraversal.length() + 7; i++) {
builder.append(" ");
}
builder.append(wordWrap(this.traversal.toString(), maxTraversalColumn, newLineIndent));
builder.append("\n\n");
for (final Pair<TraversalStrategy, Traversal.Admin<?, ?>> pairs : this.strategyTraversals) {
builder.append(pairs.getValue0());
int spacesToAdd = maxStrategyColumnLength - pairs.getValue0().toString().length() + 1;
for (int i = 0; i < spacesToAdd; i++) {
builder.append(" ");
}
builder.append("[").append(pairs.getValue0().getTraversalCategory().getSimpleName().substring(0, 1)).append("]");
for (int i = 0; i < 3; i++) {
builder.append(" ");
}
builder.append(wordWrap(pairs.getValue1().toString(), maxTraversalColumn, newLineIndent)).append("\n");
}
builder.append("\n");
builder.append(finalTraversal);
for (int i = 0; i < maxStrategyColumnLength - finalTraversal.length() + 7; i++) {
builder.append(" ");
}
builder.append(wordWrap((this.strategyTraversals.size() > 0 ?
this.strategyTraversals.get(this.strategyTraversals.size() - 1).getValue1().toString() :
this.traversal.toString()), maxTraversalColumn, newLineIndent));
return builder.toString();
}
private String wordWrap(final String longString, final int maxLengthPerLine, final int newLineIndent) {
if (longString.length() <= maxLengthPerLine)
return longString;
StringBuilder builder = new StringBuilder();
int counter = 0;
for (int i = 0; i < longString.length(); i++) {
if (0 == counter) {
builder.append(longString.charAt(i));
} else if (counter < maxLengthPerLine) {
builder.append(longString.charAt(i));
} else {
builder.append("\n");
for (int j = 0; j < newLineIndent; j++) {
builder.append(" ");
}
builder.append(longString.charAt(i));
counter = 0;
}
counter++;
}
return builder.toString();
}
}