Package com.puppycrawl.tools.checkstyle.checks.metrics

Class BooleanExpressionComplexityCheck

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.metrics.BooleanExpressionComplexityCheck

All Implemented Interfaces:

Configurable, Contextualizable

public final class BooleanExpressionComplexityCheck
extends AbstractCheck

Restricts the number of boolean operators (&&, ||, &, | and ^) in an expression.

Rationale: Too many conditions leads to code that is difficult to read and hence debug and maintain.

Note that the operators & and | are not only integer bitwise operators, they are also the non-shortcut versions of the boolean operators && and ||.

Note that &, | and ^ are not checked if they are part of constructor or method call because they can be applied to non-boolean variables and Checkstyle does not know types of methods from different classes.

• Property max - Specify the maximum number of boolean operations allowed in one expression. Type is int. Default value is 3.
• Property tokens - tokens to check Type is java.lang.String[]. Validation type is tokenSet. Default value is: LAND, BAND, LOR, BOR, BXOR.

Parent is com.puppycrawl.tools.checkstyle.TreeWalker

Violation Message Keys:

• booleanExpressionComplexity

Since:

3.4

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
private final class	BooleanExpressionComplexityCheck.Context	Represents context (method/expression) in which we check complexity.

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

AbstractAutomaticBean.OutputStreamOptions

Field Summary

Fields

Modifier and Type	Field	Description
private BooleanExpressionComplexityCheck.Context	context	Current context.
private final Deque<BooleanExpressionComplexityCheck.Context>	contextStack	Stack of contexts.
private static final int	DEFAULT_MAX	Default allowed complexity.
private int	max	Specify the maximum number of boolean operations allowed in one expression.
static final String	MSG_KEY	A key is pointing to the warning message text in "messages.properties" file.

Constructor Summary

Constructors

Constructor	Description
BooleanExpressionComplexityCheck()	Creates new instance of the check.

Method Summary

Modifier and Type	Method	Description
int[]	getAcceptableTokens()	The configurable token set.
int[]	getDefaultTokens()	Returns the default token a check is interested in.
int[]	getRequiredTokens()	The tokens that this check must be registered for.
private static boolean	isPassedInParameter(DetailAST logicalOperator)	Checks if logical operator is part of constructor or method call.
private static boolean	isPipeOperator(DetailAST binaryOr)	Checks if binary OR is applied to exceptions in multi-catch (pipe-syntax).
private void	leaveExpr(DetailAST ast)	Restores previous context.
private void	leaveMethodDef()	Removes old context.
void	leaveToken(DetailAST ast)	Called after all the child nodes have been process.
void	setMax(int max)	Setter to specify the maximum number of boolean operations allowed in one expression.
private void	visitExpr()	Creates and pushes new context.
private void	visitMethodDef(DetailAST ast)	Creates new context for a given method.
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, 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

public static final String MSG_KEY

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

See Also:

• Constant Field Values

DEFAULT_MAX

private static final int DEFAULT_MAX

Default allowed complexity.

See Also:

• Constant Field Values

contextStack

private final Deque<BooleanExpressionComplexityCheck.Context> contextStack

Stack of contexts.

max

private int max

Specify the maximum number of boolean operations allowed in one expression.

context

private BooleanExpressionComplexityCheck.Context context

Current context.

Constructor Details

BooleanExpressionComplexityCheck

public BooleanExpressionComplexityCheck()

Creates new instance of the check.

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

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

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

setMax

public void setMax(int max)

Setter to specify the maximum number of boolean operations allowed in one expression.

Parameters:

max - new maximum allowed complexity.

Since:

3.4

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

isPassedInParameter

private static boolean isPassedInParameter(DetailAST logicalOperator)

Checks if logical operator is part of constructor or method call.

Parameters:

logicalOperator - logical operator

Returns:

true if logical operator is part of constructor or method call

isPipeOperator

private static boolean isPipeOperator(DetailAST binaryOr)

Checks if binary OR is applied to exceptions in multi-catch (pipe-syntax).

Parameters:

binaryOr - binary or

Returns:

true if binary or is applied to exceptions in multi-catch.

leaveToken

public void leaveToken(DetailAST ast)

Description copied from class: AbstractCheck

Called after all the child nodes have been process.

Overrides:

leaveToken in class AbstractCheck

Parameters:

ast - the token leaving

visitMethodDef

private void visitMethodDef(DetailAST ast)

Creates new context for a given method.

Parameters:

ast - a method we start to check.

leaveMethodDef

private void leaveMethodDef()

Removes old context.

visitExpr

private void visitExpr()

Creates and pushes new context.

leaveExpr

private void leaveExpr(DetailAST ast)

Restores previous context.

Parameters:

ast - expression we leave.