org.apache.maven.shared.utils.PathTool Maven / Gradle / Ivy
package org.apache.maven.shared.utils;
/*
* 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.
*/
import java.io.File;
import java.util.StringTokenizer;
import javax.annotation.Nonnull;
import javax.annotation.Nullable;
/**
* Path tool contains static methods to assist in determining path-related
* information such as relative paths.
*
* This class originally got developed at Apache Anakia and later maintained
* in maven-utils of Apache Maven-1.
* Some external fixes by Apache Committers have been applied later.
*/
public class PathTool
{
/**
* Determines the relative path of a filename from a base directory.
* This method is useful in building relative links within pages of
* a web site. It provides similar functionality to Anakia's
* $relativePath context variable. The arguments to
* this method may contain either forward or backward slashes as
* file separators. The relative path returned is formed using
* forward slashes as it is expected this path is to be used as a
* link in a web page (again mimicking Anakia's behavior).
*
* This method is thread-safe.
*
*
* PathTool.getRelativePath( null, null ) = ""
* PathTool.getRelativePath( null, "/usr/local/java/bin" ) = ""
* PathTool.getRelativePath( "/usr/local/", null ) = ""
* PathTool.getRelativePath( "/usr/local/", "/usr/local/java/bin" ) = ".."
* PathTool.getRelativePath( "/usr/local/", "/usr/local/java/bin/java.sh" ) = "../.."
* PathTool.getRelativePath( "/usr/local/java/bin/java.sh", "/usr/local/" ) = ""
*
*
* @param basedir The base directory.
* @param filename The filename that is relative to the base
* directory.
* @return The relative path of the filename from the base
* directory. This value is not terminated with a forward slash.
* A zero-length string is returned if: the filename is not relative to
* the base directory, basedir is null or zero-length,
* or filename is null or zero-length.
*/
public static String getRelativePath( @Nullable String basedir, @Nullable String filename )
{
basedir = uppercaseDrive( basedir );
filename = uppercaseDrive( filename );
/*
* Verify the arguments and make sure the filename is relative
* to the base directory.
*/
if ( basedir == null || basedir.length() == 0 || filename == null || filename.length() == 0
|| !filename.startsWith( basedir ) )
{
return "";
}
/*
* Normalize the arguments. First, determine the file separator
* that is being used, then strip that off the end of both the
* base directory and filename.
*/
String separator = determineSeparator( filename );
basedir = StringUtils.chompLast( basedir, separator );
filename = StringUtils.chompLast( filename, separator );
/*
* Remove the base directory from the filename to end up with a
* relative filename (relative to the base directory). This
* filename is then used to determine the relative path.
*/
String relativeFilename = filename.substring( basedir.length() );
return determineRelativePath( relativeFilename, separator );
}
/**
* This method can calculate the relative path between two pathes on a file system.
*
*
* PathTool.getRelativeFilePath( null, null ) = ""
* PathTool.getRelativeFilePath( null, "/usr/local/java/bin" ) = ""
* PathTool.getRelativeFilePath( "/usr/local", null ) = ""
* PathTool.getRelativeFilePath( "/usr/local", "/usr/local/java/bin" ) = "java/bin"
* PathTool.getRelativeFilePath( "/usr/local", "/usr/local/java/bin/" ) = "java/bin"
* PathTool.getRelativeFilePath( "/usr/local/java/bin", "/usr/local/" ) = "../.."
* PathTool.getRelativeFilePath( "/usr/local/", "/usr/local/java/bin/java.sh" ) = "java/bin/java.sh"
* PathTool.getRelativeFilePath( "/usr/local/java/bin/java.sh", "/usr/local/" ) = "../../.."
* PathTool.getRelativeFilePath( "/usr/local/", "/bin" ) = "../../bin"
* PathTool.getRelativeFilePath( "/bin", "/usr/local/" ) = "../usr/local"
*
* Note: On Windows based system, the / character should be replaced by \ character.
*
* @param oldPath old path
* @param newPath new path
* @return a relative file path from oldPath.
*/
public static String getRelativeFilePath( final String oldPath, final String newPath )
{
if ( StringUtils.isEmpty( oldPath ) || StringUtils.isEmpty( newPath ) )
{
return "";
}
// normalise the path delimiters
String fromPath = new File( oldPath ).getPath();
String toPath = new File( newPath ).getPath();
// strip any leading slashes if its a windows path
if ( toPath.matches( "^\\[a-zA-Z]:" ) )
{
toPath = toPath.substring( 1 );
}
if ( fromPath.matches( "^\\[a-zA-Z]:" ) )
{
fromPath = fromPath.substring( 1 );
}
// lowercase windows drive letters.
if ( fromPath.startsWith( ":", 1 ) )
{
fromPath = Character.toLowerCase( fromPath.charAt( 0 ) ) + fromPath.substring( 1 );
}
if ( toPath.startsWith( ":", 1 ) )
{
toPath = Character.toLowerCase( toPath.charAt( 0 ) ) + toPath.substring( 1 );
}
// check for the presence of windows drives. No relative way of
// traversing from one to the other.
