////////////////////////////////////////////////////////////////////////////////
// checkstyle: Checks Java source code for adherence to a set of rules.
// Copyright (C) 2001-2008 Oliver Burn
//
// 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 com.puppycrawl.tools.checkstyle.checks.coding;
import com.google.common.collect.Sets;
import com.puppycrawl.tools.checkstyle.api.Check;
import com.puppycrawl.tools.checkstyle.api.DetailAST;
import com.puppycrawl.tools.checkstyle.api.FullIdent;
import com.puppycrawl.tools.checkstyle.api.TokenTypes;
import com.puppycrawl.tools.checkstyle.checks.CheckUtils;
import java.util.Set;
/**
* <p>Checks that if a class defines a covariant method equals,
* then it defines method equals(java.lang.Object).
* Inspired by findbugs,
* http://www.cs.umd.edu/~pugh/java/bugs/docs/findbugsPaper.pdf
* </p>
* <p>
* An example of how to configure the check is:
* </p>
* <pre>
* <module name="CovariantEquals"/>
* </pre>
* @author Rick Giles
* @version 1.0
*/
public class CovariantEqualsCheck extends Check
{
/** Set of equals method definitions */
private final Set<DetailAST> mEqualsMethods = Sets.newHashSet();
@Override
public int[] getDefaultTokens()
{
return new int[] {TokenTypes.CLASS_DEF, TokenTypes.LITERAL_NEW, };
}
@Override
public int[] getRequiredTokens()
{
return getDefaultTokens();
}
@Override
public void visitToken(DetailAST aAST)
{
mEqualsMethods.clear();
boolean hasEqualsObject = false;
// examine method definitions for equals methods
final DetailAST objBlock = aAST.findFirstToken(TokenTypes.OBJBLOCK);
if (objBlock != null) {
DetailAST child = (DetailAST) objBlock.getFirstChild();
while (child != null) {
if (child.getType() == TokenTypes.METHOD_DEF) {
if (CheckUtils.isEqualsMethod(child)) {
if (hasObjectParameter(child)) {
hasEqualsObject = true;
}
else {
mEqualsMethods.add(child);
}
}
}
child = (DetailAST) child.getNextSibling();
}
// report equals method definitions
if (!hasEqualsObject) {
for (DetailAST equalsAST : mEqualsMethods) {
final DetailAST nameNode = equalsAST
.findFirstToken(TokenTypes.IDENT);
log(nameNode.getLineNo(), nameNode.getColumnNo(),
"covariant.equals");
}
}
}
}
/**
* Tests whether a method definition AST has exactly one
* parameter of type Object.
* @param aAST the method definition AST to test.
* Precondition: aAST is a TokenTypes.METHOD_DEF node.
* @return true if aAST has exactly one parameter of type Object.
*/
private boolean hasObjectParameter(DetailAST aAST)
{
// one parameter?
final DetailAST paramsNode = aAST.findFirstToken(TokenTypes.PARAMETERS);
if (paramsNode.getChildCount() != 1) {
return false;
}
// parameter type "Object"?
final DetailAST paramNode =
paramsNode.findFirstToken(TokenTypes.PARAMETER_DEF);
final DetailAST typeNode = paramNode.findFirstToken(TokenTypes.TYPE);
final FullIdent fullIdent = FullIdent.createFullIdentBelow(typeNode);
final String name = fullIdent.getText();
return ("Object".equals(name) || "java.lang.Object".equals(name));
}
}