1 ////////////////////////////////////////////////////////////////////////////////
2 // checkstyle: Checks Java source code for adherence to a set of rules.
3 // Copyright (C) 2001-2019 the original author or authors.
4 //
5 // This library is free software; you can redistribute it and/or
6 // modify it under the terms of the GNU Lesser General Public
7 // License as published by the Free Software Foundation; either
8 // version 2.1 of the License, or (at your option) any later version.
9 //
10 // This library is distributed in the hope that it will be useful,
11 // but WITHOUT ANY WARRANTY; without even the implied warranty of
12 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 // Lesser General Public License for more details.
14 //
15 // You should have received a copy of the GNU Lesser General Public
16 // License along with this library; if not, write to the Free Software
17 // Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
18 ////////////////////////////////////////////////////////////////////////////////
19
20 package com.puppycrawl.tools.checkstyle.checks.whitespace;
21
22 import com.puppycrawl.tools.checkstyle.StatelessCheck;
23 import com.puppycrawl.tools.checkstyle.api.AbstractCheck;
24 import com.puppycrawl.tools.checkstyle.api.DetailAST;
25 import com.puppycrawl.tools.checkstyle.api.TokenTypes;
26 import com.puppycrawl.tools.checkstyle.utils.CommonUtil;
27
28 /**
29 * <p>
30 * Checks that there is no whitespace before a token.
31 * More specifically, it checks that it is not preceded with whitespace,
32 * or (if line breaks are allowed) all characters on the line before are
33 * whitespace. To allow line breaks before a token, set property
34 * allowLineBreaks to true. No check occurs before semi-colons in empty
35 * for loop initializers or conditions.
36 * </p>
37 * <p> By default the check will check the following operators:
38 * {@link TokenTypes#COMMA COMMA},
39 * {@link TokenTypes#SEMI SEMI},
40 * {@link TokenTypes#POST_DEC POST_DEC},
41 * {@link TokenTypes#POST_INC POST_INC},
42 * {@link TokenTypes#ELLIPSIS ELLIPSIS}.
43 * {@link TokenTypes#DOT DOT} is also an acceptable token in a configuration
44 * of this check.
45 * </p>
46 *
47 * <p>
48 * An example of how to configure the check is:
49 * </p>
50 * <pre>
51 * <module name="NoWhitespaceBefore"/>
52 * </pre>
53 * <p> An example of how to configure the check to allow line breaks before
54 * a {@link TokenTypes#DOT DOT} token is:
55 * </p>
56 * <pre>
57 * <module name="NoWhitespaceBefore">
58 * <property name="tokens" value="DOT"/>
59 * <property name="allowLineBreaks" value="true"/>
60 * </module>
61 * </pre>
62 */
63 @StatelessCheck
64 public class NoWhitespaceBeforeCheck
65 extends AbstractCheck {
66
67 /**
68 * A key is pointing to the warning message text in "messages.properties"
69 * file.
70 */
71 public static final String MSG_KEY = "ws.preceded";
72
73 /** Whether whitespace is allowed if the AST is at a linebreak. */
74 private boolean allowLineBreaks;
75
76 @Override
77 public int[] getDefaultTokens() {
78 return new int[] {
79 TokenTypes.COMMA,
80 TokenTypes.SEMI,
81 TokenTypes.POST_INC,
82 TokenTypes.POST_DEC,
83 TokenTypes.ELLIPSIS,
84 };
85 }
86
87 @Override
88 public int[] getAcceptableTokens() {
89 return new int[] {
90 TokenTypes.COMMA,
91 TokenTypes.SEMI,
92 TokenTypes.POST_INC,
93 TokenTypes.POST_DEC,
94 TokenTypes.DOT,
95 TokenTypes.GENERIC_START,
96 TokenTypes.GENERIC_END,
97 TokenTypes.ELLIPSIS,
98 TokenTypes.METHOD_REF,
99 };
100 }
101
102 @Override
103 public int[] getRequiredTokens() {
104 return CommonUtil.EMPTY_INT_ARRAY;
105 }
106
107 @Override
108 public void visitToken(DetailAST ast) {
109 final String line = getLine(ast.getLineNo() - 1);
110 final int before = ast.getColumnNo() - 1;
111
112 if ((before == -1 || Character.isWhitespace(line.charAt(before)))
113 && !isInEmptyForInitializerOrCondition(ast)) {
114 boolean flag = !allowLineBreaks;
115 // verify all characters before '.' are whitespace
116 for (int i = 0; i <= before - 1; i++) {
117 if (!Character.isWhitespace(line.charAt(i))) {
118 flag = true;
119 break;
120 }
121 }
122 if (flag) {
123 log(ast, MSG_KEY, ast.getText());
124 }
125 }
126 }
127
128 /**
129 * Checks that semicolon is in empty for initializer or condition.
130 * @param semicolonAst DetailAST of semicolon.
131 * @return true if semicolon is in empty for initializer or condition.
132 */
133 private static boolean isInEmptyForInitializerOrCondition(DetailAST semicolonAst) {
134 boolean result = false;
135 final DetailAST sibling = semicolonAst.getPreviousSibling();
136 if (sibling != null
137 && (sibling.getType() == TokenTypes.FOR_INIT
138 || sibling.getType() == TokenTypes.FOR_CONDITION)
139 && sibling.getChildCount() == 0) {
140 result = true;
141 }
142 return result;
143 }
144
145 /**
146 * Control whether whitespace is flagged at line breaks.
147 * @param allowLineBreaks whether whitespace should be
148 * flagged at line breaks.
149 */
150 public void setAllowLineBreaks(boolean allowLineBreaks) {
151 this.allowLineBreaks = allowLineBreaks;
152 }
153
154 }