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.api.AbstractCheck;
028import com.puppycrawl.tools.checkstyle.api.DetailAST;
029import com.puppycrawl.tools.checkstyle.api.TokenTypes;
030import com.puppycrawl.tools.checkstyle.utils.CheckUtils;
031import com.puppycrawl.tools.checkstyle.utils.CommonUtils;
032
033/**
034 * Check that method/constructor/catch/foreach parameters are final.
035 * The user can set the token set to METHOD_DEF, CONSTRUCTOR_DEF,
036 * LITERAL_CATCH, FOR_EACH_CLAUSE or any combination of these token
037 * types, to control the scope of this check.
038 * Default scope is both METHOD_DEF and CONSTRUCTOR_DEF.
039 * <p>
040 * Check has an option <b>ignorePrimitiveTypes</b> which allows ignoring lack of
041 * final modifier at
042 * <a href="http://docs.oracle.com/javase/tutorial/java/nutsandbolts/datatypes.html">
043 *  primitive data type</a> parameter. Default value <b>false</b>.
044 * </p>
045 * E.g.:
046 * <p>
047 * {@code
048 * private void foo(int x) { ... } //parameter is of primitive type
049 * }
050 * </p>
051 *
052 * @author lkuehne
053 * @author o_sukhodolsky
054 * @author Michael Studman
055 * @author <a href="mailto:nesterenko-aleksey@list.ru">Aleksey Nesterenko</a>
056 */
057public class FinalParametersCheck extends AbstractCheck {
058
059    /**
060     * A key is pointing to the warning message text in "messages.properties"
061     * file.
062     */
063    public static final String MSG_KEY = "final.parameter";
064
065    /**
066     * Contains
067     * <a href="http://docs.oracle.com/javase/tutorial/java/nutsandbolts/datatypes.html">
068     * primitive datatypes</a>.
069     */
070    private final Set<Integer> primitiveDataTypes = Collections.unmodifiableSet(
071        Arrays.stream(new Integer[] {
072            TokenTypes.LITERAL_BYTE,
073            TokenTypes.LITERAL_SHORT,
074            TokenTypes.LITERAL_INT,
075            TokenTypes.LITERAL_LONG,
076            TokenTypes.LITERAL_FLOAT,
077            TokenTypes.LITERAL_DOUBLE,
078            TokenTypes.LITERAL_BOOLEAN,
079            TokenTypes.LITERAL_CHAR, })
080        .collect(Collectors.toSet()));
081
082    /**
083     * Option to ignore primitive types as params.
084     */
085    private boolean ignorePrimitiveTypes;
086
087    /**
088     * Sets ignoring primitive types as params.
089     * @param ignorePrimitiveTypes true or false.
090     */
091    public void setIgnorePrimitiveTypes(boolean ignorePrimitiveTypes) {
092        this.ignorePrimitiveTypes = ignorePrimitiveTypes;
093    }
094
095    @Override
096    public int[] getDefaultTokens() {
097        return new int[] {
098            TokenTypes.METHOD_DEF,
099            TokenTypes.CTOR_DEF,
100        };
101    }
102
103    @Override
104    public int[] getAcceptableTokens() {
105        return new int[] {
106            TokenTypes.METHOD_DEF,
107            TokenTypes.CTOR_DEF,
108            TokenTypes.LITERAL_CATCH,
109            TokenTypes.FOR_EACH_CLAUSE,
110        };
111    }
112
113    @Override
114    public int[] getRequiredTokens() {
115        return CommonUtils.EMPTY_INT_ARRAY;
116    }
117
118    @Override
119    public void visitToken(DetailAST ast) {
120        // don't flag interfaces
121        final DetailAST container = ast.getParent().getParent();
122        if (container.getType() != TokenTypes.INTERFACE_DEF) {
123            if (ast.getType() == TokenTypes.LITERAL_CATCH) {
124                visitCatch(ast);
125            }
126            else if (ast.getType() == TokenTypes.FOR_EACH_CLAUSE) {
127                visitForEachClause(ast);
128            }
129            else {
130                visitMethod(ast);
131            }
132        }
133    }
134
135    /**
136     * Checks parameters of the method or ctor.
137     * @param method method or ctor to check.
138     */
139    private void visitMethod(final DetailAST method) {
140        final DetailAST modifiers =
141            method.findFirstToken(TokenTypes.MODIFIERS);
142        // exit on fast lane if there is nothing to check here
143
144        if (method.branchContains(TokenTypes.PARAMETER_DEF)
145                // ignore abstract and native methods
146                && !modifiers.branchContains(TokenTypes.ABSTRACT)
147                && !modifiers.branchContains(TokenTypes.LITERAL_NATIVE)) {
148            // we can now be sure that there is at least one parameter
149            final DetailAST parameters =
150                method.findFirstToken(TokenTypes.PARAMETERS);
151            DetailAST child = parameters.getFirstChild();
152            while (child != null) {
153                // children are PARAMETER_DEF and COMMA
154                if (child.getType() == TokenTypes.PARAMETER_DEF) {
155                    checkParam(child);
156                }
157                child = child.getNextSibling();
158            }
159        }
160    }
161
162    /**
163     * Checks parameter of the catch block.
164     * @param catchClause catch block to check.
165     */
166    private void visitCatch(final DetailAST catchClause) {
167        checkParam(catchClause.findFirstToken(TokenTypes.PARAMETER_DEF));
168    }
169
170    /**
171     * Checks parameter of the for each clause.
172     * @param forEachClause for each clause to check.
173     */
174    private void visitForEachClause(final DetailAST forEachClause) {
175        checkParam(forEachClause.findFirstToken(TokenTypes.VARIABLE_DEF));
176    }
177
178    /**
179     * Checks if the given parameter is final.
180     * @param param parameter to check.
181     */
182    private void checkParam(final DetailAST param) {
183        if (!param.branchContains(TokenTypes.FINAL) && !isIgnoredParam(param)
184                && !CheckUtils.isReceiverParameter(param)) {
185            final DetailAST paramName = param.findFirstToken(TokenTypes.IDENT);
186            final DetailAST firstNode = CheckUtils.getFirstNode(param);
187            log(firstNode.getLineNo(), firstNode.getColumnNo(),
188                MSG_KEY, paramName.getText());
189        }
190    }
191
192    /**
193     * Checks for skip current param due to <b>ignorePrimitiveTypes</b> option.
194     * @param paramDef {@link TokenTypes#PARAMETER_DEF PARAMETER_DEF}
195     * @return true if param has to be skipped.
196     */
197    private boolean isIgnoredParam(DetailAST paramDef) {
198        boolean result = false;
199        if (ignorePrimitiveTypes) {
200            final DetailAST parameterType = paramDef
201                .findFirstToken(TokenTypes.TYPE).getFirstChild();
202            if (primitiveDataTypes.contains(parameterType.getType())) {
203                result = true;
204            }
205        }
206        return result;
207    }
208}