com.google.errorprone.bugpatterns.EqualsReference 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.ERROR;
import com.google.errorprone.BugPattern;
import com.google.errorprone.VisitorState;
import com.google.errorprone.bugpatterns.BugChecker.MethodTreeMatcher;
import com.google.errorprone.matchers.Description;
import com.google.errorprone.matchers.Matchers;
import com.google.errorprone.util.ASTHelpers;
import com.sun.source.tree.ExpressionTree;
import com.sun.source.tree.IdentifierTree;
import com.sun.source.tree.MemberSelectTree;
import com.sun.source.tree.MethodInvocationTree;
import com.sun.source.tree.MethodTree;
import com.sun.source.tree.VariableTree;
import com.sun.source.util.TreeScanner;
import com.sun.tools.javac.code.Symbol.VarSymbol;
import java.util.Objects;
/**
* @author [email protected] (Maria Sam)
*/
@BugPattern(
summary =
"== must be used in equals method to check equality to itself"
+ " or an infinite loop will occur.",
severity = ERROR)
public class EqualsReference extends BugChecker implements MethodTreeMatcher {
@Override
public Description matchMethod(MethodTree methodTree, VisitorState visitorState) {
if (Matchers.equalsMethodDeclaration().matches(methodTree, visitorState)) {
VariableTree variableTree = methodTree.getParameters().get(0);
VarSymbol varSymbol = ASTHelpers.getSymbol(variableTree);
TreeScannerEquals treeScannerEquals = new TreeScannerEquals(methodTree);
treeScannerEquals.scan(methodTree.getBody(), varSymbol);
if (treeScannerEquals.hasIllegalEquals) {
return describeMatch(methodTree);
}
}
return Description.NO_MATCH;
}
private static class TreeScannerEquals extends TreeScanner {
private boolean hasIllegalEquals = false;
private final MethodTree methodTree;
public TreeScannerEquals(MethodTree currMethodTree) {
methodTree = currMethodTree;
}
@Override
public Void visitMethodInvocation(
MethodInvocationTree methodInvocationTree, VarSymbol varSymbol) {
ExpressionTree methodSelectTree = methodInvocationTree.getMethodSelect();
MemberSelectTree memberSelectTree;
boolean hasParameterAndSameSymbol =
methodInvocationTree.getArguments().size() == 1
&& Objects.equals(
ASTHelpers.getSymbol(methodInvocationTree.getArguments().get(0)), varSymbol);
if (methodSelectTree instanceof MemberSelectTree) {
memberSelectTree = (MemberSelectTree) methodSelectTree;
ExpressionTree e = memberSelectTree.getExpression();
// this.equals(o)
// not using o.equals(this) because all instances of this were false positives
// (people checked to see if o was an instance of this class)
if (e instanceof IdentifierTree
&& ((IdentifierTree) e).getName().contentEquals("this")
&& Objects.equals(
ASTHelpers.getSymbol(methodTree), ASTHelpers.getSymbol(memberSelectTree))
&& hasParameterAndSameSymbol) {
hasIllegalEquals = true;
}
} else if (methodInvocationTree.getMethodSelect() instanceof IdentifierTree) {
IdentifierTree methodSelect = (IdentifierTree) methodInvocationTree.getMethodSelect();
if (Objects.equals(ASTHelpers.getSymbol(methodTree), ASTHelpers.getSymbol(methodSelect))
&& hasParameterAndSameSymbol) {
hasIllegalEquals = true;
}
}
return super.visitMethodInvocation(methodInvocationTree, varSymbol);
}
}
}