Class FallThroughCheck
- java.lang.Object
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- com.puppycrawl.tools.checkstyle.api.AutomaticBean
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- com.puppycrawl.tools.checkstyle.api.AbstractViolationReporter
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- com.puppycrawl.tools.checkstyle.api.AbstractCheck
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- com.puppycrawl.tools.checkstyle.checks.coding.FallThroughCheck
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- All Implemented Interfaces:
Configurable
,Contextualizable
public class FallThroughCheck extends AbstractCheck
Checks for fall through in switch statements Finds locations where a case contains Java code - but lacks a break, return, throw or continue statement.The check honors special comments to suppress warnings about the fall through. By default the comments "fallthru", "fall through", "falls through" and "fallthrough" are recognized.
The following fragment of code will NOT trigger the check, because of the comment "fallthru" and absence of any Java code in case 5.
case 3: x = 2; // fallthru case 4: case 5: case 6: break;
The recognized relief comment can be configured with the property
reliefPattern
. Default value of this regular expression is "fallthru|fall through|fallthrough|falls through".An example of how to configure the check is:
<module name="FallThrough"> <property name="reliefPattern" value="Fall Through"/> </module>
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Field Summary
Fields Modifier and Type Field Description private boolean
checkLastCaseGroup
Do we need to check last case group.static java.lang.String
MSG_FALL_THROUGH
A key is pointing to the warning message text in "messages.properties" file.static java.lang.String
MSG_FALL_THROUGH_LAST
A key is pointing to the warning message text in "messages.properties" file.private java.util.regex.Pattern
reliefPattern
Relief regexp to allow fall through to the next case branch.
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Constructor Summary
Constructors Constructor Description FallThroughCheck()
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description private boolean
checkIf(DetailAST ast, boolean useBreak, boolean useContinue)
Checks if a given IF terminated by return, throw or, if allowed break, continue.private boolean
checkLoop(DetailAST ast)
Checks if a given loop terminated by return, throw or, if allowed break, continue.private boolean
checkSlist(DetailAST slistAst, boolean useBreak, boolean useContinue)
Checks if a given SLIST terminated by return, throw or, if allowed break, continue.private boolean
checkSwitch(DetailAST literalSwitchAst, boolean useContinue)
Checks if a given switch terminated by return, throw or, if allowed break, continue.private boolean
checkTry(DetailAST ast, boolean useBreak, boolean useContinue)
Checks if a given try/catch/finally block terminated by return, throw or, if allowed break, continue.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 boolean
hasFallThroughComment(DetailAST currentCase, DetailAST nextCase)
Determines if the fall through case betweencurrentCase
andnextCase
is relieved by a appropriate comment.private boolean
isTerminated(DetailAST ast, boolean useBreak, boolean useContinue)
Checks if a given subtree terminated by return, throw or, if allowed break, continue.private boolean
matchesComment(java.util.regex.Pattern pattern, java.lang.String line, int lineNo)
Does a regular expression match on the given line and checks that a possible match is within a comment.void
setCheckLastCaseGroup(boolean value)
Configures whether we need to check last case group or not.void
setReliefPattern(java.util.regex.Pattern pattern)
Set the relief pattern.void
visitToken(DetailAST ast)
Called to process a token.-
Methods inherited from class com.puppycrawl.tools.checkstyle.api.AbstractCheck
beginTree, destroy, finishTree, getClassLoader, getFileContents, getLine, getLines, getTabWidth, getTokenNames, init, isCommentNodesRequired, leaveToken, log, log, setClassLoader, setFileContents, setMessages, setTabWidth, setTokens
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Methods inherited from class com.puppycrawl.tools.checkstyle.api.AbstractViolationReporter
getCustomMessages, getId, getMessageBundle, getSeverity, getSeverityLevel, log, setId, setSeverity
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Methods inherited from class com.puppycrawl.tools.checkstyle.api.AutomaticBean
configure, contextualize, finishLocalSetup, getConfiguration, setupChild
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Field Detail
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MSG_FALL_THROUGH
public static final java.lang.String MSG_FALL_THROUGH
A key is pointing to the warning message text in "messages.properties" file.- See Also:
- Constant Field Values
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MSG_FALL_THROUGH_LAST
public static final java.lang.String MSG_FALL_THROUGH_LAST
A key is pointing to the warning message text in "messages.properties" file.- See Also:
- Constant Field Values
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checkLastCaseGroup
private boolean checkLastCaseGroup
Do we need to check last case group.
