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/*
* Copyright 2017 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.common.collect.Iterables.getLast;
import static com.google.errorprone.BugPattern.SeverityLevel.WARNING;
import static com.google.errorprone.matchers.Description.NO_MATCH;
import static com.google.errorprone.matchers.Matchers.anyOf;
import static com.google.errorprone.matchers.method.MethodMatchers.instanceMethod;
import static com.google.errorprone.util.ASTHelpers.getReceiver;
import static com.google.errorprone.util.ASTHelpers.sameVariable;
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.util.ASTHelpers;
import com.sun.source.tree.BlockTree;
import com.sun.source.tree.EnhancedForLoopTree;
import com.sun.source.tree.ExpressionTree;
import com.sun.source.tree.MethodInvocationTree;
import com.sun.source.tree.StatementTree;
import com.sun.source.tree.Tree;
import com.sun.source.tree.Tree.Kind;
import com.sun.source.util.TreePath;
import java.util.List;
/** @author [email protected] (Anish Visaria) */
@BugPattern(
name = "ModifyCollectionInEnhancedForLoop",
summary =
"Modifying a collection while iterating over it in a loop may cause a"
+ " ConcurrentModificationException to be thrown or lead to undefined behavior.",
severity = WARNING)
public class ModifyCollectionInEnhancedForLoop extends BugChecker
implements MethodInvocationTreeMatcher {
private static final Matcher MATCHER =
anyOf(
instanceMethod()
.onDescendantOf("java.util.Collection")
.namedAnyOf("add", "addAll", "clear", "remove", "removeAll", "retainAll"),
instanceMethod()
.onDescendantOf("java.util.Map")
.namedAnyOf(
"put",
"putAll",
"putIfAbsent",
"clear",
"remove",
"replace",
"replaceAll",
"merge"));
private static final Matcher MAP_SET_MATCHER =
instanceMethod().onDescendantOf("java.util.Map").namedAnyOf("entrySet", "keySet", "values");
@Override
public Description matchMethodInvocation(MethodInvocationTree tree, VisitorState state) {
if (!MATCHER.matches(tree, state)) {
return NO_MATCH;
}
if (state.getTypes().closure(ASTHelpers.getReceiverType(tree)).stream()
.anyMatch(
s ->
s.asElement()
.packge()
.getQualifiedName()
.toString()
.startsWith("java.util.concurrent"))) {
return NO_MATCH;
}
if (blockEndsInBreakOrReturn(state)) {
return NO_MATCH;
}
ExpressionTree collection = getReceiver(tree);
if (collection == null) {
return NO_MATCH;
}
if (!enclosingLoop(state, collection)) {
return NO_MATCH;
}
return describeMatch(tree);
}
private static boolean blockEndsInBreakOrReturn(VisitorState state) {
TreePath statementPath = state.findPathToEnclosing(StatementTree.class);
if (statementPath == null) {
return false;
}
Tree parent = statementPath.getParentPath().getLeaf();
if (!(parent instanceof BlockTree)) {
return false;
}
StatementTree statement = (StatementTree) statementPath.getLeaf();
List statements = ((BlockTree) parent).getStatements();
int idx = statements.indexOf(statement);
if (idx == -1 || idx == statements.size()) {
return false;
}
switch (getLast(statements).getKind()) {
case BREAK:
case RETURN:
return true;
default:
return false;
}
}
/** Returns true if {@code collection} is modified by an enclosing loop. */
private static boolean enclosingLoop(VisitorState state, ExpressionTree collection) {
for (Tree node : state.getPath()) {
switch (node.getKind()) {
case METHOD:
case CLASS:
case LAMBDA_EXPRESSION:
return false;
case ENHANCED_FOR_LOOP:
if (sameCollection(collection, ((EnhancedForLoopTree) node).getExpression(), state)) {
return true;
}
break;
default: // fall out
}
}
return false;
}
/**
* Returns true if {@code loopExpression} is defined over the same collection as {@code
* collection}.
*/
private static boolean sameCollection(
ExpressionTree collection, ExpressionTree loopExpression, VisitorState state) {
if (sameVariable(collection, loopExpression)) {
return true;
}
// Check if the loopExpression is a .keySet(), .entrySet, or .values() of the map
if (loopExpression.getKind() == Kind.METHOD_INVOCATION) {
ExpressionTree receiver = getReceiver(loopExpression);
return receiver != null
&& sameVariable(collection, receiver)
&& MAP_SET_MATCHER.matches(loopExpression, state);
}
return false;
}
}
