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.
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.
Similar to regexp
type mappers this task needs a supporting regular expression
library and an implementation of
org.apache.tools.ant.util.regexp.Regexp. See details below.
| Attribute | Description | Required |
| file | file for which the regular expression should be replaced. | Yes if no nested <fileset> is used |
| match | The regular expression pattern to match in the file(s) | Yes, if no nested <regexp> is used |
| replace | The substitution pattern to place in the file(s) in place of the regular expression. | Yes, if no nested <substitution> is used |
| flags | The flags to use when matching the regular expression. For more
information, consult the Perl5 syntax g : Global replacement. Replace all occurences found i : Case Insensitive. Do not consider case in the match m : Multiline. Treat the string as multiple lines of input, using "^" and "$" as the start or end of any line, respectively, rather than start or end of string. s : Singleline. Treat the string as a single line of input, using "." to match any character, including a newline, which normally, it would not match. |
No |
| byline | Process the file(s) one line at a time, executing the replacement on one line at a time (true/false). This is useful if you want to only replace the first occurence of a regular expression on each line, which is not easy to do when processing the file as a whole. Defaults to false. | No |
| encoding | The encoding of the file. since Ant 1.6 | No - defaults to default JVM encoding |
<replaceregexp file="${src}/build.properties"
match="OldProperty=(.*)"
replace="NewProperty=\1"
byline="true"/>
replaces occurrences of the property name "OldProperty"
with "NewProperty" in a properties file, preserving the existing
value, in the file ${src}/build.properties
Ant comes with wrappers for the java.util.regex package of JDK 1.4, jakarta-regexp and jakarta-ORO, See installation dependencies concerning the supporting libraries.
The system property ant.regexp.regexpimpl governs which regular expression implementation will be chosen.
Possible values for this property are :
org.apache.tools.ant.util.regexp.Regexp.
If ant.regexp.regexpimpl is not defined, ant checks in the order Jdk14Regexp, JakartaOroRegexp,
JakartaRegexp for the availability of the corresponding library. The first of these 3 which is found will be used.
There are cross-platform issues for matches related to line terminator. For example if you use $ to anchor your regular expression on the end of a line the results might be very different depending on both your platform and the regular expression library you use. It is 'highly recommended' that you test your pattern on both Unix and Windows platforms before you rely on it.
This task supports a nested FileSet element.
This task supports a nested Regexp element to specify the regular expression. You can use this element to refer to a previously defined regular expression datatype instance.
<regexp id="id" pattern="alpha(.+)beta"/>
<regexp refid="id"/>
This task supports a nested Substitution element to specify the substitution pattern. You can use this element to refer to a previously defined substitution pattern datatype instance.
<substitution id="id" expression="beta\1alpha"/>
<substitution refid="id"/>
<replaceregexp byline="true"> <regexp pattern="OldProperty=(.*)"/> <substitution expression="NewProperty=\1"/> <fileset dir="."> <includes="*.properties"/> </fileset> </replaceregexp>
replaces occurrences of the property name "OldProperty"
with "NewProperty" in a properties file, preserving the existing
value, in all files ending in .properties in the current directory
<replaceregexp match="\s+" replace=" " flags="g" byline="true">
<fileset dir="${html.dir}" includes="**/*.html" />
</replaceregexp>
replaces all whitespaces (blanks, tabs, etc) by one blank remaining the line separator. So with input
would converted to<html> <body> <<TAB>><h1> T E S T </h1> <<TAB>> <<TAB>> </body></html>
<html> <body> <h1> T E S T </h1> </body></html>
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