/*
* Copyright 2015 Google Inc. All Rights Reserved.
*
* 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.Category.JDK;
import static com.google.errorprone.BugPattern.LinkType.CUSTOM;
import static com.google.errorprone.BugPattern.SeverityLevel.SUGGESTION;
import static com.google.errorprone.matchers.Description.NO_MATCH;
import com.google.common.base.Joiner;
import com.google.common.collect.Iterables;
import com.google.common.collect.Iterators;
import com.google.common.collect.PeekingIterator;
import com.google.errorprone.BugPattern;
import com.google.errorprone.VisitorState;
import com.google.errorprone.bugpatterns.BugChecker.BlockTreeMatcher;
import com.google.errorprone.bugpatterns.BugChecker.ClassTreeMatcher;
import com.google.errorprone.fixes.Fix;
import com.google.errorprone.fixes.SuggestedFix;
import com.google.errorprone.matchers.Description;
import com.sun.source.tree.BlockTree;
import com.sun.source.tree.ClassTree;
import com.sun.source.tree.Tree;
import com.sun.source.tree.VariableTree;
import com.sun.tools.javac.tree.JCTree;
import java.util.ArrayList;
import java.util.List;
/** @author cushon@google.com (Liam Miller-Cushon) */
@BugPattern(
name = "MultiVariableDeclaration",
summary = "Variable declarations should declare only one variable",
category = JDK,
severity = SUGGESTION,
linkType = CUSTOM,
link = "https://google.github.io/styleguide/javaguide.html#s4.8.2.1-variables-per-declaration"
)
public class MultiVariableDeclaration extends BugChecker
implements ClassTreeMatcher, BlockTreeMatcher {
@Override
public Description matchBlock(BlockTree tree, VisitorState state) {
return checkDeclarations(tree.getStatements(), state);
}
@Override
public Description matchClass(ClassTree tree, VisitorState state) {
return checkDeclarations(tree.getMembers(), state);
}
private Description checkDeclarations(List<? extends Tree> children, VisitorState state) {
PeekingIterator<Tree> it = Iterators.<Tree>peekingIterator(children.iterator());
while (it.hasNext()) {
if (it.peek().getKind() != Tree.Kind.VARIABLE) {
it.next();
continue;
}
VariableTree variableTree = (VariableTree) it.next();
ArrayList<VariableTree> fragments = new ArrayList<>();
fragments.add(variableTree);
// Javac handles multi-variable declarations by lowering them in the parser into a series of
// individual declarations, all of which have the same start position. We search for the first
// declaration in the group, which is either the first variable declared in this scope or has
// a distinct end position from the previous declaration.
while (it.hasNext()
&& it.peek().getKind() == Tree.Kind.VARIABLE
&& ((JCTree) variableTree).getStartPosition()
== ((JCTree) it.peek()).getStartPosition()) {
fragments.add((VariableTree) it.next());
}
if (fragments.size() == 1) {
continue;
}
Fix fix =
SuggestedFix.replace(
((JCTree) fragments.get(0)).getStartPosition(),
state.getEndPosition(Iterables.getLast(fragments)),
Joiner.on("; ").join(fragments) + ";");
state.reportMatch(describeMatch(fragments.get(0), fix));
}
return NO_MATCH;
}
}