com.google.errorprone.bugpatterns.EmptyIfStatement Maven / Gradle / Ivy
/*
* Copyright 2012 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.isLastStatementInBlock;
import com.google.errorprone.BugPattern;
import com.google.errorprone.VisitorState;
import com.google.errorprone.bugpatterns.BugChecker.EmptyStatementTreeMatcher;
import com.google.errorprone.fixes.SuggestedFix;
import com.google.errorprone.matchers.Description;
import com.sun.source.tree.EmptyStatementTree;
import com.sun.source.tree.IfTree;
import com.sun.source.tree.Tree;
import com.sun.source.util.TreePath;
/**
* This checker finds and fixes empty statements after an if, with no else part. For example: if
* (foo == 10);
*
* It attempts to match javac's -Xlint:empty warning behavior, which can be found in
* com/sun/tools/javac/comp/Check.java.
*
* @author [email protected] (Eddie Aftandilian)
*/
@BugPattern(
name = "EmptyIf",
altNames = {"empty"},
summary = "Empty statement after if",
severity = ERROR)
public class EmptyIfStatement extends BugChecker implements EmptyStatementTreeMatcher {
/**
* Match empty statement if: - Parent statement is an if - The then part of the parent if is an
* empty statement, and - The else part of the parent if does not exist
*/
@Override
public Description matchEmptyStatement(EmptyStatementTree tree, VisitorState state) {
TreePath parentPath = state.getPath().getParentPath();
Tree parent = parentPath.getLeaf();
if (!(parent instanceof IfTree)) {
return NO_MATCH;
}
IfTree ifTree = (IfTree) parent;
if (!(ifTree.getThenStatement() instanceof EmptyStatementTree)
|| ifTree.getElseStatement() != null) {
return NO_MATCH;
}
/*
* We suggest different fixes depending on what follows the parent if statement.
* If there is no statement following the if, then suggest deleting the whole
* if statement. If the next statement is a block, then suggest deleting the
* empty then part of the if. If the next statement is not a block, then also
* suggest deleting the empty then part of the if.
*/
if (isLastStatementInBlock().matches(ifTree, state.withPath(parentPath))) {
// No following statements. Delete whole if.
return describeMatch(parent, SuggestedFix.delete(parent));
} else {
// There are more statements. Delete the empty then part of the if.
return describeMatch(
ifTree.getThenStatement(), SuggestedFix.delete(ifTree.getThenStatement()));
}
}
}