com.google.errorprone.bugpatterns.InterfaceWithOnlyStatics Maven / Gradle / Ivy
/*
* Copyright 2018 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.Iterables.getLast;
import static com.google.errorprone.bugpatterns.inject.dagger.DaggerAnnotations.isAnyModule;
import static com.google.errorprone.util.ASTHelpers.createPrivateConstructor;
import static com.google.errorprone.util.ASTHelpers.getStartPosition;
import static com.google.errorprone.util.ASTHelpers.getSymbol;
import com.google.errorprone.BugPattern;
import com.google.errorprone.BugPattern.SeverityLevel;
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.util.ErrorProneToken;
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 com.sun.tools.javac.code.Symbol.ClassSymbol;
import com.sun.tools.javac.parser.Tokens.TokenKind;
import java.util.List;
import javax.lang.model.element.Modifier;
/**
* Bugpattern to detect interfaces used only to store static fields/methods.
*
* @author [email protected] (Graeme Morgan)
*/
@BugPattern(
name = "InterfaceWithOnlyStatics",
summary =
"This interface only contains static fields and methods; consider making it a final class "
+ "instead to prevent subclassing.",
severity = SeverityLevel.WARNING)
public final class InterfaceWithOnlyStatics extends BugChecker implements ClassTreeMatcher {
@Override
public Description matchClass(ClassTree tree, VisitorState state) {
if (!tree.getImplementsClause().isEmpty()) {
return Description.NO_MATCH;
}
if (isAnyModule().matches(tree, state)) {
return Description.NO_MATCH;
}
List members = tree.getMembers();
ClassSymbol symbol = getSymbol(tree);
if (symbol == null || !symbol.isInterface() || symbol.isAnnotationType()) {
return Description.NO_MATCH;
}
int staticMembers = 0;
int nonStaticMembers = 0;
for (Tree member : members) {
Symbol memberSymbol = getSymbol(member);
if (memberSymbol == null) {
return Description.NO_MATCH;
}
if (memberSymbol.isStatic()) {
staticMembers++;
} else {
nonStaticMembers++;
}
}
if (nonStaticMembers > 0 || staticMembers == 0) {
return Description.NO_MATCH;
}
SuggestedFix.Builder suggestedFix = SuggestedFix.builder();
for (Tree member : members) {
if (member instanceof VariableTree) {
VariableTree variableTree = (VariableTree) member;
SuggestedFixes.addModifiers(
variableTree, state, Modifier.FINAL, Modifier.STATIC, Modifier.PUBLIC)
.ifPresent(suggestedFix::merge);
}
if (member instanceof MethodTree) {
MethodTree methodTree = (MethodTree) member;
SuggestedFixes.addModifiers(methodTree, state, Modifier.PUBLIC)
.ifPresent(suggestedFix::merge);
}
}
suggestedFix
.merge(fixClass(tree, state))
.postfixWith(getLast(members), "\n" + createPrivateConstructor(tree));
return describeMatch(tree, suggestedFix.build());
}
private static SuggestedFix fixClass(ClassTree classTree, VisitorState state) {
int startPos = getStartPosition(classTree);
int endPos = getStartPosition(classTree.getMembers().get(0));
List tokens = state.getOffsetTokens(startPos, endPos);
String modifiers =
getSymbol(classTree).owner.enclClass() == null ? "final class" : "static final class";
SuggestedFix.Builder fix = SuggestedFix.builder();
for (ErrorProneToken token : tokens) {
if (token.kind() == TokenKind.INTERFACE) {
fix.replace(token.pos(), token.endPos(), modifiers);
}
}
return fix.build();
}
}