JJTree

Description

Invokes the JJTreepreprocessor for the JavaCC compiler compiler. It inserts parse tree building actions at various places in the JavaCC source that it generates. The output of JJTree is run through JavaCC to create the parser.

To use the jjtree task, set the target attribute to the name of the JJTree grammar file to process. You also need to specify the directory containing the JavaCC installation using the javacchome attribute, so that ant can find the JavaCC classes. Optionally, you can also set the outputdirectory to write the generated JavaCC grammar and node files to a specific directory. Otherwise jjtree writes the generated JavaCC grammar and node files to the directory containing the JJTree grammar file. As an extra option, you can also set the outputfile to write the generated JavaCC grammar file to a specific (directory and) file. Otherwise jjtree writes the generated JavaCC grammar file as the JJTree grammar file with a suffix .jj.

Introduction This is the initial version. Right now it provides only the folowing features: Adds a context menu to jj files Lets you configure the javacc home through the options panel. Downloading, installing, and running javacc and jjtree javacc - parser generator jjtree - parser generator and abstract tree builder Downloading the javacc/jjtree tools. Getting Started with JavaCC 2006-01-31 Jonas Lundberg Software Technology Group Institute of Mathematics and System Engineering, V¨xj¨ University a o (email: Jonas.Lundberg@msi.vxu.se) Abstract This short text is targeted to students that wants to start using JavaCC.

This task only invokes JJTree if the grammar file is newer than the generated JavaCC file.

Parameters

Example

This invokes JJTree on grammar file src/Parser.jjt, writing the generated grammar file, Parser.jj, file to build/src. The grammar option NODE_USES_PARSER is set to true when invoking JJTree.

Comparison output locations between command line JJTree and different Ant taskdef versions

*) Footnote: When running JJTree with the Ant taskdef jjtree the option -OUTPUT_DIRECTORY must always be set, because the project's basedir and the ant working directory might differ. So even if you don't specify the jjtree taskdef outputdirectory JJTree will be called with the -OUTPUT_DIRECTORY set to the project's basedirectory. But when the -OUTPUT_DIRECTORY is set, the -OUTPUT_FILE setting is handled as if relative to this -OUTPUT_DIRECTORY. Thus when the -OUTPUT_FILE is absolute or contains a drive letter we have a problem. Therefore absolute outputfiles (when the outputdirectory isn't specified) are made relative to the default directory. And for this reason outputfiles that contain a drive letter can't be supported.

By the way: specifying a drive letter in the -OUTPUT_FILE when the -OUTPUT_DIRECTORY is set, also results in strange behavior when running JJTree from the command line.

Source:Apache Ant

Eclipse as of today is the industry’s major non-Microsoft software tool platform. The number of companies adopting this platform is a testimonial of the platform’s success.

(Check my previous post for more on the history of Eclipse IDE)

Eclipse has a well-designed, and extensible architecture. What is valuable about Eclipse is that it provides an open source platform for creating an extensible integrated development environment. This platform allows anyone to build tools that integrate seamlessly with the environment and other tools.

The key to the seamless integration of tools with Eclipse is the plug-in. With the exception of a small run-time kernel, everything in Eclipse is a plug-in. This means that a plug-in you develop integrates with Eclipse in exactly the same way as other plug-ins.

Any new person who is introduced to Eclipse in concerned with one important question : How to Install Eclipse Plugins ?

There are lot of useful, high quality third party plugins available and all the plugin installation instructions specify at most 2 ways to install Eclipse Plugins

Normal Ways of Installing Eclipse Plugin

I will take the Eclipse Webtools Plugin to describe the 2 “normal” ways of installing Eclipse Plugins. In the next section I will show how the same can be done in a “easy” way.

This is how the Eclipse SDK folder structure looks like:

After extracting the Webtools package you have this folder hierarchy:

One of the common method of installing is to copy the contents of the “features” into the “features” folder of eclipse, and do the same with the “plugins” folder.

The other way of installing, which Eclipse also recommends is via the Update Manager.

You can choose the components you wish to install, choose the dependent plugins etc. In this process, generally you select the default installation location specified by the wizard.

