PathResolverImpl.java
/*
** Module : PathResolverImpl.java
** Abstract : Implements PathResolver to resolve a legacy system absolute file path into its host
** system file path.
**
** Copyright (c) 2018-2024, Golden Code Development Corporation.
**
** -#- -I- --Date-- ---------------------------------Description----------------------------------
** 001 SBI 20180521 Initial version.
** 002 ECF 20180613 Performance fix: use compiled regex pattern for path splitting. Removed
** unused instance variable.
** 003 SBI 20180724 Changed to resolve legacy path names given by not canonical forms.
** 004 GBB 20240826 Moving FileSystem to osresource package.
*/
/*
** This program is free software: you can redistribute it and/or modify
** it under the terms of the GNU Affero 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 Affero General Public License for more details.
**
** You may find a copy of the GNU Affero GPL version 3 at the following
** location: https://www.gnu.org/licenses/agpl-3.0.en.html
**
** Additional terms under GNU Affero GPL version 3 section 7:
**
** Under Section 7 of the GNU Affero GPL version 3, the following additional
** terms apply to the works covered under the License. These additional terms
** are non-permissive additional terms allowed under Section 7 of the GNU
** Affero GPL version 3 and may not be removed by you.
**
** 0. Attribution Requirement.
**
** You must preserve all legal notices or author attributions in the covered
** work or Appropriate Legal Notices displayed by works containing the covered
** work. You may not remove from the covered work any author or developer
** credit already included within the covered work.
**
** 1. No License To Use Trademarks.
**
** This license does not grant any license or rights to use the trademarks
** Golden Code, FWD, any Golden Code or FWD logo, or any other trademarks
** of Golden Code Development Corporation. You are not authorized to use the
** name Golden Code, FWD, or the names of any author or contributor, for
** publicity purposes without written authorization.
**
** 2. No Misrepresentation of Affiliation.
**
** You may not represent yourself as Golden Code Development Corporation or FWD.
**
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*/
package com.goldencode.p2j.util;
import com.goldencode.p2j.util.osresource.FileSystem;
import java.io.*;
import java.util.*;
import java.util.regex.*;
/**
* Resolves the legacy file system path to the path on the host system.
*/
public class PathResolverImpl
implements PathResolver
{
/** Regexp pattern for matching any path separators */
private static final Pattern ANY_PATH_SEPARATOR = Pattern.compile(FileSystem.ANY_PATH_SEPARATOR);
/** Defines a parent reference in the path name */
private static final String PARENT_REFERENCE = "..";
/** Defines a current directory reference in the path name */
private static final String CURRENT_DIR_REFERENCE = ".";
/** The artificial root for the legacy file system */
private PathTree root;
/** A map from the given directory subset on the legacy system to the host system */
private Map<PathTree, String> mountedPaths;
/** The case insensitive mode on the legacy system */
private boolean caseInsensitive;
/**
* Builds this path resolver for the given legacy file separator for the given
* case insensitive mode.
*
* @param fileSeparator
* The given legacy file separator
* @param caseInsensitive
* The given case insensitive mode
*/
public PathResolverImpl(String fileSeparator, boolean caseInsensitive)
{
this.caseInsensitive = caseInsensitive;
this.root = new PathTree();
this.mountedPaths = new LinkedHashMap<>();
}
/**
* Resolve the given legacy path to the path on the host system.
