Let's learn in a few minutes how to write macros for this popular editor

JEdit

This fantastic editor, written in Java, is a wonderful choice for programmers in search of an ultra-flexible tool for source editing, its countless features include:

• syntax highlighting for hundreds of languages;
• has many plug-in targeted specifically at programmers;
• uses Java underneath (through the Beanshell) as scripting language;
• the search & replace function uses Java regular expressions and Beanshell, making it possible to do virtually any kind of editing.

Beanshell

Beanshell is a scripting engine based on an "augmented" Java syntax:

• type declarations are not mandatory;
• automatic set/get wrapping;
• can normally interact with host application's objects;
• can use external libraries as in any compiled Java program.

One minute tutorial

After having installed JEdit, let's proceed with our first script.

We will create a script that substitutes special XML charachters with their corresponding "entity references"; this operation is called escaping, and is necessary if we want to display those special characters in a web page, such as in code snippets. These are the translations we have to do (in order):

As you guessed this process can be cumbersome to do by hand, not to mention the risk of doing errors. So let's write a macro to handle it!

Fire up JEdit and copy'n'paste the code below in a new file:

JEditTextArea textArea = view.getTextArea();
String text = textArea.getText();
text = text.replaceAll("&", "&");
text = text.replaceAll("<", "&lt;");
text = text.replaceAll(">", "&gt;");
text = text.replaceAll("\"", "&quot;");
textArea.setText(text);

Things to note

• use of the public (and well documented) JEdit APIs: JEditTextArea classe is part of those;
• use of Java regular expressions, available since 1.4 version.

Under JEdit root directory we can find a sub-folder called "macros": save here your file, and call it EscapeXML.bsh, then click on top menu "Macros --> Rescan Macros". Our script will appear under the "Macros" sub-menu, ready to be used!

Let's try it on an XML file: copy'n'paste the code below in a new file:

<?xml version="1.0" encoding="ISO-8859-1"?>
<root>
  <elemento attributo="valore">
    Prova caratteri escape &lt; &gt; &amp; &quot;
  </elemento>
</root>

then click on "macros --> mymacros --> EscapeXML.bsh": et voilà, our xml source has been "escaped":

<?xml version="1.0" encoding="ISO-8859-1"?>
<root>
  <elemento attributo="valore">
    Prova caratteri escape < > & "
  </elemento>
</root>

The nice thing is that the snippets you see on this page have been escaped by this very script!

Implementing undo/redo

Sorry, you don't have to implement anything because JEdit does it for you...

Development

Obviously this script can be enhanced in many ways:

• performance: how can we handle very big files? (hint: escape line by line...)
• escape only selected text; beware that JEdit has many selection schemes: normal selection, rectangular selection, multiple...
• why not making a macro for Java strings escaping? There is a JakartaCommons plugin that makes Jakarta-Commons Lang (and other) library available for use by plug-ins and macros.