NoWhitespaceAfterCheck.java
///////////////////////////////////////////////////////////////////////////////////////////////
// checkstyle: Checks Java source code and other text files for adherence to a set of rules.
// Copyright (C) 2001-2022 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 java.util.Optional;
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.CommonUtil;
/**
* <p>
* Checks that there is no whitespace after a token.
* More specifically, it checks that it is not followed by whitespace,
* or (if linebreaks are allowed) all characters on the line after are
* whitespace. To forbid linebreaks after a token, set property
* {@code allowLineBreaks} to {@code false}.
* </p>
* <p>
* The check processes
* <a href="https://checkstyle.org/apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#ARRAY_DECLARATOR">
* ARRAY_DECLARATOR</a> and
* <a href="https://checkstyle.org/apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#INDEX_OP">
* INDEX_OP</a> tokens specially from other tokens. Actually it is checked that
* there is no whitespace before these tokens, not after them. Space after the
* <a href="https://checkstyle.org/apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#ANNOTATIONS">
* ANNOTATIONS</a> before
* <a href="https://checkstyle.org/apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#ARRAY_DECLARATOR">
* ARRAY_DECLARATOR</a> and
* <a href="https://checkstyle.org/apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#INDEX_OP">
* INDEX_OP</a> will be ignored.
* </p>
* <p>
* If the annotation is between the type and the array, the check will skip validation for spaces
* </p>
* <pre>
* public void foo(final char @NotNull [] param) {} // No violation
* </pre>
* <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 true}.
* </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#ARRAY_INIT">
* ARRAY_INIT</a>,
* <a href="https://checkstyle.org/apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#AT">
* AT</a>,
* <a href="https://checkstyle.org/apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#INC">
* INC</a>,
* <a href="https://checkstyle.org/apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#DEC">
* DEC</a>,
* <a href="https://checkstyle.org/apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#UNARY_MINUS">
* UNARY_MINUS</a>,
* <a href="https://checkstyle.org/apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#UNARY_PLUS">
* UNARY_PLUS</a>,
* <a href="https://checkstyle.org/apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#BNOT">
* BNOT</a>,
* <a href="https://checkstyle.org/apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#LNOT">
* LNOT</a>,
* <a href="https://checkstyle.org/apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#DOT">
* DOT</a>,
* <a href="https://checkstyle.org/apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#ARRAY_DECLARATOR">
* ARRAY_DECLARATOR</a>,
* <a href="https://checkstyle.org/apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#INDEX_OP">
* INDEX_OP</a>.
* </li>
* </ul>
* <p>
* To configure the check:
* </p>
* <pre>
* <module name="NoWhitespaceAfter"/>
* </pre>
* <p>Example:</p>
* <pre>
* class Test {
*
* public void lineBreak(String x) {
* Integer.
* parseInt(x); // Ok
* Integer.parseInt(x); // Ok
* }
*
* public void dotOperator(String s) {
* Integer.parseInt(s); // Ok
* Integer. parseInt(s); // violation, '.' is followed by whitespace
* }
*
* public void arrayDec() {
* int[] arr = arr; // Ok
* int [] arr = arr; // violation, int is followed by whitespace
* }
*
* public void bitwiseNot(int a) {
* a = ~ a; // violation '~' is followed by whitespace
* a = ~a; // Ok
* }
* }
* </pre>
* <p>To configure the check to forbid linebreaks after a DOT token:
* </p>
* <pre>
* <module name="NoWhitespaceAfter">
* <property name="tokens" value="DOT"/>
* <property name="allowLineBreaks" value="false"/>
* </module>
* </pre>
* <p>Example:</p>
* <pre>
* class Test {
*
* public void lineBreak(String x) {
* Integer.
* parseInt(x); // violation, '.' is followed by whitespace
* Integer.parseInt(x); // Ok
* }
*
* public void dotOperator(String s) {
* Integer.parseInt(s); // Ok
* Integer. parseInt(s); // violation, '.' is followed by whitespace
* }
*
* public void arrayDec() {
* int[] arr = arr; // Ok
* int [] arr = arr; // Ok
* }
*
* public void bitwiseNot(int a) {
* a = ~ a; // Ok
* a = ~a; // Ok
* }
* }
* </pre>
* <p>
* Parent is {@code com.puppycrawl.tools.checkstyle.TreeWalker}
* </p>
* <p>
* Violation Message Keys:
* </p>
* <ul>
* <li>
* {@code ws.followed}
* </li>
* </ul>
*
* @since 3.0
*/
@StatelessCheck
public class NoWhitespaceAfterCheck extends AbstractCheck {
/**
* A key is pointing to the warning message text in "messages.properties"
* file.
