com.google.errorprone.bugpatterns.UnnecessaryBoxedAssignment 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.matchers.method.MethodMatchers.staticMethod;
import com.google.errorprone.BugPattern;
import com.google.errorprone.BugPattern.SeverityLevel;
import com.google.errorprone.VisitorState;
import com.google.errorprone.bugpatterns.BugChecker.AssignmentTreeMatcher;
import com.google.errorprone.bugpatterns.BugChecker.ReturnTreeMatcher;
import com.google.errorprone.bugpatterns.BugChecker.VariableTreeMatcher;
import com.google.errorprone.fixes.SuggestedFix;
import com.google.errorprone.matchers.Description;
import com.google.errorprone.matchers.Matcher;
import com.google.errorprone.util.ASTHelpers;
import com.sun.source.tree.AssignmentTree;
import com.sun.source.tree.ExpressionTree;
import com.sun.source.tree.MethodInvocationTree;
import com.sun.source.tree.ReturnTree;
import com.sun.source.tree.VariableTree;
import com.sun.tools.javac.code.Type;
import com.sun.tools.javac.code.TypeTag;
/**
* Finds and fixes unnecessarily boxed return expressions.
*
* @author [email protected] (Andy Turner)
*/
@BugPattern(
name = "UnnecessaryBoxedAssignment",
summary = "This expression can be implicitly boxed.",
explanation =
"It is unnecessary for this assignment or return expression to be boxed explicitly.",
severity = SeverityLevel.SUGGESTION)
public class UnnecessaryBoxedAssignment extends BugChecker
implements AssignmentTreeMatcher, ReturnTreeMatcher, VariableTreeMatcher {
private static final Matcher VALUE_OF_MATCHER =
staticMethod().onClass(UnnecessaryBoxedAssignment::isBoxableType).named("valueOf");
@Override
public Description matchReturn(ReturnTree tree, VisitorState state) {
return matchCommon(tree.getExpression(), state);
}
@Override
public Description matchAssignment(AssignmentTree tree, VisitorState state) {
return matchCommon(tree.getExpression(), state);
}
@Override
public Description matchVariable(VariableTree tree, VisitorState state) {
return matchCommon(tree.getInitializer(), state);
}
private Description matchCommon(ExpressionTree expression, VisitorState state) {
if (expression == null || !VALUE_OF_MATCHER.matches(expression, state)) {
return Description.NO_MATCH;
}
MethodInvocationTree methodInvocationTree = (MethodInvocationTree) expression;
if (methodInvocationTree.getArguments().size() != 1) {
return Description.NO_MATCH;
}
ExpressionTree arg = methodInvocationTree.getArguments().get(0);
Type argType = ASTHelpers.getType(arg);
if (ASTHelpers.isSameType(argType, state.getSymtab().stringType, state)) {
return Description.NO_MATCH;
}
// Don't fix if there is an implicit primitive widening. This would need a cast, and that's not
// clearly better than using valueOf.
if (!ASTHelpers.isSameType(
state.getTypes().unboxedTypeOrType(argType),
state.getTypes().unboxedType(ASTHelpers.getType(expression)),
state)) {
return Description.NO_MATCH;
}
return describeMatch(expression, SuggestedFix.replace(expression, state.getSourceForNode(arg)));
}
private static boolean isBoxableType(Type type, VisitorState state) {
Type unboxedType = state.getTypes().unboxedType(type);
return unboxedType != null && unboxedType.getTag() != TypeTag.NONE;
}
}