001////////////////////////////////////////////////////////////////////////////////
002// checkstyle: Checks Java source code for adherence to a set of rules.
003// Copyright (C) 2001-2018 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.CheckUtil;
032import com.puppycrawl.tools.checkstyle.utils.CommonUtil;
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 */
054@StatelessCheck
055public class FinalParametersCheck extends AbstractCheck {
056
057    /**
058     * A key is pointing to the warning message text in "messages.properties"
059     * file.
060     */
061    public static final String MSG_KEY = "final.parameter";
062
063    /**
064     * Contains
065     * <a href="https://docs.oracle.com/javase/tutorial/java/nutsandbolts/datatypes.html">
066     * primitive datatypes</a>.
067     */
068    private final Set<Integer> primitiveDataTypes = Collections.unmodifiableSet(
069        Arrays.stream(new Integer[] {
070            TokenTypes.LITERAL_BYTE,
071            TokenTypes.LITERAL_SHORT,
072            TokenTypes.LITERAL_INT,
073            TokenTypes.LITERAL_LONG,
074            TokenTypes.LITERAL_FLOAT,
075            TokenTypes.LITERAL_DOUBLE,
076            TokenTypes.LITERAL_BOOLEAN,
077            TokenTypes.LITERAL_CHAR, })
078        .collect(Collectors.toSet()));
079
080    /**
081     * Option to ignore primitive types as params.
082     */
083    private boolean ignorePrimitiveTypes;
084
085    /**
086     * Sets ignoring primitive types as params.
087     * @param ignorePrimitiveTypes true or false.
088     */
089    public void setIgnorePrimitiveTypes(boolean ignorePrimitiveTypes) {
090        this.ignorePrimitiveTypes = ignorePrimitiveTypes;
091    }
092
093    @Override
094    public int[] getDefaultTokens() {
095        return new int[] {
096            TokenTypes.METHOD_DEF,
097            TokenTypes.CTOR_DEF,
098        };
099    }
100
101    @Override
102    public int[] getAcceptableTokens() {
103        return new int[] {
104            TokenTypes.METHOD_DEF,
105            TokenTypes.CTOR_DEF,
106            TokenTypes.LITERAL_CATCH,
107            TokenTypes.FOR_EACH_CLAUSE,
108        };
109    }
110
111    @Override
112    public int[] getRequiredTokens() {
113        return CommonUtil.EMPTY_INT_ARRAY;
114    }
115
116    @Override
117    public void visitToken(DetailAST ast) {
118        // don't flag interfaces
119        final DetailAST container = ast.getParent().getParent();
120        if (container.getType() != TokenTypes.INTERFACE_DEF) {
121            if (ast.getType() == TokenTypes.LITERAL_CATCH) {
122                visitCatch(ast);
123            }
124            else if (ast.getType() == TokenTypes.FOR_EACH_CLAUSE) {
125                visitForEachClause(ast);
126            }
127            else {
128                visitMethod(ast);
129            }
130        }
131    }
132
133    /**
134     * Checks parameters of the method or ctor.
135     * @param method method or ctor to check.
136     */
137    private void visitMethod(final DetailAST method) {
138        final DetailAST modifiers =
139            method.findFirstToken(TokenTypes.MODIFIERS);
140        // exit on fast lane if there is nothing to check here
141
142        if (method.findFirstToken(TokenTypes.PARAMETERS)
143                .findFirstToken(TokenTypes.PARAMETER_DEF) != null
144                // ignore abstract and native methods
145                && modifiers.findFirstToken(TokenTypes.ABSTRACT) == null
146                && modifiers.findFirstToken(TokenTypes.LITERAL_NATIVE) == null) {
147            // we can now be sure that there is at least one parameter
148            final DetailAST parameters =
149                method.findFirstToken(TokenTypes.PARAMETERS);
150            DetailAST child = parameters.getFirstChild();
151            while (child != null) {
152                // children are PARAMETER_DEF and COMMA
153                if (child.getType() == TokenTypes.PARAMETER_DEF) {
154                    checkParam(child);
155                }
156                child = child.getNextSibling();
157            }
158        }
159    }
160
161    /**
162     * Checks parameter of the catch block.
163     * @param catchClause catch block to check.
164     */
165    private void visitCatch(final DetailAST catchClause) {
166        checkParam(catchClause.findFirstToken(TokenTypes.PARAMETER_DEF));
167    }
168
169    /**
170     * Checks parameter of the for each clause.
171     * @param forEachClause for each clause to check.
172     */
173    private void visitForEachClause(final DetailAST forEachClause) {
174        checkParam(forEachClause.findFirstToken(TokenTypes.VARIABLE_DEF));
175    }
176
177    /**
178     * Checks if the given parameter is final.
179     * @param param parameter to check.
180     */
181    private void checkParam(final DetailAST param) {
182        if (param.findFirstToken(TokenTypes.MODIFIERS).findFirstToken(TokenTypes.FINAL) == null
183                && !isIgnoredParam(param)
184                && !CheckUtil.isReceiverParameter(param)) {
185            final DetailAST paramName = param.findFirstToken(TokenTypes.IDENT);
186            final DetailAST firstNode = CheckUtil.getFirstNode(param);
187            log(firstNode,
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
209}