com.google.errorprone.bugpatterns.AbstractMethodReturnsNull Maven / Gradle / Ivy
/*
* 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.errorprone.matchers.Description.NO_MATCH;
import static com.sun.source.tree.Tree.Kind.NULL_LITERAL;
import com.google.errorprone.VisitorState;
import com.google.errorprone.bugpatterns.BugChecker.ReturnTreeMatcher;
import com.google.errorprone.fixes.Fix;
import com.google.errorprone.matchers.Description;
import com.google.errorprone.matchers.Matcher;
import com.sun.source.tree.MethodTree;
import com.sun.source.tree.ReturnTree;
import com.sun.source.tree.StatementTree;
import com.sun.source.util.TreePath;
import java.util.Optional;
/** Superclass for checks that method implementations that directly {@code return null}. */
abstract class AbstractMethodReturnsNull extends BugChecker implements ReturnTreeMatcher {
private final Matcher methodTreeMatcher;
AbstractMethodReturnsNull(Matcher methodTreeMatcher) {
this.methodTreeMatcher = methodTreeMatcher;
}
protected abstract Optional provideFix(ReturnTree tree);
@Override
public final Description matchReturn(ReturnTree tree, VisitorState state) {
if (tree.getExpression() == null || tree.getExpression().getKind() != NULL_LITERAL) {
return NO_MATCH;
}
TreePath path = state.getPath();
while (path != null && path.getLeaf() instanceof StatementTree) {
path = path.getParentPath();
}
if (path == null || !(path.getLeaf() instanceof MethodTree)) {
return NO_MATCH;
}
if (!methodTreeMatcher.matches((MethodTree) path.getLeaf(), state)) {
return NO_MATCH;
}
return provideFix(tree)
.map(fix -> describeMatch(tree, fix))
.orElseGet(() -> describeMatch(tree));
}
}