Eclipse file replacement before compile (like a pre-processor)?

Question

So, given that Java has little to no support to unsigned types, I'm right now writing a small API to handle these (for now, I have UnsignedByte and UnsignedInt). The algorithm is simple: store each of them as their higher representation (byte->short, int->long), extends the Number class and implement some calculation and representation utility methods.

The problem is: it is actually very verbose - and boring - to have to, every time, code things like:

UnsignedByte value = new UnsignedByte(15);
UnsignedByte convert = new UnsignedByte(someIntValue);

I was wondering: is there any way to implement, on Eclipse, something like a "file pre-processor", in a way that it will automatically replace some pre-defined strings with other pre-defined strings before compiling the files? For example: replace U(x) with new UnsignedByte(x), so it would be possible to use:

UnsignedByte value = U(15);
UnsignedByte convert = U(someIntValue);

Yes, I could create a method called U(...) and use import static, but even then, it would be so much trouble doing it for every class that I would use my unsigned types.

I could write a simple Java program that would replace these expressions in a file, but the problem is: How could I integrate that on Eclipse, in a way that it would call/use it every time a Java file is compiled?

You might consider using Guava, which already has those libraries - and you don't need to represent an unsigned byte as a short, you can represent it with a signed byte if you do it properly. — Louis Wasserman, Nov 27 '15 at 14:59
While I have provided an answer, I don't think you are going to like it. Anyway you are in Java now, java is verbose and the tools are there to help. That said, it is a good idea to use a factories, so other than the overly shortened name "U" there may be good argument to using it like a factory. Anyway, Ctrl-Space is your friend! — Jonah Graham, Nov 27 '15 at 15:12

score 0 · Answer 1 · edited May 23 '17 at 12:15

0

I would recommend using Eclipse Templates for doing this instead. I know its not exactly what you ask for but its very simple and can be achieved out of the box.

When you write sysout in Eclipse and press Ctrl+Space it gives you an option to replace that with System.out.println();

You can find more information in the following link

How to add shortcut keys for java code in eclipse

edited May 23 '17 at 12:15

Community

1
1

answered Nov 27 '15 at 05:12

Akshay Gehi

362
1
12

I am going to save you two keystrokes... `syso` -> Ctrl+Space – Matt Clark Nov 27 '15 at 05:16
1

Well, maybe I'll use it as a last resort... but I'll still wait a little for a miraculous valid response. – João Vitor Verona Biazibetti Nov 27 '15 at 05:24
I am assuming you don't want to work on the precomplied java sources and want to work on the original one. If that's the case, it would be difficult to correlate your stack traces with your code. – Akshay Gehi Nov 28 '15 at 06:29

score 0 · Answer 2 · answered Nov 27 '15 at 09:54

I can point you at how one project I know of does this, they have a set of Python scripts that generate a whole set of classes (java files) from a template base file. They run the script manually, as opposed to part of the build.

Have a look here for the specific example. In this code they have a class for operating on double, but from this class they want to generate code to operate on float, int, etc all in the same way.

There is, of course, a big debate about whether generated code should be checked in or not to source repository. I leave that issue aside and hope that the above example is good to get you going.

Eclipse file replacement before compile (like a pre-processor)?

2 Answers2