Saturday, December 18, 2010

Integrating ABCL with Ant - the second step

While working to extend the ABCL integration into the ABCL-web Ant-based build - the project that I started in my previous post - I spent a lot of time trying to find a way to calculate the output paths, based on the names of the input paths.

Given the lisp way of 1-to-1 correspondence between a lisp file and a fasl, I expected this to be a trivial task to be done at the build system level. So, I kept searching for a solution in Ant (using standard components only). Surely I found the pathconvert and mapper building blocks, however, neither really seemed to work as the latter turned out not to be a generic mechanism but to be supported only by specific tasks (such as apply) and the former converts its output to a string instead of a set of paths.

Realizing that the issue of mapping source paths to output paths was left to the individual tasks, I turned to abcl to solve the problem as part of the compilation script. The final script between the CDATA tags as presented in the previous post looks like this:

(let* ((the-project (jcall "getProject" self))
       (src-iterator (jcall (jmethod "" "iterator")
                            (jcall "getReference" the-project "lisp-files")))
       (src-wildcard (pathname (format nil "~A**/*.lisp" (jcall "getProperty" the-project "build.src.dir"))))
       (dst-wildcard (pathname (format nil "~A**/*.abcl" (jcall "getProperty" the-project "build.dst.dir")))))
   (when (and (jcall "hasNext" src-iterator))
        for src-path = (pathname (jcall (jmethod "java.lang.Object" "toString")
                                 (jcall "next" src-iterator)))
        for dst-path = (translate-pathname src-path src-wildcard dst-wildcard)
        do (compile-file src-path :output-file dst-path)
        while (and (jcall "hasNext" src-iterator)))))

It's based on 2 properties having been defined: "build.src.dir" and "build.dst.dir". In addition, it wants a set of paths (fileset or path set) to be defined called "lisp-files". Iterating over the set of source files, it calculates the output file by replacing a path prefix and the file extension.

In my NetBeans project settings, I had to exclude "**/*.lisp" from packaging in the destination JAR file.

Now the JAR contains the fasl instead of the source file!

Do you have useful or resourceful ABCL based scripts plugged into Ant? Let me know and post a reaction.

Sunday, December 12, 2010

Integrating ABCL with Ant

While working with ABCL embedded in Java applications, you typically have java and lisp source files. Whenever I'm in that situaition, I find that I want to be able to build all sources from the same build mechanism.

Last week, Alex Mizrahi and I started to work on reviving ABCL-web (a project to create Java Servlets backed by Common Lisp code running in ABCL). That's when I found myself in need of a solution to this problem again: the project would greatly benefit from having a way to build lisp files for inclusion in the resulting JAR file.

Looking around, I found there are three options to achieve this goal:
  1. Create a custom Ant task
  2. Implement a command line switch to create fasls from the ABCL command line
  3. Use our JSR-223 support to write in-line Lisp in build files
While option (1) looked very attractive at first, it means one of two things: (1) adding an additional dependency for creation of our jar for distribution, or (2) creation of a separate jar file with only this task in it. In all cases, it adds a dependency to our release build. Because our current release build doesn't require Ant (you can build our release using the lisp-based build), I wasn't ready to accept this solution yet.

Option (2) looked very attractive, because it would not only integrate with Ant, but with build systems in general.  This option became less attractive when I found that the standard Ant project doesn't have any helpers for iterating sets. The thing that I had been thinking about was to implement the basics first, ie working the way gcc is used in most projects: 1 invocation per source file. So, in order to support the scheme that Ant does allow, the parameters ABCL would have to support became a lot more complex, needing to support file-sets to be compiled.

Then, I found the 'script' tag, which serves to integrate JSR-223 (Java scripting languages) into Ant build files. As we support JSR-223, I thought I'd give it a try! (So far I hadn't used it yet, I embed ABCL directly in my applications.) This solution -if it works out- is really great: no additional dependencies and no hacks [in our own build system, we feed the lisp that we want evaluated to ABCL through standard input.]

So, I gave it a try and within minutes, I was in business! I'm using a NetBeans generated project, so there's a "-post-compile" target which gets invoked after the "compile" target completes succesfully. 

<target name="-post-compile" description="lisp file compilation">
<script language="ABCL" classpath="lib/abcl.jar">
(let* ((the-project (jcall "getProject" self))
       (the-fileset (jcall "getReference" the-project "lisp-files"))
        (jcall (jmethod ""
   (loop while (jcall "hasNext" files-iterator)
        do (print (jcall "next" files-iterator))))

The snippet basically retrieves a path-set with the ID "lisp-files" defined elsewhere in the project file. Then, it continues to print all the (Java) objects it retrieves from the iterator. The next step is to replace the (print ...) form with a (compile-file ) form, retrieving the path string from the Path object and making a lisp pathname of it. Want to signal failed build? Just do what a real Task implementation would have done: throw a BuildException.

Concluding: while adding command line options may still be a desirable path to pursue, Ant integration is here for anybody embedding ABCL in a broader Java context.