*/
public static final String MSG_KEY = "ws.followed";
/** Control whether whitespace is allowed if the token is at a linebreak. */
private boolean allowLineBreaks = true;
@Override
public int[] getDefaultTokens() {
return new int[] {
TokenTypes.ARRAY_INIT,
TokenTypes.AT,
TokenTypes.INC,
TokenTypes.DEC,
TokenTypes.UNARY_MINUS,
TokenTypes.UNARY_PLUS,
TokenTypes.BNOT,
TokenTypes.LNOT,
TokenTypes.DOT,
TokenTypes.ARRAY_DECLARATOR,
TokenTypes.INDEX_OP,
};
}
@Override
public int[] getAcceptableTokens() {
return new int[] {
TokenTypes.ARRAY_INIT,
TokenTypes.AT,
TokenTypes.INC,
TokenTypes.DEC,
TokenTypes.UNARY_MINUS,
TokenTypes.UNARY_PLUS,
TokenTypes.BNOT,
TokenTypes.LNOT,
TokenTypes.DOT,
TokenTypes.TYPECAST,
TokenTypes.ARRAY_DECLARATOR,
TokenTypes.INDEX_OP,
TokenTypes.LITERAL_SYNCHRONIZED,
TokenTypes.METHOD_REF,
};
}
@Override
public int[] getRequiredTokens() {
return CommonUtil.EMPTY_INT_ARRAY;
}
/**
* Setter to control whether whitespace is allowed if the token is at a linebreak.
*
* @param allowLineBreaks whether whitespace should be
* flagged at linebreaks.
*/
public void setAllowLineBreaks(boolean allowLineBreaks) {
this.allowLineBreaks = allowLineBreaks;
}
@Override
public void visitToken(DetailAST ast) {
if (shouldCheckWhitespaceAfter(ast)) {
final DetailAST whitespaceFollowedAst = getWhitespaceFollowedNode(ast);
final int whitespaceColumnNo = getPositionAfter(whitespaceFollowedAst);
final int whitespaceLineNo = whitespaceFollowedAst.getLineNo();
if (hasTrailingWhitespace(ast, whitespaceColumnNo, whitespaceLineNo)) {
log(ast, MSG_KEY, whitespaceFollowedAst.getText());
}
}
}
/**
* For a visited ast node returns node that should be checked
* for not being followed by whitespace.
*
* @param ast
* , visited node.
* @return node before ast.
*/
private static DetailAST getWhitespaceFollowedNode(DetailAST ast) {
final DetailAST whitespaceFollowedAst;
switch (ast.getType()) {
case TokenTypes.TYPECAST:
whitespaceFollowedAst = ast.findFirstToken(TokenTypes.RPAREN);
break;
case TokenTypes.ARRAY_DECLARATOR:
whitespaceFollowedAst = getArrayDeclaratorPreviousElement(ast);
break;
case TokenTypes.INDEX_OP:
whitespaceFollowedAst = getIndexOpPreviousElement(ast);
break;
default:
whitespaceFollowedAst = ast;
}
return whitespaceFollowedAst;
}
/**
* Returns whether whitespace after a visited node should be checked. For example, whitespace
* is not allowed between a type and an array declarator (returns true), except when there is
* an annotation in between the type and array declarator (returns false).
*
* @param ast the visited node
* @return true if whitespace after ast should be checked
*/
private static boolean shouldCheckWhitespaceAfter(DetailAST ast) {
boolean checkWhitespace = true;
final DetailAST previousSibling = ast.getPreviousSibling();
if (previousSibling != null && previousSibling.getType() == TokenTypes.ANNOTATIONS) {
checkWhitespace = false;
}
return checkWhitespace;
}
/**
* Gets position after token (place of possible redundant whitespace).
*
* @param ast Node representing token.
* @return position after token.
*/
private static int getPositionAfter(DetailAST ast) {
final int after;
// If target of possible redundant whitespace is in method definition.
if (ast.getType() == TokenTypes.IDENT
&& ast.getNextSibling() != null
&& ast.getNextSibling().getType() == TokenTypes.LPAREN) {
final DetailAST methodDef = ast.getParent();
final DetailAST endOfParams = methodDef.findFirstToken(TokenTypes.RPAREN);
after = endOfParams.getColumnNo() + 1;
}
else {
after = ast.getColumnNo() + ast.getText().length();
}
return after;
}
/**
* Checks if there is unwanted whitespace after the visited node.
