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/*
* SonarLint Core - Server Connection
* Copyright (C) 2016-2024 SonarSource SA
* mailto:info AT sonarsource DOT com
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 3 of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program; if not, write to the Free Software Foundation,
* Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
package org.sonarsource.sonarlint.core.serverconnection.prefix;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.AbstractMap;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Set;
import javax.annotation.CheckForNull;
import javax.annotation.Nullable;
class ReversePathTree {
private final Node root = new MultipleChildrenNode();
public void index(Path path) {
Node parent = null;
var currentNode = root;
Path currentNodePath = null;
for (var i = path.getNameCount() - 1; i >= 0; i--) {
var childNodePath = path.getName(i);
var result = currentNode.computeChildrenIfAbsent(parent, currentNodePath, childNodePath);
parent = result[0];
currentNode = result[1];
currentNodePath = childNodePath;
}
currentNode.setTerminal(true);
}
public Match findLongestSuffixMatches(Path path) {
var currentNode = root;
var matchLen = 0;
while (matchLen < path.getNameCount()) {
var nextEl = path.getName(path.getNameCount() - matchLen - 1);
var nextNode = currentNode.getChild(nextEl);
if (nextNode == null) {
break;
}
matchLen++;
currentNode = nextNode;
}
return collectAllPrefixes(currentNode, matchLen);
}
private static Match collectAllPrefixes(Node node, int matchLen) {
List paths = new ArrayList<>();
if (matchLen > 0) {
collectPrefixes(node, Paths.get(""), paths);
}
return new Match(paths, matchLen);
}
private static void collectPrefixes(Node node, Path currentPath, List paths) {
if (node.isTerminal()) {
paths.add(currentPath);
}
for (Map.Entry child : node.childrenEntrySet()) {
var childPath = child.getKey().resolve(currentPath);
collectPrefixes(child.getValue(), childPath, paths);
}
}
/**
* Since it is very common that a node will have only one child, we save memory by lazily creating a children HashMap only when a second item is added.
*/
private interface Node {
Node[] computeChildrenIfAbsent(Node parent, Path currentNodePath, Path childNodePath);
Set> childrenEntrySet();
Node getChild(Path name);
void setTerminal(boolean b);
boolean isTerminal();
void put(Path path, Node node);
}
private abstract static class AbstractNode implements Node {
private boolean terminal;
@Override
public final boolean isTerminal() {
return terminal;
}
@Override
public final void setTerminal(boolean b) {
this.terminal = b;
}
}
private static class SingleChildNode extends AbstractNode {
@Nullable
private Path singleChildKey;
@Nullable
private Node singleChildValue;
@Override
public Node[] computeChildrenIfAbsent(Node parent, Path currentNodePath, Path childNodePath) {
if (singleChildKey == null) {
put(childNodePath, new SingleChildNode());
return new Node[] {this, singleChildValue};
}
if (childNodePath.equals(singleChildKey)) {
return new Node[] {this, singleChildValue};
}
var child = new SingleChildNode();
var replacement = new MultipleChildrenNode();
replacement.put(singleChildKey, singleChildValue);
replacement.put(childNodePath, child);
parent.put(currentNodePath, replacement);
return new Node[] {replacement, child};
}
@Override
public Set> childrenEntrySet() {
if (singleChildKey == null) {
return Collections.emptySet();
} else {
return Collections.singleton(new AbstractMap.SimpleEntry<>(singleChildKey, singleChildValue));
}
}
@Override
public void put(Path path, Node node) {
this.singleChildKey = path;
this.singleChildValue = node;
}
@Override
@CheckForNull
public Node getChild(Path name) {
return name.equals(singleChildKey) ? singleChildValue : null;
}
}
private static class MultipleChildrenNode extends AbstractNode {
private final Map children = new HashMap<>();
@Override
public Node[] computeChildrenIfAbsent(Node parent, Path currentNodePath, Path childNodePath) {
return new Node[] {this, children.computeIfAbsent(childNodePath, e -> new SingleChildNode())};
}
@Override
public Set> childrenEntrySet() {
return children.entrySet();
}
@CheckForNull
@Override
public Node getChild(Path name) {
return children.get(name);
}
@Override
public void put(Path path, Node node) {
children.put(path, node);
}
}
public static class Match {
private final List paths;
private final int matchLen;
private Match(List paths, int matchLen) {
this.paths = paths;
this.matchLen = matchLen;
}
public List matchPrefixes() {
return paths;
}
public int matchLen() {
return matchLen;
}
}
}