The advantage with this approach is that when you select a component you are also made aware of the dependentplugins that needs to be installed. For e.g. If I select Web Tools, I am also told to select/install GEF

The disadvantage with this approach is that it never works well in a low bandwidth environment. I have struggled so many times to install via update manager, somewhere its gets stuck and I am left with a partially installed, corrupted environment.

The Easy Way

Now for the “Easy” way of installing Eclipse Plugins. Very few people are aware of this concept and Eclipse somehow doesn’t seem to document this approach anywhere.

This method uses the concept of “Links”. Here is the step by step procedure. (In the explanation I have used the installation of Webtools as the example)

1. Create a folder named links inside the eclipse folder (See Picture below)

2. Create a new file inside this folder and name it as say wtp.link. Note that the file name can be any valid string, but the extension has to be link.

3. Assuming that I have copied the Web tools into D:thirdparty as shown below,

the contents of wtp.link has to be this:

path=D:/thirdparty/wtp

Points to Note:

• The string should alwaysstart with “path=” keyword.
• The path should point to a directory which has a “eclipse” folder which in turn has “features” and “plugins” as sub-folders
• It is recommended to use forward slash ‘/’ in the path (If you want use Backslash, see that you use the escape character i.e. in Windows it should be “”)
• The file extension shouldend with “link“
• The file (i.e wtp.link in our example) should exist in the “links” folder.
• It is recommended to create linkfilesonly for big plugins/applications. For small plugins you can create just one link file, say misc.link and copy all the small plugins to the path referred by this link.

Restart Eclipse and now all the plugins and feature descriptions should be read from the path referred by the “link” files.

Advantages

Eclipse has a lot of top level and technology projects. To experiment with these projects, the “links” concept comes to the rescue. You can extract the plugin to a “thirdparty” (or a folder of your choice) and just link it within the eclipse installation. My current configuration looks like this:

Eclipse Projects/Third Party Plugins

Corresponding Link files

The “Copy” approach just bloats the eclipse installation and you cannot remove/uninstall the plugin easily. With links approach, you can just remove the “link” file and the plugin is uninstalled !!

The same links directory can be used in another eclipse installation. For e.g. if you are working with Milestone or different version of Eclipse, you can just copy the links folder (containing .link files) and the plugins are installed.

It is very easy to manage different versions of a plugin. If a new version doesn’t work, reverting back to a previous version is pretty easy.

Also, if you use the update feature in Eclipse, you can choose one of the above folders as the installation directory.

Conclusion

How To Install Javacc In Windows

This approach seems to work fine in both windows and linux. I am not sure why this approach is not documented in Eclipse. I found out about this when I was using the trial version of RAD (Rational Application Developer). It was used primarily to manage product extensions. I believe the same concept can be used to manage plugins (Install/Uninstall).

Using Dropins to install Eclipse plugins

One of the problems with the above “link” approach is the plugin dependency resolution. This has to be take care of manually by the plugin installer. If the install is done via the UI, it manage to find and install all the dependencies.

Staring from Eclipse 3.4, Eclipse SDK has a new provisioning system called Equinox/p2.

p2 supports the notion of watched directories and this directory a user or a script can drop “files”. Eclipse platform ships with one such default watched directory called dropins

The dropins folder is configured to be scanned during startup, and for changes to be immediately applied to the running system. Thus the dropins folder can be used much like the plugins directory was used in the past.

A subtle twist on old behavior here is that plug-ins and features added to the dropins folder are properly installed into the system rather than being forced in. This means p2 has an opportunity to confirm that the new plug-in doesn’t conflict with other installed plug-ins, and it can even go out and fetch any missing prerequisites of the newly dropped in plug-ins.

This also means you can later use the GUI to install extra functionality that depends on the plug-ins in the dropins folder, since p2 knows about them and can reason about their dependencies. In other words, new plug-ins installed via the dropins folder behave exactly like plug-ins installed via the user interface.

Supported dropin formats:

1. You can just drop the plugin jar in the dropins folder

2. You can also drop in the traditional Eclipse application or extension layout directly in the dropins folder

3. You can add an additional layer of folders immediately below the dropins folder that contain traditional Eclipse extensions

4. Or you can add link files as in the Eclipse links folder

Hope this post was useful, if you had any problems using this approach, do leave a comment with the problem description.

How To Install Javacc Eclipse

Thanks to Bryan Solan for the Dropins reference.

How To Install Javacc Plugin In Eclipse