com.google.errorprone.bugpatterns.XorPower 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.ERROR;
import static com.google.errorprone.matchers.Description.NO_MATCH;
import com.google.common.base.Strings;
import com.google.errorprone.BugPattern;
import com.google.errorprone.VisitorState;
import com.google.errorprone.bugpatterns.BugChecker.BinaryTreeMatcher;
import com.google.errorprone.fixes.SuggestedFix;
import com.google.errorprone.matchers.Description;
import com.google.errorprone.util.ASTHelpers;
import com.sun.source.tree.BinaryTree;
import com.sun.source.tree.Tree;
/** A {@link BugChecker}; see the associated {@link BugPattern} annotation for details. */
@BugPattern(summary = "The `^` operator is binary XOR, not a power operator.", severity = ERROR)
public class XorPower extends BugChecker implements BinaryTreeMatcher {
@Override
public Description matchBinary(BinaryTree tree, VisitorState state) {
if (!tree.getKind().equals(Tree.Kind.XOR)) {
return NO_MATCH;
}
Integer lhs = ASTHelpers.constValue(tree.getLeftOperand(), Integer.class);
if (lhs == null) {
return NO_MATCH;
}
switch (lhs.intValue()) {
case 2:
case 10:
break;
default:
return NO_MATCH;
}
Integer rhs = ASTHelpers.constValue(tree.getRightOperand(), Integer.class);
if (rhs == null) {
return NO_MATCH;
}
if (state.getSourceForNode(tree.getRightOperand()).startsWith("0")) {
// hex and octal literals
return NO_MATCH;
}
Description.Builder description =
buildDescription(tree)
.setMessage(
String.format(
"The ^ operator is binary XOR, not a power operator, so '%s' will always"
+ " evaluate to %d.",
state.getSourceForNode(tree), lhs ^ rhs));
switch (lhs.intValue()) {
case 2:
if (rhs <= 31) {
description.addFix(SuggestedFix.replace(tree, String.format("1 << %d", rhs)));
}
break;
case 10:
if (rhs <= 9) {
description.addFix(SuggestedFix.replace(tree, "1" + Strings.repeat("0", rhs)));
}
break;
default:
throw new AssertionError(lhs);
}
return description.build();
}
}