Class FallThroughCheck
- java.lang.Object
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- com.puppycrawl.tools.checkstyle.AbstractAutomaticBean
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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 acase
contains Java code but lacks abreak
,return
,yield
,throw
orcontinue
statement.The check honors special comments to suppress the warning. By default, the texts "fallthru", "fall thru", "fall-thru", "fallthrough", "fall through", "fall-through" "fallsthrough", "falls through", "falls-through" (case-sensitive). The comment containing these words must be all on one line, and must be on the last non-empty line before the
case
triggering the warning or on the same line before thecase
(ugly, but possible). Any other comment may follow on the same line.Note: The check assumes that there is no unreachable code in the
case
.-
Property
checkLastCaseGroup
- Control whether the last case group must be checked. Type isboolean
. Default value isfalse
. -
Property
reliefPattern
- Define the RegExp to match the relief comment that suppresses the warning about a fall through. Type isjava.util.regex.Pattern
. Default value is"falls?[ -]?thr(u|ough)"
.
Parent is
com.puppycrawl.tools.checkstyle.TreeWalker
Violation Message Keys:
-
fall.through
-
fall.through.last
- Since:
- 3.4
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Nested Class Summary
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Nested classes/interfaces inherited from class com.puppycrawl.tools.checkstyle.AbstractAutomaticBean
AbstractAutomaticBean.OutputStreamOptions
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Field Summary
Fields Modifier and Type Field Description private boolean
checkLastCaseGroup
Control whether the last case group must be checked.static String
MSG_FALL_THROUGH
A key is pointing to the warning message text in "messages.properties" file.static String
MSG_FALL_THROUGH_LAST
A key is pointing to the warning message text in "messages.properties" file.private Pattern
reliefPattern
Define the RegExp to match the relief comment that suppresses the warning about a fall through.
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Constructor Summary
Constructors Constructor Description FallThroughCheck()
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Method Summary
All Methods Static Methods Instance Methods Concrete Methods Modifier and Type Method Description private boolean
checkIf(DetailAST ast, boolean useBreak, boolean useContinue, Set<String> labels)
Checks if a given IF terminated by return, throw or, if allowed break, continue.private boolean
checkLoop(DetailAST ast, Set<String> labels)
Checks if a given loop terminated by return, throw or, if allowed break, continue.private boolean
checkSlist(DetailAST slistAst, boolean useBreak, boolean useContinue, Set<String> labels)
Checks if a given SLIST terminated by return, throw or, if allowed break, continue.private boolean
checkSwitch(DetailAST literalSwitchAst, boolean useContinue, Set<String> labels)
Checks if a given switch terminated by return, throw or, if allowed break, continue.private boolean
checkSynchronized(DetailAST synchronizedAst, boolean useBreak, boolean useContinue, Set<String> labels)
Checks if a given synchronized block terminated by return, throw or, if allowed break, continue.private boolean
checkTry(DetailAST ast, boolean useBreak, boolean useContinue, Set<String> labels)
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.private static DetailAST
getNextNonCommentAst(DetailAST ast)
This method will skip the comment content while finding the next ast of current ast.int[]
getRequiredTokens()
The tokens that this check must be registered for.private boolean
hasFallThroughComment(DetailAST currentCase)
Determines if the fall through case betweencurrentCase
andnextCase
is relieved by an appropriate comment.private static boolean
hasLabel(DetailAST statement, Set<String> labelsForCurrentSwitchScope)
Checks if given break or continue ast has outer label.private boolean
hasReliefComment(DetailAST ast)
Check if there is any fall through comment.boolean
isCommentNodesRequired()
Whether comment nodes are required or not.private boolean
isTerminated(DetailAST ast, boolean useBreak, boolean useContinue, Set<String> labelsForCurrentSwitchScope)
Checks if a given subtree terminated by return, throw or, if allowed break, continue.void
setCheckLastCaseGroup(boolean value)
Setter to control whether the last case group must be checked.void
setReliefPattern(Pattern pattern)
Setter to define the RegExp to match the relief comment that suppresses the warning about a fall through.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, leaveToken, log, log, log, setFileContents, setTabWidth, setTokens
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Methods inherited from class com.puppycrawl.tools.checkstyle.api.AbstractViolationReporter
finishLocalSetup, getCustomMessages, getId, getMessageBundle, getSeverity, getSeverityLevel, setId, setSeverity
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Methods inherited from class com.puppycrawl.tools.checkstyle.AbstractAutomaticBean
configure, contextualize, getConfiguration, setupChild
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Field Detail
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MSG_FALL_THROUGH
public static final 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 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
Control whether the last case group must be checked.
