Class RegexpHeaderCheck

  • All Implemented Interfaces:
    Configurable, Contextualizable, ExternalResourceHolder, FileSetCheck

    public class RegexpHeaderCheck
    extends AbstractHeaderCheck

    Checks the header of a source file against a header that contains a pattern for each line of the source header.

    Rationale: In some projects checking against a fixed header is not sufficient, e.g. the header might require a copyright line where the year information is not static.

    For example, consider the following header:

     line  1: ^/{71}$
     line  2: ^// checkstyle:$
     line  3: ^// Checks Java source code for adherence to a set of rules\.$
     line  4: ^// Copyright \(C\) \d\d\d\d  Oliver Burn$
     line  5: ^// Last modification by \$Author.*\$$
     line  6: ^/{71}$
     line  7:
     line  8: ^package
     line  9:
     line 10: ^import
     line 11:
     line 12: ^/\*\*
     line 13: ^ \*([^/]|$)
     line 14: ^ \*/
     

    Lines 1 and 6 demonstrate a more compact notation for 71 '/' characters. Line 4 enforces that the copyright notice includes a four digit year. Line 5 is an example how to enforce revision control keywords in a file header. Lines 12-14 is a template for javadoc (line 13 is so complicated to remove conflict with and of javadoc comment). Lines 7, 9 and 11 will be treated as '^$' and will forcefully expect the line to be empty.

    Different programming languages have different comment syntax rules, but all of them start a comment with a non-word character. Hence, you can often use the non-word character class to abstract away the concrete comment syntax and allow checking the header for different languages with a single header definition. For example, consider the following header specification (note that this is not the full Apache license header):

     line 1: ^#!
     line 2: ^<\?xml.*>$
     line 3: ^\W*$
     line 4: ^\W*Copyright 2006 The Apache Software Foundation or its licensors, as applicable\.$
     line 5: ^\W*Licensed under the Apache License, Version 2\.0 \(the "License"\);$
     line 6: ^\W*$
     

    Lines 1 and 2 leave room for technical header lines, e.g. the "#!/bin/sh" line in Unix shell scripts, or the XML file header of XML files. Set the multiline property to "1, 2" so these lines can be ignored for file types where they do no apply. Lines 3 through 6 define the actual header content. Note how lines 2, 4 and 5 use escapes for characters that have special regexp semantics.

    In default configuration, if header is not specified, the default value of header is set to null and the check does not rise any violations.

    • Property headerFile - Specify the name of the file containing the required header. Type is java.net.URI. Default value is null.
    • Property charset - Specify the character encoding to use when reading the headerFile. Type is java.lang.String. Default value is the charset property of the parent <a href="https://checkstyle.org/config.html#Checker">Checker</a> module.
    • Property header - Define the required header specified inline. Individual header lines must be separated by the string "\n" (even on platforms with a different line separator). For header lines containing "\n\n" checkstyle will forcefully expect an empty line to exist. See examples below. Regular expressions must not span multiple lines. Type is java.lang.String. Default value is null.
    • Property multiLines - Specify the line numbers to repeat (zero or more times). Type is int[]. Default value is "".
    • Property fileExtensions - Specify the file type extension of files to process. Type is java.lang.String[]. Default value is "".

    To configure the check such that no violations arise. Default values of properties are used.

     <module name="RegexpHeader"/>
     

    To configure the check to use header file "config/java.header" and 10 and 13 multi-lines:

     <module name="RegexpHeader">
       <property name="headerFile" value="config/java.header"/>
       <property name="multiLines" value="10, 13"/>
     </module>
     

    To configure the check to verify that each file starts with the header

     ^// Copyright \(C\) (\d\d\d\d -)? 2004 MyCompany$
     ^// All rights reserved$
     

    without the need for an external header file:

     <module name="RegexpHeader">
       <property
         name="header"
         value="^// Copyright \(C\) (\d\d\d\d -)? 2004 MyCompany$
           \n^// All rights reserved$"/>
     </module>
     

    For regex containing "\n\n"

     <module name="RegexpHeader">
       <property
         name="header"
         value="^package .*\n\n.*"/>
     </module>
     

    "\n\n" will be treated as '^$' and will forcefully expect the line to be empty. For example -

     package com.some.package;
     public class ThisWillFail { }
     

    would fail for the regex above. Expected -

     package com.some.package;
    
     public class ThisWillPass { }
     

    Note: ignoreLines property has been removed from this check to simplify it. To make some line optional use "^.*$" regexp for this line.

    Parent is com.puppycrawl.tools.checkstyle.Checker

    Violation Message Keys:

    • header.mismatch
    • header.missing
    Since:
    6.9
    • Method Detail

      • setMultiLines

        public void setMultiLines​(int... list)
        Setter to specify the line numbers to repeat (zero or more times).
        Parameters:
        list - line numbers to repeat in header.
      • getHeaderLine

        private String getHeaderLine​(int headerLineNo)
        Returns the line from the header. Where the line is blank return the regexp pattern for a blank line.
        Parameters:
        headerLineNo - header line number to return
        Returns:
        the line from the header
      • logFirstSinglelineLine

        private void logFirstSinglelineLine​(int startHeaderLine,
                                            int headerSize)
        Logs warning if any non-multiline lines left in header regexp.
        Parameters:
        startHeaderLine - header line number to start from
        headerSize - whole header size
      • isMatch

        private boolean isMatch​(String line,
                                int headerLineNo)
        Checks if a code line matches the required header line.
        Parameters:
        line - the code line
        headerLineNo - the header line number.
        Returns:
        true if and only if the line matches the required header line.
      • isMultiLine

        private boolean isMultiLine​(int lineNo)
        Returns true if line is multiline header lines or false.
        Parameters:
        lineNo - a line number
        Returns:
        if lineNo is one of the repeat header lines.
      • setHeader

        public void setHeader​(String header)
        Setter to define the required header specified inline. Individual header lines must be separated by the string "\n" (even on platforms with a different line separator). For header lines containing "\n\n" checkstyle will forcefully expect an empty line to exist. See examples below. Regular expressions must not span multiple lines.
        Overrides:
        setHeader in class AbstractHeaderCheck
        Parameters:
        header - the header value to validate and set (in that order)