PkgImportControl.java
////////////////////////////////////////////////////////////////////////////////
// checkstyle: Checks Java source code for adherence to a set of rules.
// Copyright (C) 2001-2021 the original author or authors.
//
// This library 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 2.1 of the License, or (at your option) any later version.
//
// This library 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 library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
////////////////////////////////////////////////////////////////////////////////
package com.puppycrawl.tools.checkstyle.checks.imports;
import java.util.ArrayList;
import java.util.List;
import java.util.regex.Pattern;
/**
* Represents a tree of import rules for a specific package.
* Each instance may have zero or more children. A child may
* be a sub-package, a class, or an allow/disallow rule.
*/
class PkgImportControl extends AbstractImportControl {
/** The package separator: "." */
private static final String DOT = ".";
/** A pattern matching the package separator: "." */
private static final Pattern DOT_PATTERN = Pattern.compile(DOT, Pattern.LITERAL);
/** The regex for the package separator: "\\.". */
private static final String DOT_REGEX = "\\.";
/** List of children {@link AbstractImportControl} objects. */
private final List<AbstractImportControl> children = new ArrayList<>();
/** The full name for the package. */
private final String fullPackageName;
/**
* The regex pattern for partial match (exact and for subpackages) - only not
* null if regex is true.
*/
private final Pattern patternForPartialMatch;
/** The regex pattern for exact matches - only not null if regex is true. */
private final Pattern patternForExactMatch;
/** If this package represents a regular expression. */
private final boolean regex;
/**
* Construct a root, package node.
*
* @param packageName the name of the package.
* @param regex flags interpretation of name as regex pattern.
* @param strategyOnMismatch strategy in a case if matching allow/disallow rule was not found.
*/
/* package */ PkgImportControl(String packageName, boolean regex,
MismatchStrategy strategyOnMismatch) {
super(null, strategyOnMismatch);
this.regex = regex;
if (regex) {
// ensure that fullName is a self-contained regular expression
fullPackageName = encloseInGroup(packageName);
patternForPartialMatch = createPatternForPartialMatch(fullPackageName);
patternForExactMatch = createPatternForExactMatch(fullPackageName);
}
else {
fullPackageName = packageName;
patternForPartialMatch = null;
patternForExactMatch = null;
}
}
/**
* Construct a sub-package node. The concatenation of regular expressions needs special care:
* see {@link #ensureSelfContainedRegex(String, boolean)} for more details.
*
* @param parent the parent package.
* @param subPackageName the name of the current sub-package.
* @param regex flags interpretation of name as regex pattern.
* @param strategyOnMismatch strategy in a case if matching allow/disallow rule was not found.
*/
/* package */ PkgImportControl(PkgImportControl parent, String subPackageName, boolean regex,
MismatchStrategy strategyOnMismatch) {
super(parent, strategyOnMismatch);
if (regex || parent.regex) {
// regex gets inherited
final String parentRegex = ensureSelfContainedRegex(parent.fullPackageName,
parent.regex);
final String thisRegex = ensureSelfContainedRegex(subPackageName, regex);
fullPackageName = parentRegex + DOT_REGEX + thisRegex;
patternForPartialMatch = createPatternForPartialMatch(fullPackageName);
patternForExactMatch = createPatternForExactMatch(fullPackageName);
this.regex = true;
}
else {
fullPackageName = parent.fullPackageName + DOT + subPackageName;
patternForPartialMatch = null;
patternForExactMatch = null;
this.regex = false;
}
}
/**
* Returns a regex that is suitable for concatenation by 1) either converting a plain string
* into a regular expression (handling special characters) or 2) by enclosing {@code input} in
* a (non-capturing) group if {@code input} already is a regular expression.
*
* <p>1) When concatenating a non-regex package component (like "org.google") with a regex
* component (like "[^.]+") the other component has to be converted into a regex too, see
* {@link #toRegex(String)}.
