////////////////////////////////////////////////////////////////////////////////
// checkstyle: Checks Java source code for adherence to a set of rules.
// Copyright (C) 2001-2017 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.ArrayList;
import java.util.List;
import com.puppycrawl.tools.checkstyle.api.AbstractCheck;
import com.puppycrawl.tools.checkstyle.api.DetailAST;
import com.puppycrawl.tools.checkstyle.api.FileContents;
import com.puppycrawl.tools.checkstyle.api.TokenTypes;
import com.puppycrawl.tools.checkstyle.utils.CommonUtils;
import com.puppycrawl.tools.checkstyle.utils.JavadocUtils;
/**
* Checks for empty line separators after header, package, all import declarations,
* fields, constructors, methods, nested classes,
* static initializers and instance initializers.
*
* <p> By default the check will check the following statements:
* {@link TokenTypes#PACKAGE_DEF PACKAGE_DEF},
* {@link TokenTypes#IMPORT IMPORT},
* {@link TokenTypes#CLASS_DEF CLASS_DEF},
* {@link TokenTypes#INTERFACE_DEF INTERFACE_DEF},
* {@link TokenTypes#STATIC_INIT STATIC_INIT},
* {@link TokenTypes#INSTANCE_INIT INSTANCE_INIT},
* {@link TokenTypes#METHOD_DEF METHOD_DEF},
* {@link TokenTypes#CTOR_DEF CTOR_DEF},
* {@link TokenTypes#VARIABLE_DEF VARIABLE_DEF}.
* </p>
*
* <p>
* Example of declarations without empty line separator:
* </p>
*
* <pre>
* ///////////////////////////////////////////////////
* //HEADER
* ///////////////////////////////////////////////////
* package com.puppycrawl.tools.checkstyle.whitespace;
* import java.io.Serializable;
* class Foo
* {
* public static final int FOO_CONST = 1;
* public void foo() {} //should be separated from previous statement.
* }
* </pre>
*
* <p> An example of how to configure the check with default parameters is:
* </p>
*
* <pre>
* <module name="EmptyLineSeparator"/>
* </pre>
*
* <p>
* Example of declarations with empty line separator
* that is expected by the Check by default:
* </p>
*
* <pre>
* ///////////////////////////////////////////////////
* //HEADER
* ///////////////////////////////////////////////////
*
* package com.puppycrawl.tools.checkstyle.whitespace;
*
* import java.io.Serializable;
*
* class Foo
* {
* public static final int FOO_CONST = 1;
*
* public void foo() {}
* }
* </pre>
* <p> An example how to check empty line after
* {@link TokenTypes#VARIABLE_DEF VARIABLE_DEF} and
* {@link TokenTypes#METHOD_DEF METHOD_DEF}:
* </p>
*
* <pre>
* <module name="EmptyLineSeparator">
* <property name="tokens" value="VARIABLE_DEF, METHOD_DEF"/>
* </module>
* </pre>
*
* <p>
* An example how to allow no empty line between fields:
* </p>
* <pre>
* <module name="EmptyLineSeparator">
* <property name="allowNoEmptyLineBetweenFields" value="true"/>
* </module>
* </pre>
*
* <p>
* Example of declarations with multiple empty lines between class members (allowed by default):
* </p>
*
* <pre>
* ///////////////////////////////////////////////////
* //HEADER
* ///////////////////////////////////////////////////
*
*
* package com.puppycrawl.tools.checkstyle.whitespace;
*
*
*
* import java.io.Serializable;
*
*
* class Foo
* {
* public static final int FOO_CONST = 1;
*
*
*
* public void foo() {}
* }
* </pre>
* <p>
* An example how to disallow multiple empty lines between class members:
* </p>
* <pre>
* <module name="EmptyLineSeparator">
* <property name="allowMultipleEmptyLines" value="false"/>
* </module>
* </pre>
*
* <p>
* An example how to disallow multiple empty line inside methods, constructors, etc.:
* </p>
* <pre>
* <module name="EmptyLineSeparator">
* <property name="allowMultipleEmptyLinesInsideClassMembers" value="false"/>
* </module>
* </pre>
*
* <p> The check is valid only for statements that have body:
* {@link TokenTypes#CLASS_DEF},
* {@link TokenTypes#INTERFACE_DEF},
* {@link TokenTypes#ENUM_DEF},
* {@link TokenTypes#STATIC_INIT},
* {@link TokenTypes#INSTANCE_INIT},
* {@link TokenTypes#METHOD_DEF},
* {@link TokenTypes#CTOR_DEF}
* </p>
* <p>
* Example of declarations with multiple empty lines inside method:
* </p>
*
* <pre>
* ///////////////////////////////////////////////////
* //HEADER
* ///////////////////////////////////////////////////
*
* package com.puppycrawl.tools.checkstyle.whitespace;
*
* class Foo
* {
*
* public void foo() {
*
*
* System.out.println(1); // violation since method has 2 empty lines subsequently
* }
* }
* </pre>
* @author maxvetrenko
* @author <a href="mailto:nesterenko-aleksey@list.ru">Aleksey Nesterenko</a>
*/
public class EmptyLineSeparatorCheck extends AbstractCheck {
/**
* A key is pointing to the warning message empty.line.separator in "messages.properties"
* file.
