001////////////////////////////////////////////////////////////////////////////////
002// checkstyle: Checks Java source code for adherence to a set of rules.
003// Copyright (C) 2001-2017 the original author or authors.
004//
005// This library is free software; you can redistribute it and/or
006// modify it under the terms of the GNU Lesser General Public
007// License as published by the Free Software Foundation; either
008// version 2.1 of the License, or (at your option) any later version.
009//
010// This library is distributed in the hope that it will be useful,
011// but WITHOUT ANY WARRANTY; without even the implied warranty of
012// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
013// Lesser General Public License for more details.
014//
015// You should have received a copy of the GNU Lesser General Public
016// License along with this library; if not, write to the Free Software
017// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
018////////////////////////////////////////////////////////////////////////////////
019
020package com.puppycrawl.tools.checkstyle.checks;
021
022import java.util.Arrays;
023import java.util.Collections;
024import java.util.Set;
025import java.util.stream.Collectors;
026
027import com.puppycrawl.tools.checkstyle.StatelessCheck;
028import com.puppycrawl.tools.checkstyle.api.AbstractCheck;
029import com.puppycrawl.tools.checkstyle.api.DetailAST;
030import com.puppycrawl.tools.checkstyle.api.TokenTypes;
031import com.puppycrawl.tools.checkstyle.utils.CheckUtils;
032import com.puppycrawl.tools.checkstyle.utils.CommonUtils;
033
034/**
035 * Check that method/constructor/catch/foreach parameters are final.
036 * The user can set the token set to METHOD_DEF, CONSTRUCTOR_DEF,
037 * LITERAL_CATCH, FOR_EACH_CLAUSE or any combination of these token
038 * types, to control the scope of this check.
039 * Default scope is both METHOD_DEF and CONSTRUCTOR_DEF.
040 * <p>
041 * Check has an option <b>ignorePrimitiveTypes</b> which allows ignoring lack of
042 * final modifier at
043 * <a href="https://docs.oracle.com/javase/tutorial/java/nutsandbolts/datatypes.html">
044 *  primitive data type</a> parameter. Default value <b>false</b>.
045 * </p>
046 * E.g.:
047 * <p>
048 * {@code
049 * private void foo(int x) { ... } //parameter is of primitive type
050 * }
051 * </p>
052 *
053 * @author lkuehne
054 * @author o_sukhodolsky
055 * @author Michael Studman
056 * @author <a href="mailto:nesterenko-aleksey@list.ru">Aleksey Nesterenko</a>
057 */
058@StatelessCheck
059public class FinalParametersCheck extends AbstractCheck {
060
061    /**
062     * A key is pointing to the warning message text in "messages.properties"
063     * file.
064     */
065    public static final String MSG_KEY = "final.parameter";
066
067    /**
068     * Contains
069     * <a href="https://docs.oracle.com/javase/tutorial/java/nutsandbolts/datatypes.html">
070     * primitive datatypes</a>.
071     */
072    private final Set<Integer> primitiveDataTypes = Collections.unmodifiableSet(
073        Arrays.stream(new Integer[] {
074            TokenTypes.LITERAL_BYTE,
075            TokenTypes.LITERAL_SHORT,
076            TokenTypes.LITERAL_INT,
077            TokenTypes.LITERAL_LONG,
078            TokenTypes.LITERAL_FLOAT,
079            TokenTypes.LITERAL_DOUBLE,
080            TokenTypes.LITERAL_BOOLEAN,
081            TokenTypes.LITERAL_CHAR, })
082        .collect(Collectors.toSet()));
083
084    /**
085     * Option to ignore primitive types as params.
086     */
087    private boolean ignorePrimitiveTypes;
088
089    /**
090     * Sets ignoring primitive types as params.
091     * @param ignorePrimitiveTypes true or false.