*
* @param ast
* , visited node.
* @param whitespaceColumnNo
* , column number of a possible whitespace.
* @param whitespaceLineNo
* , line number of a possible whitespace.
* @return true if whitespace found.
*/
private boolean hasTrailingWhitespace(DetailAST ast,
int whitespaceColumnNo, int whitespaceLineNo) {
final boolean result;
final int astLineNo = ast.getLineNo();
final int[] line = getLineCodePoints(astLineNo - 1);
if (astLineNo == whitespaceLineNo && whitespaceColumnNo < line.length) {
result = CommonUtil.isCodePointWhitespace(line, whitespaceColumnNo);
}
else {
result = !allowLineBreaks;
}
return result;
}
/**
* Returns proper argument for getPositionAfter method, it is a token after
* {@link TokenTypes#ARRAY_DECLARATOR ARRAY_DECLARATOR}, in can be {@link TokenTypes#RBRACK
* RBRACK}, {@link TokenTypes#IDENT IDENT} or an array type definition (literal).
*
* @param ast
* , {@link TokenTypes#ARRAY_DECLARATOR ARRAY_DECLARATOR} node.
* @return previous node by text order.
* @throws IllegalStateException if an unexpected token type is encountered.
*/
private static DetailAST getArrayDeclaratorPreviousElement(DetailAST ast) {
final DetailAST previousElement;
if (ast.getPreviousSibling() != null
&& ast.getPreviousSibling().getType() == TokenTypes.ARRAY_DECLARATOR) {
// Covers higher dimension array declarations and initializations
previousElement = getPreviousElementOfMultiDimArray(ast);
}
else {
// first array index, is preceded with identifier or type
final DetailAST parent = ast.getParent();
switch (parent.getType()) {
// generics
case TokenTypes.TYPE_UPPER_BOUNDS:
case TokenTypes.TYPE_LOWER_BOUNDS:
previousElement = ast.getPreviousSibling();
break;
case TokenTypes.LITERAL_NEW:
case TokenTypes.TYPE_ARGUMENT:
case TokenTypes.DOT:
previousElement = getTypeLastNode(ast);
break;
// mundane array declaration, can be either java style or C style
case TokenTypes.TYPE:
previousElement = getPreviousNodeWithParentOfTypeAst(ast, parent);
break;
// java 8 method reference
case TokenTypes.METHOD_REF:
final DetailAST ident = getIdentLastToken(ast);
if (ident == null) {
// i.e. int[]::new
previousElement = ast.getParent().getFirstChild();
}
else {
previousElement = ident;
}
break;
default:
throw new IllegalStateException("unexpected ast syntax " + parent);
}
}
return previousElement;
}
/**
* Gets the previous element of a second or higher dimension of an
* array declaration or initialization.
*
* @param leftBracket the token to get previous element of
* @return the previous element
*/
private static DetailAST getPreviousElementOfMultiDimArray(DetailAST leftBracket) {
final DetailAST previousRightBracket = leftBracket.getPreviousSibling().getLastChild();
DetailAST ident = null;
// This will get us past the type ident, to the actual identifier
DetailAST parent = leftBracket.getParent().getParent();
while (ident == null) {
ident = parent.findFirstToken(TokenTypes.IDENT);
parent = parent.getParent();
}
final DetailAST previousElement;
if (ident.getColumnNo() > previousRightBracket.getColumnNo()
&& ident.getColumnNo() < leftBracket.getColumnNo()) {
// C style and Java style ' int[] arr []' in same construct
previousElement = ident;
}
else {
// 'int[][] arr' or 'int arr[][]'
previousElement = previousRightBracket;
}
return previousElement;
}
/**
* Gets previous node for {@link TokenTypes#INDEX_OP INDEX_OP} token
* for usage in getPositionAfter method, it is a simplified copy of
* getArrayDeclaratorPreviousElement method.
*
* @param ast
* , {@link TokenTypes#INDEX_OP INDEX_OP} node.
* @return previous node by text order.
