Package com.puppycrawl.tools.checkstyle.checks.indentation

Class ClassHeaderWrapOpenjdkCheck

java.lang.Object

com.puppycrawl.tools.checkstyle.AbstractAutomaticBean

com.puppycrawl.tools.checkstyle.api.AbstractViolationReporter

com.puppycrawl.tools.checkstyle.api.AbstractCheck

com.puppycrawl.tools.checkstyle.checks.indentation.ClassHeaderWrapOpenjdkCheck

All Implemented Interfaces:

Configurable, Contextualizable

public class ClassHeaderWrapOpenjdkCheck
extends AbstractCheck

Checks that a wrapped class, interface, enum, or record header is wrapped according to the OpenJDK Java Style Guide.

This check only applies when the type declaration header, from the declaration keyword through the end of its extends/implements clauses (or its name/type parameters/record components when neither clause is present), spans more than one line. A header whose content is entirely on one line is not in scope, even if its opening curly brace is pushed onto its own following line; that is a brace placement choice for other checks (such as LeftCurly) to enforce, not a wrapping concern this check is about.

The two rules enforced are:

1. Each of the extends and implements clauses, when present, must stand out on its own new line once the header has started wrapping, or once that clause's own list of supertypes wraps across lines. Wrapping that happens only inside a single supertype's type arguments (the same way method arguments may wrap) does not require the clause keyword itself to move to a new line.
2. Only checked when rule 1 above found nothing to report: the header should not have been wrapped in the first place if, joined back onto one line, it would still fit within 80 columns.

Since:

14.4.0

Nested Class Summary

Nested classes/interfaces inherited from class com.puppycrawl.tools.checkstyle.AbstractAutomaticBean

AbstractAutomaticBean.OutputStreamOptions

Field Summary

Fields

Modifier and Type	Field	Description
private static final int	MAX_COLUMN_LIMIT	The maximum number of columns a class header may occupy before wrapping it is considered necessary.
static final String	MSG_KEY_NOT_ON_NEW_LINE	A key is pointing to the warning message text in "messages.properties" file.
static final String	MSG_KEY_UNNECESSARY_WRAP	A key is pointing to the warning message text in "messages.properties" file.

Constructor Summary

Constructors

Constructor	Description
ClassHeaderWrapOpenjdkCheck()	Creates a new ClassHeaderWrapOpenjdkCheck instance.

Method Summary

Modifier and Type	Method	Description
private boolean	checkClausePlacement(DetailAST clause)	Checks that the given extends/implements clause stands out on its own new line, if required.
private void	checkNecessaryWrap(DetailAST headerStart, DetailAST lcurly)	Checks whether the header, reconstructed as a single line, would still have fit within the maximum column limit, in which case wrapping it was unnecessary.
private static int	findFromIndex(DetailAST headerStart, int lineNo)	Finds the index at which the given line's relevant content starts: the header's own starting column on the header's first line, or the start of the line otherwise.
private static DetailAST	findHeaderStart(DetailAST ast)	Finds the token that marks the true start of the header on the declaration's own line: the first modifier that already shares a line with the declaration keyword (class/interface/enum/record), skipping past any annotations placed on their own preceding line, or the declaration keyword itself if there is no such modifier.
private static int	findToIndex(DetailAST lcurly, int lineNo, int lineLength)	Finds the index at which the given line's relevant content ends: just past the opening curly brace on the line it occupies, or the end of the line otherwise.
int[]	getAcceptableTokens()	The configurable token set.
int[]	getDefaultTokens()	Returns the default token a check is interested in.
private static int	getEndLineNo(DetailAST ast)	Returns the line number of the last token in the given subtree.
int[]	getRequiredTokens()	The tokens that this check must be registered for.
private boolean	isClauseMisplaced(DetailAST clause)	Checks the given clause's placement if it is present.
private static boolean	isPrecededByWrappedClause(DetailAST previous)	Checks whether the given node is an EXTENDS_CLAUSE that already stands out on its own new line, meaning a following implements clause must match it.
private static boolean	isTopLevelWrapped(DetailAST clause)	Checks whether the given node's direct children span more than one source line, ignoring further wrapping nested inside any of those children (e.g. inside a supertype's own type arguments).
void	visitToken(DetailAST ast)	Called to process a token.

Methods inherited from class com.puppycrawl.tools.checkstyle.api.AbstractCheck

beginTree, clearViolations, destroy, finishTree, getFileContents, getFilePath, getLine, getLineCodePoints, getLines, getTabWidth, getTokenNames, getViolations, init, isCommentNodesRequired, leaveToken, log, log, log, setFileContents, setTabWidth, setTokens

Methods inherited from class com.puppycrawl.tools.checkstyle.api.AbstractViolationReporter

finishLocalSetup, getCustomMessages, getId, getMessageBundle, getSeverity, getSeverityLevel, setId, setSeverity

Methods inherited from class com.puppycrawl.tools.checkstyle.AbstractAutomaticBean

configure, contextualize, getConfiguration, setupChild

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

MSG_KEY_NOT_ON_NEW_LINE

public static final String MSG_KEY_NOT_ON_NEW_LINE

A key is pointing to the warning message text in "messages.properties" file.