if ( ( toPath.startsWith( ":", 1 ) && fromPath.startsWith( ":", 1 ) )
&& ( !toPath.substring( 0, 1 ).equals( fromPath.substring( 0, 1 ) ) ) )
{
// they both have drive path element but they dont match, no
// relative path
return null;
}
if ( ( toPath.startsWith( ":", 1 ) && !fromPath.startsWith( ":", 1 ) )
|| ( !toPath.startsWith( ":", 1 ) && fromPath.startsWith( ":", 1 ) ) )
{
// one has a drive path element and the other doesnt, no relative
// path.
return null;
}
String resultPath = buildRelativePath( toPath, fromPath, File.separatorChar );
if ( newPath.endsWith( File.separator ) && !resultPath.endsWith( File.separator ) )
{
return resultPath + File.separator;
}
return resultPath;
}
// ----------------------------------------------------------------------
// Private methods
// ----------------------------------------------------------------------
/**
* Determines the relative path of a filename. For each separator
* within the filename (except the leading if present), append the
* "../" string to the return value.
*
* @param filename The filename to parse.
* @param separator The separator used within the filename.
* @return The relative path of the filename. This value is not
* terminated with a forward slash. A zero-length string is
* returned if: the filename is zero-length.
*/
private @Nonnull static String determineRelativePath( @Nonnull String filename, @Nonnull String separator )
{
if ( filename.length() == 0 )
{
return "";
}
/*
* Count the slashes in the relative filename, but exclude the
* leading slash. If the path has no slashes, then the filename
* is relative to the current directory.
*/
int slashCount = StringUtils.countMatches( filename, separator ) - 1;
if ( slashCount <= 0 )
{
return ".";
}
/*
* The relative filename contains one or more slashes indicating
* that the file is within one or more directories. Thus, each
* slash represents a "../" in the relative path.
*/
StringBuilder sb = new StringBuilder();
for ( int i = 0; i < slashCount; i++ )
{
sb.append( "../" );
}
/*
* Finally, return the relative path but strip the trailing
* slash to mimic Anakia's behavior.
*/
return StringUtils.chop( sb.toString() );
}
/**
* Helper method to determine the file separator (forward or
* backward slash) used in a filename. The slash that occurs more
* often is returned as the separator.
*
* @param filename The filename parsed to determine the file
* separator.
* @return The file separator used within filename.
* This value is either a forward or backward slash.
*/
private static String determineSeparator( String filename )
{
int forwardCount = StringUtils.countMatches( filename, "/" );
int backwardCount = StringUtils.countMatches( filename, "\\" );
return forwardCount >= backwardCount ? "/" : "\\";
}
/**
* Cygwin prefers lowercase drive letters, but other parts of maven use uppercase
*
* @param path old path
* @return String
*/
static String uppercaseDrive( @Nullable String path )
{
if ( path == null )
{
return null;
}
if ( path.length() >= 2 && path.charAt( 1 ) == ':' )
{
path = Character.toUpperCase( path.charAt( 0 ) ) + path.substring( 1 );
}
return path;
}
private @Nonnull static String buildRelativePath( @Nonnull String toPath, @Nonnull String fromPath, final char separatorChar )
{
// use tokeniser to traverse paths and for lazy checking
StringTokenizer toTokeniser = new StringTokenizer( toPath, String.valueOf( separatorChar ) );
StringTokenizer fromTokeniser = new StringTokenizer( fromPath, String.valueOf( separatorChar ) );
int count = 0;
// walk along the to path looking for divergence from the from path
while ( toTokeniser.hasMoreTokens() && fromTokeniser.hasMoreTokens() )
{
if ( separatorChar == '\\' )
{
if ( !fromTokeniser.nextToken().equalsIgnoreCase( toTokeniser.nextToken() ) )
{
break;
}
}
else
{
if ( !fromTokeniser.nextToken().equals( toTokeniser.nextToken() ) )
{
break;
}
}
count++;
}
// reinitialise the tokenisers to count positions to retrieve the
// gobbled token
toTokeniser = new StringTokenizer( toPath, String.valueOf( separatorChar ) );
fromTokeniser = new StringTokenizer( fromPath, String.valueOf( separatorChar ) );
while ( count-- > 0 )
{
fromTokeniser.nextToken();
toTokeniser.nextToken();
}
StringBuilder relativePath = new StringBuilder();
// add back refs for the rest of from location.
while ( fromTokeniser.hasMoreTokens() )
{
fromTokeniser.nextToken();
relativePath.append( ".." );
if ( fromTokeniser.hasMoreTokens() )
{
relativePath.append( separatorChar );
}
}
if ( relativePath.length() != 0 && toTokeniser.hasMoreTokens() )
{
relativePath.append( separatorChar );
}
// add fwd fills for whatevers left of newPath.
while ( toTokeniser.hasMoreTokens() )
{
relativePath.append( toTokeniser.nextToken() );
if ( toTokeniser.hasMoreTokens() )
{
relativePath.append( separatorChar );
}
}
return relativePath.toString();
}
}
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