com.google.errorprone.bugpatterns.ClassCanBeStatic Maven / Gradle / Ivy
/*
* Copyright 2012 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.Description.NO_MATCH;
import static com.google.errorprone.util.ASTHelpers.hasAnnotation;
import com.google.errorprone.BugPattern;
import com.google.errorprone.BugPattern.StandardTags;
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.ASTHelpers;
import com.sun.source.tree.ClassTree;
import com.sun.tools.javac.code.Symbol.ClassSymbol;
import javax.lang.model.element.Modifier;
import javax.lang.model.element.NestingKind;
/**
* @author [email protected] (Alex Loh)
* @author [email protected] (Liam Miller-Cushon)
*/
@BugPattern(
summary = "Inner class is non-static but does not reference enclosing class",
severity = WARNING,
tags = {StandardTags.STYLE, StandardTags.PERFORMANCE})
public class ClassCanBeStatic extends BugChecker implements ClassTreeMatcher {
private static final String REFASTER_ANNOTATION =
"com.google.errorprone.refaster.annotation.BeforeTemplate";
@Override
public Description matchClass(ClassTree tree, VisitorState state) {
ClassSymbol currentClass = ASTHelpers.getSymbol(tree);
if (currentClass == null || !currentClass.hasOuterInstance()) {
return NO_MATCH;
}
if (currentClass.getNestingKind() != NestingKind.MEMBER) {
// local or anonymous classes can't be static
return NO_MATCH;
}
switch (currentClass.owner.enclClass().getNestingKind()) {
case TOP_LEVEL:
break;
case MEMBER:
// class is nested inside an inner class, so it can't be static
if (currentClass.owner.enclClass().hasOuterInstance()) {
return NO_MATCH;
}
break;
case LOCAL:
case ANONYMOUS:
// members of local and anonymous classes can't be static
return NO_MATCH;
}
if (tree.getExtendsClause() != null
&& ASTHelpers.getType(tree.getExtendsClause()).tsym.hasOuterInstance()) {
return NO_MATCH;
}
if (CanBeStaticAnalyzer.referencesOuter(tree, currentClass, state)) {
return NO_MATCH;
}
if (tree.getMembers().stream().anyMatch(m -> hasAnnotation(m, REFASTER_ANNOTATION, state))) {
return NO_MATCH;
}
return describeMatch(
tree,
SuggestedFixes.addModifiers(tree, state, Modifier.STATIC).orElse(SuggestedFix.emptyFix()));
}
}