001//////////////////////////////////////////////////////////////////////////////// 002// checkstyle: Checks Java source code for adherence to a set of rules. 003// Copyright (C) 2001-2015 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 org.apache.commons.lang3.ArrayUtils; 023 024import com.puppycrawl.tools.checkstyle.api.Check; 025import com.puppycrawl.tools.checkstyle.api.DetailAST; 026import com.puppycrawl.tools.checkstyle.api.TokenTypes; 027 028/** 029 * <p> 030 * Checks that there is no whitespace before a token. 031 * More specifically, it checks that it is not preceded with whitespace, 032 * or (if line breaks are allowed) all characters on the line before are 033 * whitespace. To allow line breaks before a token, set property 034 * allowLineBreaks to true. 035 * </p> 036 * <p> By default the check will check the following operators: 037 * {@link TokenTypes#SEMI SEMI}, 038 * {@link TokenTypes#POST_DEC POST_DEC}, 039 * {@link TokenTypes#POST_INC POST_INC}. 040 * {@link TokenTypes#DOT DOT} is also an acceptable token in a configuration 041 * of this check. 042 * </p> 043 * 044 * <p> 045 * An example of how to configure the check is: 046 * </p> 047 * <pre> 048 * <module name="NoWhitespaceBefore"/> 049 * </pre> 050 * <p> An example of how to configure the check to allow line breaks before 051 * a {@link TokenTypes#DOT DOT} token is: 052 * </p> 053 * <pre> 054 * <module name="NoWhitespaceBefore"> 055 * <property name="tokens" value="DOT"/> 056 * <property name="allowLineBreaks" value="true"/> 057 * </module> 058 * </pre> 059 * @author Rick Giles 060 * @author lkuehne 061 */ 062public class NoWhitespaceBeforeCheck 063 extends Check { 064 065 /** 066 * A key is pointing to the warning message text in "messages.properties" 067 * file. 068 */ 069 public static final String MSG_KEY = "ws.preceded"; 070 071 /** Whether whitespace is allowed if the AST is at a linebreak. */ 072 private boolean allowLineBreaks; 073 074 @Override 075 public int[] getDefaultTokens() { 076 return new int[] { 077 TokenTypes.COMMA, 078 TokenTypes.SEMI, 079 TokenTypes.POST_INC, 080 TokenTypes.POST_DEC, 081 }; 082 } 083 084 @Override 085 public int[] getAcceptableTokens() { 086 return new int[] { 087 TokenTypes.COMMA, 088 TokenTypes.SEMI, 089 TokenTypes.POST_INC, 090 TokenTypes.POST_DEC, 091 TokenTypes.DOT, 092 TokenTypes.GENERIC_START, 093 TokenTypes.GENERIC_END, 094 }; 095 } 096 097 @Override 098 public int[] getRequiredTokens() { 099 return ArrayUtils.EMPTY_INT_ARRAY; 100 } 101 102 @Override 103 public void visitToken(DetailAST ast) { 104 final String line = getLine(ast.getLineNo() - 1); 105 final int before = ast.getColumnNo() - 1; 106 107 if ((before < 0 || Character.isWhitespace(line.charAt(before))) 108 && !isInEmptyForInitializer(ast)) { 109 110 boolean flag = !allowLineBreaks; 111 // verify all characters before '.' are whitespace 112 for (int i = 0; !flag && i < before; i++) { 113 if (!Character.isWhitespace(line.charAt(i))) { 114 flag = true; 115 } 116 } 117 if (flag) { 118 log(ast.getLineNo(), before, MSG_KEY, ast.getText()); 119 } 120 } 121 } 122 123 /** 124 * Checks that semicolon is in empty for initializer. 125 * @param semicolonAst DetailAST of semicolon. 126 * @return true if semicolon is in empty for initializer. 127 */ 128 private static boolean isInEmptyForInitializer(DetailAST semicolonAst) { 129 boolean result = false; 130 if (semicolonAst.getType() == TokenTypes.SEMI) { 131 final DetailAST sibling = semicolonAst.getPreviousSibling(); 132 if (sibling != null 133 && sibling.getType() == TokenTypes.FOR_INIT 134 && sibling.getChildCount() == 0) { 135 result = true; 136 } 137 } 138 return result; 139 } 140 141 /** 142 * Control whether whitespace is flagged at line breaks. 143 * @param allowLineBreaks whether whitespace should be 144 * flagged at line breaks. 145 */ 146 public void setAllowLineBreaks(boolean allowLineBreaks) { 147 this.allowLineBreaks = allowLineBreaks; 148 } 149}