string - Replacing characters in Ant property

Question

Is there a simple way of taking the value of a property and then copy it to another property with certain characters replaced?

Say propA=This is a value. I want to replace all the spaces in it into underscores, resulting in propB=This_is_a_value.

Answer 1

Here is the solution without scripting and no external jars like ant-conrib:

The trick is to use ANT's resources:

• There is one resource type called "propertyresource" which is like a source file, but provides an stream from the string value of this resource. So you can load it and use it in any task like "copy" that accepts files
• There is also the task "loadresource" that can load any resource to a property (e.g., a file), but this one could also load our propertyresource. This task allows for filtering the input by applying some token transformations. Finally the following will do what you want:

<loadresource property="propB">
  <propertyresource name="propA"/>
  <filterchain>
    <tokenfilter>
      <filetokenizer/>
      <replacestring from=" " to="_"/>
    </tokenfilter>
  </filterchain>
</loadresource>

This one will replace all " " in propA by "_" and place the result in propB. "filetokenizer" treats the whole input stream (our property) as one token and appies the string replacement on it.

You can do other fancy transformations using other tokenfilters: http://ant.apache.org/manual/Types/filterchain.html