Class SuppressionCommentFilter

  • All Implemented Interfaces:
    Configurable, Contextualizable, TreeWalkerFilter

    public class SuppressionCommentFilter
    extends AutomaticBean
    implements TreeWalkerFilter

    Filter SuppressionCommentFilter uses pairs of comments to suppress audit events.

    Rationale: Sometimes there are legitimate reasons for violating a check. When this is a matter of the code in question and not personal preference, the best place to override the policy is in the code itself. Semi-structured comments can be associated with the check. This is sometimes superior to a separate suppressions file, which must be kept up-to-date as the source file is edited.

    Note that the suppression comment should be put before the violation. You can use more than one suppression comment each on separate line.

    Attention: This filter may only be specified within the TreeWalker module (<module name="TreeWalker"/>) and only applies to checks which are also defined within this module. To filter non-TreeWalker checks like RegexpSingleline, a SuppressWithPlainTextCommentFilter or similar filter must be used.

    offCommentFormat and onCommentFormat must have equal paren counts.

    SuppressionCommentFilter can suppress Checks that have Treewalker as parent module.

    • Property offCommentFormat - Specify comment pattern to trigger filter to begin suppression. Type is java.util.regex.Pattern. Default value is "CHECKSTYLE:OFF".
    • Property onCommentFormat - Specify comment pattern to trigger filter to end suppression. Type is java.util.regex.Pattern. Default value is "CHECKSTYLE:ON".
    • Property checkFormat - Specify check pattern to suppress. Type is java.util.regex.Pattern. Default value is ".*".
    • Property messageFormat - Specify message pattern to suppress. Type is java.util.regex.Pattern. Default value is null.
    • Property idFormat - Specify check ID pattern to suppress. Type is java.util.regex.Pattern. Default value is null.
    • Property checkCPP - Control whether to check C++ style comments (//). Type is boolean. Default value is true.
    • Property checkC - Control whether to check C style comments (/* ... */). Type is boolean. Default value is true.

    To configure a filter to suppress audit events between a comment containing CHECKSTYLE:OFF and a comment containing CHECKSTYLE:ON:

     <module name="TreeWalker">
                   ...
       <module name="SuppressionCommentFilter"/>
                   ...
     </module>
     

    To configure a filter to suppress audit events between a comment containing line BEGIN GENERATED CODE and a comment containing line END GENERATED CODE:

     <module name="SuppressionCommentFilter">
       <property name="offCommentFormat" value="BEGIN GENERATED CODE"/>
       <property name="onCommentFormat" value="END GENERATED CODE"/>
     </module>
     
     //BEGIN GENERATED CODE
     @Override
     public boolean equals(Object obj) { ... } // No violation events will be reported
    
     @Override
     public int hashCode() { ... } // No violation events will be reported
     //END GENERATED CODE
     . . .
     

    To configure a filter so that // stop constant check and // resume constant check marks legitimate constant names:

     <module name="SuppressionCommentFilter">
       <property name="offCommentFormat" value="stop constant check"/>
       <property name="onCommentFormat" value="resume constant check"/>
       <property name="checkFormat" value="ConstantNameCheck"/>
     </module>
     
     //stop constant check
     public static final int someConstant; // won't warn here
     //resume constant check
     public static final int someConstant; // will warn here as constant's name doesn't match the
     // pattern "^[A-Z][A-Z0-9]*$"
     

    To configure a filter so that UNUSED OFF: <i>var</i> and UNUSED ON: <i>var</i> marks a variable or parameter known not to be used by the code by matching the variable name in the message:

     <module name="SuppressionCommentFilter">
       <property name="offCommentFormat" value="UNUSED OFF\: (\w+)"/>
       <property name="onCommentFormat" value="UNUSED ON\: (\w+)"/>
       <property name="checkFormat" value="Unused"/>
       <property name="messageFormat" value="^Unused \w+ '$1'.$"/>
     </module>
     
     private static void foo(int a, int b) // UNUSED OFF: b
     {
     System.out.println(a);
     }
    
     private static void foo1(int a, int b) // UNUSED ON: b
     {
     System.out.println(a);
     }
     

