com.github.sevntu.checkstyle.checks.coding

Class AvoidNotShortCircuitOperatorsForBooleanCheck

java.lang.Object

com.puppycrawl.tools.checkstyle.api.AutomaticBean

com.puppycrawl.tools.checkstyle.api.AbstractViolationReporter

com.puppycrawl.tools.checkstyle.api.AbstractCheck

com.github.sevntu.checkstyle.checks.coding.AvoidNotShortCircuitOperatorsForBooleanCheck

All Implemented Interfaces:

com.puppycrawl.tools.checkstyle.api.Configurable, com.puppycrawl.tools.checkstyle.api.Contextualizable

public class AvoidNotShortCircuitOperatorsForBooleanCheck
extends com.puppycrawl.tools.checkstyle.api.AbstractCheck

This check limits using of not short-circuit operators ("|", "&", "|=", "&=") in boolean expressions.
Reason:
Short-circuit operators ("||", "&&") are more safer and can accelerate the evaluation of complex boolean expressions. Check identifies an expression as a boolean if it contains at least one boolean operand or if result of expression evaluation sets the value of a boolean variable.

Using boolean variables that do not belong to the current class and all calls to boolean methods are not handled by this check.

Examples:

1. Using of not short-circuit operators while determining a Boolean variable

 boolean x = true;
 boolean result = true | x || false; // a warning here
 

2. Using of not short-circuit operators while overriding a Boolean variable.

 boolean x = true;
 boolean result = false;
 // any code
 result &= true | x || false; // a warning here
 

3. Expression calculated with not short-circuit operators contains at least one boolean operand.

 public boolean isTrue() {
     return this.z | MyObject.is() // no warnings here
             || isModifier() && isNotTrue();
 }
 ...
 boolean r=true;
 public boolean isTrue() {
     return this.z | true && r // a warning here
             || isModifier() && isNotTrue();
 }
 

Since:

1.8.0

Author:

Daniil Yaroslavtsev

Nested Class Summary

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

com.puppycrawl.tools.checkstyle.api.AutomaticBean.OutputStreamOptions

Field Summary

Fields

Modifier and Type	Field and Description
static String	MSG_KEY A key to search the warning message text in "messages.properties" file.

Constructor Summary

Constructors

Constructor and Description
AvoidNotShortCircuitOperatorsForBooleanCheck()

Method Summary

Modifier and Type	Method and Description
int[]	getAcceptableTokens()
int[]	getDefaultTokens()
int[]	getRequiredTokens()
List<String>	getSupportedOperandsNames(com.puppycrawl.tools.checkstyle.api.DetailAST exprParentAST) Searches for all supported operands names in current expression.
boolean	hasTrueOrFalseLiteral(com.puppycrawl.tools.checkstyle.api.DetailAST parentAST) Checks is the current expression has keywords "true" or "false".
boolean	isBooleanExpression(com.puppycrawl.tools.checkstyle.api.DetailAST node) Checks that current expression is calculated using "|", "&", "|=", "&=" operators contains at least one Boolean operand.
void	visitToken(com.puppycrawl.tools.checkstyle.api.DetailAST detailAST)

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

beginTree, clearMessages, destroy, finishTree, getFileContents, getLine, getLines, getMessages, getTabWidth, getTokenNames, 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.api.AutomaticBean

configure, contextualize, getConfiguration, setupChild

Methods inherited from class java.lang.Object

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

Field Detail

MSG_KEY

public static final String MSG_KEY

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

See Also:

Constant Field Values

Constructor Detail

AvoidNotShortCircuitOperatorsForBooleanCheck

public AvoidNotShortCircuitOperatorsForBooleanCheck()

Method Detail

getDefaultTokens

public final int[] getDefaultTokens()

Specified by:

getDefaultTokens in class com.puppycrawl.tools.checkstyle.api.AbstractCheck

getAcceptableTokens

public int[] getAcceptableTokens()

Specified by:

getAcceptableTokens in class com.puppycrawl.tools.checkstyle.api.AbstractCheck

getRequiredTokens

public int[] getRequiredTokens()

Specified by:

getRequiredTokens in class com.puppycrawl.tools.checkstyle.api.AbstractCheck

visitToken

public final void visitToken(com.puppycrawl.tools.checkstyle.api.DetailAST detailAST)

Overrides:

visitToken in class com.puppycrawl.tools.checkstyle.api.AbstractCheck

isBooleanExpression

public final boolean isBooleanExpression(com.puppycrawl.tools.checkstyle.api.DetailAST node)

Checks that current expression is calculated using "|", "&", "|=", "&=" operators contains at least one Boolean operand.

Parameters:

node - - current TokenTypes.EXPR node to check.

Returns:

"true" if current expression is calculated using "|", "&", "|=". "&=" operators contains at least one Boolean operand or false otherwise.

getSupportedOperandsNames

public final List<String> getSupportedOperandsNames(com.puppycrawl.tools.checkstyle.api.DetailAST exprParentAST)

Searches for all supported operands names in current expression. When checking, treatments to external class variables, method calls, etc are not considered as expression operands.

Parameters:

exprParentAST - - the current TokenTypes.EXPR parent node.

Returns:

List of supported operands contained in current expression.

hasTrueOrFalseLiteral

public final boolean hasTrueOrFalseLiteral(com.puppycrawl.tools.checkstyle.api.DetailAST parentAST)

Checks is the current expression has keywords "true" or "false".

Parameters:

parentAST - - the current TokenTypes.EXPR parent node.

Returns:

true if the current processed expression contains "true" or "false" keywords and false otherwise.