/** Creates a copy of rules.pl and compiles it into Java sources. */
private void compileProlog(ObjectId prolog, File tempDir)
throws IOException, CompileException {
File tempRules = copyToTempFile(prolog, tempDir);
try {
Compiler comp = new Compiler();
comp.prologToJavaSource(tempRules.getPath(), tempDir.getPath());
} finally {
tempRules.delete();
}
}