    To configure a filter so that name of suppressed check mentioned in comment CSOFF: <i>regexp</i> and CSON: <i>regexp</i> mark a matching check:

     <module name="SuppressionCommentFilter">
       <property name="offCommentFormat" value="CSOFF\: ([\w\|]+)"/>
       <property name="onCommentFormat" value="CSON\: ([\w\|]+)"/>
       <property name="checkFormat" value="$1"/>
     </module>
     
     public static final int lowerCaseConstant; // CSOFF: ConstantNameCheck
     public static final int lowerCaseConstant1; // CSON: ConstantNameCheck
     

    To configure a filter to suppress all audit events between a comment containing CHECKSTYLE_OFF: ALMOST_ALL and a comment containing CHECKSTYLE_OFF: ALMOST_ALL except for the EqualsHashCode check:

     <module name="SuppressionCommentFilter">
       <property name="offCommentFormat" value="CHECKSTYLE_OFF: ALMOST_ALL"/>
       <property name="onCommentFormat" value="CHECKSTYLE_ON: ALMOST_ALL"/>
       <property name="checkFormat" value="^((?!(EqualsHashCode)).)*$"/>
     </module>
     
     public static final int array []; // CHECKSTYLE_OFF: ALMOST_ALL
     private String [] strArray;
     private int array1 []; // CHECKSTYLE_ON: ALMOST_ALL
     

    To configure a filter to suppress Check's violation message which matches specified message in messageFormat (so suppression will be not only by Check's name, but by message text additionally, as the same Check could report different by message format violations) between a comment containing stop and comment containing resume:

     <module name="SuppressionCommentFilter">
       <property name="offCommentFormat" value="stop"/>
       <property name="onCommentFormat" value="resume"/>
       <property name="checkFormat" value="IllegalTypeCheck"/>
       <property name="messageFormat"
           value="^Declaring variables, return values or parameters of type 'GregorianCalendar'
             is not allowed.$"/>
     </module>
     

    Code before filter above is applied with Check's audit events:

     ...
     // Warning below: Declaring variables, return values or parameters of type 'GregorianCalendar'
     // is not allowed.
     GregorianCalendar calendar;
     // Warning below here: Declaring variables, return values or parameters of type 'HashSet'
     // is not allowed.
     HashSet hashSet;
     ...
     

    Code after filter is applied:

     ...
     //stop
     GregorianCalendar calendar; // No warning here as it is suppressed by filter.
     HashSet hashSet;
     // Warning above here: Declaring variables, return values or parameters of type 'HashSet'
     //is not allowed.
    
     //resume
     ...
     

    It is possible to specify an ID of checks, so that it can be leveraged by the SuppressionCommentFilter to skip validations. The following examples show how to skip validations near code that is surrounded with // CSOFF &lt;ID&gt; (reason) and // CSON &lt;ID&gt;, where ID is the ID of checks you want to suppress.

    Examples of Checkstyle checks configuration:

     <module name="RegexpSinglelineJava">
       <property name="id" value="ignore"/>
       <property name="format" value="^.*@Ignore\s*$"/>
       <property name="message" value="@Ignore should have a reason."/>
     </module>
    
     <module name="RegexpSinglelineJava">
       <property name="id" value="systemout"/>
       <property name="format" value="^.*System\.(out|err).*$"/>
       <property name="message" value="Don't use System.out/err, use SLF4J instead."/>
     </module>
     

    Example of SuppressionCommentFilter configuration (checkFormat which is set to '$1' points that ID of the checks is in the first group of offCommentFormat and onCommentFormat regular expressions):

     <module name="SuppressionCommentFilter">
       <property name="offCommentFormat" value="CSOFF (\w+) \(\w+\)"/>
       <property name="onCommentFormat" value="CSON (\w+)"/>
       <property name="idFormat" value="$1"/>
     </module>
     
     // CSOFF ignore (test has not been implemented yet)
     @Ignore // should NOT fail RegexpSinglelineJava
     @Test
     public void testMethod() { }
     // CSON ignore
    
     // CSOFF systemout (debug)
     public static void foo() {
       System.out.println("Debug info."); // should NOT fail RegexpSinglelineJava
     }
     // CSON systemout
     

    Example of how to configure the check to suppress more than one checks.

