BrainJVM is a simple Brainf*ck parser and compiler that generates java source code, as well as JVM byte code. The byte code assembler uses the Java 6 JavaCompiler libraries as part of a two stage compilation pipeline (Brainf*ck -> Java -> JVM byte code).

The package includes output writer classes allowing you to write the resulting compiled code to a file on disk, memory as a byte array, a StringBuffer instance or to STDOUT.

Below is an example compiling Brainf*ck to Java source and writing it to the console:

package com.mypackage;

import brainjvm.compiler.BrainfuckCompiler;
import brainjvm.utils.BrainfuckConsoleOutputWriter;

public class WriteJavaSource {

    public static void main(String[] args) {
        BrainfuckCompiler instance = new BrainfuckCompiler();
        BrainfuckConsoleOutputWriter writer = new BrainfuckConsoleOutputWriter();
        writer.setRaw(false);
        instance.setOutputWriter(writer);
        instance.compile("HelloWorld", "++++++++++[>+++++++>++++++++++>+++>+<<<<-]>++.\ 
>+.+++++++..+++.>++.<<+++++++++++++++.>.+++.------.--------.>+.>.");
    }

}

Here's an example compiling Brainf*ck to JVM byte code and writing it to a file:

package com.mypackage;

import brainjvm.assembler.BrainfuckAssembler;
import brainjvm.utils.BrainfuckFileOutputWriter;

public class WriteJVMByteCode {

    public static void main(String[] args) {
        BrainfuckFileOutputWriter writer = new BrainfuckFileOutputWriter("HelloWorld", "/tmp/");
        writer.setRaw(true);
        BrainfuckAssembler instance = new BrainfuckAssembler();
        instance.setOutputWriter(writer);
        instance.compile("HelloWorld", "++++++++++[>+++++++>++++++++++>+++>+<<<<-]>++.>+.\
+++++++..+++.>++.<<+++++++++++++++.>.+++.------.--------.>+.>.");
    }

}

I won't bother writing examples for every possible use case, you can just generate and read the javadoc for the project if you want to know more about the inner workings of the API.

I dunno, why not? I got interested in screwing around with Brainf*ck while writing brainf*ckjs and wanted to write a simple compiler instead of an interpreter.

Originally I was planning on writing the assembler using Apache BCEL, but after playing around with it for a while I realized I was going to end up ploughing way too many hours into the project and instead chose to use the JavaCompiler package included in Java 6. BCEL is pretty neat, you should definitely check it out, I doubt you'll end up assembling more efficient byte code than the javac compiler though.

If you want to see the actual byte code for the classes generated by brainjvm just use the javap cli utility included in the Java toolchain:

javap -c -private HelloWorld

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