*/
public static final String MSG_SHOULD_BE_SEPARATED = "empty.line.separator";
/**
* A key is pointing to the warning message empty.line.separator.multiple.lines
* in "messages.properties"
* file.
*/
public static final String MSG_MULTIPLE_LINES = "empty.line.separator.multiple.lines";
/**
* A key is pointing to the warning message empty.line.separator.lines.after
* in "messages.properties" file.
*/
public static final String MSG_MULTIPLE_LINES_AFTER =
"empty.line.separator.multiple.lines.after";
/**
* A key is pointing to the warning message empty.line.separator.multiple.lines.inside
* in "messages.properties" file.
*/
public static final String MSG_MULTIPLE_LINES_INSIDE =
"empty.line.separator.multiple.lines.inside";
/** Allows no empty line between fields. */
private boolean allowNoEmptyLineBetweenFields;
/** Allows multiple empty lines between class members. */
private boolean allowMultipleEmptyLines = true;
/** Allows multiple empty lines inside class members. */
private boolean allowMultipleEmptyLinesInsideClassMembers = true;
/**
* Allow no empty line between fields.
* @param allow
* User's value.
*/
public final void setAllowNoEmptyLineBetweenFields(boolean allow) {
allowNoEmptyLineBetweenFields = allow;
}
/**
* Allow multiple empty lines between class members.
* @param allow User's value.
*/
public void setAllowMultipleEmptyLines(boolean allow) {
allowMultipleEmptyLines = allow;
}
/**
* Allow multiple empty lines inside class members.
* @param allow User's value.
*/
public void setAllowMultipleEmptyLinesInsideClassMembers(boolean allow) {
allowMultipleEmptyLinesInsideClassMembers = allow;
}
@Override
public boolean isCommentNodesRequired() {
return true;
}
@Override
public int[] getDefaultTokens() {
return getAcceptableTokens();
}
@Override
public int[] getAcceptableTokens() {
return new int[] {
TokenTypes.PACKAGE_DEF,
TokenTypes.IMPORT,
TokenTypes.CLASS_DEF,
TokenTypes.INTERFACE_DEF,
TokenTypes.ENUM_DEF,
TokenTypes.STATIC_INIT,
TokenTypes.INSTANCE_INIT,
TokenTypes.METHOD_DEF,
TokenTypes.CTOR_DEF,
TokenTypes.VARIABLE_DEF,
};
}
@Override
public int[] getRequiredTokens() {
return CommonUtils.EMPTY_INT_ARRAY;
}
@Override
public void visitToken(DetailAST ast) {
if (hasMultipleLinesBefore(ast)) {
log(ast.getLineNo(), MSG_MULTIPLE_LINES, ast.getText());
}
if (!allowMultipleEmptyLinesInsideClassMembers) {
processMultipleLinesInside(ast);
}
DetailAST nextToken = ast.getNextSibling();
while (nextToken != null && isComment(nextToken)) {
nextToken = nextToken.getNextSibling();
}
if (nextToken != null) {
final int astType = ast.getType();
switch (astType) {
case TokenTypes.VARIABLE_DEF:
processVariableDef(ast, nextToken);
break;
case TokenTypes.IMPORT:
processImport(ast, nextToken, astType);
break;
case TokenTypes.PACKAGE_DEF:
processPackage(ast, nextToken);
break;
default:
if (nextToken.getType() == TokenTypes.RCURLY) {
if (hasNotAllowedTwoEmptyLinesBefore(nextToken)) {
log(ast.getLineNo(), MSG_MULTIPLE_LINES_AFTER, ast.getText());
}
}
else if (!hasEmptyLineAfter(ast)) {
log(nextToken.getLineNo(), MSG_SHOULD_BE_SEPARATED,
nextToken.getText());
}
}
}
}
/**
* Log violation in case there are multiple empty lines inside constructor,
* initialization block or method.
