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<title>ReplaceRegExp Task</title>
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<h2><a name="replaceregexp">ReplaceRegExp</a></h2>
<h3>Description</h3>
<p>ReplaceRegExp is a directory based task for replacing the
occurrence of a given regular expression with a substitution pattern
in a selected file or set of files.</p>
<p>The output file is only written if it differs from the existing
file. This prevents spurious rebuilds based on unchanged files which
have been regenerated by this task.</p>
<p>Similar to <a href="../CoreTypes/mapper.html#regexp-mapper">regexp
type mappers</a> this task needs a supporting regular expression
library and an implementation of
<code>org.apache.tools.ant.util.regexp.Regexp</code>.
See details in the documentation of the <a href="../CoreTypes/regexp.html#implementation">Regexp Type</a>. </p>
<h3>Parameters</h3>
<table border="1" cellpadding="2" cellspacing="0">
<tr>
<td valign="top"><b>Attribute</b></td>
<td valign="top"><b>Description</b></td>
<td align="center" valign="top"><b>Required</b></td>
</tr>
<tr>
<td valign="top">file</td>
<td valign="top">file for which the regular expression should be replaced.</td>
<td align="center">Yes if no nested <fileset> is used</td>
</tr>
<tr>
<td valign="top">match</td>
<td valign="top">The regular expression pattern to match in the file(s)</td>
<td align="center">Yes, if no nested <regexp> is used</td>
</tr>
<tr>
<td valign="top">replace</td>
<td valign="top">The substitution pattern to place in the file(s) in place
of the regular expression.</td>
<td align="center">Yes, if no nested <substitution> is used</td>
</tr>
<tr>
<td valign="top">flags</td>
<td valign="top">The flags to use when matching the regular expression. For more
information, consult the Perl5 syntax<br />
g : Global replacement. Replace all occurences found<br />
i : Case Insensitive. Do not consider case in the match<br />
m : Multiline. Treat the string as multiple lines of input, using "^" and "$" as the start or end of any line, respectively, rather than start or end of string.<br />
s : Singleline. Treat the string as a single line of input, using "." to match any character, including a newline, which normally, it would not match.<br />
</td>
<td valign="top" align="center">No</td>
</tr>
<tr>
<td valign="top">byline</td>
<td valign="top">Process the file(s) one line at a time, executing the replacement
on one line at a time (<i>true/false</i>). This is useful if you
want to only replace the first occurence of a regular expression on
each line, which is not easy to do when processing the file as a whole.
Defaults to <i>false</i>.</td>
<td valign="top" align="center">No</td>
</tr>
<tr>
<td valign="top">encoding</td>
<td valign="top">The encoding of the file. <em>since Ant 1.6</em></td>
<td align="center">No - defaults to default JVM encoding</td>
</tr>
</table>
<h3>Examples</h3>
<pre> <replaceregexp file="${src}/build.properties"
match="OldProperty=(.*)"
replace="NewProperty=\1"
byline="true"/>
</pre>
<p>replaces occurrences of the property name "OldProperty"
with "NewProperty" in a properties file, preserving the existing
value, in the file <code>${src}/build.properties</code></p>
<h3>Parameters specified as nested elements</h3>
<p>This task supports a nested <a href="../CoreTypes/fileset.html">FileSet</a>
element.</p>
<p>This task supports a nested <i><a href="../CoreTypes/regexp.html">Regexp</a></i> element to specify
the regular expression. You can use this element to refer to a previously
defined regular expression datatype instance.</p>
<blockquote>
<regexp id="id" pattern="alpha(.+)beta"/><br />
<regexp refid="id"/>
</blockquote>
<p>This task supports a nested <i>Substitution</i> element to specify
the substitution pattern. You can use this element to refer to a previously
defined substitution pattern datatype instance.</p>
<blockquote>
<substitution id="id" expression="beta\1alpha"/><br />
<substitution refid="id"/>
</blockquote>
<h3>Examples</h3>
<blockquote>
<pre>
<replaceregexp byline="true">
<regexp pattern="OldProperty=(.*)"/>
<substitution expression="NewProperty=\1"/>
<fileset dir=".">
<includes="*.properties"/>
</fileset>
</replaceregexp>
</pre></blockquote>
<p>replaces occurrences of the property name "OldProperty"
with "NewProperty" in a properties file, preserving the existing
value, in all files ending in <code>.properties</code> in the current directory</p>
<blockquote>
<pre><replaceregexp match="\s+" replace=" " flags="g" byline="true">
<fileset dir="${html.dir}" includes="**/*.html" />
</replaceregexp>
</pre></blockquote>
<p>replaces all whitespaces (blanks, tabs, etc) by one blank remaining the
line separator. So with input
<blockquote>
<pre>
<html> <body>
<<TAB>><h1> T E S T </h1> <<TAB>>
<<TAB>> </body></html>
</pre></blockquote>
would converted to
<pre>
<html> <body>
<h1> T E S T </h1> </body></html>
</pre>
</p>
<hr/>
<p align="center">Copyright © 2001-2004 The Apache Software Foundation. All rights
Reserved.</p>
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