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reliefPattern
private Pattern reliefPattern
Define the RegExp to match the relief comment that suppresses the warning about a fall through.
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Constructor Detail
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FallThroughCheck
public FallThroughCheck()
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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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isCommentNodesRequired
public boolean isCommentNodesRequired()
Description copied from class:AbstractCheck
Whether comment nodes are required or not.- Overrides:
isCommentNodesRequired
in classAbstractCheck
- Returns:
- false as a default value.
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setReliefPattern
public void setReliefPattern(Pattern pattern)
Setter to define the RegExp to match the relief comment that suppresses the warning about a fall through.- Parameters:
pattern
- The regular expression pattern.- Since:
- 4.0
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setCheckLastCaseGroup
public void setCheckLastCaseGroup(boolean value)
Setter to control whether the last case group must be checked.- Parameters:
value
- new value of the property.- Since:
- 4.0
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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, Set<String> labelsForCurrentSwitchScope)
Checks if a given subtree terminated by return, throw or, if allowed break, continue. When analyzing fall-through cases in switch statements, a Set of String labels is used to keep track of the labels encountered in the enclosing switch statements.- Parameters:
ast
- root of given subtreeuseBreak
- should we consider break as terminatoruseContinue
- should we consider continue as terminatorlabelsForCurrentSwitchScope
- the Set labels for the current scope of the switch- Returns:
- true if the subtree is terminated.
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hasLabel
private static boolean hasLabel(DetailAST statement, Set<String> labelsForCurrentSwitchScope)
Checks if given break or continue ast has outer label.- Parameters:
statement
- break or continue nodelabelsForCurrentSwitchScope
- the Set labels for the current scope of the switch- Returns:
- true if local label used
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checkSlist
private boolean checkSlist(DetailAST slistAst, boolean useBreak, boolean useContinue, Set<String> labels)
Checks if a given SLIST terminated by return, throw or, if allowed break, continue.- Parameters:
slistAst
- SLIST to checkuseBreak
- should we consider break as terminatoruseContinue
- should we consider continue as terminatorlabels
- label names- Returns:
- true if SLIST is terminated.
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checkIf
private boolean checkIf(DetailAST ast, boolean useBreak, boolean useContinue, Set<String> labels)
Checks if a given IF terminated by return, throw or, if allowed break, continue.- Parameters:
ast
- IF to checkuseBreak
- should we consider break as terminatoruseContinue
- should we consider continue as terminatorlabels
- label names- Returns:
- true if IF is terminated.
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getNextNonCommentAst
private static DetailAST getNextNonCommentAst(DetailAST ast)
This method will skip the comment content while finding the next ast of current ast.- Parameters:
ast
- current ast- Returns:
- next ast after skipping comment
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checkLoop
private boolean checkLoop(DetailAST ast, Set<String> labels)
Checks if a given loop terminated by return, throw or, if allowed break, continue.- Parameters:
ast
- loop to checklabels
- label names- Returns:
- true if loop is terminated.
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checkTry
private boolean checkTry(DetailAST ast, boolean useBreak, boolean useContinue, Set<String> labels)
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 terminatoruseContinue
- should we consider continue as terminatorlabels
- label names- Returns:
- true if try/catch/finally block is terminated
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checkSwitch
private boolean checkSwitch(DetailAST literalSwitchAst, boolean useContinue, Set<String> labels)
Checks if a given switch terminated by return, throw or, if allowed break, continue.- Parameters:
literalSwitchAst
- loop to checkuseContinue
- should we consider continue as terminatorlabels
- label names- Returns:
- true if switch is terminated
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checkSynchronized
private boolean checkSynchronized(DetailAST synchronizedAst, boolean useBreak, boolean useContinue, Set<String> labels)
Checks if a given synchronized block terminated by return, throw or, if allowed break, continue.- Parameters:
synchronizedAst
- synchronized block to check.useBreak
- should we consider break as terminatoruseContinue
- should we consider continue as terminatorlabels
- label names- Returns:
- true if synchronized block is terminated
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hasFallThroughComment
private boolean hasFallThroughComment(DetailAST currentCase)
Determines if the fall through case betweencurrentCase
andnextCase
is relieved by an appropriate comment.Handles
case 1: /* FALLTHRU */ case 2: switch(i) { default: /* FALLTHRU */} case 1: // FALLTHRU case 2: switch(i) { default: // FALLTHRU
- Parameters:
currentCase
- AST of the case that falls through to the next case.- Returns:
- True if a relief comment was found
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hasReliefComment
private boolean hasReliefComment(DetailAST ast)
Check if there is any fall through comment.- Parameters:
ast
- ast to check- Returns:
- true if relief comment found
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