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 java.util.Arrays; 023 024import com.puppycrawl.tools.checkstyle.StatelessCheck; 025import com.puppycrawl.tools.checkstyle.api.AbstractCheck; 026import com.puppycrawl.tools.checkstyle.api.DetailAST; 027import com.puppycrawl.tools.checkstyle.utils.CodePointUtil; 028import com.puppycrawl.tools.checkstyle.utils.CommonUtil; 029 030/** 031 * <p> 032 * Checks that non-whitespace characters are separated by no more than one 033 * whitespace. Separating characters by tabs or multiple spaces will be 034 * reported. Currently, the check doesn't permit horizontal alignment. To inspect 035 * whitespaces before and after comments, set the property 036 * {@code validateComments} to true. 037 * </p> 038 * 039 * <p> 040 * Setting {@code validateComments} to false will ignore cases like: 041 * </p> 042 * 043 * <pre> 044 * int i; // Multiple whitespaces before comment tokens will be ignored. 045 * private void foo(int /* whitespaces before and after block-comments will be 046 * ignored */ i) { 047 * </pre> 048 * 049 * <p> 050 * Sometimes, users like to space similar items on different lines to the same 051 * column position for easier reading. This feature isn't supported by this 052 * check, so both braces in the following case will be reported as violations. 053 * </p> 054 * 055 * <pre> 056 * public long toNanos(long d) { return d; } // 2 violations 057 * public long toMicros(long d) { return d / (C1 / C0); } 058 * </pre> 059 * <ul> 060 * <li> 061 * Property {@code validateComments} - Control whether to validate whitespaces 062 * surrounding comments. 063 * Type is {@code boolean}. 064 * Default value is {@code false}. 065 * </li> 066 * </ul> 067 * <p> 068 * Parent is {@code com.puppycrawl.tools.checkstyle.TreeWalker} 069 * </p> 070 * <p> 071 * Violation Message Keys: 072 * </p> 073 * <ul> 074 * <li> 075 * {@code single.space.separator} 076 * </li> 077 * </ul> 078 * 079 * @since 6.19 080 */ 081@StatelessCheck 082public class SingleSpaceSeparatorCheck extends AbstractCheck { 083 084 /** 085 * A key is pointing to the warning message text in "messages.properties" 086 * file. 087 */ 088 public static final String MSG_KEY = "single.space.separator"; 089 090 /** Control whether to validate whitespaces surrounding comments. */ 091 private boolean validateComments; 092 093 /** 094 * Setter to control whether to validate whitespaces surrounding comments. 095 * 096 * @param validateComments {@code true} to validate surrounding whitespaces at comments. 097 * @since 6.19 098 */ 099 public void setValidateComments(boolean validateComments) { 100 this.validateComments = validateComments; 101 } 102 103 @Override 104 public int[] getDefaultTokens() { 105 return getRequiredTokens(); 106 } 107 108 @Override 109 public int[] getAcceptableTokens() { 110 return getRequiredTokens(); 111 } 112 113 @Override 114 public int[] getRequiredTokens() { 115 return CommonUtil.EMPTY_INT_ARRAY; 116 } 117 118 @Override 119 public boolean isCommentNodesRequired() { 120 return validateComments; 121 } 122 123 @Override 124 public void beginTree(DetailAST rootAST) { 125 if (rootAST != null) { 126 visitEachToken(rootAST); 127 } 128 } 129 130 /** 131 * Examines every sibling and child of {@code node} for violations. 132 * 133 * @param node The node to start examining. 134 */ 135 private void visitEachToken(DetailAST node) { 136 DetailAST currentNode = node; 137 138 do { 139 final int columnNo = currentNode.getColumnNo() - 1; 140 141 // in such expression: "j =123", placed at the start of the string index of the second 142 // space character will be: 2 = 0(j) + 1(whitespace) + 1(whitespace). It is a minimal 143 // possible index for the second whitespace between non-whitespace characters. 