     <module name="SuppressionCommentFilter">
       <property name="offCommentFormat" value="@cs-\: ([\w\|]+)"/>
       <property name="checkFormat" value="$1"/>
     </module>
     
     // @cs-: ClassDataAbstractionCoupling
     // @cs-: MagicNumber
     @Service // no violations from ClassDataAbstractionCoupling here
     @Transactional
     public class UserService {
       private int value = 10022; // no violations from MagicNumber here
     }
     

    Parent is com.puppycrawl.tools.checkstyle.TreeWalker

    Since:
    3.5
    • Method Detail

      • setOffCommentFormat

        public final void setOffCommentFormat​(Pattern pattern)
        Setter to specify comment pattern to trigger filter to begin suppression.
        Parameters:
        pattern - a pattern.
      • setOnCommentFormat

        public final void setOnCommentFormat​(Pattern pattern)
        Setter to specify comment pattern to trigger filter to end suppression.
        Parameters:
        pattern - a pattern.
      • getFileContents

        private FileContents getFileContents()
        Returns FileContents for this filter.
        Returns:
        the FileContents for this filter.
      • setFileContents

        public void setFileContents​(FileContents fileContents)
        Set the FileContents for this filter.
        Parameters:
        fileContents - the FileContents for this filter.
      • setCheckFormat

        public final void setCheckFormat​(String format)
        Setter to specify check pattern to suppress.
        Parameters:
        format - a String value
      • setMessageFormat

        public void setMessageFormat​(String format)
        Setter to specify message pattern to suppress.
        Parameters:
        format - a String value
      • setIdFormat

        public void setIdFormat​(String format)
        Setter to specify check ID pattern to suppress.
        Parameters:
        format - a String value
      • setCheckCPP

        public void setCheckCPP​(boolean checkCpp)
        Setter to control whether to check C++ style comments (//).
        Parameters:
        checkCpp - true if C++ comments are checked.
      • setCheckC

        public void setCheckC​(boolean checkC)
        Setter to control whether to check C style comments (&#47;* ... *&#47;).
        Parameters:
        checkC - true if C comments are checked.
      • finishLocalSetup

        protected void finishLocalSetup()
        Description copied from class: AutomaticBean
        Provides a hook to finish the part of this component's setup that was not handled by the bean introspection.

        The default implementation does nothing.

        Specified by:
        finishLocalSetup in class AutomaticBean
      • accept

        public boolean accept​(TreeWalkerAuditEvent event)
        Description copied from interface: TreeWalkerFilter
        Determines whether or not a filtered TreeWalkerAuditEvent is accepted.
        Specified by:
        accept in interface TreeWalkerFilter
        Parameters:
        event - the TreeWalkerAuditEvent to filter.
        Returns:
        true if the event is accepted.
      • tagSuppressions

        private void tagSuppressions()
        Collects all the suppression tags for all comments into a list and sorts the list.
      • tagSuppressions

        private void tagSuppressions​(Collection<TextBlock> comments)
        Appends the suppressions in a collection of comments to the full set of suppression tags.
        Parameters:
        comments - the set of comments.
      • tagCommentLine

        private void tagCommentLine​(String text,
                                    int line,
                                    int column)
        Tags a string if it matches the format for turning checkstyle reporting on or the format for turning reporting off.
        Parameters:
        text - the string to tag.
        line - the line number of text.
        column - the column number of text.
      • addTag

        private void addTag​(String text,
                            int line,
                            int column,
                            SuppressionCommentFilter.TagType reportingOn)
        Adds a Tag to the list of all tags.
        Parameters:
        text - the text of the tag.
        line - the line number of the tag.
        column - the column number of the tag.
        reportingOn - true if the tag turns checkstyle reporting on.