////////////////////////////////////////////////////////////////////////////////
// checkstyle: Checks Java source code for adherence to a set of rules.
// Copyright (C) 2001-2017 the original author or authors.
//
// 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 java.util.HashSet;
import java.util.Set;
import com.puppycrawl.tools.checkstyle.api.AbstractCheck;
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.utils.CheckUtils;
/**
* <p>Checks that if a class defines a covariant method equals,
* then it defines method equals(java.lang.Object).
* Inspired by findbugs,
* http://findbugs.sourceforge.net/bugDescriptions.html#EQ_SELF_NO_OBJECT
* </p>
* <p>
* An example of how to configure the check is:
* </p>
* <pre>
* <module name="CovariantEquals"/>
* </pre>
* @author Rick Giles
*/
public class CovariantEqualsCheck extends AbstractCheck {
/**
* A key is pointing to the warning message text in "messages.properties"
* file.
*/
public static final String MSG_KEY = "covariant.equals";
/** Set of equals method definitions. */
private final Set<DetailAST> equalsMethods = new HashSet<>();
@Override
public int[] getDefaultTokens() {
return new int[] {TokenTypes.CLASS_DEF, TokenTypes.LITERAL_NEW, TokenTypes.ENUM_DEF, };
}
@Override
public int[] getRequiredTokens() {
return getDefaultTokens();
}
@Override
public int[] getAcceptableTokens() {
return new int[] {TokenTypes.CLASS_DEF, TokenTypes.LITERAL_NEW, TokenTypes.ENUM_DEF, };
}
@Override
public void visitToken(DetailAST ast) {
equalsMethods.clear();
// examine method definitions for equals methods
final DetailAST objBlock = ast.findFirstToken(TokenTypes.OBJBLOCK);
if (objBlock != null) {
DetailAST child = objBlock.getFirstChild();
boolean hasEqualsObject = false;
while (child != null) {
if (child.getType() == TokenTypes.METHOD_DEF
&& CheckUtils.isEqualsMethod(child)) {
if (isFirstParameterObject(child)) {
hasEqualsObject = true;
}
else {
equalsMethods.add(child);
}
}
child = child.getNextSibling();
}
// report equals method definitions
if (!hasEqualsObject) {
for (DetailAST equalsAST : equalsMethods) {
final DetailAST nameNode = equalsAST
.findFirstToken(TokenTypes.IDENT);
log(nameNode.getLineNo(), nameNode.getColumnNo(),
MSG_KEY);
}
}
}
}
/**
* Tests whether a method's first parameter is an Object.
* @param methodDefAst the method definition AST to test.
* Precondition: ast is a TokenTypes.METHOD_DEF node.
* @return true if ast has first parameter of type Object.
*/
private static boolean isFirstParameterObject(DetailAST methodDefAst) {
final DetailAST paramsNode = methodDefAst.findFirstToken(TokenTypes.PARAMETERS);
// 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);
}
}