/*
* Copyright 2013 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.MaturityLevel.EXPERIMENTAL;
import static com.google.errorprone.BugPattern.SeverityLevel.ERROR;
import static com.google.errorprone.matchers.Matchers.anyOf;
import static com.google.errorprone.matchers.Matchers.kindIs;
import com.google.errorprone.BugPattern;
import com.google.errorprone.VisitorState;
import com.google.errorprone.bugpatterns.BugChecker.BinaryTreeMatcher;
import com.google.errorprone.bugpatterns.BugChecker.CompoundAssignmentTreeMatcher;
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.CompoundAssignmentTree;
import com.sun.source.tree.ExpressionTree;
import com.sun.source.tree.LiteralTree;
import com.sun.source.tree.StatementTree;
import com.sun.source.tree.Tree;
import com.sun.source.tree.Tree.Kind;
/**
* Matches the behaviour of javac's divzero xlint warning.
*
* @author cushon@google.com (Liam Miller-Cushon)
*/
@BugPattern(name = "DivZero", altNames = "divzero",
summary = "Division by integer literal zero",
explanation = "This code will cause a runtime arithmetic exception if it is executed.",
category = JDK, severity = ERROR, maturity = EXPERIMENTAL)
public class DivZero extends BugChecker
implements BinaryTreeMatcher, CompoundAssignmentTreeMatcher {
@Override
public Description matchBinary(BinaryTree tree, VisitorState state) {
return matchDivZero(tree, tree.getRightOperand(), state);
}
@Override
public Description matchCompoundAssignment(CompoundAssignmentTree tree, VisitorState state) {
return matchDivZero(tree, tree.getExpression(), state);
}
private Description matchDivZero(Tree tree, ExpressionTree operand, VisitorState state) {
if (!anyOf(kindIs(Kind.DIVIDE), kindIs(Kind.DIVIDE_ASSIGNMENT)).matches(tree, state)) {
return Description.NO_MATCH;
}
if (!kindIs(Kind.INT_LITERAL).matches(operand, state)) {
return Description.NO_MATCH;
}
LiteralTree rightOperand = (LiteralTree) operand;
if (((Integer) rightOperand.getValue()) != 0) {
return Description.NO_MATCH;
}
// Find and replace enclosing Statement.
StatementTree enclosingStmt =
ASTHelpers.findEnclosingNode(state.getPath(), StatementTree.class);
return (enclosingStmt != null)
? describeMatch(tree,
SuggestedFix.replace(enclosingStmt, "throw new ArithmeticException(\"/ by zero\");"))
: describeMatch(tree);
}
}