This is a simple compiler for a small subset of the Java(tm) programming language. The supported language, Joos0, is the smallest of a hierarchy of Java 1.3 subsets. For more language details and an overview of the hierarchy, see [https://services.brics.dk/java/courseadmin/dOvs2012/pages/The+Joos+Languages].

The compiler emits Java bytecode in the Jasmin format. You'll need to install the Jasmin assembler to turn the emitted .j files into .class files. For more information on Jasmin, see http://jasmin.sourceforge.net/.

To build the compiler you'll also need to install the Menhir parser generator, see http://gallium.inria.fr/~fpottier/menhir/.

The compiler was developed as part of (a previous version of) the undergraduate compiler course at Aarhus University.

$ make

Example 1:

$ ./joos0 tests/IntegerToString.java 
[...]
$ jasmin tests/IntegerToString.j
$ java -classpath . IntegerToString
Enter a number: 42
In base 8 that is: 52

(hence the program tests/IntegerToString.java compiles with the Joos0 compiler, the output can be assembled with Jasmin, and the resulting output run on the JVM)

Example 2:

$ ./joos0 tests/Cons.java tests/ConsMain.java
[...]
$ jasmin tests/Cons.j tests/ConsMain.j
$ java -classpath . ConsMain
truefalse

(hence the compiler supports programs that span multiple files)

Example 3:

$ ./joos0 tests/ClassName2.java 
[...]
Error at tests/ClassName2.java: line 3, col 11
    public A() throws Exception { }

Constructor must have the same name as its enclosing class

(hence the program is properly rejected by the compiler with an error message)