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reliefPattern
private java.util.regex.Pattern reliefPattern
Relief regexp to allow fall through to the next case branch.
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Method Detail
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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 classAbstractCheck
- Returns:
- the default tokens
- See Also:
TokenTypes
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getRequiredTokens
public int[] getRequiredTokens()
Description copied from class:AbstractCheck
The tokens that this check must be registered for.- Specified by:
getRequiredTokens
in classAbstractCheck
- Returns:
- the token set this must be registered for.
- See Also:
TokenTypes
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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 classAbstractCheck
- Returns:
- the token set this check is designed for.
- See Also:
TokenTypes
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setReliefPattern
public void setReliefPattern(java.util.regex.Pattern pattern)
Set the relief pattern.- Parameters:
pattern
- The regular expression pattern.
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setCheckLastCaseGroup
public void setCheckLastCaseGroup(boolean value)
Configures whether we need to check last case group or not.- Parameters:
value
- new value of the property.
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visitToken
public void visitToken(DetailAST ast)
Description copied from class:AbstractCheck
Called to process a token.- Overrides:
visitToken
in classAbstractCheck
- Parameters:
ast
- the token to process
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isTerminated
private boolean isTerminated(DetailAST ast, boolean useBreak, boolean useContinue)
Checks if a given subtree terminated by return, throw or, if allowed break, continue.- Parameters:
ast
- root of given subtreeuseBreak
- should we consider break as terminator.useContinue
- should we consider continue as terminator.- Returns:
- true if the subtree is terminated.
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checkSlist
private boolean checkSlist(DetailAST slistAst, boolean useBreak, boolean useContinue)
Checks if a given SLIST terminated by return, throw or, if allowed break, continue.- Parameters:
slistAst
- SLIST to checkuseBreak
- should we consider break as terminator.useContinue
- should we consider continue as terminator.- Returns:
- true if SLIST is terminated.
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checkIf
private boolean checkIf(DetailAST ast, boolean useBreak, boolean useContinue)
Checks if a given IF terminated by return, throw or, if allowed break, continue.- Parameters:
ast
- IF to checkuseBreak
- should we consider break as terminator.useContinue
- should we consider continue as terminator.- Returns:
- true if IF is terminated.
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checkLoop
private boolean checkLoop(DetailAST ast)
Checks if a given loop terminated by return, throw or, if allowed break, continue.- Parameters:
ast
- loop to check- Returns:
- true if loop is terminated.
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checkTry
private boolean checkTry(DetailAST ast, boolean useBreak, boolean useContinue)
Checks if a given try/catch/finally block terminated by return, throw or, if allowed break, continue.- Parameters:
ast
- loop to checkuseBreak
- should we consider break as terminator.useContinue
- should we consider continue as terminator.- Returns:
- true if try/catch/finally block is terminated.
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checkSwitch
private boolean checkSwitch(DetailAST literalSwitchAst, boolean useContinue)
Checks if a given switch terminated by return, throw or, if allowed break, continue.- Parameters:
literalSwitchAst
- loop to checkuseContinue
- should we consider continue as terminator.- Returns:
- true if switch is terminated.
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hasFallThroughComment
private boolean hasFallThroughComment(DetailAST currentCase, DetailAST nextCase)
Determines if the fall through case betweencurrentCase
andnextCase
is relieved by a appropriate comment.- Parameters:
currentCase
- AST of the case that falls through to the next case.nextCase
- AST of the next case.- Returns:
- True if a relief comment was found
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matchesComment
private boolean matchesComment(java.util.regex.Pattern pattern, java.lang.String line, int lineNo)
Does a regular expression match on the given line and checks that a possible match is within a comment.- Parameters:
pattern
- The regular expression pattern to use.line
- The line of test to do the match on.lineNo
- The line number in the file.- Returns:
- True if a match was found inside a comment.
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