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<document xmlns="http://maven.apache.org/XDOC/2.0"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://maven.apache.org/XDOC/2.0 http://maven.apache.org/xsd/xdoc-2.0.xsd">

  <properties>
    <title>Headers</title>
    <author>Checkstyle Development Team</author>
  </properties>

  <body>
    <section name="Header">
      <subsection name="Description">
        <p>
          Checks that a source file begins with a specified header. Property
          <code> headerFile</code> specifies a file that contains
          the required header.  Alternatively, the header specification can be
          set directly in the <code>header</code> property
          without the need for an external file.
        </p>

        <p>
          Property <code>ignoreLines</code> specifies the line
          numbers to ignore when matching lines in a header file. This
          property is very useful for supporting headers that contain
          copyright dates. For example, consider the following header:
        </p>

        <source>
line 1: ////////////////////////////////////////////////////////////////////
line 2: // checkstyle:
line 3: // Checks Java source code for adherence to a set of rules.
line 4: // Copyright (C) 2002  Oliver Burn
line 5: ////////////////////////////////////////////////////////////////////
        </source>

        <p>
          Since the year information will change over time, you can tell
          Checkstyle to ignore line 4 by setting property <code>ignoreLines</code> to <code> 4</code>.
        </p>
      </subsection>

      <subsection name="Properties">
        <table>
          <tr>
            <th>name</th>
            <th>description</th>
            <th>type</th>
            <th>default value</th>
          </tr>
          <tr>
            <td>headerFile</td>
            <td>name of the file containing the required header</td>
            <td><a href="property_types.html#string">string</a></td>
            <td><code>null</code></td>
          </tr>
          <tr>
            <td>charset</td>
            <td>character encoding to use when reading the headerFile</td>
            <td><a href="property_types.html#string">string</a></td>
            <td>the charset property of the parent
            <a href="config.html#Checker">Checker</a> module</td>
          </tr>
          <tr>
            <td>header</td>
            <td>
              the required header specified inline. Individual header lines
              must be separated by the string <code>&quot;\n&quot;</code> (even on platforms with a
              different line separator), see examples below.
            </td>
            <td><a href="property_types.html#string">string</a></td>
            <td><code>null</code></td>
          </tr>
          <tr>
            <td>ignoreLines</td>
            <td>line numbers to ignore</td>
            <td><a href="property_types.html#intSet">list of integers</a></td>
            <td><code>{}</code></td>
          </tr>
          <tr>
            <td>fileExtensions</td>
            <td>file type extension of files to process</td>
            <td><a href="property_types.html#stringSet">String Set</a></td>
            <td><code>{}</code></td>
          </tr>
        </table>
      </subsection>

      <subsection name="Example">
        <p>
          To configure the check to use header file <code>&quot;java.header&quot;</code> and ignore lines <code>2</code>, <code>3</code>, and <code> 4</code> and only process Java files:
        </p>

        <source>
&lt;module name=&quot;Header&quot;&gt;
    &lt;property name=&quot;headerFile&quot; value=&quot;java.header&quot;/&gt;
    &lt;property name=&quot;ignoreLines&quot; value=&quot;2, 3, 4&quot;/&gt;
    &lt;property name=&quot;fileExtensions&quot; value=&quot;java&quot;/&gt;
&lt;/module&gt;
        </source>

        <p>
          To configure the check to verify that each file starts with the
          header
        </p>
        <source>
// Copyright (C) 2004 MyCompany
// All rights reserved
        </source>

        <p>
          without the need for an external header file:
        </p>
        <source>
&lt;module name=&quot;Header&quot;&gt;
    &lt;property name=&quot;header&quot;
              value=&quot;// Copyright (C) 2004 MyCompany\n// All rights reserved&quot;/&gt;
&lt;/module&gt;
        </source>
      </subsection>

      <subsection name="Package">
        <p> com.puppycrawl.tools.checkstyle.checks.header </p>
      </subsection>

