com.google.errorprone.bugpatterns.OptionalMapToOptional Maven / Gradle / Ivy
/*
* Copyright 2019 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.matchers.Matchers.allOf;
import static com.google.errorprone.matchers.Matchers.anyOf;
import static com.google.errorprone.matchers.Matchers.not;
import static com.google.errorprone.matchers.method.MethodMatchers.instanceMethod;
import com.google.common.collect.ImmutableList;
import com.google.errorprone.BugPattern;
import com.google.errorprone.VisitorState;
import com.google.errorprone.bugpatterns.BugChecker.MethodInvocationTreeMatcher;
import com.google.errorprone.matchers.Description;
import com.google.errorprone.matchers.Matcher;
import com.google.errorprone.predicates.TypePredicate;
import com.google.errorprone.predicates.TypePredicates;
import com.google.errorprone.util.ASTHelpers;
import com.google.errorprone.util.ASTHelpers.TargetType;
import com.sun.source.tree.ExpressionTree;
import com.sun.source.tree.MemberSelectTree;
import com.sun.source.tree.MethodInvocationTree;
import com.sun.source.util.TreePath;
import com.sun.tools.javac.code.Type;
import java.util.List;
/** Matches {@code Optional#map} mapping to another {@code Optional}. */
@BugPattern(
summary = "Mapping to another Optional will yield a nested Optional. Did you mean flatMap?",
severity = WARNING)
public final class OptionalMapToOptional extends BugChecker implements MethodInvocationTreeMatcher {
private static final Matcher MAP =
anyOf(
instanceMethod().onExactClass("java.util.Optional").named("map"),
instanceMethod().onExactClass("com.google.common.base.Optional").named("transform"));
private static final Matcher ANYTHING_BUT_ISPRESENT =
anyOf(
allOf(
instanceMethod().onExactClass("java.util.Optional"),
not(instanceMethod().onExactClass("java.util.Optional").named("isPresent"))),
allOf(
instanceMethod().onExactClass("com.google.common.base.Optional"),
not(
instanceMethod()
.onExactClass("com.google.common.base.Optional")
.named("isPresent"))));
private static final TypePredicate OPTIONAL =
TypePredicates.isDescendantOfAny(
ImmutableList.of("java.util.Optional", "com.google.common.base.Optional"));
@Override
public Description matchMethodInvocation(MethodInvocationTree tree, VisitorState state) {
if (!MAP.matches(tree, state)) {
return NO_MATCH;
}
TreePath path = state.getPath();
// Heuristic: if another Optional instance method is invoked on this, it's usually clear what's
// going on, unless that method is `isPresent()`.
if (path.getParentPath().getLeaf() instanceof MemberSelectTree
&& path.getParentPath().getParentPath().getLeaf() instanceof MethodInvocationTree
&& ANYTHING_BUT_ISPRESENT.matches(
(MethodInvocationTree) path.getParentPath().getParentPath().getLeaf(), state)) {
return NO_MATCH;
}
TargetType targetType =
ASTHelpers.targetType(
state.withPath(new TreePath(state.getPath(), tree.getArguments().get(0))));
if (targetType == null) {
return NO_MATCH;
}
List typeArguments = targetType.type().getTypeArguments();
// If the receiving Optional is raw, so will the target type of Function.
if (typeArguments.isEmpty()) {
return NO_MATCH;
}
Type typeMappedTo = typeArguments.get(1);
if (!OPTIONAL.apply(typeMappedTo, state)) {
return NO_MATCH;
}
return describeMatch(tree);
}
}