* @param ast the ast to check.
*/
private void processMultipleLinesInside(DetailAST ast) {
final int astType = ast.getType();
if (isClassMemberBlock(astType)) {
final List<Integer> emptyLines = getEmptyLines(ast);
final List<Integer> emptyLinesToLog = getEmptyLinesToLog(emptyLines);
for (Integer lineNo : emptyLinesToLog) {
// Checkstyle counts line numbers from 0 but IDE from 1
log(lineNo + 1, MSG_MULTIPLE_LINES_INSIDE);
}
}
}
/**
* Whether the AST is a class member block.
* @param astType the AST to check.
* @return true if the AST is a class member block.
*/
private static boolean isClassMemberBlock(int astType) {
return astType == TokenTypes.STATIC_INIT
|| astType == TokenTypes.INSTANCE_INIT
|| astType == TokenTypes.METHOD_DEF
|| astType == TokenTypes.CTOR_DEF;
}
/**
* Get list of empty lines.
* @param ast the ast to check.
* @return list of line numbers for empty lines.
*/
private List<Integer> getEmptyLines(DetailAST ast) {
final DetailAST lastToken = ast.getLastChild().getLastChild();
int lastTokenLineNo = 0;
if (lastToken != null) {
lastTokenLineNo = lastToken.getLineNo();
}
final List<Integer> emptyLines = new ArrayList<>();
final FileContents fileContents = getFileContents();
for (int lineNo = ast.getLineNo(); lineNo < lastTokenLineNo; lineNo++) {
if (fileContents.lineIsBlank(lineNo)) {
emptyLines.add(lineNo);
}
}
return emptyLines;
}
/**
* Get list of empty lines to log.
* @param emptyLines list of empty lines.
* @return list of empty lines to log.
*/
private static List<Integer> getEmptyLinesToLog(List<Integer> emptyLines) {
final List<Integer> emptyLinesToLog = new ArrayList<>();
if (emptyLines.size() > 1) {
int previousEmptyLineNo = emptyLines.get(0);
for (int emptyLineNo : emptyLines) {
if (previousEmptyLineNo + 1 == emptyLineNo) {
emptyLinesToLog.add(emptyLineNo);
}
previousEmptyLineNo = emptyLineNo;
}
}
return emptyLinesToLog;
}
/**
* Whether the token has not allowed multiple empty lines before.
* @param ast the ast to check.
* @return true if the token has not allowed multiple empty lines before.
*/
private boolean hasMultipleLinesBefore(DetailAST ast) {
boolean result = false;
if ((ast.getType() != TokenTypes.VARIABLE_DEF
|| isTypeField(ast))
&& hasNotAllowedTwoEmptyLinesBefore(ast)) {
result = true;
}
return result;
}
/**
* Process Package.
* @param ast token
* @param nextToken next token
*/
private void processPackage(DetailAST ast, DetailAST nextToken) {
if (ast.getLineNo() > 1 && !hasEmptyLineBefore(ast)) {
if (getFileContents().getFileName().endsWith("package-info.java")) {
if (ast.getFirstChild().getChildCount() == 0 && !isPrecededByJavadoc(ast)) {
log(ast.getLineNo(), MSG_SHOULD_BE_SEPARATED, ast.getText());
}
}
else {
log(ast.getLineNo(), MSG_SHOULD_BE_SEPARATED, ast.getText());
}
}
if (!hasEmptyLineAfter(ast)) {
log(nextToken.getLineNo(), MSG_SHOULD_BE_SEPARATED, nextToken.getText());
}
}
/**
* Process Import.
* @param ast token
* @param nextToken next token
* @param astType token Type
*/
private void processImport(DetailAST ast, DetailAST nextToken, int astType) {
if (astType != nextToken.getType() && !hasEmptyLineAfter(ast)) {
log(nextToken.getLineNo(), MSG_SHOULD_BE_SEPARATED, nextToken.getText());
}
}
/**
* Process Variable.
* @param ast token
* @param nextToken next Token
*/
private void processVariableDef(DetailAST ast, DetailAST nextToken) {
if (isTypeField(ast) && !hasEmptyLineAfter(ast)
&& isViolatingEmptyLineBetweenFieldsPolicy(nextToken)) {
log(nextToken.getLineNo(), MSG_SHOULD_BE_SEPARATED,
nextToken.getText());
}
}
/**
* Checks whether token placement violates policy of empty line between fields.