      <subsection name="Parent Module">
        <p>
          <a href="config.html#Checker">Checker</a>
        </p>
      </subsection>
    </section>

    <section name="RegexpHeader">
      <subsection name="Description">
        <p>
          Checks the header of a source file against a header that contains a
          <a
          href="http://java.sun.com/j2se/1.4.2/docs/api/java/util/regex/Pattern.html">regular
          expression</a> for each line of the source header.
        </p>

        <p>
          Rationale: In some projects <a href="#Header">checking against a
          fixed header</a> is not sufficient, e.g. the header might require a
          copyright line where the year information is not static.
        </p>

        <p>
          For example, consider the following header:
        </p>
        <source>
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: ^ \*/
        </source>

        <p>
          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).
        </p>

        <p>
          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):
        </p>
        <source>
line 1: ^#!
line 2: ^&lt;\?xml.*&gt;$
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*$
        </source>

        <p>
          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.
        </p>
      </subsection>

      <subsection name="Properties">
        <table>
          <tr>
            <th>name</th>
            <th>description</th>
            <th>type</th>
            <th>default value</th>
          </tr>
          <tr>
            <td>headerFile</td>
            <td>name of the file containing the required header</td>
            <td><a href="property_types.html#string">string</a></td>
            <td><code>null</code></td>
          </tr>
          <tr>
            <td>charset</td>
            <td>character encoding to use when reading the headerFile</td>
            <td><a href="property_types.html#string">string</a></td>
            <td>the charset property of the parent
            <a href="config.html#Checker">Checker</a> module</td>
          </tr>
          <tr>
            <td>header</td>
            <td>
              the required header specified inline. Individual header lines
              must be separated by the string <code>&quot;\n&quot;</code> (even on platforms with a
              different line separator), and regular expressions must not span
              multiple lines.
            </td>
            <td><a href="property_types.html#string">string</a></td>
            <td><code>null</code></td>
          </tr>
          <tr>
            <td>multiLines</td>
            <td>line numbers to repeat (zero or more times)</td>
            <td><a href="property_types.html#intSet">list of integers</a></td>
            <td><code>{}</code></td>
          </tr>
          <tr>
            <td>fileExtensions</td>
            <td>file type extension of files to process</td>
            <td><a href="property_types.html#stringSet">String Set</a></td>
            <td><code>{}</code></td>
          </tr>
        </table>
      </subsection>

      <subsection name="Example">
        <p>
          To configure the check to use header file <code>&quot;java.header&quot;</code> and <code>10</code> and <code>13</code> muli-lines:
        </p>
        <source>
&lt;module name=&quot;RegexpHeader&quot;&gt;
    &lt;property name=&quot;headerFile&quot; value=&quot;java.header&quot;/&gt;
    &lt;property name=&quot;multiLines&quot; value=&quot;10, 13&quot;/&gt;
&lt;/module&gt;
        </source>

        <p>
          To configure the check to verify that each file starts with the
          header
        </p>
        <source>
^// Copyright \(C\) (\d\d\d\d -)? 2004 MyCompany$
^// All rights reserved$
        </source>

        <p>
          without the need for an external header file:
        </p>
        <source>
&lt;module name=&quot;RegexpHeader&quot;&gt;
  &lt;property
    name=&quot;header&quot;
    value=&quot;^// Copyright \(C\) (\d\d\d\d -)? 2004 MyCompany$\n^// All rights reserved$&quot;/&gt;
&lt;/module&gt;
        </source>

        <p>
          <u>Note</u>: <code>ignoreLines</code> property has been
          removed from this check to simplify it.  To make some line optional
          use &quot;^.*$&quot; regexp for this line.
        </p>
      </subsection>

      <subsection name="Package">
        <p>
          com.puppycrawl.tools.checkstyle.checks.header
        </p>
      </subsection>

      <subsection name="Parent Module">
        <p>
          <a href="config.html#Checker">Checker</a>
        </p>
      </subsection>
    </section>
  </body>
</document>