*/
private static DetailAST getIndexOpPreviousElement(DetailAST ast) {
final DetailAST result;
final DetailAST firstChild = ast.getFirstChild();
if (firstChild.getType() == TokenTypes.INDEX_OP) {
// second or higher array index
result = firstChild.findFirstToken(TokenTypes.RBRACK);
}
else if (firstChild.getType() == TokenTypes.IDENT) {
result = firstChild;
}
else {
final DetailAST ident = getIdentLastToken(ast);
if (ident == null) {
final DetailAST rparen = ast.findFirstToken(TokenTypes.RPAREN);
// construction like new int[]{1}[0]
if (rparen == null) {
final DetailAST lastChild = firstChild.getLastChild();
result = lastChild.findFirstToken(TokenTypes.RCURLY);
}
// construction like ((byte[]) pixels)[0]
else {
result = rparen;
}
}
else {
result = ident;
}
}
return result;
}
/**
* Searches parameter node for a type node.
* Returns it or its last node if it has an extended structure.
*
* @param ast
* , subject node.
* @return type node.
*/
private static DetailAST getTypeLastNode(DetailAST ast) {
final DetailAST typeLastNode;
final DetailAST parent = ast.getParent();
final boolean isPrecededByTypeArgs =
parent.findFirstToken(TokenTypes.TYPE_ARGUMENTS) != null;
final Optional<DetailAST> objectArrayType = Optional.ofNullable(getIdentLastToken(ast));
if (isPrecededByTypeArgs) {
typeLastNode = parent.findFirstToken(TokenTypes.TYPE_ARGUMENTS)
.findFirstToken(TokenTypes.GENERIC_END);
}
else if (objectArrayType.isPresent()) {
typeLastNode = objectArrayType.get();
}
else {
typeLastNode = parent.getFirstChild();
}
return typeLastNode;
}
/**
* Finds previous node by text order for an array declarator,
* which parent type is {@link TokenTypes#TYPE TYPE}.
*
* @param ast
* , array declarator node.
* @param parent
* , its parent node.
* @return previous node by text order.
*/
private static DetailAST getPreviousNodeWithParentOfTypeAst(DetailAST ast, DetailAST parent) {
final DetailAST previousElement;
final DetailAST ident = getIdentLastToken(parent.getParent());
final DetailAST lastTypeNode = getTypeLastNode(ast);
final boolean isTypeCast = parent.getParent().getType() == TokenTypes.TYPECAST;
// sometimes there are ident-less sentences
// i.e. "(Object[]) null", but in casual case should be
// checked whether ident or lastTypeNode has preceding position
// determining if it is java style or C style
if (ident == null || isTypeCast || ident.getLineNo() > ast.getLineNo()) {
previousElement = lastTypeNode;
}
else if (ident.getLineNo() < ast.getLineNo()) {
previousElement = ident;
}
// ident and lastTypeNode lay on one line
else {
final int instanceOfSize = 13;
// +2 because ast has `[]` after the ident
if (ident.getColumnNo() >= ast.getColumnNo() + 2
// +13 because ident (at most 1 character) is followed by
// ' instanceof ' (12 characters)
|| lastTypeNode.getColumnNo() >= ident.getColumnNo() + instanceOfSize) {
previousElement = lastTypeNode;
}
else {
previousElement = ident;
}
}
return previousElement;
}
/**
* Gets leftmost token of identifier.
*
* @param ast
* , token possibly possessing an identifier.
* @return leftmost token of identifier.
*/
private static DetailAST getIdentLastToken(DetailAST ast) {
final DetailAST result;
final DetailAST dot = getPrecedingDot(ast);
// method call case
if (dot == null || ast.getFirstChild().getType() == TokenTypes.METHOD_CALL) {
final DetailAST methodCall = ast.findFirstToken(TokenTypes.METHOD_CALL);
if (methodCall == null) {
result = ast.findFirstToken(TokenTypes.IDENT);
}
else {
result = methodCall.findFirstToken(TokenTypes.RPAREN);
}
}
// qualified name case
else {
result = dot.getFirstChild().getNextSibling();
}
return result;
}
/**
* Gets the dot preceding a class member array index operation or class
* reference.
*
* @param leftBracket the ast we are checking
* @return dot preceding the left bracket
*/
private static DetailAST getPrecedingDot(DetailAST leftBracket) {
final DetailAST referencedClassDot =
leftBracket.getParent().findFirstToken(TokenTypes.DOT);
final DetailAST referencedMemberDot = leftBracket.findFirstToken(TokenTypes.DOT);
return Optional.ofNullable(referencedMemberDot).orElse(referencedClassDot);
}
}