001///////////////////////////////////////////////////////////////////////////////////////////////
002// checkstyle: Checks Java source code and other text files for adherence to a set of rules.
003// Copyright (C) 2001-2023 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.whitespace;
021
022import com.puppycrawl.tools.checkstyle.StatelessCheck;
023import com.puppycrawl.tools.checkstyle.api.AbstractCheck;
024import com.puppycrawl.tools.checkstyle.api.DetailAST;
025import com.puppycrawl.tools.checkstyle.api.TokenTypes;
026import com.puppycrawl.tools.checkstyle.utils.TokenUtil;
027
028/**
029 * <p>
030 * Checks that there is no whitespace before the colon in a switch block.
031 * </p>
032 * <p>
033 * To configure the check:
034 * </p>
035 * <pre>
036 * &lt;module name=&quot;NoWhitespaceBeforeCaseDefaultColon&quot;/&gt;
037 * </pre>
038 * <p>Example:</p>
039 * <pre>
040 * class Test {
041 *   {
042 *     switch(1) {
043 *         case 1 : // violation, whitespace before ':' is not allowed here
044 *             break;
045 *         case 2: // ok
046 *             break;
047 *         default : // violation, whitespace before ':' is not allowed here
048 *             break;
049 *     }
050 *
051 *     switch(2) {
052 *         case 2: // ok
053 *             break;
054 *         case 3, 4
055 *                  : break; // violation, whitespace before ':' is not allowed here
056 *         case 4,
057 *               5: break; // ok
058 *         default
059 *               : // violation, whitespace before ':' is not allowed here
060 *             break;
061 *     }
062 *
063 *     switch(day) {
064 *         case MONDAY, FRIDAY, SUNDAY: System.out.println("  6"); break;
065 *         case TUESDAY               : System.out.println("  7"); break; // violation
066 *   }
067 * }
068 * </pre>
069 * <p>
070 * Parent is {@code com.puppycrawl.tools.checkstyle.TreeWalker}
071 * </p>
072 * <p>
073 * Violation Message Keys:
074 * </p>
075 * <ul>
076 * <li>
077 * {@code ws.preceded}
078 * </li>
079 * </ul>
080 *
081 * @since 8.45
082 */
083@StatelessCheck
084public class NoWhitespaceBeforeCaseDefaultColonCheck
085    extends AbstractCheck {
086
087    /**
088     * A key is pointing to the warning message text in "messages.properties"
089     * file.
090     */
091    public static final String MSG_KEY = "ws.preceded";
092
093    @Override
094    public int[] getDefaultTokens() {
095        return getRequiredTokens();
096    }
097
098    @Override
099    public int[] getAcceptableTokens() {
100        return getRequiredTokens();
101    }
102
103    @Override
104    public int[] getRequiredTokens() {
105        return new int[] {TokenTypes.COLON};
106    }
107
108    @Override
109    public boolean isCommentNodesRequired() {
110        return true;
111    }
112
113    @Override
114    public void visitToken(DetailAST ast) {
115        if (isInSwitch(ast) && isWhiteSpaceBeforeColon(ast)) {
116            log(ast, MSG_KEY, ast.getText());
117        }
118    }
119
120    /**
121     * Checks if the colon is inside a switch block.
122     *
123     * @param colonAst DetailAST to check.
124     * @return true, if colon case is inside a switch block.
125     */
126    private static boolean isInSwitch(DetailAST colonAst) {
127        return TokenUtil.isOfType(colonAst.getParent(), TokenTypes.LITERAL_CASE,
128                TokenTypes.LITERAL_DEFAULT);
129    }
130
131    /**
132     * Checks if there is a whitespace before the colon of a switch case or switch default.
133     *
134     * @param colonAst DetailAST to check.
135     * @return true, if there is whitespace preceding colonAst.
136     */
137    private static boolean isWhiteSpaceBeforeColon(DetailAST colonAst) {
138        final DetailAST parent = colonAst.getParent();
139        final boolean result;
140        if (isOnDifferentLineWithPreviousToken(colonAst)) {
141            result = true;
142        }
143        else if (parent.getType() == TokenTypes.LITERAL_CASE) {
144            result = isWhitespaceBeforeColonOfCase(colonAst);
145        }
146        else {
147            result = isWhitespaceBeforeColonOfDefault(colonAst);
148        }
149        return result;
150    }
151
152    /**
153     * Checks if there is a whitespace before the colon of a switch case.
154     *
155     * @param colonAst DetailAST to check.
156     * @return true, if there is whitespace preceding colonAst.
157     */
158    private static boolean isWhitespaceBeforeColonOfCase(DetailAST colonAst) {
159        final DetailAST previousSibling = colonAst.getPreviousSibling();
160        int offset = 0;
161        if (previousSibling.getType() == TokenTypes.BLOCK_COMMENT_BEGIN) {
162            offset = 1;
163        }
164        return colonAst.getColumnNo() != getLastColumnNumberOf(previousSibling) + offset;
165    }
166
167    /**
168     * Checks if there is a whitespace before the colon of a switch default.
169     *
170     * @param colonAst DetailAST to check.
171     * @return true, if there is whitespace preceding colonAst.
172     */
173    private static boolean isWhitespaceBeforeColonOfDefault(DetailAST colonAst) {
174        final boolean result;
175        final DetailAST previousSibling = colonAst.getPreviousSibling();
176        if (previousSibling == null) {
177            final DetailAST literalDefault = colonAst.getParent();
178            result = colonAst.getColumnNo()
179                    != literalDefault.getColumnNo() + literalDefault.getText().length();
180        }
181        else {
182            result =
183                    colonAst.getColumnNo() != getLastColumnNumberOf(previousSibling) + 1;
184        }
185        return result;
186    }
187
188    /**
189     * Checks if the colon is on same line as of case or default.
190     *
191     * @param colonAst DetailAST to check.
192     * @return true, if colon case is in different line as of case or default.
193     */
194    private static boolean isOnDifferentLineWithPreviousToken(DetailAST colonAst) {
195        final DetailAST previousSibling;
196        final DetailAST parent = colonAst.getParent();
197        if (parent.getType() == TokenTypes.LITERAL_CASE) {
198            previousSibling = colonAst.getPreviousSibling();
199        }
200        else {
201            previousSibling = colonAst.getParent();
202        }
203        return !TokenUtil.areOnSameLine(previousSibling, colonAst);
204    }
205
206    /**
207     * Returns the last column number of an ast.
208     *
209     * @param ast DetailAST to check.
210     * @return ast's last column number.
211     */
212    private static int getLastColumnNumberOf(DetailAST ast) {
213        DetailAST lastChild = ast;
214        while (lastChild.hasChildren()) {
215            lastChild = lastChild.getLastChild();
216        }
217        return lastChild.getColumnNo() + lastChild.getText().length();
218    }
219
220}