See Also:

• Constant Field Values

MSG_KEY_UNNECESSARY_WRAP

public static final String MSG_KEY_UNNECESSARY_WRAP

A key is pointing to the warning message text in "messages.properties" file.

See Also:

• Constant Field Values

MAX_COLUMN_LIMIT

private static final int MAX_COLUMN_LIMIT

The maximum number of columns a class header may occupy before wrapping it is considered necessary.

See Also:

• Constant Field Values

Constructor Details

ClassHeaderWrapOpenjdkCheck

public ClassHeaderWrapOpenjdkCheck()

Creates a new ClassHeaderWrapOpenjdkCheck instance.

Method Details

getDefaultTokens

public int[] getDefaultTokens()

Description copied from class: AbstractCheck

Returns the default token a check is interested in. Only used if the configuration for a check does not define the tokens.

Specified by:

getDefaultTokens in class AbstractCheck

Returns:

the default tokens

See Also:

• TokenTypes

getAcceptableTokens

public int[] getAcceptableTokens()

Description copied from class: AbstractCheck

The configurable token set. Used to protect Checks against malicious users who specify an unacceptable token set in the configuration file. The default implementation returns the check's default tokens.

Specified by:

getAcceptableTokens in class AbstractCheck

Returns:

the token set this check is designed for.

See Also:

• TokenTypes

getRequiredTokens

public int[] getRequiredTokens()

Description copied from class: AbstractCheck

The tokens that this check must be registered for.

Specified by:

getRequiredTokens in class AbstractCheck

Returns:

the token set this must be registered for.

See Also:

• TokenTypes

visitToken

public void visitToken(DetailAST ast)

Description copied from class: AbstractCheck

Called to process a token.

Overrides:

visitToken in class AbstractCheck

Parameters:

ast - the token to process

isClauseMisplaced

private boolean isClauseMisplaced(@Nullable
 DetailAST clause)

Checks the given clause's placement if it is present.

Parameters:

clause - the EXTENDS_CLAUSE or IMPLEMENTS_CLAUSE to check, or null if the type declaration has none

Returns:

true if a violation was logged for this clause

findHeaderStart

private static DetailAST findHeaderStart(DetailAST ast)

Finds the token that marks the true start of the header on the declaration's own line: the first modifier that already shares a line with the declaration keyword (class/interface/enum/record), skipping past any annotations placed on their own preceding line, or the declaration keyword itself if there is no such modifier.

Parameters:

ast - the class, interface, enum, or record declaration

Returns:

the token that starts the header

checkClausePlacement

private boolean checkClausePlacement(DetailAST clause)

Checks that the given extends/implements clause stands out on its own new line, if required. It is required once a preceding extends clause has already achieved its own new line (so implements must match it), or once this clause's own list of supertypes wraps across multiple lines. Wrapping in whatever precedes the clause for some other reason, such as a wrapped type parameter or record component list, does not by itself require the clause to move.

Parameters:

clause - the EXTENDS_CLAUSE or IMPLEMENTS_CLAUSE to check

Returns:

true if a violation was logged for this clause

isPrecededByWrappedClause

private static boolean isPrecededByWrappedClause(DetailAST previous)

Checks whether the given node is an EXTENDS_CLAUSE that already stands out on its own new line, meaning a following implements clause must match it.

Parameters:

previous - the node immediately preceding the clause under check

Returns:

true if previous is an EXTENDS_CLAUSE that does not share a line with whatever precedes it

checkNecessaryWrap

private void checkNecessaryWrap(DetailAST headerStart,
 DetailAST lcurly)

Checks whether the header, reconstructed as a single line, would still have fit within the maximum column limit, in which case wrapping it was unnecessary.

Parameters:

headerStart - the declaration keyword (class/interface/ enum/record) that starts the header

lcurly - the opening brace of the type's body

findFromIndex

private static int findFromIndex(DetailAST headerStart,
 int lineNo)

Finds the index at which the given line's relevant content starts: the header's own starting column on the header's first line, or the start of the line otherwise.

Parameters:

headerStart - the token that starts the header

lineNo - the 1-indexed line number currently being processed

Returns:

the index at which to start extracting content from this line

findToIndex

private static int findToIndex(DetailAST lcurly,
 int lineNo,
 int lineLength)

Finds the index at which the given line's relevant content ends: just past the opening curly brace on the line it occupies, or the end of the line otherwise.

Parameters:

lcurly - the opening brace of the type's body

lineNo - the 1-indexed line number currently being processed

lineLength - the length of the line currently being processed

Returns:

the index at which to stop extracting content from this line

isTopLevelWrapped

private static boolean isTopLevelWrapped(DetailAST clause)

Checks whether the given node's direct children span more than one source line, ignoring further wrapping nested inside any of those children (e.g. inside a supertype's own type arguments).

Parameters:

clause - the EXTENDS_CLAUSE or IMPLEMENTS_CLAUSE to inspect

Returns:

true if two direct children of clause start on different lines

getEndLineNo

private static int getEndLineNo(DetailAST ast)

Returns the line number of the last token in the given subtree.

Parameters:

ast - the root of the subtree to inspect

Returns:

the 1-indexed line number of the deepest last child of ast