092     */
093    public void setIgnorePrimitiveTypes(boolean ignorePrimitiveTypes) {
094        this.ignorePrimitiveTypes = ignorePrimitiveTypes;
095    }
096
097    @Override
098    public int[] getDefaultTokens() {
099        return new int[] {
100            TokenTypes.METHOD_DEF,
101            TokenTypes.CTOR_DEF,
102        };
103    }
104
105    @Override
106    public int[] getAcceptableTokens() {
107        return new int[] {
108            TokenTypes.METHOD_DEF,
109            TokenTypes.CTOR_DEF,
110            TokenTypes.LITERAL_CATCH,
111            TokenTypes.FOR_EACH_CLAUSE,
112        };
113    }
114
115    @Override
116    public int[] getRequiredTokens() {
117        return CommonUtils.EMPTY_INT_ARRAY;
118    }
119
120    @Override
121    public void visitToken(DetailAST ast) {
122        // don't flag interfaces
123        final DetailAST container = ast.getParent().getParent();
124        if (container.getType() != TokenTypes.INTERFACE_DEF) {
125            if (ast.getType() == TokenTypes.LITERAL_CATCH) {
126                visitCatch(ast);
127            }
128            else if (ast.getType() == TokenTypes.FOR_EACH_CLAUSE) {
129                visitForEachClause(ast);
130            }
131            else {
132                visitMethod(ast);
133            }
134        }
135    }
136
137    /**
138     * Checks parameters of the method or ctor.
139     * @param method method or ctor to check.
140     */
141    private void visitMethod(final DetailAST method) {
142        final DetailAST modifiers =
143            method.findFirstToken(TokenTypes.MODIFIERS);
144        // exit on fast lane if there is nothing to check here
145
146        if (method.findFirstToken(TokenTypes.PARAMETERS)
147                .findFirstToken(TokenTypes.PARAMETER_DEF) != null
148                // ignore abstract and native methods
149                && modifiers.findFirstToken(TokenTypes.ABSTRACT) == null
150                && modifiers.findFirstToken(TokenTypes.LITERAL_NATIVE) == null) {
151            // we can now be sure that there is at least one parameter
152            final DetailAST parameters =
153                method.findFirstToken(TokenTypes.PARAMETERS);
154            DetailAST child = parameters.getFirstChild();
155            while (child != null) {
156                // children are PARAMETER_DEF and COMMA
157                if (child.getType() == TokenTypes.PARAMETER_DEF) {
158                    checkParam(child);
159                }
160                child = child.getNextSibling();
161            }
162        }
163    }
164
165    /**
166     * Checks parameter of the catch block.
167     * @param catchClause catch block to check.
168     */
169    private void visitCatch(final DetailAST catchClause) {
170        checkParam(catchClause.findFirstToken(TokenTypes.PARAMETER_DEF));
171    }
172
173    /**
174     * Checks parameter of the for each clause.
175     * @param forEachClause for each clause to check.
176     */
177    private void visitForEachClause(final DetailAST forEachClause) {
178        checkParam(forEachClause.findFirstToken(TokenTypes.VARIABLE_DEF));
179    }
180
181    /**
182     * Checks if the given parameter is final.
183     * @param param parameter to check.
184     */
185    private void checkParam(final DetailAST param) {
186        if (param.findFirstToken(TokenTypes.MODIFIERS).findFirstToken(TokenTypes.FINAL) == null
187                && !isIgnoredParam(param)
188                && !CheckUtils.isReceiverParameter(param)) {
189            final DetailAST paramName = param.findFirstToken(TokenTypes.IDENT);
190            final DetailAST firstNode = CheckUtils.getFirstNode(param);
191            log(firstNode.getLineNo(), firstNode.getColumnNo(),
192                MSG_KEY, paramName.getText());
193        }
194    }
195
196    /**
197     * Checks for skip current param due to <b>ignorePrimitiveTypes</b> option.
198     * @param paramDef {@link TokenTypes#PARAMETER_DEF PARAMETER_DEF}
199     * @return true if param has to be skipped.
200     */
201    private boolean isIgnoredParam(DetailAST paramDef) {
202        boolean result = false;
203        if (ignorePrimitiveTypes) {
204            final DetailAST parameterType = paramDef
205                .findFirstToken(TokenTypes.TYPE).getFirstChild();
206            if (primitiveDataTypes.contains(parameterType.getType())) {
207                result = true;
208            }
209        }
210        return result;
211    }
212}