////////////////////////////////////////////////////////////////////////////////
// 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.ArrayDeque;
import java.util.Collections;
import java.util.Deque;
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.TokenTypes;
import com.puppycrawl.tools.checkstyle.utils.CheckUtils;
/**
* <p>
* Disallow assignment of parameters.
* </p>
* <p>
* Rationale:
* Parameter assignment is often considered poor
* programming practice. Forcing developers to declare
* parameters as final is often onerous. Having a check
* ensure that parameters are never assigned would give
* the best of both worlds.
* </p>
* @author <a href="mailto:simon@redhillconsulting.com.au">Simon Harris</a>
*/
public final class ParameterAssignmentCheck extends AbstractCheck {
/**
* A key is pointing to the warning message text in "messages.properties"
* file.
*/
public static final String MSG_KEY = "parameter.assignment";
/** Stack of methods' parameters. */
private final Deque<Set<String>> parameterNamesStack = new ArrayDeque<>();
/** Current set of parameters. */
private Set<String> parameterNames;
@Override
public int[] getDefaultTokens() {
return new int[] {
TokenTypes.CTOR_DEF,
TokenTypes.METHOD_DEF,
TokenTypes.ASSIGN,
TokenTypes.PLUS_ASSIGN,
TokenTypes.MINUS_ASSIGN,
TokenTypes.STAR_ASSIGN,
TokenTypes.DIV_ASSIGN,
TokenTypes.MOD_ASSIGN,
TokenTypes.SR_ASSIGN,
TokenTypes.BSR_ASSIGN,
TokenTypes.SL_ASSIGN,
TokenTypes.BAND_ASSIGN,
TokenTypes.BXOR_ASSIGN,
TokenTypes.BOR_ASSIGN,
TokenTypes.INC,
TokenTypes.POST_INC,
TokenTypes.DEC,
TokenTypes.POST_DEC,
};
}
@Override
public int[] getRequiredTokens() {
return getDefaultTokens();
}
@Override
public int[] getAcceptableTokens() {
return new int[] {
TokenTypes.CTOR_DEF,
TokenTypes.METHOD_DEF,
TokenTypes.ASSIGN,
TokenTypes.PLUS_ASSIGN,
TokenTypes.MINUS_ASSIGN,
TokenTypes.STAR_ASSIGN,
TokenTypes.DIV_ASSIGN,
TokenTypes.MOD_ASSIGN,
TokenTypes.SR_ASSIGN,
TokenTypes.BSR_ASSIGN,
TokenTypes.SL_ASSIGN,
TokenTypes.BAND_ASSIGN,
TokenTypes.BXOR_ASSIGN,
TokenTypes.BOR_ASSIGN,
TokenTypes.INC,
TokenTypes.POST_INC,
TokenTypes.DEC,
TokenTypes.POST_DEC,
};
}
@Override
public void beginTree(DetailAST rootAST) {
// clear data
parameterNamesStack.clear();
parameterNames = Collections.emptySet();
}
@Override
public void visitToken(DetailAST ast) {
switch (ast.getType()) {
case TokenTypes.CTOR_DEF:
case TokenTypes.METHOD_DEF:
visitMethodDef(ast);
break;
case TokenTypes.ASSIGN:
case TokenTypes.PLUS_ASSIGN:
case TokenTypes.MINUS_ASSIGN:
case TokenTypes.STAR_ASSIGN:
case TokenTypes.DIV_ASSIGN:
case TokenTypes.MOD_ASSIGN:
case TokenTypes.SR_ASSIGN:
case TokenTypes.BSR_ASSIGN:
case TokenTypes.SL_ASSIGN:
case TokenTypes.BAND_ASSIGN:
case TokenTypes.BXOR_ASSIGN:
case TokenTypes.BOR_ASSIGN:
visitAssign(ast);
break;
case TokenTypes.INC:
case TokenTypes.POST_INC:
case TokenTypes.DEC:
case TokenTypes.POST_DEC:
visitIncDec(ast);
break;
default:
throw new IllegalStateException(ast.toString());
}
}
@Override
public void leaveToken(DetailAST ast) {
switch (ast.getType()) {
case TokenTypes.CTOR_DEF:
case TokenTypes.METHOD_DEF:
leaveMethodDef();
break;
case TokenTypes.ASSIGN:
case TokenTypes.PLUS_ASSIGN:
case TokenTypes.MINUS_ASSIGN:
case TokenTypes.STAR_ASSIGN:
case TokenTypes.DIV_ASSIGN:
case TokenTypes.MOD_ASSIGN:
case TokenTypes.SR_ASSIGN:
case TokenTypes.BSR_ASSIGN:
case TokenTypes.SL_ASSIGN:
case TokenTypes.BAND_ASSIGN:
case TokenTypes.BXOR_ASSIGN:
case TokenTypes.BOR_ASSIGN:
case TokenTypes.INC:
case TokenTypes.POST_INC:
case TokenTypes.DEC:
case TokenTypes.POST_DEC:
// Do nothing
break;
default:
throw new IllegalStateException(ast.toString());
}
}
/**
* Checks if this is assignments of parameter.
* @param ast assignment to check.
*/
private void visitAssign(DetailAST ast) {
checkIdent(ast);
}
/**
* Checks if this is increment/decrement of parameter.
* @param ast dec/inc to check.
*/
private void visitIncDec(DetailAST ast) {
checkIdent(ast);
}
/**
* Check if ident is parameter.
* @param ast ident to check.
*/
private void checkIdent(DetailAST ast) {
if (!parameterNames.isEmpty()) {
final DetailAST identAST = ast.getFirstChild();
if (identAST != null
&& identAST.getType() == TokenTypes.IDENT
&& parameterNames.contains(identAST.getText())) {
log(ast.getLineNo(), ast.getColumnNo(),
MSG_KEY, identAST.getText());
}
}
}
/**
* Creates new set of parameters and store old one in stack.
* @param ast a method to process.
*/
private void visitMethodDef(DetailAST ast) {
parameterNamesStack.push(parameterNames);
parameterNames = new HashSet<>();
visitMethodParameters(ast.findFirstToken(TokenTypes.PARAMETERS));
}
/** Restores old set of parameters. */
private void leaveMethodDef() {
parameterNames = parameterNamesStack.pop();
}
/**
* Creates new parameter set for given method.
* @param ast a method for process.
*/
private void visitMethodParameters(DetailAST ast) {
DetailAST parameterDefAST =
ast.findFirstToken(TokenTypes.PARAMETER_DEF);
while (parameterDefAST != null) {
if (parameterDefAST.getType() == TokenTypes.PARAMETER_DEF
&& !CheckUtils.isReceiverParameter(parameterDefAST)) {
final DetailAST param =
parameterDefAST.findFirstToken(TokenTypes.IDENT);
parameterNames.add(param.getText());
}
parameterDefAST = parameterDefAST.getNextSibling();
}
}
}