* @param detailAST token to be analyzed
* @return true if policy is violated and warning should be raised; false otherwise
*/
private boolean isViolatingEmptyLineBetweenFieldsPolicy(DetailAST detailAST) {
return allowNoEmptyLineBetweenFields
&& detailAST.getType() != TokenTypes.VARIABLE_DEF
&& detailAST.getType() != TokenTypes.RCURLY
|| !allowNoEmptyLineBetweenFields
&& detailAST.getType() != TokenTypes.RCURLY;
}
/**
* Checks if a token has empty two previous lines and multiple empty lines is not allowed.
* @param token DetailAST token
* @return true, if token has empty two lines before and allowMultipleEmptyLines is false
*/
private boolean hasNotAllowedTwoEmptyLinesBefore(DetailAST token) {
return !allowMultipleEmptyLines && hasEmptyLineBefore(token)
&& isPrePreviousLineEmpty(token);
}
/**
* Checks if a token has empty pre-previous line.
* @param token DetailAST token.
* @return true, if token has empty lines before.
*/
private boolean isPrePreviousLineEmpty(DetailAST token) {
boolean result = false;
final int lineNo = token.getLineNo();
// 3 is the number of the pre-previous line because the numbering starts from zero.
final int number = 3;
if (lineNo >= number) {
final String prePreviousLine = getLines()[lineNo - number];
result = CommonUtils.isBlank(prePreviousLine);
}
return result;
}
/**
* Checks if token have empty line after.
* @param token token.
* @return true if token have empty line after.
*/
private boolean hasEmptyLineAfter(DetailAST token) {
DetailAST lastToken = token.getLastChild().getLastChild();
if (lastToken == null) {
lastToken = token.getLastChild();
}
DetailAST nextToken = token.getNextSibling();
if (isComment(nextToken)) {
nextToken = nextToken.getNextSibling();
}
// Start of the next token
final int nextBegin = nextToken.getLineNo();
// End of current token.
final int currentEnd = lastToken.getLineNo();
return hasEmptyLine(currentEnd + 1, nextBegin - 1);
}
/**
* Checks, whether there are empty lines within the specified line range. Line numbering is
* started from 1 for parameter values
* @param startLine number of the first line in the range
* @param endLine number of the second line in the range
* @return <code>true</code> if found any blank line within the range, <code>false</code>
* otherwise
*/
private boolean hasEmptyLine(int startLine, int endLine) {
// Initial value is false - blank line not found
boolean result = false;
if (startLine <= endLine) {
final FileContents fileContents = getFileContents();
for (int line = startLine; line <= endLine; line++) {
// Check, if the line is blank. Lines are numbered from 0, so subtract 1
if (fileContents.lineIsBlank(line - 1)) {
result = true;
break;
}
}
}
return result;
}
/**
* Checks if a token has a empty line before.
* @param token token.
* @return true, if token have empty line before.
*/
private boolean hasEmptyLineBefore(DetailAST token) {
boolean result = false;
final int lineNo = token.getLineNo();
if (lineNo != 1) {
// [lineNo - 2] is the number of the previous line as the numbering starts from zero.
final String lineBefore = getLines()[lineNo - 2];
result = CommonUtils.isBlank(lineBefore);
}
return result;
}
/**
* Check if token is preceded by javadoc comment.
* @param token token for check.
* @return true, if token is preceded by javadoc comment.
*/
private static boolean isPrecededByJavadoc(DetailAST token) {
boolean result = false;
final DetailAST previous = token.getPreviousSibling();
if (previous.getType() == TokenTypes.BLOCK_COMMENT_BEGIN
&& JavadocUtils.isJavadocComment(previous)) {
result = true;
}
return result;
}
/**
* Check if token is a comment.
* @param ast ast node
* @return true, if given ast is comment.
*/
private static boolean isComment(DetailAST ast) {
return ast.getType() == TokenTypes.SINGLE_LINE_COMMENT
|| ast.getType() == TokenTypes.BLOCK_COMMENT_BEGIN;
}
/**
* If variable definition is a type field.
* @param variableDef variable definition.
* @return true variable definition is a type field.
*/
private static boolean isTypeField(DetailAST variableDef) {
final int parentType = variableDef.getParent().getParent().getType();
return parentType == TokenTypes.CLASS_DEF;
}
}