*
* <p>2) The grouping is strictly necessary if a) {@code input} is a regular expression that b)
* contains the alteration character ('|') and if c) the pattern is not already enclosed in a
* group - as you see in this example: {@code parent="com|org", child="common|uncommon"} will
* result in the pattern {@code "(?:org|com)\.(?common|uncommon)"} what will match
* {@code "com.common"}, {@code "com.uncommon"}, {@code "org.common"}, and {@code
* "org.uncommon"}. Without the grouping it would be {@code "com|org.common|uncommon"} which
* would match {@code "com"}, {@code "org.common"}, and {@code "uncommon"}, which clearly is
* undesirable. Adding the group fixes this.
*
* <p>For simplicity the grouping is added to regular expressions unconditionally.
*
* @param input the input string.
* @param alreadyRegex signals if input already is a regular expression.
* @return a regex string.
*/
private static String ensureSelfContainedRegex(String input, boolean alreadyRegex) {
final String result;
if (alreadyRegex) {
result = encloseInGroup(input);
}
else {
result = toRegex(input);
}
return result;
}
/**
* Enclose {@code expression} in a (non-capturing) group.
*
* @param expression the input regular expression
* @return a grouped pattern.
*/
private static String encloseInGroup(String expression) {
return "(?:" + expression + ")";
}
/**
* Converts a normal package name into a regex pattern by escaping all
* special characters that may occur in a java package name.
*
* @param input the input string.
* @return a regex string.
*/
private static String toRegex(String input) {
return DOT_PATTERN.matcher(input).replaceAll(DOT_REGEX);
}
/**
* Creates a Pattern from {@code expression} that matches exactly and child packages.
*
* @param expression a self-contained regular expression matching the full package exactly.
* @return a Pattern.
*/
private static Pattern createPatternForPartialMatch(String expression) {
// javadoc of encloseInGroup() explains how to concatenate regular expressions
// no grouping needs to be added to fullPackage since this already have been done.
return Pattern.compile(expression + "(?:\\..*)?");
}
/**
* Creates a Pattern from {@code expression}.
*
* @param expression a self-contained regular expression matching the full package exactly.
* @return a Pattern.
*/
private static Pattern createPatternForExactMatch(String expression) {
return Pattern.compile(expression);
}
@Override
public AbstractImportControl locateFinest(String forPkg, String forFileName) {
AbstractImportControl finestMatch = null;
// Check if we are a match.
if (matchesAtFront(forPkg)) {
// If there won't be match so I am the best there is.
finestMatch = this;
// Check if any of the children match.
for (AbstractImportControl child : children) {
final AbstractImportControl match = child.locateFinest(forPkg, forFileName);
if (match != null) {
finestMatch = match;
break;
}
}
}
return finestMatch;
}
/**
* Adds new child import control.
*
* @param importControl child import control
*/
public void addChild(AbstractImportControl importControl) {
children.add(importControl);
}
/**
* Matches other package name exactly or partially at front.
*
* @param pkg the package to compare with.
* @return if it matches.
*/
private boolean matchesAtFront(String pkg) {
final boolean result;
if (regex) {
result = patternForPartialMatch.matcher(pkg).matches();
}
else {
result = matchesAtFrontNoRegex(pkg);
}
return result;
}
/**
* Non-regex case. Ensure a trailing dot for subpackages, i.e. "com.puppy"
* will match "com.puppy.crawl" but not "com.puppycrawl.tools".
*
* @param pkg the package to compare with.
* @return if it matches.
*/
private boolean matchesAtFrontNoRegex(String pkg) {
return pkg.startsWith(fullPackageName)
&& (pkg.length() == fullPackageName.length()
|| pkg.charAt(fullPackageName.length()) == '.');
}
@Override
protected boolean matchesExactly(String pkg, String fileName) {
final boolean result;
if (regex) {
result = patternForExactMatch.matcher(pkg).matches();
}
else {
result = fullPackageName.equals(pkg);
}
return result;
}
}