*
* @param path
* The given legacy path to be resolved on the host system
*
* @return The resolved path on the host system
*
* @throws UnresolvedPathException
* If the given path can't be resolved
*/
@Override
public String resolvePath(String path)
throws PathResolver.UnresolvedPathException
{
// permit paths with mixed '/' and '\\' separators
String[] pathComponents = ANY_PATH_SEPARATOR.split(path);
int size = pathComponents.length;
PathTree parent = this.root;
int resolvedIndex = -1;
for(int i = 0; i < size; i++)
{
if (pathComponents[i].isEmpty() || CURRENT_DIR_REFERENCE.equals(pathComponents[i]))
{
// skip empty path components
continue;
}
else if (PARENT_REFERENCE.equals(pathComponents[i]))
{
if (parent.parent != null)
{
parent = parent.parent;
}
continue;
}
PathTree child = parent.findChild(pathComponents[i]);
if (child != null)
{
parent = child;
resolvedIndex = i;
}
else
{
break;
}
}
if (resolvedIndex == -1)
{
throw UNRESOLVED_ERROR;
}
String commonResolvedPath;
while ((commonResolvedPath = this.mountedPaths.get(parent)) == null &&
resolvedIndex >= 0 &&
parent.parent != null &&
parent.parent != this.root
)
{
parent = parent.parent;
resolvedIndex--;
}
if (commonResolvedPath == null)
{
throw UNRESOLVED_ERROR;
}
StringBuilder resolvedPath = new StringBuilder(commonResolvedPath);
for (int i = resolvedIndex + 1; i < size; i++)
{
if (pathComponents[i].isEmpty())
{
// skip empty path components
continue;
}
resolvedPath.append(File.separatorChar).append(pathComponents[i]);
}
return resolvedPath.toString();
}
/**
* Mounts the legacy system paths in the given map to their host system paths.
*
* @param pathMap
* Map of legacy system paths to host system paths.
*/
public void setPathMap(Map<String, String> pathMap)
{
for(Map.Entry<String, String> entry : pathMap.entrySet())
{
mount(entry.getKey(), entry.getValue());
}
}
/**
* Mounts the given legacy system path to its host system path.
*
* @param path
* The given legacy system path
* @param mappedPath
* The host system path
*/
public void mount(String path, String mappedPath)
{
mountedPaths.put(addPathTree(path), mappedPath);
}
/**
* Builds a case insensitive key if the current legacy system mode is insensitive.
*
* @param path
* The given legacy system path or path component
*
* @return The low case for the given input if the current legacy system mode is
* insensitive.
*/
private String doCaseInsensitive(String path)
{
if (this.caseInsensitive && path != null)
{
return path.toLowerCase(Locale.ROOT);
}
return path;
}
/**
* Builds the tree node for the given legacy system path.
*
* @param path
* The given legacy system path
*
* @return The corresponding tree node for the given legacy system path
*/
private PathTree addPathTree(String path)
{
// consider paths to be case insensitive
// permit paths with mixed '/' and '\\' separators
String[] pathComponents = ANY_PATH_SEPARATOR.split(doCaseInsensitive(path));
int size = pathComponents.length;
PathTree parent = this.root;
PathTree leaf = null;
for(int i = 0; i < size; i++)
{
if (pathComponents[i].isEmpty())
{
// skip empty path components
continue;
}
PathTree child = parent.findChild(pathComponents[i]);
if (child != null)
{
parent = child;
}
else
{
for(int j = size - 1; j >= i; j--)
{
if (pathComponents[j].isEmpty())
{
// skip empty path components
continue;
}
PathTree node = new PathTree(pathComponents[j]);
if (child == null)
{
child = node;
leaf = child;
}
else
{
node.addChild(child);
child = node;
}
}
parent.addChild(child);
break;
}
}
if (leaf == null)
{
leaf = parent;
}
return leaf;
}
/**
* Defines a tree node container.
*/
class PathTree
{
/** The node id */
private String id;
/** The children nodes */
private Map<String, PathTree> children;
/** The parent node */
private PathTree parent;
/**
* Defines the root node constructor.
*/
public PathTree()
{
this(null);
}
/**
* The directory node constructor
*
* @param component
* The path component (folder name)
*/
public PathTree(String component)
{
this.id = doCaseInsensitive(component);
children = new LinkedHashMap<>();
}
/**
* Find the child node by its path component.
*
* @param component
* The target component
*
* @return The child node
*/
public PathTree findChild(String component)
{
return children.get(doCaseInsensitive(component));
}
/**
* Add a path node.
*
* @param pathTree
* The target node to add.
*/
public void addChild(PathTree pathTree)
{
children.put(pathTree.id, pathTree);
pathTree.parent = this;
}
}
}