144 final int minSecondWhitespaceColumnNo = 2; 145 146 if (columnNo >= minSecondWhitespaceColumnNo 147 && !isTextSeparatedCorrectlyFromPrevious( 148 getLineCodePoints(currentNode.getLineNo() - 1), 149 columnNo)) { 150 log(currentNode, MSG_KEY); 151 } 152 if (currentNode.hasChildren()) { 153 currentNode = currentNode.getFirstChild(); 154 } 155 else { 156 while (currentNode.getNextSibling() == null && currentNode.getParent() != null) { 157 currentNode = currentNode.getParent(); 158 } 159 currentNode = currentNode.getNextSibling(); 160 } 161 } while (currentNode != null); 162 } 163 164 /** 165 * Checks if characters in {@code line} at and around {@code columnNo} has 166 * the correct number of spaces. to return {@code true} the following 167 * conditions must be met: 168 * <ul> 169 * <li> the character at {@code columnNo} is the first in the line. </li> 170 * <li> the character at {@code columnNo} is not separated by whitespaces from 171 * the previous non-whitespace character. </li> 172 * <li> the character at {@code columnNo} is separated by only one whitespace 173 * from the previous non-whitespace character. </li> 174 * <li> {@link #validateComments} is disabled and the previous text is the 175 * end of a block comment. </li> 176 * </ul> 177 * 178 * @param line Unicode code point array of line in the file to examine. 179 * @param columnNo The column position in the {@code line} to examine. 180 * @return {@code true} if the text at {@code columnNo} is separated 181 * correctly from the previous token. 182 */ 183 private boolean isTextSeparatedCorrectlyFromPrevious(int[] line, int columnNo) { 184 return isSingleSpace(line, columnNo) 185 || !CommonUtil.isCodePointWhitespace(line, columnNo) 186 || isFirstInLine(line, columnNo) 187 || !validateComments && isBlockCommentEnd(line, columnNo); 188 } 189 190 /** 191 * Checks if the {@code line} at {@code columnNo} is a single space, and not 192 * preceded by another space. 193 * 194 * @param line Unicode code point array of line in the file to examine. 195 * @param columnNo The column position in the {@code line} to examine. 196 * @return {@code true} if the character at {@code columnNo} is a space, and 197 * not preceded by another space. 198 */ 199 private static boolean isSingleSpace(int[] line, int columnNo) { 200 return isSpace(line, columnNo) && !CommonUtil.isCodePointWhitespace(line, columnNo - 1); 201 } 202 203 /** 204 * Checks if the {@code line} at {@code columnNo} is a space. 205 * 206 * @param line Unicode code point array of line in the file to examine. 207 * @param columnNo The column position in the {@code line} to examine. 208 * @return {@code true} if the character at {@code columnNo} is a space. 209 */ 210 private static boolean isSpace(int[] line, int columnNo) { 211 return line[columnNo] == ' '; 212 } 213 214 /** 215 * Checks if the {@code line} up to and including {@code columnNo} is all 216 * non-whitespace text encountered. 217 * 218 * @param line Unicode code point array of line in the file to examine. 219 * @param columnNo The column position in the {@code line} to examine. 220 * @return {@code true} if the column position is the first non-whitespace 221 * text on the {@code line}. 222 */ 223 private static boolean isFirstInLine(int[] line, int columnNo) { 224 return CodePointUtil.isBlank(Arrays.copyOfRange(line, 0, columnNo)); 225 } 226 227 /** 228 * Checks if the {@code line} at {@code columnNo} is the end of a comment, 229 * '*/'. 230 * 231 * @param line Unicode code point array of line in the file to examine. 232 * @param columnNo The column position in the {@code line} to examine. 233 * @return {@code true} if the previous text is an end comment block. 234 */ 235 private static boolean isBlockCommentEnd(int[] line, int columnNo) { 236 final int[] strippedLine = CodePointUtil 237 .stripTrailing(Arrays.copyOfRange(line, 0, columnNo)); 238 return CodePointUtil.endsWith(strippedLine, "*/"); 239 } 240 241}