com.google.errorprone.bugpatterns.ComparableAndComparator Maven / Gradle / Ivy
/* Copyright 2017 The Error Prone 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.errorprone.bugpatterns;
import static com.google.errorprone.BugPattern.SeverityLevel.WARNING;
import static com.google.errorprone.matchers.Matchers.allOf;
import static com.google.errorprone.matchers.Matchers.isSubtypeOf;
import static com.google.errorprone.util.ASTHelpers.getSymbol;
import com.google.common.collect.Lists;
import com.google.errorprone.BugPattern;
import com.google.errorprone.VisitorState;
import com.google.errorprone.bugpatterns.BugChecker.ClassTreeMatcher;
import com.google.errorprone.matchers.Description;
import com.google.errorprone.matchers.Matcher;
import com.sun.source.tree.ClassTree;
import com.sun.source.tree.Tree;
import com.sun.tools.javac.code.Symbol.ClassSymbol;
import java.util.Comparator;
import java.util.List;
/**
* @author [email protected] (Marsela Sulku)
* @author [email protected] (Maria Sam)
*/
@BugPattern(
name = "ComparableAndComparator",
summary = "Class should not implement both `Comparable` and `Comparator`",
severity = WARNING)
public class ComparableAndComparator extends BugChecker implements ClassTreeMatcher {
private static final String COMPARABLE = Comparable.class.getCanonicalName();
private static final String COMPARATOR = Comparator.class.getCanonicalName();
/** Matches if a class/interface is subtype of Comparable */
private static final Matcher COMPARABLE_MATCHER = isSubtypeOf(COMPARABLE);
/** Matches if a class/interface is subtype of Comparator */
private static final Matcher COMPARATOR_MATCHER = isSubtypeOf(COMPARATOR);
/** Matches if a class/interface is subtype of Comparable _and_ Comparator */
private static final Matcher COMPARABLE_AND_COMPARATOR_MATCHER =
allOf(COMPARABLE_MATCHER, COMPARATOR_MATCHER);
private static boolean matchAnySuperType(ClassTree tree, VisitorState state) {
List superTypes = Lists.newArrayList(tree.getImplementsClause());
Tree superClass = tree.getExtendsClause();
if (superClass != null) {
superTypes.add(superClass);
}
return superTypes.stream()
.anyMatch(superType -> COMPARABLE_AND_COMPARATOR_MATCHER.matches(superType, state));
}
@Override
public Description matchClass(ClassTree tree, VisitorState state) {
if (COMPARABLE_AND_COMPARATOR_MATCHER.matches(tree, state)) {
// Filter out inherited case to not warn again
if (matchAnySuperType(tree, state)) {
return Description.NO_MATCH;
}
// enums already implement Comparable and are simultaneously allowed to implement Comparator
ClassSymbol symbol = getSymbol(tree);
if (symbol.isEnum()) {
return Description.NO_MATCH;
}
return describeMatch(tree);
}
return Description.NO_MATCH;
}
}