001///////////////////////////////////////////////////////////////////////////////////////////////
002// checkstyle: Checks Java source code and other text files for adherence to a set of rules.
003// Copyright (C) 2001-2024 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 * <div>
030 * Checks that there is no whitespace before the colon in a switch block.
031 * </div>
032 *
033 * <p>
034 * Parent is {@code com.puppycrawl.tools.checkstyle.TreeWalker}
035 * </p>
036 *
037 * <p>
038 * Violation Message Keys:
039 * </p>
040 * <ul>
041 * <li>
042 * {@code ws.preceded}
043 * </li>
044 * </ul>
045 *
046 * @since 8.45
047 */
048@StatelessCheck
049public class NoWhitespaceBeforeCaseDefaultColonCheck
050    extends AbstractCheck {
051
052    /**
053     * A key is pointing to the warning message text in "messages.properties"
054     * file.
055     */
056    public static final String MSG_KEY = "ws.preceded";
057
058    @Override
059    public int[] getDefaultTokens() {
060        return getRequiredTokens();
061    }
062
063    @Override
064    public int[] getAcceptableTokens() {
065        return getRequiredTokens();
066    }
067
068    @Override
069    public int[] getRequiredTokens() {
070        return new int[] {TokenTypes.COLON};
071    }
072
073    @Override
074    public boolean isCommentNodesRequired() {
075        return true;
076    }
077
078    @Override
079    public void visitToken(DetailAST ast) {
080        if (isInSwitch(ast) && isWhiteSpaceBeforeColon(ast)) {
081            log(ast, MSG_KEY, ast.getText());
082        }
083    }
084
085    /**
086     * Checks if the colon is inside a switch block.
087     *
088     * @param colonAst DetailAST to check.
089     * @return true, if colon case is inside a switch block.
090     */
091    private static boolean isInSwitch(DetailAST colonAst) {
092        return TokenUtil.isOfType(colonAst.getParent(), TokenTypes.LITERAL_CASE,
093                TokenTypes.LITERAL_DEFAULT);
094    }
095
096    /**
097     * Checks if there is a whitespace before the colon of a switch case or switch default.
098     *
099     * @param colonAst DetailAST to check.
100     * @return true, if there is whitespace preceding colonAst.
101     */
102    private static boolean isWhiteSpaceBeforeColon(DetailAST colonAst) {
103        final DetailAST parent = colonAst.getParent();
104        final boolean result;
105        if (isOnDifferentLineWithPreviousToken(colonAst)) {
106            result = true;
107        }
108        else if (parent.getType() == TokenTypes.LITERAL_CASE) {
109            result = isWhitespaceBeforeColonOfCase(colonAst);
110        }
111        else {
112            result = isWhitespaceBeforeColonOfDefault(colonAst);
113        }
114        return result;
115    }
116
117    /**
118     * Checks if there is a whitespace before the colon of a switch case.
119     *
120     * @param colonAst DetailAST to check.
121     * @return true, if there is whitespace preceding colonAst.
122     */
123    private static boolean isWhitespaceBeforeColonOfCase(DetailAST colonAst) {
124        final DetailAST previousSibling = colonAst.getPreviousSibling();
125        int offset = 0;
126        if (previousSibling.getType() == TokenTypes.BLOCK_COMMENT_BEGIN) {
127            offset = 1;
128        }
129        return colonAst.getColumnNo() != getLastColumnNumberOf(previousSibling) + offset;
130    }
131
132    /**
133     * Checks if there is a whitespace before the colon of a switch default.
134     *
135     * @param colonAst DetailAST to check.
136     * @return true, if there is whitespace preceding colonAst.
137     */
138    private static boolean isWhitespaceBeforeColonOfDefault(DetailAST colonAst) {
139        final boolean result;
140        final DetailAST previousSibling = colonAst.getPreviousSibling();
141        if (previousSibling == null) {
142            final DetailAST literalDefault = colonAst.getParent();
143            result = colonAst.getColumnNo()
144                    != literalDefault.getColumnNo() + literalDefault.getText().length();
145        }
146        else {
147            result =
148                    colonAst.getColumnNo() != getLastColumnNumberOf(previousSibling) + 1;
149        }
150        return result;
151    }
152
153    /**
154     * Checks if the colon is on same line as of case or default.
155     *
156     * @param colonAst DetailAST to check.
157     * @return true, if colon case is in different line as of case or default.
158     */
159    private static boolean isOnDifferentLineWithPreviousToken(DetailAST colonAst) {
160        final DetailAST previousSibling;
161        final DetailAST parent = colonAst.getParent();
162        if (parent.getType() == TokenTypes.LITERAL_CASE) {
163            previousSibling = colonAst.getPreviousSibling();
164        }
165        else {
166            previousSibling = colonAst.getParent();
167        }
168        return !TokenUtil.areOnSameLine(previousSibling, colonAst);
169    }
170
171    /**
172     * Returns the last column number of an ast.
173     *
174     * @param ast DetailAST to check.
175     * @return ast's last column number.
176     */
177    private static int getLastColumnNumberOf(DetailAST ast) {
178        DetailAST lastChild = ast;
179        while (lastChild.hasChildren()) {
180            lastChild = lastChild.getLastChild();
181        }
182        return lastChild.getColumnNo() + lastChild.getText().length();
183    }
184
185}