NoWhitespaceBeforeCheck.java
///////////////////////////////////////////////////////////////////////////////////////////////
// checkstyle: Checks Java source code and other text files for adherence to a set of rules.
// Copyright (C) 2001-2024 the original author or authors.
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
//
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
// Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
///////////////////////////////////////////////////////////////////////////////////////////////
package com.puppycrawl.tools.checkstyle.checks.whitespace;
import com.puppycrawl.tools.checkstyle.StatelessCheck;
import com.puppycrawl.tools.checkstyle.api.AbstractCheck;
import com.puppycrawl.tools.checkstyle.api.DetailAST;
import com.puppycrawl.tools.checkstyle.api.TokenTypes;
import com.puppycrawl.tools.checkstyle.utils.CodePointUtil;
import com.puppycrawl.tools.checkstyle.utils.CommonUtil;
/**
* <p>
* Checks that there is no whitespace before a token.
* More specifically, it checks that it is not preceded with whitespace,
* or (if linebreaks are allowed) all characters on the line before are
* whitespace. To allow linebreaks before a token, set property
* {@code allowLineBreaks} to {@code true}. No check occurs before semicolons in empty
* for loop initializers or conditions.
* </p>
* <ul>
* <li>
* Property {@code allowLineBreaks} - Control whether whitespace is allowed
* if the token is at a linebreak.
* Type is {@code boolean}.
* Default value is {@code false}.
* </li>
* <li>
* Property {@code tokens} - tokens to check
* Type is {@code java.lang.String[]}.
* Validation type is {@code tokenSet}.
* Default value is:
* <a href="https://checkstyle.org/apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#COMMA">
* COMMA</a>,
* <a href="https://checkstyle.org/apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#SEMI">
* SEMI</a>,
* <a href="https://checkstyle.org/apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#POST_INC">
* POST_INC</a>,
* <a href="https://checkstyle.org/apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#POST_DEC">
* POST_DEC</a>,
* <a href="https://checkstyle.org/apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#ELLIPSIS">
* ELLIPSIS</a>,
* <a href="https://checkstyle.org/apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#LABELED_STAT">
* LABELED_STAT</a>.
* </li>
* </ul>
* <p>
* Parent is {@code com.puppycrawl.tools.checkstyle.TreeWalker}
* </p>
* <p>
* Violation Message Keys:
* </p>
* <ul>
* <li>
* {@code ws.preceded}
* </li>
* </ul>
*
* @since 3.0
*/
@StatelessCheck
public class NoWhitespaceBeforeCheck
extends AbstractCheck {
/**
* A key is pointing to the warning message text in "messages.properties"
* file.
*/
public static final String MSG_KEY = "ws.preceded";
/** Control whether whitespace is allowed if the token is at a linebreak. */
private boolean allowLineBreaks;
@Override
public int[] getDefaultTokens() {
return new int[] {
TokenTypes.COMMA,
TokenTypes.SEMI,
TokenTypes.POST_INC,
TokenTypes.POST_DEC,
TokenTypes.ELLIPSIS,
TokenTypes.LABELED_STAT,
};
}
@Override
public int[] getAcceptableTokens() {
return new int[] {
TokenTypes.COMMA,
TokenTypes.SEMI,
TokenTypes.POST_INC,
TokenTypes.POST_DEC,
TokenTypes.DOT,
TokenTypes.GENERIC_START,
TokenTypes.GENERIC_END,
TokenTypes.ELLIPSIS,
TokenTypes.LABELED_STAT,
TokenTypes.METHOD_REF,
};
}
@Override
public int[] getRequiredTokens() {
return CommonUtil.EMPTY_INT_ARRAY;
}
@Override
public void visitToken(DetailAST ast) {
final int[] line = getLineCodePoints(ast.getLineNo() - 1);
final int columnNoBeforeToken = ast.getColumnNo() - 1;
final boolean isFirstToken = columnNoBeforeToken == -1;
if ((isFirstToken || CommonUtil.isCodePointWhitespace(line, columnNoBeforeToken))
&& !isInEmptyForInitializerOrCondition(ast)) {
final boolean isViolation = !allowLineBreaks
|| !isFirstToken
&& !CodePointUtil.hasWhitespaceBefore(columnNoBeforeToken, line);
if (isViolation) {
log(ast, MSG_KEY, ast.getText());
}
}
}
/**
* Checks that semicolon is in empty for initializer or condition.
*
* @param semicolonAst DetailAST of semicolon.
* @return true if semicolon is in empty for initializer or condition.
*/
private static boolean isInEmptyForInitializerOrCondition(DetailAST semicolonAst) {
boolean result = false;
final DetailAST sibling = semicolonAst.getPreviousSibling();
if (sibling != null
&& (sibling.getType() == TokenTypes.FOR_INIT
|| sibling.getType() == TokenTypes.FOR_CONDITION)
&& !sibling.hasChildren()) {
result = true;
}
return result;
}
/**
* Setter to control whether whitespace is allowed if the token is at a linebreak.
*
* @param allowLineBreaks whether whitespace should be
* flagged at line breaks.
* @since 3.0
*/
public void setAllowLineBreaks(boolean allowLineBreaks) {
this.allowLineBreaks = allowLineBreaks;
}
}