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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.lucene.monitor;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Comparator;
import java.util.List;
import java.util.Optional;
import java.util.function.BiConsumer;
import java.util.function.Function;
import java.util.stream.Collectors;
import org.apache.lucene.index.Term;
import org.apache.lucene.util.BytesRef;
/**
* A representation of a node in a query tree
*
* Queries are analyzed and converted into an abstract tree, consisting of conjunction and
* disjunction nodes, and leaf nodes containing terms.
*
*
Terms may be collected from a node, which will use the weights of its sub-nodes to determine
* which paths are followed. The path may be changed by calling {@link #advancePhase(double)}
*/
public abstract class QueryTree {
/** The weight of this node */
public abstract double weight();
/** Collect terms from the most highly-weighted path below this node */
public abstract void collectTerms(BiConsumer termCollector);
/**
* Find the next-most highly-weighted path below this node
*
* @param minWeight do not advance if the next path has a weight below this value
* @return {@code false} if there are no more paths above the minimum weight
*/
public abstract boolean advancePhase(double minWeight);
/**
* Returns a string representation of the node
*
* @param depth the current depth of this node in the overall query tree
*/
public abstract String toString(int depth);
@Override
public String toString() {
return toString(0);
}
/** Returns a string of {@code width} spaces */
protected String space(int width) {
StringBuilder sb = new StringBuilder();
for (int i = 0; i < width; i++) {
sb.append(" ");
}
return sb.toString();
}
/** Returns a leaf node for a particular term */
public static QueryTree term(Term term, TermWeightor weightor) {
return term(term.field(), term.bytes(), weightor.applyAsDouble(term));
}
/**
* Returns a leaf node for a particular term and weight
*
* The weight must be greater than 0
*/
public static QueryTree term(Term term, double weight) {
return term(term.field(), term.bytes(), weight);
}
/**
* Returns a leaf node for a particular term and weight
*
*
The weight must be greater than 0
*/
public static QueryTree term(String field, BytesRef term, double weight) {
return new QueryTree() {
@Override
public double weight() {
if (weight <= 0) {
throw new IllegalArgumentException("Term weights must be greater than 0");
}
return weight;
}
@Override
public void collectTerms(BiConsumer termCollector) {
termCollector.accept(field, term);
}
@Override
public boolean advancePhase(double minWeight) {
return false;
}
@Override
public String toString(int depth) {
return space(depth) + field + ":" + term.utf8ToString() + "^" + weight;
}
};
}
/** Returns a leaf node that will match any document */
public static QueryTree anyTerm(String reason) {
return new QueryTree() {
@Override
public double weight() {
return 0;
}
@Override
public void collectTerms(BiConsumer termCollector) {
termCollector.accept(
TermFilteredPresearcher.ANYTOKEN_FIELD, new BytesRef(TermFilteredPresearcher.ANYTOKEN));
}
@Override
public boolean advancePhase(double minWeight) {
return false;
}
@Override
public String toString(int depth) {
return space(depth) + "ANY[" + reason + "]";
}
};
}
/** Returns a conjunction of a set of child nodes */
public static QueryTree conjunction(
List> children, TermWeightor weightor) {
if (children.size() == 0) {
throw new IllegalArgumentException("Cannot build a conjunction with no children");
}
if (children.size() == 1) {
return children.get(0).apply(weightor);
}
List qt = children.stream().map(f -> f.apply(weightor)).collect(Collectors.toList());
List restricted =
qt.stream().filter(t -> t.weight() > 0).collect(Collectors.toList());
if (restricted.size() == 0) {
// all children are ANY, so just return the first one
return qt.get(0);
}
return new ConjunctionQueryTree(qt);
}
static QueryTree conjunction(QueryTree... children) {
return new ConjunctionQueryTree(Arrays.asList(children));
}
/** Returns a disjunction of a set of child nodes */
public static QueryTree disjunction(
List> children, TermWeightor weightor) {
if (children.size() == 0) {
throw new IllegalArgumentException("Cannot build a disjunction with no children");
}
if (children.size() == 1) {
return children.get(0).apply(weightor);
}
List qt = children.stream().map(f -> f.apply(weightor)).collect(Collectors.toList());
Optional firstAnyChild = qt.stream().filter(q -> q.weight() == 0).findAny();
// if any of the children is an ANY node, just return that, otherwise build the disjunction
return firstAnyChild.orElseGet(() -> new DisjunctionQueryTree(qt));
}
static QueryTree disjunction(QueryTree... children) {
return new DisjunctionQueryTree(Arrays.asList(children));
}
private static class ConjunctionQueryTree extends QueryTree {
private static final Comparator COMPARATOR =
Comparator.comparingDouble(QueryTree::weight).reversed();
final List children = new ArrayList<>();
ConjunctionQueryTree(List children) {
this.children.addAll(children);
this.children.sort(COMPARATOR);
}
@Override
public double weight() {
return children.get(0).weight();
}
@Override
public void collectTerms(BiConsumer termCollector) {
children.get(0).collectTerms(termCollector);
}
@Override
public boolean advancePhase(double minWeight) {
if (children.get(0).advancePhase(minWeight)) {
this.children.sort(COMPARATOR);
return true;
}
if (children.size() == 1) {
return false;
}
if (children.get(1).weight() <= minWeight) {
return false;
}
children.remove(0);
return true;
}
@Override
public String toString(int depth) {
StringBuilder sb =
new StringBuilder(space(depth))
.append("Conjunction[")
.append(children.size())
.append("]^")
.append(weight())
.append("\n");
for (QueryTree child : children) {
sb.append(child.toString(depth + 2)).append("\n");
}
return sb.toString();
}
}
private static class DisjunctionQueryTree extends QueryTree {
final List children = new ArrayList<>();
private DisjunctionQueryTree(List children) {
this.children.addAll(children);
this.children.sort(Comparator.comparingDouble(QueryTree::weight));
}
@Override
public double weight() {
return children.get(0).weight();
}
@Override
public void collectTerms(BiConsumer termCollector) {
for (QueryTree child : children) {
child.collectTerms(termCollector);
}
}
@Override
public boolean advancePhase(double minWeight) {
boolean changed = false;
for (QueryTree child : children) {
changed |= child.advancePhase(minWeight);
}
if (changed == false) {
return false;
}
children.sort(Comparator.comparingDouble(QueryTree::weight));
return true;
}
@Override
public String toString(int depth) {
StringBuilder sb = new StringBuilder(space(depth)).append("Disjunction[");
sb.append(children.size()).append("]^");
sb.append(weight()).append("\n");
for (QueryTree child : children) {
sb.append(child.toString(depth + 2)).append("\n");
}
return sb.toString();
}
}
}