com.google.errorprone.bugpatterns.OptionalMapUnusedValue 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.BugPattern.SeverityLevel.ERROR;
import static com.google.errorprone.matchers.Description.NO_MATCH;
import static com.google.errorprone.matchers.Matchers.anyOf;
import static com.google.errorprone.matchers.Matchers.argument;
import static com.google.errorprone.matchers.Matchers.kindIs;
import static com.google.errorprone.matchers.Matchers.parentNode;
import static com.google.errorprone.matchers.method.MethodMatchers.instanceMethod;
import com.google.errorprone.BugPattern;
import com.google.errorprone.VisitorState;
import com.google.errorprone.bugpatterns.BugChecker.MethodInvocationTreeMatcher;
import com.google.errorprone.fixes.SuggestedFixes;
import com.google.errorprone.matchers.Description;
import com.google.errorprone.matchers.Matcher;
import com.sun.source.tree.ExpressionTree;
import com.sun.source.tree.LambdaExpressionTree;
import com.sun.source.tree.MethodInvocationTree;
import com.sun.source.tree.Tree.Kind;
/** Replaces {@code Optional.map} with {@code Optional.ifPresent} if the value is unused. */
@BugPattern(
summary = "Optional.ifPresent is preferred over Optional.map when the return value is unused",
severity = ERROR)
public final class OptionalMapUnusedValue extends BugChecker
implements MethodInvocationTreeMatcher {
private static final Matcher METHOD_IS_OPTIONAL_MAP =
instanceMethod().onExactClass("java.util.Optional").named("map");
private static final Matcher PARENT_IS_STATEMENT =
parentNode(kindIs(Kind.EXPRESSION_STATEMENT));
private static final Matcher ARG_IS_VOID_COMPATIBLE =
argument(
0, anyOf(kindIs(Kind.MEMBER_REFERENCE), OptionalMapUnusedValue::isVoidCompatibleLambda));
@Override
public Description matchMethodInvocation(MethodInvocationTree tree, VisitorState state) {
if (METHOD_IS_OPTIONAL_MAP.matches(tree, state)
&& PARENT_IS_STATEMENT.matches(tree, state)
&& ARG_IS_VOID_COMPATIBLE.matches(tree, state)) {
return describeMatch(tree, SuggestedFixes.renameMethodInvocation(tree, "ifPresent", state));
}
return NO_MATCH;
}
// TODO(b/170476239): Cover all the cases in which the argument is void-compatible, see
// JLS 15.12.2.1
private static boolean isVoidCompatibleLambda(ExpressionTree tree, VisitorState state) {
if (tree instanceof LambdaExpressionTree) {
LambdaExpressionTree lambdaTree = (LambdaExpressionTree) tree;
if (lambdaTree.getBodyKind().equals(LambdaExpressionTree.BodyKind.EXPRESSION)) {
return kindIs(Kind.METHOD_INVOCATION).matches(lambdaTree.getBody(), state);
}
}
return false;
}
}