/*
* Contributions to FindBugs
* Copyright (C) 2006, Institut for Software
* An Institut of the University of Applied Sciences Rapperswil
*
* Author: Marco Busarello, Thierry Wyss
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
package edu.umd.cs.findbugs.quickfix.resolution;
import static edu.umd.cs.findbugs.quickfix.util.ASTUtil.getASTNode;
import static java.lang.Integer.parseInt;
import static org.eclipse.jdt.core.dom.InfixExpression.Operator.EQUALS;
import static org.eclipse.jdt.core.dom.InfixExpression.Operator.REMAINDER;
import javax.annotation.CheckForNull;
import org.eclipse.jdt.core.dom.ASTNode;
import org.eclipse.jdt.core.dom.ASTVisitor;
import org.eclipse.jdt.core.dom.CompilationUnit;
import org.eclipse.jdt.core.dom.Expression;
import org.eclipse.jdt.core.dom.InfixExpression;
import org.eclipse.jdt.core.dom.NumberLiteral;
import org.eclipse.jdt.core.dom.ParenthesizedExpression;
import org.eclipse.jdt.core.dom.rewrite.ASTRewrite;
import edu.umd.cs.findbugs.BugInstance;
import edu.umd.cs.findbugs.quickfix.exception.BugResolutionException;
/**
* The code <CODE>x % 2 == 1</CODE> to check if a value is odd won't work for
* negative numbers. The <CODE>CorrectOddnessCheckResolution</CODE> provides a
* resolution to replace this bad check by an <CODE>expression</CODE> that works
* also for negative numbers.
*
* @see <a
* href="http://findbugs.sourceforge.net/bugDescriptions.html#IM_BAD_CHECK_FOR_ODD">IM_BAD_CHECK_FOR_ODD</a>
* @author <a href="mailto:mbusarel@hsr.ch">Marco Busarello</a>
* @author <a href="mailto:twyss@hsr.ch">Thierry Wyss</a>
* @version 1.0
*/
public abstract class CorrectOddnessCheckResolution extends BugResolution {
@Override
protected boolean resolveBindings() {
return false;
}
@Override
protected void repairBug(ASTRewrite rewrite, CompilationUnit workingUnit, BugInstance bug) throws BugResolutionException {
assert rewrite != null;
assert workingUnit != null;
assert bug != null;
InfixExpression oddnessCheck = findOddnessCheck(getASTNode(workingUnit, bug.getPrimarySourceLineAnnotation()));
if (oddnessCheck == null) {
throw new BugResolutionException("No matching oddness check found at the specified source line.");
}
Expression numberExpression = findNumberExpression(oddnessCheck);
if (numberExpression == null) {
throw new BugResolutionException();
}
InfixExpression correctOddnessCheck = createCorrectOddnessCheck(rewrite, numberExpression);
rewrite.replace(oddnessCheck, correctOddnessCheck, null);
}
@CheckForNull
protected InfixExpression findOddnessCheck(ASTNode node) {
OddnessCheckFinder finder = new OddnessCheckFinder();
node.accept(finder);
return finder.getOddnessCheck();
}
@CheckForNull
protected Expression findNumberExpression(InfixExpression oddnessCheck) {
NumberExpressionFinder finder = new NumberExpressionFinder();
oddnessCheck.accept(finder);
return finder.getNumberExpression();
}
/**
* Creates and returns a correct <CODE>expression</CODE> that checks if a
* value is odd or not.
*
* @param ast
* the <CODE>AST</CODE> instance under which the created
* <CODE>InfixExpression</CODE> will be created.
* @param replaceField
* the field name of the bad oddness-check which will be used for
* the new <CODE>InfixExpression</CODE>.
* @return the correct <CODE>InfixExpression</CODE>.
*/
protected abstract InfixExpression createCorrectOddnessCheck(ASTRewrite rewrite, Expression numberExpression);
protected static boolean isOddnessCheck(InfixExpression oddnessCheck) {
if (EQUALS.equals(oddnessCheck.getOperator())) {
if (isRemainderExp(oddnessCheck.getLeftOperand())) {
return isNumber(oddnessCheck.getRightOperand(), 1);
}
if (isRemainderExp(oddnessCheck.getRightOperand())) {
return isNumber(oddnessCheck.getLeftOperand(), 1);
}
}
return false;
}
protected static boolean isRemainderExp(Expression remainderExp) {
while (remainderExp instanceof ParenthesizedExpression) {
remainderExp = ((ParenthesizedExpression) remainderExp).getExpression();
}
if (remainderExp instanceof InfixExpression) {
InfixExpression exp = ((InfixExpression) remainderExp);
return REMAINDER.equals(exp.getOperator()) && isNumber(exp.getRightOperand(), 2);
}
return false;
}
protected static boolean isNumber(Expression exp, int number) {
return exp instanceof NumberLiteral && parseInt(((NumberLiteral) exp).getToken()) == number;
}
protected static class OddnessCheckFinder extends ASTVisitor {
private InfixExpression oddnessCheck = null;
@Override
public boolean visit(InfixExpression node) {
if (oddnessCheck == null) {
if (!isOddnessCheck(node)) {
return true;
}
oddnessCheck = node;
}
return false;
}
public InfixExpression getOddnessCheck() {
return oddnessCheck;
}
}
protected static class NumberExpressionFinder extends ASTVisitor {
private Expression numberExpression = null;
@Override
public boolean visit(InfixExpression node) {
if (numberExpression == null) {
if (!isRemainderExp(node)) {
return true;
}
numberExpression = node.getLeftOperand();
}
return false;
}
public Expression getNumberExpression() {
return numberExpression;
}
}
}