/
ProtectedMembersInFinalClass.java
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/
ProtectedMembersInFinalClass.java
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/*
* Copyright 2020 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.common.collect.ImmutableList.toImmutableList;
import static com.google.errorprone.BugPattern.SeverityLevel.WARNING;
import static com.google.errorprone.matchers.Description.NO_MATCH;
import static com.google.errorprone.matchers.Matchers.hasModifier;
import static java.util.stream.Collectors.joining;
import static javax.lang.model.element.Modifier.FINAL;
import static javax.lang.model.element.Modifier.PROTECTED;
import com.google.common.collect.ImmutableList;
import com.google.errorprone.BugPattern;
import com.google.errorprone.VisitorState;
import com.google.errorprone.bugpatterns.BugChecker.ClassTreeMatcher;
import com.google.errorprone.fixes.SuggestedFix;
import com.google.errorprone.fixes.SuggestedFixes;
import com.google.errorprone.matchers.Description;
import com.google.errorprone.matchers.Matcher;
import com.google.errorprone.util.ASTHelpers;
import com.sun.source.tree.ClassTree;
import com.sun.source.tree.MethodTree;
import com.sun.source.tree.Tree;
import com.sun.source.tree.VariableTree;
import com.sun.tools.javac.code.Symbol;
import javax.lang.model.element.Modifier;
/**
* Flags protected members in final classes.
*
* @author bhagwani@google.com (Sumit Bhagwani)
*/
@BugPattern(
summary = "Protected members in final classes can be package-private",
severity = WARNING)
public class ProtectedMembersInFinalClass extends BugChecker implements ClassTreeMatcher {
private static final Matcher<ClassTree> HAS_FINAL = hasModifier(FINAL);
private static final Matcher<Tree> HAS_PROTECTED = hasModifier(PROTECTED);
private static boolean methodHasNoParentMethod(MethodTree methodTree, VisitorState state) {
return ASTHelpers.findSuperMethods(ASTHelpers.getSymbol(methodTree), state.getTypes())
.isEmpty();
}
@Override
public Description matchClass(ClassTree tree, VisitorState state) {
if (!HAS_FINAL.matches(tree, state)) {
return NO_MATCH;
}
ImmutableList<Tree> relevantMembers =
tree.getMembers().stream()
.filter(m -> (m instanceof MethodTree || m instanceof VariableTree))
.filter(m -> HAS_PROTECTED.matches(m, state))
.filter(
m -> !(m instanceof MethodTree) || methodHasNoParentMethod((MethodTree) m, state))
.filter(m -> !isSuppressed(m, state))
.collect(toImmutableList());
if (relevantMembers.isEmpty()) {
return NO_MATCH;
}
SuggestedFix.Builder fix = SuggestedFix.builder();
relevantMembers.forEach(
m -> SuggestedFixes.removeModifiers(m, state, Modifier.PROTECTED).ifPresent(fix::merge));
if (fix.isEmpty()) {
return NO_MATCH;
}
String message =
String.format(
"Make members of final classes package-private: %s",
relevantMembers.stream()
.map(
m -> {
Symbol symbol = ASTHelpers.getSymbol(m);
return symbol.isConstructor()
? symbol.owner.name.toString()
: symbol.name.toString();
})
.collect(joining(", ")));
return buildDescription(relevantMembers.get(0)).setMessage(message).addFix(fix.build()).build();
}
}