PathUtil.java
/*
* Copyright 2008 The Closure Compiler Authors.
*
* Licensed 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 com.google.javascript.jscomp.deps;
import static com.google.common.base.StandardSystemProperty.USER_DIR;
import com.google.common.base.CharMatcher;
import com.google.common.base.Joiner;
import com.google.common.base.Splitter;
import com.google.common.base.Strings;
import com.google.common.collect.Lists;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
/**
* Utility methods for manipulation of UNIX-like paths.
* TODO(tbreisacher): We can probably nuke this entire class and replace it with
* https://docs.oracle.com/javase/8/docs/api/java/nio/file/Path.html
*
*/
public final class PathUtil {
private static final CharMatcher SLASH_MATCHER = CharMatcher.is('/');
private static final CharMatcher NON_SLASH_MATCHER = CharMatcher.isNot('/');
private PathUtil() {
}
/**
* Removes all ../ and ./ entries from within the given path. If there are extra ..s that move
* beyond the first directory given, they are removed.
*
* Examples:
* "a/b/../c" results in "a/c"
* "./foo/./../bar" results in "bar"
* "a/.." results in ""
* "a/../../foo" results in "foo"
*
* @param path The path to remove dots from.
* @return The path with all dots collapsed.
*/
public static String collapseDots(String path) {
path = removeExtraneousSlashes(path);
// Optimization: Most paths don't contain dots.
if (!path.contains(".")) {
return path;
}
List<String> dstFragments = new ArrayList<>();
for (String fragment : Splitter.on('/').split(path)) {
if (fragment.equals("..")) {
if (!dstFragments.isEmpty()) {
dstFragments.remove(dstFragments.size() - 1);
}
} else if (!fragment.equals(".")) {
dstFragments.add(fragment);
}
}
// Special case for Join.join([""]); -> "/"
if (dstFragments.size() == 1 && dstFragments.get(0).isEmpty()) {
return "/";
}
return Joiner.on("/").join(dstFragments);
}
/**
* Determines if a path is absolute or not by testing for the presence of "/"
* at the front of the string.
*
* @param path The path to test
* @return true if the path starts with DELIMITER, false otherwise.
*/
static boolean isAbsolute(String path) {
return path.startsWith("/");
}
/**
* Removes extra slashes from a path. Leading slash is preserved, trailing
* slash is stripped, and any runs of more than one slash in the middle is
* replaced by a single slash.
*/
static String removeExtraneousSlashes(String s) {
int lastNonSlash = NON_SLASH_MATCHER.lastIndexIn(s);
if (lastNonSlash != -1) {
s = s.substring(0, lastNonSlash + 1);
}
return SLASH_MATCHER.collapseFrom(s, '/');
}
/**
* Converts the given path into an absolute one. This prepends the current
* working directory and removes all .'s from the path. If an absolute path
* is given, it will not be prefixed.
*
* <p>Unlike File.getAbsolutePath(), this function does remove .'s from the
* path and unlike File.getCanonicalPath(), this function does not resolve
* symlinks and does not use filesystem calls.</p>
*
* @param path The path to make absolute.
* @return The path made absolute.
*/
public static String makeAbsolute(String path) {
return makeAbsolute(path, USER_DIR.value());
}
/**
* Converts the given path into an absolute one. This prepends the given
* rootPath and removes all .'s from the path. If an absolute path is given,
* it will not be prefixed.
*
* <p>Unlike File.getAbsolutePath(), this function does remove .'s from the
* path and unlike File.getCanonicalPath(), this function does not resolve
* symlinks and does not use filesystem calls.</p>
*
* @param rootPath The path to prefix to path if path is not already absolute.
* @param path The path to make absolute.
* @return The path made absolute.
*/
public static String makeAbsolute(String path, String rootPath) {
if (!isAbsolute(path)) {
path = rootPath + "/" + path;
}
return collapseDots(path);
}
/**
* Returns targetPath relative to basePath.
*
* <p>basePath and targetPath must either both be relative, or both be
* absolute paths.</p>
*
* <p>This function is different from makeRelative
* in that it is able to add in ../ components and collapse existing ones as well.</p>
*
* Examples:
* base="some/relative/path" target="some/relative/path/foo" return="foo"
* base="some/relative/path" target="some/relative" return=".."
* base="some/relative/path" target="foo/bar" return="../../../foo/bar"
* base="/some/abs/path" target="/foo/bar" return="../../../foo/bar"
*
* @param basePath The path to make targetPath relative to.
* @param targetPath The path to make relative.
* @return A path relative to targetPath. The returned value will never start
* with a slash.
*/
public static String makeRelative(String basePath, String targetPath) {
// Ensure the paths are both absolute or both relative.
if (isAbsolute(basePath) !=
isAbsolute(targetPath)) {
throw new IllegalArgumentException(
"Paths must both be relative or both absolute.\n" +
" basePath: " + basePath + "\n" +
" targetPath: " + targetPath);
}
basePath = collapseDots(basePath);
targetPath = collapseDots(targetPath);
String[] baseFragments = basePath.split("/");
String[] targetFragments = targetPath.split("/");
int i = -1;
do {
i += 1;
if (i == baseFragments.length && i == targetFragments.length) {
// Eg) base: /java/com/google
// target: /java/com/google
// result: . <-- . is better than "" since "" + "/path" = "/path"
return ".";
} else if (i == baseFragments.length) {
// Eg) base: /java/com/google
// target: /java/com/google/c/ui
// result: c/ui
return Joiner.on("/").join(
Lists.newArrayList(
Arrays.asList(targetFragments).listIterator(i)));
} else if (i == targetFragments.length) {
// Eg) base: /java/com/google/c/ui
// target: /java/com/google
// result: ../..
return Strings.repeat("../", baseFragments.length - i - 1) + "..";
}
} while (baseFragments[i].equals(targetFragments[i]));
// Eg) base: /java/com/google/c
// target: /java/com/google/common/base
// result: ../common/base
return Strings.repeat("../", baseFragments.length - i) +
Joiner.on("/").join(
Lists.newArrayList(Arrays.asList(targetFragments).listIterator(i)));
}
}